virology 1st quiz Flashcards
What 2 DNA viruses are ss?
Parvovirus and circo
Which DNA virus replicates in cytoplasm?
Poxviridae
What are general characteristics of RNA viruses?
Single stranded, enveloped, replicate In cytoplasm
What are characteristics of most DNA viruses?
Double stranded, icosahedrons, replicate in nucleus
Which 2 RNA viruses are ds?
Reo and birna
Which 2 RNA viruses replicate in nucleus?
Retro and orthomyxo
Which 3 RNA viruses are ss and segmented?
Orthomyxo, bunyaviridae, arenaviridae
which group taxonomizes viruses?
international committe on taxonomy of viruses - ictv
what does classification of a virus depend on?
type of genome
strategy of replication
structure of virion
what is the viral capsid made of and what else can it contain?
capsomeres
may contain enzymes, non structural proteins, no organelles
what is the range of virus sizes?
17 to 250 nm
what are the 2 smallest dna viruses?
circo and parvo
what is the biggest dna virus?
poxviridae
which rna viruses dont have an envelope?
picorna calici astro reo birna
which dna viruses have circular genomes?
hepadna
papo
circo
what is the eclipse period?
after penetration the virus cannot be detected for 2-12 hours until progeny become detectable
unrelated to incubation
what does dna viral replication need in nucleus of cell?
cellular dna dependent rna polymerase 2
what viral enzyme is needed for dna viruses that replicate in cytoplasm?
dna dependent rna polymerase
what way do enveloped viruses enter the cell?
membrane fusion
what way do naked viruses enter the cell?
endocytosis
what must ss negative rna viruses carry inside the cell?
specific viral rna dependent rna polymerase
which virus buds from nuclear membrane and exits thru ER?
herpes
what kind of viremia is needed to infect cns and has high titer?
secondary
which cells does parvo infect?
crypt cells in s phase
what are the 3 main changes after respiratory viral infection?
cessation of cilial beating
mucus layer gone
destruction of epithelial cells
what are the 3 ways viral lytic infections cause encephalitis?
neuronal necrosis
neuronophagia
perivascular cuffing
which viruses are lytic to cns?
toga
herpes
what 2 viruses cause demyelination in sheep?
maedi
visna
which 2 viruses can travel from cns to periphery?
herpes
rabies
what are macules formed by?
lasting local dilation of dermal bv
what causes papules?
from macules if there is edema and infiltration of cells
what causes vesicles?
seperation of epidermis from dermis by fluid pressure
what causes pustules?
vesicles infiltrated by neutrophils
which dna virus is oncogenic?
herpes
which rna virus is oncogenic?
retro
how can viruses activate cellular oncogenes? 4 ways
insertional mutagenesis
transposition
gene amplification
mutation
what controls viral oncogenes?
long terminal repeats
oncogenes from what kind of viruses do not have cell homologs?
dna viruses
which retrovirus is both replication competent and carries a v- oncogene?
rous sarcoma
what are the 3 ways retroviruses cause tumors?
transducing
cis activating
trans activating
what is the tumor latency period and efficiency of a transducing retrovirus?
short latency
high efficiency
what is the tumor latency period and efficiency of a cis activating retrovirus?
intermediate ( weeks to months) latency
high to intermediate efficiency
what is the oncogenic factor of cis activating retrovirus?
cellular oncogene activated in situ by provirus
what is the viral genome of a transducing retrovirus?
viral-cellular chimera, replication defective
term for virus infection replicating continuously at very low level?
persistence
where might the genome go during true latency infection?
viral genome integrated into cellular genome or exist as episomes
What is the half life of maternal antibodies in cattle and horses?
21 days
What is the half life of maternal antibodies in dogs and cats?
10 days
What is the translocation cutoff time for colostrum in domestic animals?
2 days
What are the most important antibodies in colostrum for cattle, swine, and horses?
IgG
What are the most important antibodies in colostrum for dogs and humans?
IgA
What are the most important antibodies in milk of cattle and horses? Milk of swine and dogs?
Cattle and horses - IgG
Swine and dogs - IgA
What is degeneracy as relating to viral evolution?
redundancy, no ambiguity (codons encoding one AA may differ in any of their 3 positions)
What are the 3 types of genetic drift in viruses?
substitutions, insertions, deletions
What are the 3 forms of genetic shift in viruses?
recombination
reassortment
defective interfering particles
What is a frameshift mutation?
indels of a non-multiple of 3 nucleotide bases
What is the mutation rate for RNA viruses?
10-3 (DNA have 10-9)
What is the term for RNA viruses having one clone predominant in an infection within a host?
quasispecies
What is it called when an RNA dependent RNA polymerase attaches to a different template during recombination?
copy choice mechanism
What type of evolution result in mixed infections because of recombination?
genomic shift
What kind of viruses undergo reassortment?
segmented genome viruses
What do defective interfering particles need to replicate?
normal viral genomes
How are defective interfering particles highly flexible?
can tolerate large deletions or sequence rearangements
What is the term used when a cell infected with 2 viruses increases the yield of one virus or both?
complementation
What is the term that virus progeny can acquire phenotypic characteristics from both parents but only have one of their genomes?
phenotypic mixing
Which virus is not haploid?
retrovirus
What is it called when several nucleocapsids are found in a single envelope?
polyploidy
What kind of mutations can bring virulence back?
back mutations and complementary mutations
If reproduction number is greater than one, what does that mean?
epidemic
If the repro number is less than 1, what does that mean?
infection will die out
Which type of vaccine needs an adjuvant?
inactivated
Which vaccine only needs one dose?
attenuated
Which vaccine has a duration of immunity less than 1 year?
inactivated
What are the factors affecting efficacy of a vaccine?
heat liability
vaccination frequency
phsyiologic and immunolgic conditions
human errors
What are the factors affecting safety of a vaccine?
underattenuation genetic instability contamination adverse effects in pregnant animals innoculation site rxns
What are the ways adjuvants increase immunogenicity?
prolong release of antigen
activate macrophages
induce mitogenicity for lymphocytes
How does Acyclovir, an anti-viral drug work?
it is a PRODRUG, requires viral coded enzyme to be active inside infected cells
At what temperature do viral surface proteins denature?
60 degrees C
What can be used to disinfect drinking water, food, utensils, dairies?
sodium hypochlorite (chlorox), and detergent iodophores (betadine)
What can be used to disinfect laundry, bedding and surface as a vapor?
formeldahyde
What can be used to disinfect hands, exam tables, cages and hospital surfaces?
Phenol derivatives (lysol)
What can be used to disinfect a wide range of hospital surfaces?
chlorohexadine
What can be used to disinfect heat sensitive medical supplies?
ethylene dioxide
What can be used to disinfect cold sterilization of instruments with lenses?
glutaraldehyde
What can be used to disinfect hands and thermometers?
alcohol
What can be used to disinfect wounds?
quarternary ammonium compounds (zephiran, roccal, savlon)
What is the term for infecting all culture cells simultaneously?
one step growth curve
Which DNA viruses are naked?
Circo, parvo, papo, adeno
Which RNA viruses are naked?
Picorna, calici, astro, reo, birna
What are the 9 DNA viruses?
Circo, Parvo, Hepadna, Papova, Adeno, Herpes, Asfa, Irido, Pox
What is the suffix for virus order?
-virales
What is the suffix for virus family?
-viridae
What is the suffix for virus subfamily?
-virinae
What is the suffix for virus genus and species?
-virus
What are the INDIRECT ways cell can acquire damage from viruses?
integration of viral genome
induction of mutations in host genome
inflammation
host immune response
What are viral infections osmotically more severe in newborns?
Milk is osmotically active
