Term
| Double stranded RNA viruses (Baltimore Class III):reoviridae |
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Definition
Rotavirus- Naked nucleocapsids with two icosahedral capsid shellUpon ingestion of the virus, the outer shell is digested via proteolytic cleavage and releases the infectious sub-viral particle (ISVP) that contains only one capsid. The virus seems to be able to penetrate into the cytoplasm though the cytoplasmic membrane. Contains at least 10 segments of dsRNA, each coding for a different gene.Causes disease in infants.
Fecal-oral transmission. Major cause of gastroenteritis in infants under age 3 in this country. Major cause of death in infants in many developing countries. A live tetravalent attenuated oral vaccine (rotashield) was approved in 1998.
Orbivirus- arbovirus spread by ticks causes a viremia and then infects erythrocyte precursors.
Orthoreovirus- cause a mild cold like illness or gastrointestinal disease. |
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Term
| features of Baltimore Virus Groups III, IV, and V |
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Definition
• Generally replicate in the cytoplasm of infected cells and do not integrate with host genetic material.
• Their genetic material replicates by synthesis of complementary RNA, and DNA is not involved.
• Their genomes code for enzymes, known as RNA-dependent RNA polymerases, which catalyze the replication of their genetic material, and production of viral messenger RNA.
• These viruses show a high mutation frequency, partly because of a lack of the proofreading enzymes that assure fidelity of DNA replication. (DNA mutation rate is as low as 10-8 to 10-11/nucleotide; RNA mutation rate is between 10-3 and 10-4/nucleotide.) |
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Term
| Positive strand ssRNA viruses- Baltimore Class IV, RNA alone is infectious. It acts as messenger RNA: |
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Definition
Picornaviridae (small RNA viruses)
-Enteroviruses, Poliovirus,ECHO viruses,Enterovirus 70,Enterovirus 71,Coxsackie viruses A and B, Hepatitis A Virus, Rhinovirus
Caliciviridae
-Norwalk Virus (Norovirus), Hepatitis E virus
Togaviridae
-Arboviruses,Rubiviruses
Flaviviridae
-Arboviruses,West Nile Virus, Dengue Fever,Hepatitis C virus (HCV) (also a flavivirus)
Coronaviridae
-SARS, |
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Term
| Negative Strand (-) ssRNA viruses (Baltimore Class V) |
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Definition
Orthomyxoviridae (influenzaviridae), Paramyxoviradae
-Parainfluenza viruses, measles(rubeola), mumps
Rhabdoviridae (Rhabdo-rod)
-rabies virus
Filoviridae (filum-thread)
-Marburg virus, ebola virus
Bunyaviridae
-Arboviruses, Hantaviruses
Arenaviridae (arenosus-sandy)
-Lassa virus, Lymphocytic choriomeningitis (LCM) |
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Term
| Retroviridae (RNA Viruses that replicate with a DNA intermediate.) Baltimore Class VI |
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Definition
Oncornavirinae (Oncovirinae)
-Human T-Cell Lymphotropic Viruses (HTLV Viruses)
Lentivirinae
-HIV |
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Term
| features of Baltimore Virus Group VI |
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Definition
• Enveloped virus particles with a capsid containing two identical copies of +SSRNA per virus particle. Also contain some tRNA needed as a primer for transcription and reverse transcriptase (RT)
• Makes a DNA intermediate for replication using reverse transcriptase
• The double stranded DNA intermediate circularizes and integrates into a host chromosome. There is 500 to 1000 highly preferred sites.
• In that location, the viral DNA is transcribed to form viral RNA
• Reverse Transcriptase is even more error-prone than the other viral RNA enzymes. It lacks an editing function. |
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