005 Virus structure and properties Flashcards
What is the size of a virus?
20-200nm
What type of genetic material is found in herpes virus?
dsDNA
What type of genetic material is found in adenovirus?
dsDNA
What type of genetic material is found in poxvirus?
dsDNA
What type of genetic material is found in retrovirus?
ssRNA
Which virus is unenveloped?
adenovirus
What is Koch’s postulate?
To establish a caudal relationship between microbe and disease you must be able to:
- Must be found in all lesions
- Must be isolated in pure culture
- When re-inoculated into the patient, must cause disease in that lesion.
- Must be reisolated from new lesion and should be identical to original causative agent
How do you determine cytopathic effect from tissue cultures?
With phenol indicator - if it is alkali, then it means cells have died. If it is red - then CO2 is being produced and something is growing.
What does the Hershey Chase experiment demonstrate?
This demonstrates that it is nucleic acid not protein that is responsible for viral infections.
What symmetry do spherical capsids show?
icosahedral symmetry
What symmetry do rod capsids show?
helical symmetry
What are prions and what is their pathogenesis? How can prions be transmitted?
Modified mutated proteins that can 1. trigger normal proteins to fold abnormally 2. resistant to enzymes 3. clump inside the brain causing disease 4. cause spongiform encephalopathy (holes degeneration in brain). It can be transmitted by infected meat products.
How was hepatitis C discovered?
Infected patients serum was injected into a test monkey. The test monkey’s plasma was ultracentrifuged and its nucleic acid was extracted and packageged into phage. It infected a bacterial lawn on an agar plate. Plaques formed on the plate in which virus had killed backteria. Probed with patient serum, which generated antibodies against the plaque. The antibodies were sequenced for DNA to work backwards to find the virus.
How do we classify viruses?
Morphology, size, genome, strategy of replication.
