Download - Rhino Viruses
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Genus Rhinoviruses
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RHINOVIRUSES
Rhinoviruses are the mostimportant cause of :
the common cold
and upper respiratoryinfection (URI).
> 100 serotypes have been
identified by: neutralization withspecific antisera.
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PICORNA VIRUSESPICORNA VIRUSESPICORNA VIRUSESPICORNA VIRUSESI. Genus enterovirusesI. Genus enteroviruses
II. Genus rhino > 100 antigenic typesII. Genus rhino > 100 antigenic types
III. Genus hepatovirus: Hepatitis A virusIII. Genus hepatovirus: Hepatitis A virus
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GenusGenusenterovirusesenteroviruses
Genus rhinoGenus rhino
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PICORNA VIRUSES
Small 20-30nm
Icosahedral symmetry
Non enveloped-Ether resistant
Single stranded positive sense RNA
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PICORNA VIRUSES
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Pathogenesis:
In contrast to enteroviruses, rhinoviruses are unable toreplicate in the gastrointestinal tract.
Rhinoviruses grow best at 33 C, which may partly account for
their predilection for the cooler environment of the nasalmucosa.
Most viral replication occurs in the nose, and the severity ofsymptoms correlates with the quantity (titer) of virus in
nasal secretions.
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Epidemiology:
Rhinoviruses can be transmitted by twomechanisms:aerosols
NOT THE MAJOR ROUTEandcontact: (DIRECT & INDIRECT)
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ContactDIRECT & INDIRECT
Hands appear to be the most important vehicle through either
1. Direct Contact i.e,Direct Person-to-person Contactshaking hands
NOTE: Rhinoviruses can be recovered from:
the hands of 40 to 90% of persons with coldsor
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ContactDIRECT & INDIRECT
Hands & un contained sneezing & coughing cancontaminate inanimate objects
2. Indirect contactcontaminated inanimate objects
Rhinoviruses can be recovered from:
16 to 15% of inanimate objectsaround them.
The virus can survive on these objects formany hours
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Epidemiology:
50% of rhinovirus infections are asymptomatic
i.e. Rhinoviruses produce clinical illness in only half those personsinfected.
Many asymptomatic individuals are capable of spreading thevirus even though they have lower viral titers.
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Clinical Syndromes:
URIs caused by rhinoviruses usually begin with sneezing, followed soon byrhinorrhea.
The rhinorrhea increases and is then accompanied by symptoms of nasalobstruction.
Mild sore throat occurs along
With
headache, malaise and the chills (rigors).
The illness peaks in three to four days or longer.
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Laboratory Diagnosis:
The clinical syndrome of the common cold isusually so characteristic that laboratorydiagnosis is unnecessary.
Rhinoviruses cause up to one half of URIs,DD: coronaviruses,
parainfluenza viruses,
and other agents allergic rhinitis
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LABORATORY
DIAGNOSISDirect detection of rhinovirus antigen
an ELISA has been developed for the detection of rhinovirus antigen in nasalwashings.
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Laboratory Diagnosis
Culture:
Nasal washing is the best clinical
specimen for recovering the virus.
Rhinoviruses grow ONLY IN in vitro on: Cells of primate origin,
Human diploid fibroblast cells
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LABORATORY
DIAGNOSISVirus isolation Rhinoviruses are best isolated in human embryo lung fibroblasts or
a sensitive continuous cell line such as HeLa.
Samples should be inoculated into triplicates and rolled at 33oC.
The virus CPE, which consists of the rounding of cells similar to that induced by enteroviruses should appearwithin 8 days of inoculation.The identity can be confirmed by acid lability tests. (pH3)
Direct detection of rhinovirus antigen
an ELISA has been developed for the detection of rhinovirus antigen in nasal washings.
Serology - virus neutralization tests remain the best method.ELISAs have been described.
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Serology:
Serologic testing to document rhinovirus infection is not practical.
virus neutralization tests remain the best method.
ELISAs have been described.
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Good luck