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33 Cards in this Set
- Front
- Back
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What is single-stranded RNA?
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Ribonucleic acid that has 1 strand of nucleic acid.
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What are two classifications of ssRNA?
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Positive ssRNA
Negative ssRNA |
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What is positive ssRNA
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Positive ssRNA is a form fo RNA which can be translated into proteins using host cell machinery, thus being directly infectious
Similar to mRNA |
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What is negative ssRNA?
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Negative ssRNA must first be used as a template for positive strand synthesis.
The positive strand is then translated into proteins or used as a template to synthesize progeny genomic RNA. |
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What enzymes do positive ssRNA need for replication?
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Virus-encoded RNA-dependent RNA polymerases
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What is the general site of nucleic acid replication of RNA viruses?
What RNA viruses are the exceptions? Where do they replicate? |
Cytoplasm
1) Retrovirus (+ssRNA) 2) Orthomyxoviridae (-ssRNA) Nucleus |
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What is an enveloped virus?
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A virus which has a lipid bilayer outer membrane surrounding its nucleic acid which plays an important role in viral penetration.
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Where do viruses acquire this envelope?
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From host cell membranes secondary to viral host cell budding.
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How do enveloped viruses enter host cells?
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Fusion of the viral envelope with the host cell membrane.
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What is a nonenveloped virus?
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A virus without an outer membrane
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What are two mechanisms by which nonenveloped viruses enter host cells?
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1) Injection of nucleic acid through the cytoplasmic membrane of host cells.
2) Receptor-mediated endocytosis of the virus. |
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What are capsids
What are two conformatoins that they assume? |
Proteinaceous shells that surround viruses
Icosahedral Helical |
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What are the three nonenveloped positive ssRNA families?
What is their capsid geometry? |
Picornaviridae
Caliciviridae Astroviridae Icosahedral |
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What are the four enveloped positive ssRNA virus families and capsid geometry?
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1) Coronaviridae, helical
2) Togaviridae, icosahedral 3) Flaviviridae, icosahedral 4) Retroviridae, complex |
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What are the arthropod borne viruses?
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Flaviviridae (+ssRNA)
Togaviridae (-ssRNA) Bunyaviridae (-ssRNA) |
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What viral RNA genomes are translated immediately by host cell machinery upon entry into a cell and are analogous to mRNA?
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Positive-strand RNA
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What type of nucleic acid do Picornaviridae contain in their genome?
What is their capsid geometry? Do they contain an envelope? |
Positive ssRNA
Picornaviridae has teh smallest RNA genome Icosahedral NO |
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What are five genera of Picornaviridae?
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Polio
Echovirus Rhinovirus Coxsackievirus Hepatitis A virus PERCH |
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What are enteroviruses?
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Viruses that affect the GI tract.
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What type of nucleic acid do Togaviridae contain in their genome?
What is their capsid geometry? do they contain an envelope? |
+ssRNA
Icosahedral YES |
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What genera are in the Togaviridae family?
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Alphaviridae
Rubivirus |
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How are alphaviruses transmitted?
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Mosquitos transmit to humans and domestic animals.
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What name is given to viruses that are transmitted via mosquito?
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Arboviruses
ARthropod BOrne viruses |
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What are four viruses in the alphaviridae?
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1) Eastern equine encephalitis viruses
2) Western equine encephalitis viruses 3) Chikungunya viruses 4) Venezuelan equine encephalitis viruses |
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What are three clinical manifestations of Alphaviridae?
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1) Eastern/Western equine encephalitis viruses-acute encephalitis
2) Chikungunya viruses-acute arthropathy 3) Venezuelan equine encephalitis viruses - febrile illness with flu-like symptoms |
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What virus belongs to the Rubiviridae genus?
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Rubella virus (German measles)
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What are the clinical features of rubella?
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General maculopapular rash beginning on the face and progressing to extremities, along with posterior auricular occipital lymphadenopathy
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How is rubella most commonly transmitted?
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Respiratory droplets
Transplacentally |
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What are the clinical complications of rubella infection during pregnancy?
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Teratogenic effects on teh developing fetal CNS, liver, heart, and eye in the first trimester of pregnancy.
Tubella is the "r" in TORCHEs, i.e., the mneumonic given to remember common congenital infections: Toxoplasmosis Other (HIV) Rubella Cytomegalovirus Herpes Syphilis |
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What are the CNS complications of congenital rubella?
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Deafness
Microencephaly Mental Retardation |
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What are the heart complications of congenital rubella?
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Patent ductus
Interventricular septal defects Pulmonary artery stenosis |
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What are the eye complications of congenital rubella?
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Cataracts and chorioretinitis
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When are these complications most severe?
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When rubella infection occurs during the first trimester
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