Virology--structures, genetics, vaccines, viral genomes, viral replication, viral envelopes Flashcards
name the structures of a naked virus with a icosahedral capsule
- capsid
- nucleic acid

name the structures of a enveloped virus with icosahedral capsid
- surface protein
- lipid bilayer
- capsid
- nucleic acid

name the structures of an enveloped virus with helical capsid
- surface protein
- lipid bilayer
- hilical nucleocapsid with integrated RNA

explain recombination
- exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology
explain reassortment
- when viruses with segmented genomes (ie. influenza virus) exchange genetic material
- example: novel H1N1 influenza A pandemic emerged via complex viral reassortment of genes from human, swine, and avian viruses
- has potential to cause antigenic shift
explain complementation
- when 1 of 2 viruses that infect the cell has a mutation that results in a nonfunctional protein, the nonmutated virus “complements” the mutated one by making a functional protein that serves both viruses
- example: hepatitis D virus requires the presence of replicating hepatitis B virus to supply HBsAg, the envelope protein for HDV
explain phenotypic mixing
- occurs with simultaneous infection of a cell with 2 viruses
- genome of virus A can be partially or completely coated (forming pseudovirion) with the surface proteins of virus B
- type B protein coat determines the tropism (infectivity) of the hybrid virus
- however, the progeny from this infection have a type A coat that is encoded by its type A genetic material
live attenuated vaccines–mechanism
- induce humoral and cell mediated immunitybut have reverted to virulence on rare occasions
- no booster needed for live attenuated virus
which vaccines are LIVE attenuated vaccines?
- smallpx
- yellow fever
- rotavirus
- chickenpox (VZV)
- Sabin polio virus
-
Influenza (intranasal)
- “Live! One night only! See small yellow rotating chickens get vaccinated with SabinandMMR!It’sincredible!”
live vaccines and immunocompromised patients
- dangerous to give live vaccines to immunocompromised patients
- close contacts may be vaccinated with live vaccines (except live polio or influenza)
MMR vaccine
- measles, mumps, rubella
- live attenuated vaccine that can be given to HIV + patients who do not show signs of immunodeficiency
killed vaccines–mechanism
- killed/inactivated vaccines induce only humoral immunity but are stable
which vaccines are Killed vaccines?
- Rabies
- Influenza (injected)
- Salk Polio
- HAV
- “SalK = Killed”
- “RIP Always”
which vaccines are subunit vaccines?
- HBV (antigen = HBsAg)
- HPV (types 6, 11, 16, and 18)
which DNA viruses are double stranded?
- all DNA viruses are double stranded
- EXCEPT Parvoviridae
- “all are dsDNA (like our cells), except “part-of-a-virus” (parvovirus) is ssDNA”
- EXCEPT Parvoviridae
which DNA viruses are linear?
- all are linear except papilloma-, polyoma-, and hepadnaviruses (circular)
which RNA viruses are single stranded?
which RNA viruses are + stranded?
- all RNA viruses except Reoviridae are ssRNA
- stranded RNA viruses:
- “I went to a retro (retrovirus) toga (togavirus) party, where I drank flavored (flavivirus) Corona (coronavirus) and ate hippie (hepevirus) California (calicivirus) pickles (picornavirus).”
- retrovirus
- togavirus
- flavivirus
- coronavirus
- hepevirus
- calicivirus
- “I went to a retro (retrovirus) toga (togavirus) party, where I drank flavored (flavivirus) Corona (coronavirus) and ate hippie (hepevirus) California (calicivirus) pickles (picornavirus).”
- stranded RNA viruses:
naked viral genome infectivity
- purified nucleic acids of most dsDNA (except poxviruses and HBV) and + strand ssRNA (= mRNA) viruses are infectious.
- naked nucleic acids of - strand ssRNA and dsRNA viruses are not infectious
- they require polymerases contained in the complete virus
DNA viruses–viral replication
- all replicate in the nucleus
- except poxvirus
RNA viruses–viral replication
- all replicate in the cytoplasm
- except influenza virus and retroviruses
name the naked (nonenveloped) viruses
- Papillomavirus
- Adenovirus
- Parvovirus
- Polyomavirus
- Calicivirus
- Picornavirus
- Reovirus
-
Hepevirus
- “Give PAPP smears and CPR to a naked hippie”
which of the naked (nonenveloped) viruses are DNA?
-
PAPP
- Papillomavirus
- Adenovirus
- Parvovirus
- Polyomavirus
which of the naked (nonenveloped) viruses are RNA?
-
CPR and hip
- Calicivirus
- Picornavirus
- Reovirus
- hepevirus