enteroviruses. genera of picornaviruses enterovirus polio coxsackie a and b echo other enteroviruses...
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Enteroviruses
Genera of Picornaviruses
Enterovirus
Polio
Coxsackie A and B
Echo
Other enteroviruses
Diseases of the human (and other) alimentary tract
(e.g. polio virus)
Rhinovirus Disease of the nasopharyngeal region (e.g. common cold virus)
Cardiovirus Murine encephalomyocarditis, Theiler's murine encephalomyelitis virus
Aphthovirus Foot and mouth disease in cloven footed animals
Hepatovirus Human hepatitis virus A
Others Drosophila C virus, equine rhinoviruses, cricket paralysis virus
Categories of Enteroviruses
Viral meningitis, rash,ARD
4 types(68-71)Other Enteroviruses
Viral meningitis, with orchitis
32 typesEchioviruses
Viral meningitis, but no orchitis
6 types (B1-B6)Coxsackie B viruses
Viral meningitis plus, rash, ARD, myocarditis, orchitis
23 types ( A1-A22, A24)
Coxsackie A viruses
Asymptomatic infection, viral meningitis, paraalytic disease, poliomyelitis
3 typesPolioviruses
Clinical DiseasesSerotypesVirus
Properties of enterovirusesProperty EnterovirusesSize (nm)Capsid form PolypeptideRNA typeRNA molecular weightAcidOptimal temperature for growth(o
C)Density in caesium chloride (g/m)
22-30
Icosahedral VP1, VP2, VP3, VP4SS-PS2000,000-2600,000Stable*371.34*
Transmission
Fecal – oral route: poor hygiene, dirty diapers( especially in day-care settings) Ingestion via contaminated food and waterContact with infected hands Inhalation of infectious aerosols
Pathogenesis of enterovirus infection
Rhino,echo,coxsackie,polio
Replication in oropharynx
Primary viremia
Target Tissue Secondary viremia
Skin Muscle Brain Meninges Liver
Echo
Coxsackie
A
Echo
Coxsackie
A, B
Polio
Coxsackie
Echo
Polio
Coxsackie
Echo
Coxsackie
Pathogenicity(1)
ASYMPTOMATICAll enteroviruses PARALYSIS - permanent
Polio 1, 2, 3Coxsackie A7 PARALYSIS - temporaryCoxsackie B1-6MENINGITIS (aseptic)Echo, Coxsackie A and BPolio, Entero 71 ENCEPHALITISEntero 71Polio, Echo
Pathogenicity(2)RASH- macularMany enteroviruses- vesicular - (e.g. 'Hand Foot Mouth')Coxsackie ASUMMER FEBRILE ILLNESSMany enterovirusesVESICULAR PHARYNGITIS ('Herpangina')Coxsackie AMYOCARDITISCoxsackie B
Pathogenicity(3)EPIDEMIC MYALGIA ('Bornholm')Coxsackie BUPPER RESPIRATORY INFECTION (cold)Echo, Coxsackie APANCREATITISCoxsackie BGASTRO-ENTERITISMany enteroviusessCONJUNCTIVITIS (Haemorrhagic)Entero 70HEPATITISEntero 72 (hepatitis A virus)
Human diseases caused by enteroviruses
Polio Cox A Cox B Echo Other
Asymptomatic infection Yes Yes Yes Yes Yes
Meningitis( 脑膜炎 ) Yes Yes Yes Yes Yes
Paralysis( 麻痹 , 瘫痪 ) Yes Yes Yes Yes No
Febrile exanthems( 热疹) No Yes Yes Yes Yes
Acute respiratory disease No Yes Yes Yes Yes
Myocarditis( 心肌炎 ) No Yes Yes Yes No
Orchitis( 睾丸炎 No No Yes Yes No
ImmunityAntibody is the major protective immune response to the enteroviruses . Secretory antibody can prevent the initial establishment of infection in the oropharynx and gastrointestinal tract, and serum antibody prevents viremic spread to the target tissue and therefore disease.Cell-mediated immunity is not usually involved in protection but may play a role in pathogenesis.
Laboratory Diagnosis
Culture
Serology
Genome
PoliovirusPoliovirus
Important Characteristics
Important Characteristics
D or N antigen: Type specific (CFA)C or H antigen: Common antigen (CFA)Type 1-3
Pathogenesis
1. Source of infection: Apparent and subclinical patients
2. Incubation: 7-14 days3. Pathogenesis: Only much less than 0.1% su
bjects exposed to polio virus form the flaccid paralysis
Clinical Syndromes
Asymptomatic illness: 90%Abortive poliomyelitis, the minor illness: 5% infected peopleNonparalytic poliomyelitis or aseptic meningitis: 1%-2% of patients with poliovirus infections.Paralytic polio, the major illness: 0.1% to 2%of persons with poliovirus
Victims of paralytic polio
Child with polio sequelae
Paralyzed child in an iron lung
Iron lung ward in the 1950's
Franklin D. RooseveltBorn in 1882 at Hyde Park, New York--now a national historic site--he attended Harvard University and Columbia Law School. On St. Patrick's Day, 1905, he married Eleanor Roosevelt. Following the example of his fifth cousin, President Theodore Roosevelt, whom he greatly admired, Franklin D. Roosevelt entered public service through politics, but as a Democrat. He won election to the New York Senate in 1910. President Wilson appointed him Assistant Secretary of the Navy, and he was the Democratic nominee for Vice President in 1920. In the summer of 1921, when he was 39, disaster hit-he was stricken with poliomyelitis. Demonstrating indomitable courage, he fought to regain the use of his legs, particularly through swimming. At the 1924 Democratic Convention he dramatically appeared on crutches to nominate Alfred E. Smith as "the Happy Warrior." In 1928 Roosevelt became Governor of New York. He was elected President in November 1932, to the first of four terms.
Immunity
sIgA and neutralizing antibody (IgG, IgA, IgM) persist for life span
Lab DiagnosisDefinitive diagnosis is made by osolation of the virus from stool, CFS, oropharyngeal secretionsCell culture involves fibroblastic MRC-5 cellsCPE is usually evident within 36 hoursSerotyping is based on neutralization of CPE by standardized antisera using intersecting pool followed by specific sera.ELISAIFAneutralizing TestCFT
Prevention
Both oral polio vaccine( OPV live, attenuated , Sabin, 1957) and inactivated poliovirus vaccine(IPV , Salk, 1954) are avilable****IPV is used for adult immunization and Immunocopromised patients
Advantages and disadvantages of opv
AdvantagesEffectivenessLifelong immunity Induction of secretory antibody response similar to that of natural infectionPossibility of attenuated virus circulating in community by spread to contacts (indirect immunization)(herd immunity)Ease of administration Lack of need for repeated boostersDisadvantagesRisk of vaccine-associated poliomyelites in vaccine recipients or contactsSpread of vaccine to contacts without their consentUnsafe administration for immunodeficient patients
Advantages and disadvantages of IPV
AdvantagesEffectivenessGood stability during transport and in storage Safe administration in immunodeficient patientsNo risk of vaccine-related diseaseDisadvantagesLack of induction of local (gut) immunityNeed for booster vacine for lifelong immunityFact that injection is more painful than oral administrationFact that higher cominity immunization levels are needed than with live vaccine
Rep
ort
ed c
ases
per
100
000
po
pu
lati
on
100
10
1
0.1
0.001
0.01
1950 1960 1970 1980 1990
Inactivated (Salk) vaccine
Oral vaccine
Cases per 100,000 population United States
10000
1000
100
10
10
Rep
ort
ed c
ases
1950 1955 1960 1965 1970 1975
Killed (Salk) vaccine
Total casesSweden and Finland
Rec
ipro
cal v
irus
antib
ody
titer
512
128
32
8
2
1
Serum IgG
Serum IgG
Serum IgM Serum IgM
Nasal and duodenal IgA
Nasal IgASerum Ig
A
Serum IgA
Duodenal IgA
DaysVaccination Vaccination
48 4896 96
Killed (Salk) Vaccine
Live (Sabin) Vaccine
Coxsackie VirusCoxsackie Virus
Features of coxsackievirus infection in the labortory
Types Growth in MK Effect in cell culture sucking mice
Coxsackie A virus 1-24 a + ParalysisCoxsackie B virus 1-6 + Spasticity MK , monkey kidney a Coxsackievirus A23 now classified as echovirus 9
Features of coxsackievirus infection in man
Coxsackievirus A 1-24Asptic meningitis
Febrile illnessHerpangina 疱疹性咽峡炎
Hand-foot-and-mouth disease
Coxsackievirus B 1-6Neonatal disease
Myocarditis, hepatitisMeningitis
Disease AssociationsParalytic Disease - most commonly associated with polioviruses but other enteroviruses may also be responsible, notably enterovirus 71
Meningitis - caused by all groups of enteroviruses, most commonly seen in children under 5 years of age.
Encephalitis - focal or generalized encephalitis may accompany meningitis. Most patients recover completely with no neurological deficit.
Undifferentiated febrile illness - may be seen with all groups of enteroviruses.
Hand foot mouth disease - usually caused by group A coxsackieviruses although group B coxsackieviruses and other enteroviruses have been caused outbreaks.Herpangina 疱疹性咽峡炎 - caused by group A coxsackieviruses.
Epidemic Pleurodynia 胸膜痛 (Bornholm disease) - normally caused by group B coxsackieviruses.
Myocarditis - group B coxsackieviruses are the major cause of myocarditis, although it may be caused by other enteroviruses. It may present in neonates as part of neonatal infection and is often fatal. In adults, the disease is rarely fatal.Respiratory Infections - several enteroviruses are associated with the common cold.Rubelliform rashes - a rash disease resembling rubella may be seen with several coxsackie A, B, and echoviruses.Neonatal Infection - some coxsackie B viruses and echoviruses may cause infection in newborn infants. The virus is usually transmitted perinatally during the birth process and symptoms vary from a mild febrile illness to a severe fulminating multisystem disease and death.Conjunctivitis - associated with several types of enteroviruses, notably Coxsackie A24 and Enterovirus 70 (haemorrhagic conjunctivitis)Pancreatitis 胰腺炎 /Diabetes - associated with Coxsackie B virus infection. The extent of the role of the virus in diabetes is unknown.
Exanthems – Rubelliform rashes
- EV leading cause in summer & fall. All types of rash
Hand-foot-and-mouth disease
Hand-foot-and-mouth
disease: mostly coxackie A
fever, malaise, sore throat,
vesicles on bucal mucosa,
tongue, hands, feet, buttocks
highly infectious
resolution – 1w
Herpangina疱疹性咽峡炎
Herpangina – usually coxackie A
acute onset, fever, sore throat,
dysphagia
lesions – posterior pharynx
can persist w’s
no gingivitis
ECHO virusECHO virus
Important Characteristics
Not produce diseases in sucking mice, rabbits, or monkeys;Cause aseptic meningitis, infantile diarrhea, Monkey kidney and human embryonated kidney cell culture
Clinical syndromes associated with echoviruses
Main syndromesAseptic meningitisParalysisRashRespiratory diseaseOther featuresPericarditis 心包炎 and myocarditisNeonatal infection
Illness associated with recently identified enteroviruses
Enterovirus 68 Pneumonia and bronchiolitisEnterovirus 69
Isolated from an ill person in MexicoEnterovirus 70
Acute hameorrhagic conjunctivitisEnterovirus 70, 71
Paralysis, meningo-encephalitisEnterovirus 71 hand-foot-and-mouth diseaseEnterovirus 72 Hepatovirus( Hepatitis A)