Flashcards in Microbiology Virology - First Aid Deck (149)
exchange of genes between 2 chromosomes by crossing over within regions of significant base sequence homology
when viruses with segmented genomes (influenza) exchange segments
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
simultaneous infection of a cell with 2 viruses; genome of virus A can be partially or completely coated with the surface proteins of virus B. Type B protein coat determines the tropism of the hybrid virus but the progeny have a type A coat encoded by the type A genetic material
Live attenuated viruses induce...
humoral and cell-mediated immunity but have reverted to virulence on occasion. No booster needed.
Killed/inactivated viruses induce....
only humoral immunity but are stable.
Live attenuated vaccines (6)
2. yellow fever
4. Sabin polio virus
6. influenza (intranasal)
Killed vaccines (4)
2. Influenza (injected)
3. Salk Polio
Recombinant vaccines (2)
All DNA viruses are dsDNA except...
All DNA viruses are linear except...
papilloma, polyoma and hepadna (which are circular).
All RNA viruses are ssRNA excpet...
Positive stranded RNA viruses (7)
Purified nucleic acids of most dsDNA and + strand ssRNA viruses are...
Naked nucleic acids of - strand ssRNA and dsRNA viruses are...
not infectious. They require polymerases conatined in the complete virion.
DNA viruses replicate in...
the nucleus, except poxvirus.
RNA viruses replicate in...
the cytoplasm, except influenza and retroviruses).
Nake viruses include:
Generally, viruses acqurie an envelope from...
plasma membrane when they exit a cell.
(exception: herpesvirus acquires its envelope from the nuclear membrane)
DNA viruses (7)
DNA viruses general rules (4):
1. are double stranded
2. are linear
3. are icosahedral
4. replicate in the nuclus
The DNA virus that is not double stranded is...
The DNA viruses that are not linear are...
papillomavirus/polyomavirus (circular, supercoiled) and hepadnavirus (circular, incomplete).
The DNA virus that is not icosahedral is...
The DNA virus that does not replicate in the nucleus is...
poxvirus (it carries its own DNA-dependent RNA polymerase).
DNA viruses w/ an envelope
-hepatitis (acute or chronic)
-vaccine (contains surface Ag)
-not a retrovirus but has reverse transcriptase
Adenovirus medical importance
-febrile pharyngitis (sore throat)
-acute hemorrhagic cystitis
-conjunctivitis ("pink eye")
Parvovirus features (4)
-B19 virus: aplastic crises in sickle cell
-"slapped cheeks" rash in children: eythema infectiosum (fifth disease)
-RBC destructino in fetus leads to hydrops fetalis and death
-pure RBC aplasia/RA-like symptoms in adults