Micro - Virology (Part 1) Flashcards Preview

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Flashcards in Micro - Virology (Part 1) Deck (191)
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A recent renal transplant recipient has fever, malaise, allograft dysfunction, and cells with "owl's eye" inclusions. Diagnosis?

Cytomegalovirus infection


What are the two components of the naked icosahedral virus structure?

Nucleocapsid and nucleic acid


What are the four components of an enveloped icosahedral virus structure?

Surface protein, lipid bilayer, capsid, and nucleic acid


What are the four components of the enveloped helical virus structure?

Surface protein; matrix or core protein; lipid bilayer; and nucleic acid and nucleocapsid protein


Structurally, what are the three main classes of viruses?

Naked icosahedral, enveloped icosahedreal, enveloped helical


In viral genetics, what is recombination?

It is the exchange of genes between two chromosomes by crossing over within regions of significant base sequence homology


In viral genetics, what is reassortment?

It is the exchange of segments among viruses with segmented genomes (eg, influenza virus)


Which type of viral genetic event can cause worldwide pandemics?

Reassortment, which happens when viruses with segmented genomes (eg, influenza virus) exchange segments


In viral genetics, when does complementation occur?

Complementation occurs when one of two viruses that infect the cell has a mutation that results in a nonfunctional protein and the nonmutated virus makes a functional protein that serves both viruses (the nonmutated virus "complements" the mutated one)


In viral genetics, when does phenotype mixing occur?

Phenotype mixing occurs when the genome of virus A is coated with the surface proteins of virus B and infectivity is determined by the virus B protein coat, but the progeny is encoded by virus A generic material and will have the virus A coat


Viral genome reassortment occurs in viruses with what type of genomic structure?

Segmented genomes


What is a pseudovirion?

The genetic material of one virus coated by the surface proteins of a different virus


What is the difference between the immunity induced by a live, attenuated virus and that of killed virus vaccines?

Live, attenuated vaccines induce humoral and cell-mediated immunity whereas killed vaccines induce only humoral immunity


What is the advantage of killed vaccines over live, attenuated vaccines?

Killed vaccines are more stable, whereas live, attenuated vaccines have reverted to virulence on very rare occasions


Live vaccines are dangerous to give to which populations?

Immunocompromised patients or their contacts


Name five live, attenuated vaccines.

MMR (measles, mumps, rubella), Sabin polio, varicella zoster virus, yellow fever, smallpox (remember: "Live! One night only! See small yellow chickens get vaccinated with Sabins and MMR")


Name four killed virus vaccines.

Rabies, Influenza, Salk Polio, and hepatitis A virus (remember: RIP Always, and SalK = Killed)


Name two recombinant vaccines.

Hepatitis B virus and human papilloma virus vaccines


What is the antigen that is present in the hepatitis B virus vaccine?

Recombinant hepatitis B surface antigen


Which human papillomavirus types does the human papillomavirus vaccine protect against?

Types 6, 11, 16, and 18; the types most likely to cause cervical cancer and genital warts


What is the only live, attenuated vaccine that can be given to HIV-positive individuals?

MMR (measles, mumps, rubella)


All DNA viruses contain double-stranded DNA, except for which family?

Parvoviridae, which has single-stranded DNA (remember: part-of-a-virus)


Which three DNA viruses contain nonlinear DNA?

Papilloma, polyoma, and hepadna viruses, which contain circular DNA


All RNA viruses contain single-stranded RNA, except for which family?

Reoviridae (remember: all are single-strand RNA except "repeatovirus" [reovirus] is double-stranded RNA])


Purified nucleic acids from which viruses are considered infectious?

Most double-stranded DNA viruses and positive-strand single-stranded RNA viruses


Why are negative-strand single-stranded RNA and double-stranded RNA viruses not infectious?

They require enzymes found in the complete virion to become infectious


The purified nucleic acids of what two double-stranded DNA viruses are not considered infectious?

Poxviruses and hepatitis B virus; both require enzymes not found in human cells for replication


Are most viruses haploid or diploid?

Most are haploid (one copy of genetic material)


What is the only virus that is not haploid?

Retroviruses (2 copies of single-stranded RNA)


With one exception, all DNA viruses replicate in what part of the host cell?