Retroviridae pt 1 Flashcards
What enzyme does this virus family use to produce DNA intermediates from their RNA genome?
Reverse Transcriptase
An RNA-dependant DNA polymerase that is present within the virions of all members of the family.
Reverse Transcriptase
True or FalseRetro viruses infect a wide variety of animals and humans , can produce latent infections, and are associated with certain types of cancers.
TRUE
RetroENVELOPED or NOT?
ENVELOPED
Name the 3 genes that all non defective retroviruses have.
GAG- encodes virion core proteinsPOL- encodes reverse transcriptase and integraseENV- encodes the envelope proteins
How does the virus penetrate the cell membrane?
Membrane Fusion
Can the virus use endocytosis or exocytosis to gain entry inside the cell?
Endocytosis
Unlike HIV, Retros do not need a co factor. True or False
FalseRetro viruses may require a co receptor like HIV
What enzyme is used to intergrate the viral DNA into the host cellular chromosomal DNA ?
Integrase enzyme
Maturation of virions occurs by _________ through the host cell plasma membrane.
BUDDING
Assembly and packaging of viral protein, encapsidation or viral RNA occurs in the ___________.
Cytoplasm
_____________ is replicated with host genome and can be passed to daughter cells resulting in transmission from one generation to the next.
PROVIRUS
The replication of retros is accompanied by high mutation frequency that is due to the lack of _________________ by reverse transcriptase.
3’ to 5’ exonuclease proofreading mechanism
What are non pathogenic DNA stretches found widely in genome of most vertebraes that closely resemble retros?
Endogenous retroviruses
All RNA tumor viruses belong to the family Retroviridae. TRUE or FALSE
TRUE TRUE TRUE
What gene does the acute transforming retroviruses carry that makes them directly oncogenic by having the power of unregulated expression and are under the control of viral LTRs?
v-onc Remember: c onc/proto oncogenes are host genes that encode important cell signaling porducts that regulate normal cell proliferation
What gene does the virus loose during recombination and what gene does the virus aquire?
Looses its own ENV gene Gains the host PROTO-ONCOGENENote: This makes v-onc containing viruses unable to synthesize a complete envelope, are replication defective and must associate with non defective viruses to replicateEXCEPTION: Rous sarcoma virus
A type of Retrovirus that does not contain the v-onc gene.
Slow/Chronic Transforming Retrovirus
EtiologyBovine Leukemia (Enzootic Bovine Leukosis)
Deltaretrovirus
What is the unique sequence in Bovine Leukemia Virus that is not of host cell origin between ENV and 3’LTR?
pX
What is the regulatory protein that is encoded in the pX region, activates the replication of BLV and contributes to the induction of lymphoma(oncogenesis)?
Tax protein
In what cells is the Bovine Leukemia virus mostly present?
B lymphocytes Therefore can be found in blood, milk and tumor masses.
Name the 6 modes of transmission for the Bovine Leukemia Virus *Remember virus is in B lymphocytes, so how can B lymphocytes be transmitted*
- Blood Transfusion2. Iatrogenic 3. Rectal Palpation4. Mechanically by blood sucking insects5. Vertical(in utero) 6. Colostrum or milk
What cells and what immunoglobulin are the primary target of Bovine Leukemia Virus?
B Lympohocytes that express IgM
What 2 ways does Bovine Leukemia virus escape immune elimination?
1.By controlling viral gene expression in vivo2. Promoting cells survival by inhibiting apoptosis
Cattle with BoLA-Aw7 alleles are:resistant or susceptibleto Bovine Leukemia Virus?
BoLA-Aw7RESISTANT TO THAT SHIT!7 is God’s favorite number = good= resistant
Cattle with BoLA-Aw12 alleles are:resistant or susceptible to Bovine Leukemia Virus?
BoLA-Aw12 allele SUSCEPTIBLE :( Poor Cow
Primary infection of Bovine Leukemia virus gives of what kind of clinical signs?
Asymptomatic or flu like
When can you detect the levels of antibodies after infection of Bovine Leukemia Virus?
4 to 12 weeks after exposure
In what phase of pathogenesis of BLV lasts for several months/years, the animal shows no signs, and they become latent carriers of the infection?Primary PhasePersistant InfectionPersistant LymphocytosisTumor Phase
PERSISTANT INFECTION Lucky cows to be persistantly infected but show no signs.
Persistant lymphocytosis and benign proliferation of B lymphocytes are characteristcs of what pahse of Bovine Leukemia Virus?
Persistant Lymphocytosis Morbidity, weakness and opportunistic infections
In what phase of pathogenesis does the animal infected with Bovine Leukemia begin to develop lymphosarcomas?
TUMOR PHASE Animal undergoes sudden death because of hemorrhage of the spleen.