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76 Cards in this Set

  • Front
  • Back
Can viruses contain both DNA and RNA?
NO
Viruses consist of a ____________ reproductive cycle and an ________________transmissive cycle.
-intracellular
-extracellular
Viroids, primarily plant pathogens, replicate in the....
nucleus
Virusoids, primarily plant pathogens, replicate in the....
cytoplasm
What type of viruses are: parvo, papova, adeno, herpes, hepadna, and pox.
DNA
What does an enveloped virus contain that a non-enveloped does not have?
peplomer (glycoprotein) or spike, matrix proteins, lipids
Does an enveloped virus survive in all seasons?
no - it is seasonal
Are enveloped viruses larger or smaller than non-enveloped?
larger
What composes the non-enveloped viruses?
only the nucleocapsid
Are non-enveloped viruses more likely to cause acute or chronic infections?
acute
Are enveloped viruses more likely to cause acute or chronic infections?
chronic
What is the largest and smallest of the virions?
largest - pox
smallest - parvo/picorna
Are all animal helical viruses enveloped or non?
enveloped
What are the four components to a virus?
-nucleic acids
-proteins
-carbohydrates (glycoproteins)
-lipids
Do introns code for proteins?
no
Can RNA viruses be circular?
no they are always linear
The word - virales at the end of the word meant that it is in what? (order, family, genera, or species)?
order
The word - Viridae at the end of the word meant that it is in what? (order, family, genera, or species)?
family
The word - virus at the end of the word meant that it is in what? (order, family, genera, or species)?
genera
What does an arbovirus mean?
arthropod borne
What type of characteristics are described in the following names of viruses?
-picornavirus
-togavirus
-retrovirus
-picorna (small, RNA)
-toga (mantle, surrounding the membrane)
-retro (reverse, reverse transcription)
What does the papovavirus describe?
-pa = papilloma
-po = polyloma
-va = vacuolating virus
How do the following names decribe where the virus was isolated?
-reoviruses
-re = respiratory, e = enteric, o = orphan
What does permissivity mean?
ability to replicate and produce progeny viruses
What are the steps to the virus replication cycle?
1 - attachment
2 - penetration
3 - uncoating
4 - transcription of early mRNA
5 - translation of early proteins
6 - replication of viral DNA
7 - transcription of late DNA
8 - transcription of late proteins
9 - assembly of virions
Is energy or temperature required for attachment?
no
Describe the attachement process in one word?
highly specific
Is energy required for penetration?

What are the 3 types of penetration.
yes

-translocation, endocytosis, fusion
How is penetration achieved with enveloped viruses?

with non-enveloped viruses
endocytosis (some with fusion)

-translocation
What are virokines?
they modulate infection in the uninfected cell by - negating the effects of interferon, TNF, ect, and reducing inflammatory response
Where do most RNA viruses replicate?
in the cytoplasm
Why are most RNA viruses prone to mutation?
don't have proof-reading ability in it spolymerase
Can cells replicate RNA genome?
no - RNA viruses must encode (ss+) or carry (ss-) an RdRp.
Which of the DNA viruses does not replicate in the nucleus?
poxvirus
Where do most DNA viruses replicate?
nucleus
Do early or late genes encode for nonstructureal proteins?
early
Do early or late genes encode for structural proteins?
late
What does DNA polymerase need to replicate the viral genome?
a primer
Is the poxvirus more or less dependent on the host for replication?
less --> larger DNA viruses have more control over the replication of their genomes and are less dependent on the cells
What do ds DNA viruses use to transcribe viral RNA and translate viral proteins in the nucleus?
use cellular enzymes
What type of proteins are the non-structural ones that are produces early in transcription in ds DNA?
regulatory
Why is it the pox virus replicates in the cytoplasm, even though all of the other DNA viruses replicate in the nucleus?
host transcriptional factors are not needed and thus replication can take place in the cytoplasm - the poxsvirus is the largest virus and carriers everything it needs with it for transcription and translation
Are naked ds DNA viral genomes infectious?
yes
Where do parvoviruses (autonomous) replicate?
ONLY in the nucleus of rapidly dividing cells
Where do adeno-associated parvoviruses (dependovirus) replicate?
only in cells co-infected with adenovirus (helper virus)
What must first occur with the replication of the ss DNA viruses?
the synthesis of a strand of DNA complementary to the single-strand parental viral DNA in the nucleus
What three things add to an inherited error-prone mutation ability?
1 - poor fidelity of the viral polymerase
2 - rapid rate of genome replication
3 - RNA viruses lacking proof-reading mechanism
Reassortment occurs in what type of viruses?
those with segmented genomes --> results in a new hybrid
What does cytopathic effect (CPE) mean?
morphological changes of infected cells such as rounding, lysis, detachment, syncytia, inclusion bodies
What are the 2 causes of CPE?
1 - direct injury to infected cells (pathology)
2 - side effect - altered metabolism due to virus replication
What is the exception to the rule for RNA viruses replicating in the cytoplasm?
coronaviruses and orthomyxoviruses and retroviruses
What are the steps to macromolecular synthesis?
1 - early mRNA transcription and protein synthesis --> NS proteins
2 - replication of viral genome
3 - late mRNA transcription and proteins synthesis --> structural proteins
4 - PTM of proteins
What does attachment mean?
when VAPs (viral attachment proteins) bind to receptors on the cell
Where are VAPs on:

-non-enveloped viruses
-enveloped viruses
- part of the capsid or a protein extending from the capsid

- spike or peplomer glycoproteins on the envelope
What is the target cells for the influenza A virus?
epithelial cells - sialic acid is the receptor
What type of enzyme do most DNA viruses use to transcribe viral mRNA?
DNA-dependent RNA polymerase II
ALL DNA viruses but this one's naked genome can self-initiate replication upon injection into a susceptible host.
poxvirus
ALL (+) sense RNA viruses but this one's can self-initiate replication upon injection into a susceptible host.
retrovirus
What is a characteristic effect for several enveloped viruses?
formation of syncytia - fusion of cells
What are inclusion bodies?
cytoskeletal components incorporated into infected cell structures
What are the five routes of entry of viruses?
1 - Respiratory Tract
2 - GI tract
3 - Conjunctiva
4 - genitourinary tract
5 - skin (epidermis)
high viremia=
virulence
What is the transport speed for neural spread of viruses?
2-16mm/day along nerve axons
What are the routes of virus shedding?
1 - skin
2- respiratory secretions
3 - saliva
4- feces
5 - genital secretions
6 - urine
7 - milk
What type of antibody is IgA?
local, mucosal diseases
What type of antibody is IgG?
systemic spread/viremia, virus in cells not affected by Ab
What types of Ig are gotten from colostral means?
IgA
What types of antibodies are gotten from milk, transplacental, and translocation across the GI, providing systemic protection against viremia?
IgG
What is important for the protection of young - passive immunity?
early and continuous suckling
What Ig is important in intestinal diseases?
IgA
What is the major Ig in cattle, swine and horses colostrum?
igG
What is the major Ig in dog's colostrum?
IgA
What is the major Ig in milk of swine, horse and dog?
IgA
What is the most effective type of vaccine?
MLV
Does a MLV or a killed vaccine have a lower level and shorter duration of immunity?
killed
What antibody class is activated in live vaccines and killed?
live - IgG and IgA

killed - IgG