review article pathogenesis and diagnostic approaches of...

Review ArticlePathogenesis and Diagnostic Approaches ofAvian Infectious Bronchitis

Faruku Bande12 Siti Suri Arshad1 Abdul Rahman Omar13 Mohd Hair Bejo13

Muhammad Salisu Abubakar1 and Yusuf Abba1

1Department of Veterinary Pathology and Microbiology Faculty of Veterinary Medicine Universiti Putra Malaysia (UPM)43400 Serdang Selangor Malaysia2Department of Veterinary Services Ministry of Animal Health and Fisheries Development PMB 2109 Usman Faruk SecretariatSokoto 840221 Sokoto State Nigeria3Laboratory of Vaccine and Immunotherapeutics Institute of Bioscience Universiti Putra Malaysia (UPM)43400 Serdang Selangor Malaysia

Correspondence should be addressed to Siti Suri Arshad suriupmedumy

Received 26 October 2015 Accepted 5 January 2016

Academic Editor Stefan Pohlmann

Copyright copy 2016 Faruku Bande et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Infectious bronchitis (IB) is one of the major economically important poultry diseases distributed worldwide It is caused byinfectious bronchitis virus (IBV) and affects both galliform and nongalliform birds Its economic impact includes decreased eggproduction and poor egg quality in layers stunted growth poor carcass weight and mortality in broiler chickens Althoughprimarily affecting the respiratory tract IBV demonstrates a wide range of tissues tropism including the renal and reproductivesystems Thus disease outcome may be influenced by the organ or tissue involved as well as pathotypes or strain of the infectingvirus Knowledge on the epidemiology of the prevalent IBV strains in a particular region is therefore important to guide control andpreventions Meanwhile previous diagnostic methods such as serology and virus isolations are less sensitive and time consumingrespectively current methods such as reverse transcription polymerase chain reaction (RT-PCR) Restriction Fragment LengthPolymorphism (RFLP) and sequencing offer highly sensitive rapid and accurate diagnostic results thus enabling the genotypingof new viral strains within the shortest possible time This review discusses aspects on pathogenesis and diagnostic methods forIBV infection

1 Introduction

Infectious bronchitis (IB) causes significant economic lossesto the poultry industry worldwide [1 2] The disease wasfirst identified in North Dakota USA when Schalk andHawn reported a new respiratory disease in young chickens[3] Since then IBV has been recognized widely especiallyin countries with large commercial poultry populationsApart from respiratory infections IB affects the kidney andreproductive tract causing renal dysfunction and decreasedegg production respectively Although the disease first wasbelieved to occur primarily in young chickens howeverchickens of all age are also susceptible [1]

2 Aetiology and Molecular Biology

Infectious bronchitis is caused by infectious bronchitis virus(IBV) a single stranded positive sense enveloped RNA virusof 27ndash32 kb length [4] The virus has been classified underthe Gammacoronavirus genus in the family Coronaviridaeorder Nidovirales Like othermembers of coronavirus familythe IBV genome is composed of structural and nonstruc-tural proteins Structural proteins include the spike [S]glycoprotein envelope [E] matrix [M] and nucleocapsid[N] These proteins together play different roles in viralattachment replication and inducing clinical disease Ofmajor structural proteins theMprotein is themost abundant

Hindawi Publishing CorporationAdvances in VirologyVolume 2016 Article ID 4621659 11 pageshttpdxdoiorg10115520164621659

2 Advances in Virology

transmembrane protein which play vital role in coronavirusassembly through interaction with viral ribonucleocapsidand spike glycoprotein [5 6] IBV E protein is howeverscant and contains highly hydrophobic transmembrane N-terminal and cytoplasmic C-terminal domains Studies haveshown that the E protein is localized to the Golgi complexin IBV infected cells and is integrally associated with viralenvelope formation assembly budding ion channel activityand apoptosis [7 8] Similar to other coronaviruses thephosphorylated 409 amino acid of IBV-N protein is highlyconserved between amino acid residues 238 and 293 [9]IBV-N protein binds with the genomic RNA to form ahelical ribonucleoprotein complex (RNP) thus aiding tran-scription replication translation and packaging of the viralgenome during replication [10] The S1 portion of the spikeglycoprotein plays important role in the attachment andentry of the virus into the cell via sialic acid receptors andhas been considered as the determinant for viral diversityand immune protection [11] This protein has been targetedfor genotypic characterization as well as recombinant IBVserotypes vaccines [6 12 13]

3 Pathogenesis

Infectious bronchitis virus infects primarily the respiratorysystem However some variants and several field isolatesaffect the reproductive renal and digestive systems of chick-ens Disease pathogenesis differs according to the systeminvolved as well as the strain of the virus [1]

31 Host Susceptibility Although domestic fowl (Gallus gal-lus) and pheasant (Phasianus spp) are considered to benatural hosts for IBV [14] other IBV-like coronaviruseshave been identified in nondomestic avian species includingpheasant peafowl turkey teal geese pigeon penguins quailduck and Amazon parrot [15ndash18] Antigenic similaritiesbetween turkey coronavirus (TCoV) and avian infectiousbronchitis virus (AIBV) have also been demonstrated [19]Antibodies to IBV have been demonstrated in humans withclose contact to poultry but the virus has not been reportedto cause human clinical disease [20]

32 Age and Breed Predisposition Chickens of all ages andbreed types are susceptible to IBV infection but the extentand severity of the disease is pronounced in young chickscompared to adults Similarly resistance to infection wassuggested to increase with increasing age [21] Experimentalevidence suggests that line Cwhite leghorn chickens aremoreresistant toM41 IBV challenge compared to line 151 althoughboth lines had similar virus shedding rate [22 23] perhapsinfluenced by genetic polymorphism in the chicken majorhistocompatibility complex (MHC) as observed betweenBlowast15 Blowast13 or Blowast21 chicken haplotypes [24]

33 Receptor and Entry The IBV receptor-binding domain(RBD) in the S1-spike plays a major role in attachment ofthe virus to host cells [25 26] Thus variation in the S1glycoprotein partly determines tissue tropism and virulence

[27 28] IBV affects trachea kidney and reproductive tractthrough interaction of S1 glycoproteins RBD (AAs 19ndash69in M41) with 120572-23-sialic acid receptors on the surface ofthe cells [29 30] In addition to the sialic acid receptorattenuated Baudette-IBV strain has been shown to interactwith a putative heparan sulfate- (HS-) binding site thatmight contribute to its wide host range [31] Following viralattachment conformational changes occurring in the S1glycoprotein mediate the membrane fusion activity of theS2 carboxylic acid terminal of the spike glycoprotein [1]Subsequently IBV enters the cell and releases its nucleocapsidinto the cellrsquos cytoplasm thus triggering replication virusbudding and release [32]

34 Infection and Transmission The virus is transmitted viathe respiratory secretions as well as faecal droplets frominfected poultry Contaminated objects and utensils mayaid transmission and spread of the virus from one flock toanother Evidence of virus was shown in trachea kidneyand Bursa of Fabricius 24 hrs following aerosol transmission[33] The nature of IBV persistence remains to be elucidatedhowever detection of the virus in the caecal tonsils (up to14 weeks) and from faeces (20 weeks) after infection mightsuggest a role of faecal shedding in viral transmission andpersistence [34]

35 Incubation Period Generally the short incubation periodfor IBV varies with infective dose and route of infection Forexample while infection via the tracheal route may take acourse as short as 18 hours ocular inoculation leads to anincubation period of 36 hours [33]

36 Clinical Course and Manifestations In the host initialinfection occurs at epithelia of Harderian gland trachealungs and air sacs The virus then moves to the kidneyand urogenital tract to establish systemic infection [3335] In this regard the severity and clinical features of IBdepend on the organ or system involved Infection of therespiratory systemmay result in clinical signs such as gaspingsneezing tracheal rales listlessness and nasal dischargesAffected birds appeared listless and dull with ruffled feathers(Figure 1) Other signs may include weight loss and huddlingof birds together under a common heat source [33]

Other clinical outcomes associated with IB infectioninclude frothy conjunctivitis profuse lacrimation oedemaand cellulitis of periorbital tissues Infected birds may alsoappear lethargic with evidence of dyspnoea and reluctance tomove [36] Nephropathogenic IBV strains aremost describedin broiler-type chickens Clinical signs include depressionwet droppings and excessive water intake Infection ofreproductive tract is associated with lesions of the oviductleading to decreased egg production and quality Eggs mayappearmisshapen rough-shelled or softwithwatery egg yolk(Figure 2) Unless effective measures are instituted declinein egg production does not return to normal laying thuscontributing to high economic loss [1 37]

37 Gross andHistopathology Pathological changes observedgrossly at necropsy include congestion and oedema of

Advances in Virology 3

Figure 1 Dullness exhibited in chickens infected following experi-mental infection with IBV (courtesy Siti Suri Arshad)

tracheal mucosa and extrapulmonary bronchi (Figure 3) [3839]

Histopathological changes include loss of cilia oedemarounding and sloughing of epithelial cells and infiltrationby lymphocytes (Figure 4) Presence of Russell bodies inHarderian cells has been observed following infection withH120 IBV serotype [40]

Nephropathogenic IBV strains cause nephritis charac-terized by swelling and congestion of the kidney (Figure 5)sometimes with pallor of ureters that contain urate depositsCoinfection with bacterial pathogens such as E coli maylead to a more complex outcome usually associated withhigh morbidity and mortality Similarly infection withnephropathogenic IBV strains may result in pale swollenand mottled kidneys [39 41] Histological findings includeinterstitial nephritis tubular degeneration and infiltrationby heterophils In some cases necrotic and dilated tubulesare filled with urates and casts [33] Experimental studieshave shown that IBV-T-strain causes necrosis of the proximalconvoluted tubule and distension of distal convoluted tubuleIn addition necrotic foci heterophils and lymphocytes areobserved in the interstitial spaces Oedema of Bowmanrsquoscapsule and granulocytic infiltration has been reported in thecollecting ducts and spheroids [42 43]

When the reproductive system is affected there may benonpatent and hypoglandular oviduct especially in severelyaffected chickens [43 44] Large accumulation of yolk fluidmay be seen in the abdominal cavity (Figure 6) often associ-ated with bacterial infection in laying hens [45 46] Cysticoviduct has also been observed in young layers followinginfection with certain IBV strains (Figure 7)

38 Morbidity andMortality Morbidity due to IBV infectioncan reach up to 100 Mortality rate may range from 25 to30 in young chicks but may increase to 80 as a resultof factors that are host-associated (age immune status)virus-associated (strain pathogenicity virulence and tissuetropism) or environmental (cold and heat stresses dust and

presence of ammonia) Secondary bacterial infections (Ecoli) or coinfection with immunosuppressive viruses such asMarekrsquos disease virus infectious bursal disease virus (IBDV)[33 47 48] may worsen the outcomes of IBV infectionGenerally nephropathogenic IBV strain causes high mortal-ity compared with strains infecting only the respiratory orreproductive systems [49]

4 Diagnosis

Conventional and more advanced methods have been usedfor the diagnosis of IBV infection The choice of one testover another is guided by type of sample availability of testmaterials and facilities test reporting time purpose of thetest and whether the test is carried out in the field or at thelaboratory Selected testing procedures are discussed below

41 Serology In the past serological assays such as virusneutralization (VN) and haemagglutination inhibition (HI)were used widely for detecting and serotyping IBV strainsThese tests also have been used to measure flock protectionfollowing vaccination [50 51] Serotype-specific antibodiesusually are detected using HI even though the HI test isless reliable [51] On the other hand ELISA assays are moresensitive and easily applied for field use and in monitor-ing antibody response following vaccination or exposureHowever emergence of different IBV serotypes that donot cross-react with commonly available antisera generallymade serological tests less applicable and nonconclusive inclassifying new or emerging IBV isolates [52 53]

42 Virus Isolation and Identification Virus isolation hasbeen the gold standard for the diagnosis of IBV [54 55]Taking samples during early onset of the disease and ensuringthe right sampling techniques are important keys for suc-cessful isolation of IBV To support successful virus isolationfrom swabs recommended to place swab sample in bufferedsolutions of media or PBS before transporting them to thelaboratory If tissue samples are to be collected recom-mended tissues are trachea kidney proventriculus tonsiland oviduct Tissue samples must be collected asepticallyfrom scarified chickens or immediately upon death placed insterile tightly sealed plastic specimen bags and transportedto the laboratory on ice for further processing [56] Thestringent technique requirements and factors such as thetime required for several passages of virus in egg or cellculture limit the use of virus isolation as a diagnostic methodof choice for IBV infection Notwithstanding different labo-ratories use various isolation methods as described below

421 Embryonated Chicken Egg Most IBV strains grow wellwhen inoculated into the allantoic cavity of a 9ndash11-day-oldchicken embryo Clinical samples from tracheal swab brothor tissue homogenate (10wv) are inoculated into the allan-toic cavity of specific pathogen-free eggs and incubated at34ndash37∘C after inoculation Eggs are candled daily to monitorembryo viability death within 24 hrs is considered nonspe-cific After 48ndash72 hrs allantoic fluid (AF) is harvested from


(a) (b)

Figure 2 Irregularity in the shape and sizes of eggs from natural IBV infected breeder chickens (a) Watery albumen from IBV infectedchicken ((b) left) compared to normal egg ((b) right)

(a) (b)

Figure 3 Gross lesions observed on respiratory organs of chicken naturally infected with IBV Presence of mucoid secretion congestion andhyperaemia in the trachea (a) mild focal areas of lung consolidation (b)

(a) (b)

Figure 4 Histopathological changes in the trachea of naturally IBV infected chicken Note the marked infiltration of lymphocytes withinthe epithelia (black arrow (b)) and evidence of mucosal secretions of goblet cells (yellow arrow (a))


Figure 5 Gross lesions in kidney of chicken following experimentalinfection with a nephropathogenic infectious bronchitis virus Noteswelling and congestion of the kidney (arrow) (courtesy Siti SuriArshad)

(a)

(d)

(c)(b)

(e)

Figure 6 Chicken showing natural IBV infection Accumulation ofegg yolk in abdominal cavity (a) slightly enlarged pale friable liver(b) and multiple petechial haemorrhages on the serosal surfaces ofproventriculus (c) gizzard (d) and small intestine (e)

representative eggs that were chilled overnight and testedfor the presence of IBV using serological tests or RT-PCRassay Sometimes the allantoic fluid needs to be subjectedto several passages to allow the virus to adapt and replicateto high titre thus increasing the period that is needed toobtain results The latter may vary among viral strains [54]After 5ndash7 days inoculated eggs are opened and observed forcharacteristic IB lesions such as curling and dwarfism of theinfected embryo (Figure 8) It is important to note that suchfindings are suggestive but not pathognomonic [57]

422 Cell Cultures Isolation of IBV has been attemptedin various primary and secondary cells such as chickenembryo kidney fibroblast and Vero cells respectively [58 59]Infected cultures are characterized by rounding developmentof syncytia and subsequent detachment from the surface ofthe plate [59] A major limitation of cell culture methods forIBV isolation is that not all strains of IBV are easily adaptedin cell culture Even for some cell culture adaptable IBV (M41Iowa 97 and NZ) strains growth of the virus often requiresprimary isolation in embryonated eggs and several passages

Figure 7 Cystic oviduct in 11-week-old chicken experimentallyinfected with a CR88 infectious bronchitis virus strain Note thedistention of the entire oviduct and fluid accumulation (arrow)

Figure 8 Embryo development at 17 days old following inoculationswith IBV-CR88 strain Note evidence of dwarfism and curling ofthe toes in IBV infected embryo (right) compared to a noninfectedcontrol embryo (left)

prior to adaptation In some cases attempts to grow IBV invarious cell lines either failed or resulted in very low viral titre[58]

423 Organ Cultures Tracheal organ culture (TOC) can beused to propagate both embryo-adapted and non-embryo-adapted IBV strains TOC is prepared from tracheal ringsof 20-day-old chicken embryo The tracheal rings are main-tained in a roller bottle and infected with IBV-suspectedsamplesThe culture is observedmicroscopically for evidenceof ciliostasis under light microscope Complete impairmentof ciliary activity usually is considered as a positive culture[60] Successful growth of IBV has been demonstrated inorgan cultures derived from kidney intestine proventriculusand oviduct However susceptibility of these organs to IBVcan be influenced by the strain of the virus and the amount ofvirus presence in the sample (infective dose) While a studysuggested the universality of using kidney bursa and proven-triculus in growing IBV a poor result was obtained when IBV


was propagated in cultures derived from different intestinalsegments [61] An advantage of this method includes easytitration and serotyping of IBV since no virus adaptationis required [62] Possible constraints include lack of affinityof some IBV strain for some organ cells and difficulty indifferentiating ciliostasis arising from other viruses such asNewcastle disease virus and avian adenovirus [33]

43 Electron Microscopy Electron microscopy provides adirect means of detecting and identifying IBV in biologicalsamples based on morphological characteristics of coron-avirus Positive cultures are confirmed based on the presenceof coronavirus-like pleomorphic structures with spike pro-jections following negative staining with phosphotungsticacid (Figure 9) Importantly the shape and diameter (120 nm)of the virus are taken into consideration when makingdiagnostic judgements Apart from the negative stainingmethod transmission electron microscopy (TEM) is alsoa useful tool which enables the visualization of virus-likeparticles in infected cells [59 63] However this method isoften applied to understand viral attachment and entry intothe cell but is not a specific diagnostic test [35]

44 Immunohistochemistry Immunoperoxidase and im-munofluorescenc are two important histochemistry methodsfor detection and confirmation of IBV antigen from infectedtissue andor cells These methods work based on antigen-antibody reactions [64 65] Immunoperoxidase methodssuch as the avidin-biotin complex (ABC) have been usedsuccessfully to localize IBV antigen in tissue samples [66]Likewise indirect immunofluorescent assay is the mostfrequently used fluorescent technique [66 67]

45 Molecular Diagnostic Assays In view of their increasedsensitivity and reduced reporting time molecular methodssuch as Reverse Transcriptase Polymerase Chain Reaction(RT-PCR) real-time PCR Restriction Fragment LengthPolymorphism (RFLP) and genome sequencing have nearlyreplaced conventional serology and virus cultivation meth-ods of IBV diagnosis [68 69]

451 RT-PCR Methods This approach uses viral RNAamplified either directly (one-step RT-PCR) or followingcDNA synthesis (two-step RT-PCR) An RT-PCR assay wasdesigned and introduced in 1991 for detecting the IBV-S2gene [70] Subsequently general and serotype-specific RT-PCR assays were designed to target different regions andorfragments (Figure 10) in the IBV viral genome [71ndash73] TheUTR and N-gene-based RT-PCR are used for universaldetection because of the conserved nature of the target regionin many IBV serotypes [68 71] A pan-coronavirus primertargeting a conserved region of different coronavirus isolatescould also be used in one-step RT-PCR amplification of IBVstrains [55] However amplification and sequencing of theS1 gene provide a reliable means for genotypic classificationof new IBV strains [74] A serotype-specific PCR assay hasbeen designed to enable differentiation of MassachusettsConnecticut Arkansas and Delaware field isolates [73]

Figure 9 Negative staining electron microscope showing sphericalshape of virus with typical spike projections (arrow) surroundingthe virion of avian infectious bronchitis virus (courtesy Siti SuriArshad)

(a) (b)

Figure 10 Electropherogram showing 17 kb RT-PCR amplifiedS1 genes from vaccine (H120) and virulent (M41) IBV strains (a)compared to a 320 bp RT-PCR amplified N-gene (b) of H120 andM41 IBV serotypes Lane M = 1 kb molecular ladder (a) and 100 bpladder (b) lane NC negative control (no template control)

452 Restriction Fragment Length Polymorphism (RFLP)This is an IBV genotyping method carried out to differentiatedifferent known strains of IBV and to identify new variantsfollowing RT-PCR amplification [75] Full-length sequenceof IBV S1 glycoprotein could be targeted for amplificationand enzymes analysis [72 76] RFLP allows differentiationof various known IBV strains based on their unique elec-trophoresis banding patterns defined by restriction enzymedigestion [72 77]The assay was found to be comparable withtraditional virus neutralization assay although some strainssuch as the Gray and JMK strains were reportedly difficult todifferentiate using arrays of restriction enzymes thus limitingthe universal application of this method [72]

453 Real-Time RT-PCR andOther Forms of PCRAssays Forincreased test sensitivity and specificity real-time RT-PCR


06256109 (Sweden)RF082010 (Russia)

L-1148 (Netherlands)L-1449T04 (Netherlands)FRL-1450L05 (France)FRL-1450T05 (France)

ITA902542005 (Italy)LaSP1708 (Spain)

LaSP11609 (Spain)UKAV215007 (UK)

K101903 (Korea)K127703 (Korea)

AF1934231 (China)SDLY0612 (serotype (H120) China)

THA80151 (Thailand)HNSG (China)

TX94a (China)TX94b (China)

THA001 (Thailand)MH536595 (Malaysia)

V904 (Malaysia)Ark52052 (USA)ArkC6dpv vaccinated S1 (USA)

Classical IBV

Variant IBV

Conn32062 (USA)ConnCvial2 (USA)

Florida 18288 (USA)M41 S1 (India)

EgyptF03 (Egypt)M41(S1) (USA)NV M41(S1) (USA)100

6198

99

002

99

95

74

64

3945824355

15

6551

34

80

100

100

100

83

100

100

100

100

100

Figure 11 Neighbour joining phylogenetic analysis based on nucleotide acid sequence of S1-spike gene of classical and variant IBV strainsidentified in different countries The tree was drawn with MEGA5 software using 1000 bootstrap replicates

assays [78 79] have been introduced for detecting IBV Apartfrom detection it is possible to quantify IBV viral load fromtissue andor clinical samples by real-time RT-PCR assaysbased on viral copy number or fold changes [80 81] Likewisedifferentiation of Massachusetts from non-Massachusetts ispossible by real-time RT-PCR assay targeting S1 glycoproteingene [79 82] Recently a high resolution melt curve analysis(HRM) was also developed to allow differentiation of fieldfrom vaccine IBV strains as well as for rapid and sensitivedetection of recombinant variants [83 84] Meir et al [85]reported that real-time RT-PCR was comparable to virusisolation and one or two times more sensitive in detectingM41 IBV than ordinary N-gene and S1 gene specific RT-PCRassays On the other hand real-time RT-PCR was tenfoldmore sensitive compared to virus isolation and 30- or 40-foldcompared to N-gene or S1 gene-based RT-PCR respectivelyThe authors however reported variations in sensitivity wheneither N-gene or S1 genes were targeted as well as whendifferent samples are used for viral amplificationOther formsof PCR methods used in detecting IBV include nested PCR[68] multiplex PCR [86] and reverse transcription loop-mediated isothermal amplification (RT-LAMP) [87] Whilethese methods are more sensitive than standard RT-PCRthey are more expensive as well and might be beyond thefinancial capacity of many producers

454 Sequence and Phylogenetic Analyses For genotypingS1 gene usually is amplified using RT-PCR sequenced andsubjected to bioinformatics analyses [88 89] Following S1gene sequencing isolates are characterized through bioinfor-matics analyses based on their phylogenetic relatedness withreference sequences available in sequence databases such asthe NCBI EMBL and DDBJ (Figure 11) Lack of methodstandardization among laboratories particularly with respectto the S1 gene segment length that is used in phylogeneticanalysis limits genotyping to some extent Currently molec-ularmethods such as next generation sequencing (NGS) havebeen introduced to sequence whole genomes within limitedperiods of time though this approach has been used only inthe laboratory

5 Differential Diagnosis

Several respiratory diseases such as Newcastle disease (ND)infectious laryngotracheitis infectious coryza avian metap-neumovirus (aMPV) and avian influenza (AI) may produceclinical signs similar to avian infectious bronchitis Howevercertain clinical features including neurological signs anddiarrhoea in ND high mortality in AI and pronounced headswelling in coryza are uncommon in IBV infection and thus


may be used in ruling out or arriving at narrowed tentativedifferential list [33 90]

6 Conclusion

Ever since the first identification of IBV in 1930s the poultryindustry has suffered a growing number of emerging IBVserotypes Importantly the newly evolved strains have beenfavoured by selection pressure mutation andor recombi-nations thus allowing them to avoid detection evade hostimmune response and cause diverse pathological outcomesLack of effective diagnostic methods and vaccines that couldeasily tackle the menace caused by multiple IBV serotypes ispartly blamed for the serious economic losses as results ofinfectious bronchitis disease Conventional detection assayssuch as virus neutralization and virus isolation have beenused extensively but due to lack of sensitivity and specificityof serological assays and laborious nature of virus isolationmethods these assays have gradually been replaced by thenew sensitive and specific assays such as RT-PCR RFLP andqRT-PCR that enable rapid genotyping and identification ofnew IBV strains However there is a need for standardizationacross laboratories with respect to the type and length oftarget gene to be considered for genotyping so as to ensurecommon understanding of genotype distributions in order toguide vaccine selection for prevention and control

Conflict of Interests

The authors declared no conflict of interests regarding thepresent paper

Authorsrsquo Contribution

Faruku Bande conceived the idea collected and studied pub-lished papers drafted the review paper and made all uncitedphotos from cases handled in his PhD work available SitiSuri Arshad Abdul Rahman Omar Mohd Hair Bejo YusufAbba and Muhammad Salisu Abubakar all participated inconceptualization of the idea study design review andediting of paper Siti Suri Arshad provided photos used inFigures 1 5 and 9 All authors have read and agreed withsubmission of final paper to the journal

Acknowledgments

The authors would like to thank the Universiti PutraMalaysia and Ministry of Science Technology and Inno-vation (MOSTI) Project no 02-01-04-SF1070 for fundingsupports Dennis F Lawler also provided paper-editing assis-tance

References

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[2] S S Arshad ldquoInfectious bronchitisrdquo in Diseases of Poultry inSouth East Asia M Zamri-Saad Ed pp 199ndash206 UniversitiPutra Malaysia Press Serdang Malaysia 2006

[3] A Schalk andMHawn ldquoAn apparently new respiratory diseaseof baby chicksrdquo Journal of the American Veterinary MedicalAssociation vol 78 pp 413ndash422 1931

[4] M M Lai and D Cavanagh ldquoThe molecular biology ofcoronavirusesrdquo Advances in Virus Research vol 48 pp 1ndash1001997

[5] CAM deHaanHVennema andP JM Rottier ldquoAssembly ofthe coronavirus envelope homotypic interactions between theM proteinsrdquo Journal of Virology vol 74 no 11 pp 4967ndash49782000

[6] F Bande S S Arshad M Hair Bejo H Moeini and AR Omar ldquoProgress and challenges toward the developmentof vaccines against avian infectious bronchitisrdquo Journal ofImmunology Research vol 2015 Article ID 424860 12 pages2015 1011552015424860

[7] E Corse and C E Machamer ldquoThe cytoplasmic tails ofinfectious bronchitis virus E and M proteins mediate theirinteractionrdquo Virology vol 312 no 1 pp 25ndash34 2003

[8] L Wilson P Gage and G Ewart ldquoHexamethylene amilorideblocks E protein ion channels and inhibits coronavirus replica-tionrdquo Virology vol 353 no 2 pp 294ndash306 2006

[9] A K Williams W Li L W Sneed and E W CollissonldquoComparative analyses of the nucleocapsid genes of severalstrains of infectious bronchitis virus and other coronavirusesrdquoVirus Research vol 25 no 3 pp 213ndash222 1992

[10] J Jayaram S Youn and E W Collisson ldquoThe virion N proteinof infectious bronchitis virus is more phosphorylated than theN protein from infected cell lysatesrdquoVirology vol 339 no 1 pp127ndash135 2005

[11] M W Jackwood D Hall and A Handel ldquoMolecular evolutionand emergence of avian gammacoronavirusesrdquo Infection Genet-ics and Evolution vol 12 no 6 pp 1305ndash1311 2012

[12] Z J Wei P Wei M L Mo M Li T C Wei and K RLi ldquoGenetic variation of S1 gene hypervariable region I ofinfectious bronchitis viruses isolated in different periods inGuangxirdquoChinese Journal of Virology vol 24 no 2 pp 126ndash1322008

[13] X-M Shi Y Zhao H-B Gao et al ldquoEvaluation of recombinantfowlpox virus expressing infectious bronchitis virus S1 geneand chicken interferon-7 gene for immune protection againstheterologous strainsrdquoVaccine vol 29 no 8 pp 1576ndash1582 2011

[14] D Cavanagh K Mawditt D D B Welchman P Brittonand R E Gough ldquoCoronaviruses from pheasants (Phasianuscolchicus) are genetically closely related to coronaviruses ofdomestic fowl (infectious bronchitis virus) and turkeysrdquo AvianPathology vol 31 no 1 pp 81ndash93 2002

[15] S Dea and P Tijssen ldquoDetection of turkey enteric coronavirusby enzyme-linked immunosorbent assay and differentiationfrom other coronavirusesrdquo American Journal of VeterinaryResearch vol 50 no 2 pp 226ndash231 1989

[16] C M Jonassen T Kofstad I-L Larsen et al ldquoMolecular iden-tification and characterization of novel coronaviruses infectinggraylag geese (Anser anser) feral pigeons (Columbia livia) andmallards (Anas platyrhynchos)rdquo Journal of General Virology vol86 no 6 pp 1597ndash1607 2005

[17] D Cavanagh ldquoCoronaviridae a review of coronaviruses andtorovirusesrdquo in Coronaviruses with Special Emphasis on FirstInsights Concerning SARS pp 1ndash54 Birkhauser Basel Switzer-land 2005

[18] E Circella A Camarda V Martella G Bruni A Lavazzaand C Buonavoglia ldquoCoronavirus associated with an enteric


syndrome on a quail farmrdquo Avian Pathology vol 36 no 3 pp251ndash258 2007

[19] J S Guy ldquoTurkey coronavirus is more closely related to avianinfectious bronchitis virus than to mammalian coronaviruses areviewrdquo Avian Pathology vol 29 no 3 pp 207ndash212 2000

[20] L T Miller and V J Yates ldquoNeutralization of infectious bron-chitis virus human serardquoAmerican Journal of Epidemiology vol88 no 3 pp 406ndash409 1968

[21] R A Crinion and M S Hofstad ldquoPathogenicity of fourserotypes of avian infectious bronchitis virus for the oviduct ofyoung chickens of various agesrdquo Avian Diseases vol 16 no 2pp 351ndash363 1972

[22] K Otsuki M Huggins and J K Cook ldquoComparison of thesusceptibility to avian infectious bronchitis virus infection oftwo inbred lines of white leghorn chickensrdquo Avian Pathologyvol 19 no 3 pp 467ndash475 1990

[23] N Bumstead ldquoGenetic resistance to avian virusesrdquo OIE RevueScientifique et Technique vol 17 no 1 pp 249ndash255 1998

[24] L D Bacon D B Hunter H M Zhang K Brand and REtches ldquoRetrospective evidence that the MHC (B haplotype) ofchickens influences genetic resistance to attenuated infectiousbronchitis vaccine strains in chickensrdquo Avian Pathology vol 33no 6 pp 605ndash609 2004

[25] G J Babcock D J Esshaki W D Thomas Jr and D MAmbrosino ldquoAmino acids 270 to 510 of the severe acuterespiratory syndrome coronavirus spike protein are required forinteraction with receptorrdquo Journal of Virology vol 78 no 9 pp4552ndash4560 2004

[26] N Promkuntod R E W van Eijndhoven G de VriezeA Grone and M H Verheije ldquoMapping of the receptor-binding domain and amino acids critical for attachment in thespike protein of avian coronavirus infectious bronchitis virusrdquoVirology vol 448 pp 26ndash32 2014

[27] R Casais B Dove D Cavanagh and P Britton ldquoRecombinantavian infectious bronchitis virus expressing a heterologousspike gene demonstrates that the spike protein is a determinantof cell tropismrdquo Journal of Virology vol 77 no 16 pp 9084ndash9089 2003

[28] D E Wentworth and K V Holmes Coronavirus Binding andEntry Coronaviruses Molecular and Cellular Biology CaisterAcademic Press Norfolk UK 2007

[29] CWinter C Schwegmann-Weszligels D Cavanagh U Neumannand G Herrler ldquoSialic acid is a receptor determinant forinfection of cells by avian infectious bronchitis virusrdquo Journalof General Virology vol 87 no 5 pp 1209ndash1216 2006

[30] K Shahwan M Hesse A-K Mork G Herrler and C WinterldquoSialic acid binding properties of soluble coronavirus spike (S1)proteins differences between infectious bronchitis virus andtransmissible gastroenteritis virusrdquo Viruses vol 5 no 8 pp1924ndash1933 2013

[31] I GMadu V C ChuH Lee A D Regan B E Bauman andGR Whittaker ldquoHeparan sulfate is a selective attachment factorfor the avian coronavirus infectious bronchitis virus BeaudetterdquoAvian Diseases vol 51 no 1 pp 45ndash51 2007

[32] V C Chu L J McElroy V Chu B E Bauman and G RWhittaker ldquoThe avian coronavirus infectious bronchitis virusundergoes direct low-pH-dependent fusion activation duringentry into host cellsrdquo Journal of Virology vol 80 no 7 pp 3180ndash3188 2006

[33] D Cavanagh and J Gelb ldquoInfectious bronchitisrdquo in Diseases ofPoultry pp 117ndash135 Wiley-Blackwell 12th edition 2008

[34] D J Alexander and R E Gough ldquoIsolation of avian infec-tious bronchitis virus from experimentally infected chickensrdquoResearch in Veterinary Science vol 23 no 3 pp 344ndash347 1977

[35] S Arshad K Al-Salihi and M Noordin ldquoUltrastructuralpathology of trachea in chicken experimentally infectedwith infectious bronchitis Virus-MH-536595rdquo Annals ofMicroscopy vol 3 pp 43ndash47 2002

[36] C Terregino A Toffan M Serena Beato et al ldquoPathogenicityof a QX strain of infectious bronchitis virus in specific pathogenfree and commercial broiler chickens and evaluation of pro-tection induced by a vaccination programme based on the Ma5and 491 serotypesrdquo Avian Pathology vol 37 no 5 pp 487ndash4932008

[37] R W Winterfield H L Thacker and S F Badylak ldquoEffects ofsubtype variations in the Holland strain of infectious bronchitisvirus when applied as a vaccinerdquo Poultry Science vol 63 no 2pp 246ndash250 1984

[38] D A Purcell and J B McFerran ldquoThe histopathology of infec-tious bronchitis in the domestic fowlrdquo Research in VeterinaryScience vol 13 no 2 pp 116ndash122 1972

[39] Z Boroomand K Asasi and A Mohammadi ldquoPathogenesisand tissue distribution of avian infectious bronchitis virusisolate IRFIBV32 (793B serotype) in experimentally infectedbroiler chickensrdquoThe Scientific World Journal vol 2012 ArticleID 402537 6 pages 2012

[40] H Toro V Godoy J Larenas E Reyes and E F KaletaldquoAvian infectious bronchitis viral persistence in the harderiangland andhistological changes after eyedrop vaccinationrdquoAvianDiseases vol 40 no 1 pp 114ndash120 1996

[41] F Cong X Liu Z Han Y Shao X Kong and S LiuldquoTranscriptome analysis of chicken kidney tissues followingcoronavirus avian infectious bronchitis virus infectionrdquo BMCGenomics vol 14 no 1 article 743 2013

[42] K K Chousalkar J R Roberts and R Reece ldquoHistopathologyof two serotypes of infectious bronchitis virus in laying hensvaccinated in the rearing phaserdquo Poultry Science vol 86 no 1pp 59ndash62 2007

[43] K K Chousalkar and J R Roberts ldquoUltrastructural studyof infectious bronchitis virus infection in infundibulum andmagnum of commercial laying hensrdquo Veterinary Microbiologyvol 122 no 3-4 pp 223ndash236 2007

[44] K K Chousalkar J R Roberts and R Reece ldquoComparativehistopathology of two serotypes of infectious bronchitis virus(T andN188) in laying hens and cockerelsrdquo Poultry Science vol86 no 1 pp 50ndash58 2007

[45] R W Winterfield and S B Hitchner ldquoEtiology of an infectiousnephritis-nephrosis syndrome of chickensrdquoAmerican Journal ofVeterinary Research vol 23 pp 1273ndash1279 1962

[46] J J de Wit J Nieuwenhuisen-van Wilgen A Hoogkamer Hvande Sande G J Zuidam and T H F Fabri ldquoInductionof cystic oviducts and protection against early challenge withinfectious bronchitis virus serotype D388 (genotype QX) bymaternally derived antibodies and by early vaccinationrdquo AvianPathology vol 40 no 5 pp 463ndash471 2011

[47] M P Ariaans M G R Matthijs D van Haarlem et al ldquoTherole of phagocytic cells in enhanced susceptibility of broilersto colibacillosis after infectious bronchitis virus infectionrdquoVeterinary Immunology and Immunopathology vol 123 no 3-4 pp 240ndash250 2008

[48] R A Gallardo V L van Santen andH Toro ldquoEffects of chickenanaemia virus and infectious bursal disease virus-induced


immunodeficiency on infectious bronchitis virus replicationand genotypic driftrdquoAvian Pathology vol 41 no 5 pp 451ndash4582012

[49] J Ignjatovic D F Ashton R Reece P Scott and P HooperldquoPathogenicity of Australian strains of avian infectious bronchi-tis virusrdquo Journal of Comparative Pathology vol 126 no 2-3 pp115ndash123 2002

[50] D King and D Cavanagh ldquoInfectious bronchitisrdquo Diseases ofPoultry vol 9 pp 471ndash484 1991

[51] OIE Avian Infectious Bronchitis chapter 2 3 2 2008[52] D Cavanagh P J Davis and J K Cook ldquoInfectious bronchitis

virus evidence for recombination within the Massachusettsserotyperdquo Avian Pathology vol 21 no 3 pp 401ndash408 1992

[53] A Kant G Koch D J Van Roozelaar J G Kusters F A JPoelwijk and B A M Van der Zeijst ldquoLocation of antigenicsites defined by neutralizing monoclonal antibodies on the S1avian infectious bronchitis virus glycopolypeptiderdquo Journal ofGeneral Virology vol 73 no 3 pp 591ndash596 1992

[54] F Beaudette and C Hudson ldquoCultivation of the virus of infec-tious bronchitisrdquo Journal of the American Veterinary MedicalAssociation vol 90 pp 51ndash60 1937

[55] C B Stephensen D B Casebolt and N N GangopadhyayldquoPhylogenetic analysis of a highly conserved region of thepolymerase gene from 11 coronaviruses and development of aconsensus polymerase chain reaction assayrdquoVirus Research vol60 no 2 pp 181ndash189 1999

[56] J Gelb Jr W A Nix and S D Gellman ldquoInfectious bronchitisvirus antibodies in tears and their relationship to immunityrdquoAvian Diseases vol 42 no 2 pp 364ndash374 1998

[57] L N Loomis C H Cunningham M L Gray and F ThorpJr ldquoPathology of the chicken embryo infected with infectiousbronchitis virusrdquo American Journal of Veterinary Research vol11 no 40 pp 245ndash251 1950

[58] K Otsuki H Yamamoto and M Tsubokura ldquoStudies onavian infectious bronchitis virus (IBV)mdashI Resistance of IBV tochemical and physical treatmentsrdquo Archives of Virology vol 60no 1 pp 25ndash32 1979

[59] S S Arshad A study on two malaysian isolates of infectiousbronchitis virus [PhD thesis] Universiti Pertanian Malaysia1993

[60] B V Jones and R M Hennion ldquoThe preparation of chickentracheal organ cultures for virus isolation propagation andtitrationrdquo Methods in Molecular Biology vol 454 pp 103ndash1072008

[61] P S Bhattacharjee and R C Jones ldquoSusceptibility of organcultures from chicken tissues for strains of infectious bronchitisvirus isolated from the intestinerdquo Avian Pathology vol 26 no3 pp 553ndash563 1997

[62] MArmesto S Evans D Cavanagh A-B Abu-Median S Keepand P Britton ldquoA recombinant Avian infectious bronchitis virusexpressing a heterologous spike gene belonging to the 491serotyperdquo PLoS ONE vol 6 no 8 Article ID e24352 2011

[63] S Patterson and R W Bingham ldquoElectron microscope obser-vations on the entry of avian infectious bronchitis virus intosusceptible cellsrdquoArchives of Virology vol 52 no 3 pp 191ndash2001976

[64] A Bezuidenhout S P Mondal and E L Buckles ldquoHistopatho-logical and immunohistochemical study of air sac lesionsinduced by two strains of infectious bronchitis virusrdquo Journalof Comparative Pathology vol 145 no 4 pp 319ndash326 2011

[65] S S Arshad and K A Al-Salihi ldquoImmunohistochemical detec-tion of infectious bronchitis virus antigen in chicken respiratoryand kidney tissuesrdquo inProceedings of the 12th Federation of AsianVeterinary Associations Congress14th Veterinary AssociationMalaysia Scientific Congress p 51 August 2002

[66] A S Abdel-Moneim P Zlotowski J Veits G M Keil andJ P Teifke ldquoImmunohistochemistry for detection of avianinfectious bronchitis virus strainM41 in the proventriculus andnervous system of experimentally infected chicken embryosrdquoVirology Journal vol 6 article 15 2009

[67] K Yagyu and S Ohta ldquoDetection of infectious bronchitisvirus antigen from experimentally infected chickens by indirectimmunofluorescent assay with monoclonal antibodyrdquo AvianDiseases vol 34 no 2 pp 246ndash252 1990

[68] A Adzhar K Shaw P Britton and D Cavanagh ldquoUniversaloligonucleotides for the detection of infectious bronchitis virusby the polymerase chain reactionrdquo Avian Pathology vol 25 no4 pp 817ndash836 1996

[69] A Adzhar R E Gough D Haydon K Shaw P Britton andD Cavanagh ldquoMolecular analysis of the 793B serotype ofinfectious bronchitis virus in Great Britainrdquo Avian Pathologyvol 26 no 3 pp 625ndash640 1997

[70] Z Lin A Kato Y Kudou K Umeda and S Ueda ldquoTyping ofrecent infectious bronchitis virus isolates causing nephritis inchickenrdquoArchives of Virology vol 120 no 1-2 pp 145ndash149 1991

[71] K A Zwaagstra B A M van der Zeijst and J G KustersldquoRapid detection and identification of avian infectious bronchi-tis virusrdquo Journal of Clinical Microbiology vol 30 no 1 pp 79ndash84 1992

[72] H M Kwon M W Jackwood and J Gelb Jr ldquoDifferentiationof infectious bronchitis virus serotypes using polymerase chainreaction and restriction fragment length polymorphism analy-sisrdquo Avian Diseases vol 37 no 1 pp 194ndash202 1993

[73] C L Keeler Jr K L Reed W A Nix and J Gelb Jr ldquoSerotypeidentification of avian infectious bronchitis virus by RT-PCR ofthe peplomer (S-1) generdquoAvian Diseases vol 42 no 2 pp 275ndash284 1998

[74] J G Zhu H D Qian Y L Zhang X G Hua and Z L WuldquoAnalysis of similarity of the S1 gene in infectious bronchitisvirus (IBV) isolates in Shanghai Chinardquo Archivos de MedicinaVeterinaria vol 39 no 3 pp 223ndash228 2007

[75] Z Lin A Kato Y Kudou and S Ueda ldquoA new typing methodfor the avian infectious bronchitis virus using polymerase chainreaction and restriction enzyme fragment length polymor-phismrdquo Archives of Virology vol 116 no 1ndash4 pp 19ndash31 1991

[76] K Mardani A H Noormohammadi J Ignatovic and G FBrowning ldquoTyping infectious bronchitis virus strains usingreverse transcription-polymerase chain reaction and restrictionfragment length polymorphism analysis to compare the 31015840 75 kbof their genomesrdquo Avian Pathology vol 35 no 1 pp 63ndash692006

[77] M D F S Montassier L Brentano H J Montassier and L JRichtzenhain ldquoGenetic grouping of avian infectious bronchitisvirus isolated in Brazil based on RT-PCRRFLP analysis of theS1 generdquo Pesquisa Veterinaria Brasileira vol 28 no 3 pp 190ndash194 2008

[78] K K Chousalkar B F Cheetham and J R Roberts ldquoLNAprobe-based real-time RT-PCR for the detection of infectiousbronchitis virus from the oviduct of unvaccinated and vacci-nated laying hensrdquo Journal of Virological Methods vol 155 no1 pp 67ndash71 2009


[79] A M Acevedo C L Perera A Vega et al ldquoA duplexSYBR Green I-based real-time RT-PCR assay for the simul-taneous detection and differentiation of Massachusetts andnon-Massachusetts serotypes of infectious bronchitis virusrdquoMolecular and Cellular Probes vol 27 no 5-6 pp 184ndash192 2013

[80] M W Jackwood D A Hilt and S A Callison ldquoDetection ofinfectious bronchitis virus by real-time reverse transcriptase-polymerase chain reaction and identification of a quasispeciesin the Beaudette strainrdquo Avian Diseases vol 47 no 3 pp 718ndash724 2003

[81] S A Callison D A Hilt T O Boynton et al ldquoDevelopmentand evaluation of a real-time Taqman RT-PCR assay for thedetection of infectious bronchitis virus from infected chickensrdquoJournal of Virological Methods vol 138 no 1-2 pp 60ndash65 2006

[82] R M Jones R J Ellis W J Cox et al ldquoDevelopment andvalidation of RT-PCR tests for the detection and S1 genotypingof infectious bronchitis virus and other closely related gam-macoronaviruses within clinical samplesrdquo Transboundary andEmerging Diseases vol 58 no 5 pp 411ndash420 2011

[83] K Hewson A H Noormohammadi J M Devlin K Mar-dani and J Ignjatovic ldquoRapid detection and non-subjectivecharacterisation of infectious bronchitis virus isolates usinghigh-resolutionmelt curve analysis and amathematical modelrdquoArchives of Virology vol 154 no 4 pp 649ndash660 2009

[84] K A Hewson G F Browning J M Devlin J Ignjatovic andA H Noormohammadi ldquoApplication of high-resolution meltcurve analysis for classification of infectious bronchitis virusesin field specimensrdquo Australian Veterinary Journal vol 88 no10 pp 408ndash413 2010

[85] R Meir O Maharat Y Farnushi and L Simanov ldquoDevelop-ment of a real-time TaqMan RT-PCR assay for the detectionof infectious bronchitis virus in chickens and comparison ofRT-PCR and virus isolationrdquo Journal of VirologicalMethods vol163 no 2 pp 190ndash194 2010

[86] H-W Chen and C-H Wang ldquoA multiplex reversetranscriptase-PCR assay for the genotyping of avian infectiousbronchitis virusesrdquo Avian Diseases vol 54 no 1 pp 104ndash1082010

[87] H-T Chen J Zhang Y-P Ma et al ldquoReverse transcriptionloop-mediated isothermal amplification for the rapid detectionof infectious bronchitis virus in infected chicken tissuesrdquoMolecular and Cellular Probes vol 24 no 2 pp 104ndash106 2010

[88] Z M Zulperi A R Omar and S S Arshad ldquoSequence andphylogenetic analysis of S1 S2 M and N genes of infectiousbronchitis virus isolates fromMalaysiardquoVirus Genes vol 38 no3 pp 383ndash391 2009

[89] S H Abro L H M Renstrom K Ullman et al ldquoEmergenceof novel strains of avian infectious bronchitis virus in SwedenrdquoVeterinary Microbiology vol 155 no 2ndash4 pp 237ndash246 2012

[90] R Droual and PWoolcock ldquoSwollen head syndrome associatedwith E coli and infectious bronchitis virus in the Central Valleyof CaliforniardquoAvian Pathology vol 23 no 4 pp 733ndash742 1994

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


transmembrane protein which play vital role in coronavirusassembly through interaction with viral ribonucleocapsidand spike glycoprotein [5 6] IBV E protein is howeverscant and contains highly hydrophobic transmembrane N-terminal and cytoplasmic C-terminal domains Studies haveshown that the E protein is localized to the Golgi complexin IBV infected cells and is integrally associated with viralenvelope formation assembly budding ion channel activityand apoptosis [7 8] Similar to other coronaviruses thephosphorylated 409 amino acid of IBV-N protein is highlyconserved between amino acid residues 238 and 293 [9]IBV-N protein binds with the genomic RNA to form ahelical ribonucleoprotein complex (RNP) thus aiding tran-scription replication translation and packaging of the viralgenome during replication [10] The S1 portion of the spikeglycoprotein plays important role in the attachment andentry of the virus into the cell via sialic acid receptors andhas been considered as the determinant for viral diversityand immune protection [11] This protein has been targetedfor genotypic characterization as well as recombinant IBVserotypes vaccines [6 12 13]

3 Pathogenesis

Infectious bronchitis virus infects primarily the respiratorysystem However some variants and several field isolatesaffect the reproductive renal and digestive systems of chick-ens Disease pathogenesis differs according to the systeminvolved as well as the strain of the virus [1]

31 Host Susceptibility Although domestic fowl (Gallus gal-lus) and pheasant (Phasianus spp) are considered to benatural hosts for IBV [14] other IBV-like coronaviruseshave been identified in nondomestic avian species includingpheasant peafowl turkey teal geese pigeon penguins quailduck and Amazon parrot [15ndash18] Antigenic similaritiesbetween turkey coronavirus (TCoV) and avian infectiousbronchitis virus (AIBV) have also been demonstrated [19]Antibodies to IBV have been demonstrated in humans withclose contact to poultry but the virus has not been reportedto cause human clinical disease [20]

32 Age and Breed Predisposition Chickens of all ages andbreed types are susceptible to IBV infection but the extentand severity of the disease is pronounced in young chickscompared to adults Similarly resistance to infection wassuggested to increase with increasing age [21] Experimentalevidence suggests that line Cwhite leghorn chickens aremoreresistant toM41 IBV challenge compared to line 151 althoughboth lines had similar virus shedding rate [22 23] perhapsinfluenced by genetic polymorphism in the chicken majorhistocompatibility complex (MHC) as observed betweenBlowast15 Blowast13 or Blowast21 chicken haplotypes [24]

33 Receptor and Entry The IBV receptor-binding domain(RBD) in the S1-spike plays a major role in attachment ofthe virus to host cells [25 26] Thus variation in the S1glycoprotein partly determines tissue tropism and virulence

[27 28] IBV affects trachea kidney and reproductive tractthrough interaction of S1 glycoproteins RBD (AAs 19ndash69in M41) with 120572-23-sialic acid receptors on the surface ofthe cells [29 30] In addition to the sialic acid receptorattenuated Baudette-IBV strain has been shown to interactwith a putative heparan sulfate- (HS-) binding site thatmight contribute to its wide host range [31] Following viralattachment conformational changes occurring in the S1glycoprotein mediate the membrane fusion activity of theS2 carboxylic acid terminal of the spike glycoprotein [1]Subsequently IBV enters the cell and releases its nucleocapsidinto the cellrsquos cytoplasm thus triggering replication virusbudding and release [32]

34 Infection and Transmission The virus is transmitted viathe respiratory secretions as well as faecal droplets frominfected poultry Contaminated objects and utensils mayaid transmission and spread of the virus from one flock toanother Evidence of virus was shown in trachea kidneyand Bursa of Fabricius 24 hrs following aerosol transmission[33] The nature of IBV persistence remains to be elucidatedhowever detection of the virus in the caecal tonsils (up to14 weeks) and from faeces (20 weeks) after infection mightsuggest a role of faecal shedding in viral transmission andpersistence [34]

35 Incubation Period Generally the short incubation periodfor IBV varies with infective dose and route of infection Forexample while infection via the tracheal route may take acourse as short as 18 hours ocular inoculation leads to anincubation period of 36 hours [33]

36 Clinical Course and Manifestations In the host initialinfection occurs at epithelia of Harderian gland trachealungs and air sacs The virus then moves to the kidneyand urogenital tract to establish systemic infection [3335] In this regard the severity and clinical features of IBdepend on the organ or system involved Infection of therespiratory systemmay result in clinical signs such as gaspingsneezing tracheal rales listlessness and nasal dischargesAffected birds appeared listless and dull with ruffled feathers(Figure 1) Other signs may include weight loss and huddlingof birds together under a common heat source [33]

Other clinical outcomes associated with IB infectioninclude frothy conjunctivitis profuse lacrimation oedemaand cellulitis of periorbital tissues Infected birds may alsoappear lethargic with evidence of dyspnoea and reluctance tomove [36] Nephropathogenic IBV strains aremost describedin broiler-type chickens Clinical signs include depressionwet droppings and excessive water intake Infection ofreproductive tract is associated with lesions of the oviductleading to decreased egg production and quality Eggs mayappearmisshapen rough-shelled or softwithwatery egg yolk(Figure 2) Unless effective measures are instituted declinein egg production does not return to normal laying thuscontributing to high economic loss [1 37]

37 Gross andHistopathology Pathological changes observedgrossly at necropsy include congestion and oedema of









4 Diagnosis






(a) (b)


(a) (b)


(a) (b)




(a)

(d)

(c)(b)

(e)















(a) (b)















Classical IBV

Variant IBV




6198

99

002

99

95

74

64

3945824355

15

6551

34

80

100

100

100

83

100

100

100

100

100








6 Conclusion






Acknowledgments


References







































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology









4 Diagnosis






(a) (b)


(a) (b)


(a) (b)




(a)

(d)

(c)(b)

(e)















(a) (b)















Classical IBV

Variant IBV




6198

99

002

99

95

74

64

3945824355

15

6551

34

80

100

100

100

83

100

100

100

100

100








6 Conclusion






Acknowledgments


References







































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


(a) (b)


(a) (b)


(a) (b)




(a)

(d)

(c)(b)

(e)















(a) (b)















Classical IBV

Variant IBV




6198

99

002

99

95

74

64

3945824355

15

6551

34

80

100

100

100

83

100

100

100

100

100








6 Conclusion






Acknowledgments


References







































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology



(a)

(d)

(c)(b)

(e)















(a) (b)















Classical IBV

Variant IBV




6198

99

002

99

95

74

64

3945824355

15

6551

34

80

100

100

100

83

100

100

100

100

100








6 Conclusion






Acknowledgments


References







































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








(a) (b)















Classical IBV

Variant IBV




6198

99

002

99

95

74

64

3945824355

15

6551

34

80

100

100

100

83

100

100

100

100

100








6 Conclusion






Acknowledgments


References







































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology












Classical IBV

Variant IBV




6198

99

002

99

95

74

64

3945824355

15

6551

34

80

100

100

100

83

100

100

100

100

100








6 Conclusion






Acknowledgments


References







































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology



6 Conclusion






Acknowledgments


References







































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology





















































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

review article pathogenesis and diagnostic approaches of...

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