9.16 Introduction to Virology – Flashcards
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| What is a virus? |
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| originally defined as a filterable agent but now they are defined as obligate intracellular parasites with an RNA or DNA genome |
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| T/F Human genome contains viral DNA. |
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| true |
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| T/F Rabies, polio, smallpox, yellow fever, and measles are all relatively recent viral diseases in the history of humans. |
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| False, they are considered "ancient diseases" because they have been around for a long time |
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| The term virus is derived from a Latin word meaning... |
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| a slimy liquid or a poisonous liquid |
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| What was the first human virus discovered? |
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| yellow fever in 1901 |
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| How are viruses classified? |
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| by the disease they cause, their mode of transmission, structure, and biochemical characteristics |
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| How big are viruses? |
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| anywhere from 20 nm to 300 nm |
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| Nucleocapsid and capsid proteins are typical of what kinds of viruses? |
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| enveloped viruses |
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| Which DNA virus is bigger: a parvovirus or a poxvirus? |
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| poxvirus (300 versus 25 nm) |
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| Which RNA virus is bigger a picornavirus or a paramyxovirus? |
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| a paramyxovirus |
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| What is the genome of parvoviruses? |
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| SS linear DNA |
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| What is the genome of a hepadnavirus? |
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| DS circular DNA |
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| What is the genome of a papovavirus? |
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| DS circular DNA |
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| What is the genome of an adenovirus? |
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| DS linear DNA |
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| What is the genome of a herpes virus? |
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| DS linear DNA |
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| What is the DNA of a poxvirus? |
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| DS linear DNA |
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| What is the genome of a picornavirus? |
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| SS+ RNA |
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| What is the genome of a calicivirus? |
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| SS+ RNA |
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| What is the genome of a reovirus? |
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| DS (+/-) RNA |
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| What is the genome of a togavirus? |
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| ss+ |
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| What is the genome of a flavivirus? |
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| SS+ RNA |
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| What is the genome of a rhabdovirus? |
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| SS- RNA |
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| What is the genome of a paramyxovirus? |
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| SS- RNA |
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| What is the genome of an orthomyxovirus? |
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| SS- RNA |
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| What is the genome of a retrovirus? |
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| SS+ RNA (two identical) |
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| What is the genome of a filovirus? |
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| SS- RNA |
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| What is the genome of an arenavirus? |
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| SS- RNA |
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| What is the genome of a bunyavirus? |
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| SS- RNA |
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| What is the genome of a coronavirus? |
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| SS+ RNA |
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| Name the two simplest capsid structures. |
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| helical and icosahedral |
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| Describe the icosahedral capsid structure. |
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| 20 triangular faces; 5:3:2 symmetry |
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| What are the parts formed together to make a mature capsid? |
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| protomers -> capsomers -> procapsid -> mature capsid |
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| What is a capsid? |
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| the protein coat surrounding the nucleic acid genome |
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| What's the difference between capsomers and protomers? |
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| capsomers are the repeating protein subunits that make up the capsid. Protomers are the polypeptide chains which make up the capsomers |
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| What do you call capsids composed of multiple copies of a single kind of protein subunit in a close-packed helix? |
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| helical capsids |
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| What are some examples of helical capsids? |
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| rhabdovirus (VSV), influenza, tobacco mosaic virus |
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| What is a virion? |
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| the complete virus particle |
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| What is a nucleocapsid? |
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| the capsid proteins associated with the viral nucleic acid |
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| What is a nucleoprotein? |
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| proteins associated with the viral nucleic acid |
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| What is the viral envelope? |
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| membrane composed of lipids, proteins and glycoproteins that is obtained from the cellular membranes. Virus encoded envelope proteins or "spikes" serve as the viral attachment proteins |
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| What type of capsid does the adenovirus have? |
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| icosahedral |
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| Describe the outer coverings of a herpes virus? |
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| enveloped icosahedral |
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| Describe the outer coverings of the influenza virus? |
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| enveloped helical virus |
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| Describe the outer coverings of HIV? |
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| enveloped icosahedral |
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| Describe the different ways a virus can enter a cell? |
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| fusion with the cell membrane either at cell membrane or in an endosome or receptor mediated endocytosis |
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| What are the different types of RNA viruses? |
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| can be + or - polarity, single-stranded or double-stranded, circular or linear, unimolecular or segmented. |
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| Where do RNA viruses generally replicate? |
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| in the cytoplasm (retrovirus and influenza are exceptions) |
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| What does it mean for an RNA virus to be negative or positive? |
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| + means the genome is used as mRNA, - means the viral polymerase produces mRNA |
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| What are the different types of DNA genomes? |
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| single-stranded, double stranded, circular and linear |
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| Where do DNA viruses generally replicate? |
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| in the nucleus (poxvirus is the exception) |
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| In general which viruses are more dependent on host machinery and which are more independent and encode thier own enzymes and proteins? |
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| smaller is more dependent, larger encodes its own |
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| What are the different classes of genes in the life cycle of herpesvirus? |
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| imediate early, early and late |
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| Describe the herpes life cycle. |
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| 1) Circularization of genome oand transcription of immediate-early genes 2) alpha proteins, products of immediate-early genes, stimulate transcription of early genes 3) beta-proteins, products of early genes, function in DNA replication, yielding concatemeric DNA. Late genes are trnascribed 4) gamma proteins, products of late genes, participate in virion assembly |
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| Hepatitis is caused by what viruses? |
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| HAV, HBV, HCV, HDV, HEV, CMV, and EBV |
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| What viruses cause encephalitis? |
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| HSV, togaviruses, vlaviviruses, rabies, picornaviruses |
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| What viruses cause meningitis? |
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| enteroviruses, mumps, HSV-2 and VZV |
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| Rotavirus, caliciviruses, and adenoviruses (40-41) all cause disease the in... |
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| GI tract |
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| Which viruses cause the common cold? |
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| rhinoviruses, coronaviruses, and adenoviruses |
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| What viruses cause disease in the lower respiratory tract? |
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| influenza, parainfluenza, ReSV, adenoviruses |
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| What viruses cause congenital and neonatal infections? |
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| CMV, parvovirus B19, rubella, HSV, HIV, and lymphocytic choriomeningitis |
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| What viruses cause congenital and neonatal infections? |
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| CMV, parvovirus B19, rubella, HSV, HIV, and lymphocytic choriomeningitis |
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| What are examples of viruses that present as localized infections of the respiratory tract? |
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| influenza and the common cold (rhinoviruses, coronaviruses, adenoviruses) |
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| What viruses can cause disseminated infections via respiratory transmission? |
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| varicella-zoster virus, measles |
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| What is an early physical sign of disseminated infection with the measles virus? |
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| koplik's spots (white spots on the buccal mucosa) |
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| What type of virus is the measles? |
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| paramyxovirus |
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| Which virus causes the chicken pox and shingles? |
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| varicella zoster virus (HHV-3) |
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| Name the important viruses that are spread fecal-orally. |
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| picornavirus, rotavirus, reovirus, caliciviruses, astrovirus, adenovirus |
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| What virus is a frequent cause of acute disease outbreaks on cruise ships and in day care centers and nursing homes? |
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| norovirus |
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| What virus causes about 50% of acute gastroenteritis in infants and children under 2 years? |
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| rotavirus |
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| Which viruses are fecal oral and cause GI symptoms of vomiting and diarrhea? |
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| norovirus, rotavirus, astroviruses, and adenoviruses |
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| Which viruses have fecal oral transmission but cause disease at a secondary site? |
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| enteroviruses (in the piconavirus family: poliovirus, Coxsackie virus, echovirus and enterovirus) and hepatitis A and E |
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| Give examples of chronic viral diseases. |
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| HIV, hepatitis, HTLV-1 (hep B is a chronic disease while HIV and HTVL-1 are chronic with late disease) |
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| When was the last US case of small pox? When was the last naturally occurring case of small pox? |
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| 1949, 1977 in Somalia (certified eradication in Dec. 1979) |
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| What are the different types of zoonoses? |
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| arboviruses (togaviruses [alpha], flaviviruses, bunyaviruses), pox viruses (orf, monkeypox), hantavirus (deer mouse), rabies (bats, raccoons, skunk dogs) |
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| How can West Nile be transmitted human to human? |
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| transplanted organs, blood transfusions, breast milk, transplacental, occupational exposure |
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| T/F Most humans with West Nile develop no clinical symptoms. |
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| true! only 20% develop disease (west nile fever) |
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| What are the symptoms of west nile? |
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| range from febrile headache to aseptic meningitis to encephalitis |
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| T/F Humans are the primary host for West Nile virus. |
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| False, birds are the primary host, humans are only incidental hosts |
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| What is SARS? |
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| characterization of a novel coronavirus associated with severe acute respiratory syndrome |
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| What are the best methods for controlling viruses? |
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| prophylaxis is best, vaccines, universal precautions, education |
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| Name common live attenuated virus vaccines. |
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| MMR, varicella-zoster, yellow fever |
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| Name common killed or inactivated vaccines. |
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| IPV [salk], influenza A and B, hepatitis A, and rabies |
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| T/F Recombinant/subunit vaccines are considered live vaccines. |
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| false |
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| Name the type of vaccine and the target population for hep a vaccine. |
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| nonliving travelers, or persons living in high risk areas |
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| Name the type of vaccine and target population for hep b vaccine. |
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| non-living (recombinant) universal childhood (healthcare workers) |
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| What type of vaccine and what is the target population for influenza A and B vaccines? |
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| 1)non-living and 2) live elderly, at risk population, others, medical personnel |
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| What is the type of vaccine and the target population for japanese encephalitis virus? |
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| non-living travelers to endemic regions |
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| What is the type of vaccine and target population for measles? |
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| live universal childhood |
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| What is the type of vaccine and target population for mumps? |
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| live universal childhood |
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| What is the type of vaccine and target population for poliovirus [salk]? |
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| nonliving universal childhood |
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| What is the type of vaccine and target population for rabies (preexposure, HDCV)? |
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| non-living veterinarians, high risk persons |
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| What is the type of vaccine and target population for rubella? |
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| live universal childhood |
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| What is the type of vaccine and target population for varicella? |
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| live universal childhood |
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| What is the type of vaccine and target population for yellow fever? |
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| live travelers to endemic regions |
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| What is RotaTeq? |
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| new vaccine for rotavirus live, oral pentavalent vaccine that contains 5 reassortant rotaviruses 3 doses given to infants @ 2,4,6 months |
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| What type of vaccine is gardasil? |
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| vaccine for cervical cancer via HPV infection noninfectious viral like particles with capsid proteins of HPV types 6, 11, 16, 18. 3 doses IM to girls 11-12 yrs before sexual activity |
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| What type of vaccine is zostavax? |
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| for shingles, live attenuated vaccine for adults > 60 yrs |
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| T/F Use of the Sabin poliovirus has been replaced by the attenuated salk vaccine. |
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| true |
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| What type of vaccine is the smallpox vaccine? |
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| live vaccine given intradermally to select first line defense personnel |
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| What are lytic infections? |
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| viral infections that kill the cell via a number of different mechanisms such as apoptosis |
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| What does it mean for a virus to cause a persistent infection? |
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| when it does not cause cell death and may be chronic, latent recurrent or transforming. Must be able to limit its cytolytic effects, maintain its genome within host cells and avoid elimination by the host's immune system |
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| Which viruses inhibit cellular protein synthesis? |
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| polioviruses, herpes simplex, pox viruses, toagaviruses |
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| Which viruses inhibit or degrade DNA? |
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| herpes viruses |
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| Which viruses use syncytia to harm host cells? |
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| herpes simplex, HIV, varicella zoster, paramyxoviruses |
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| Which viruses cause inclusion bodies in the host cell? |
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| rabies, adenovirus, poxvirus, reovirus, CMV |
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| What is a syncytia? |
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| a mass of cytoplasm containing several nuclei. The expression of cell surface glycoproteins of some viruses like HIV, herpes, and RSV (a paramyxovirus) can trigger the fusion of neighboring cells into multinucleated giant cells called syncytia |
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| Negri bodies are characteristic of what infection? |
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| rabies virus in the CNS |
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| What is a viral quasispecies? |
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| a heterogenous group of sequences clustering around a consensus (aka viral swarm) |
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| Where would you take a specimen from if your patient had a maculopapular rash? |
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| throat, stool, or rectal swabs (I know it doesn't make sense but its on the powerpoint) |
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| Where do you collect biological specimens from if your patient has a virus causes CNS illness (encephalitis and meningitis)? |
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| stool, tissue, saliva, brain biopsy, CSF |
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| What are the visible, cytopathic effects of viral infection? |
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| rounding/detachment, syncytia, shrinkage, increased refractility, aggregation, loss of adherence, cell lysis/death |
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| What is hemagglutination? |
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| when viruses contain proteins that bind to erythrocytes can cause an easily visualized and quick indicator of viral presence |
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| What are the criteria for diagnosing primary infection via serology? |
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| 4 fold or more increase in titer of IgG or total antibody between acute and convalescent sera, presence of IgM, seroconversion, and a single high titer of IgG (or total antibody)-very unreliable |
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| For which types of viruses would serology NOT be a useful diagnostic tool and why? |
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| most respiratory and diarrheal viruses produce clinical disease before the appearance of antibodies |
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| How do you detect antibodies via serology? |
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| ELISA |
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| How do you diagnose a viral illness via direct examination? |
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| visualization by EM, histologically via inclusion bodies, viral antigens, viral nucleic acid |
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| What labratory method is used for detection of viral genomes? |
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| PCR |
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| Which viruses are FDA approved for in vitro nucleic acid amplification and detection? |
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| HIV, HCV, and west nile |
