Virology Flashcards
(26 cards)
How do RNA oncogenic viruses transform cells? (Two ways)
- Contain oncogenes and express them in infected cells
2. Insert their promoters into a chromosome and cause expression of regional oncogenes
How do DNA oncogenic viruses transform cells?
Degrade cell cycle genes
What is complementation?
Virus A helps express virus B which helps express virus A. Progeny is same as parents and will not be able to be expressed without the other virus
What is phenotypic mixing?
The exchange of viral capsid proteins. Progeny is the same as parents
What is recombination?
Exchange of genes by CROSSING OVER at regions of homology. Progeny is DIFFERENT from parents
What is reassortment?
Transfer of separate segments of genome. Simple, more frequent, and rapid changes to viruses. Progeny is different. Ex) influenza
What are two problems with the use of gene therapy?
Short duration of expression of foreign gene
Low efficiency of gene transfer-need a lot of virus
What are two problems with the use of viruses for gene therapy?
Sever inflammatory response is possible
Insertion of virus into recipient’s genome is possible leading to malignant disease (leukemia)
What characteristic of DNA viruses makes them more genetically stable than RNA viruses?
Higher fidelity of viral and cellular DNA polymerases=proofreading. (As opposed to RDRP-RNA dependent RNA polymerase)
What does replication of LARGE DNA viral genomes require?
Viral DNA Polymerase and accessory proteins.
In which cell type does the initial phase of human papilloma virus infection occur?
Basal epithelium.
What is poliovirus’ genome?
(+) ssRNA genome, with linear mRNA molecue
Where does poliovirus infect in the human body?
GI epithelial cells (may spread to muscles and neurons)
What is RDRP?
RNA-dependent RNA Polymerase
What does RDRP do and where does it function?
RDRP transcribes viral RNA to mRNA (to be translated by host cell ribosomes) and replicates RNA
RDRP functions mainly in the cytoplasm
Where does replication of viral RNA take place? (specifically)
RDRP replicates viral RNA on organelle membranes (ER vesicles, lysosomes, endosomes)
This increases efficiency because all components are concentrated
What is the structure and genome of Rotavirus (Reoviurs)?
Genome is segmented, dsRNA, naked icosahedron
Where does Rotavirus infect and what disease does it cause?
Affects the GI tract epithelium, causes profuse diarrhea in infants and children.
What is the structure and genome of Influenza (Orthomyxovirus)?
Genome is segmented, (-) ssRNA, enveloped
Where does transcription and translation of Influenza RNA occur?
In the nucleus by RDRP
What is the structure and genome of HIV (Retrovirus)?
(+)ssRNA, two copies (diploid) segmented, enveloped
What is special that HIV genome does once inside the cell?
Uses its Reverse Transcriptase (inside the virion) to convert to ssDNA (diploid) then import into the nucleus and then integrated into the host cell DNA for life
What are the four ways that antiviral drugs target essential viral functions?
Viral entry
Genome replication
Assembly
Release from cell
How does the inhibition of neuraminidase by the drugs zanamivir and oseltamivir treat influenza?
Neuraminidase cleaves sialic acid which allows virions to be released from the cell. Inhibition therefore leaves virions attached to the cell.
