Rhino Viruses

8/14/2019 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

Rhino Viruses

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