Virology (1)

zijimubo1's version from 2016-12-16 00:44

Section 1

Question Answer
define a virusObligate intracellular
structural components of virus1) nucleic acid 2) capsid 3) membrane envelope
what is a nucleocapsid ?capsid + nucleic acid
What is a naked virus?Nucleocapsid only; NO membrane envelope
Helical vs Icosahedralhelical flexible ; icosahdral strong
What type of RNA viral genome does NOT require viron-associated polymerase activity?ssRNA sense strand because it can function as mRNA for translation.
Which to types of viral genome require viron-associated polymerase activity?Anti-sense(- strand) ssRNA and dsDNA
What is the viral life cycle?Attach > Penetrate > Uncoat genome > Synthesis > Assembly > Release
Three types of penetration.Translocation - entire virus across membrane; endocytosis - virus inside vacuole ; fusion of cellular membrane
What is the eclipse phase? Period in the beginning when no virons can be recovered from cell.
Where does uncoating happen?DNA virus - nucleus ; RNA virus - cytoplasm
What are replicases?Viral proteins required for viral nucleic acid replication.
What is tissue tropism?defines the cell or tissue type that supports the replication of a given virus.

Section 2

Question Answer
Positive sense RNAmRNA that can be translated to viral proteins
What does Replicase do?gives you the opposite sense strand; sense or antisense
Retrovirus requires what 2 enzymes?reverse transcriptase and integrase
Steps for DNA virusParental DNA transcribed to mRNA of early genes;
What is the sequence of virus spread?Implantation at portal of entry; local replication and spread; Dissemination from the portal of entry; multiplication in target organs; shedding of virus
What step in virus spread causes a secondary viremia?Shedding
Define Viremia.Virus in the blood that causes dissemination.
Define incubation period.The time between exposure to virus and onset of disease.

Viral Diversity

Question Answer
Mechanisms of viral diversitymutations and recombination
What causes an Antigenic drift?subtle genetic changes occur through mutation
What causes an Antigenic shift?Major genetic changes through recombination
Why do DNA viruses have low mutation rates?Unlikine RNA viruses, DNA viruses possess proofreading mechanisms for DNA polymerase
What is an advantage of RNA viruses?RNA viruses have no proofreading mechanism leading to an increase in DIVERSITY, thus antibodies may no bind.
Name a virus that has great diversityHIV
What are the three mechanisms for viral diversity?Independet reassortment, homologous recombination, and Breakage/re-joining
In order to undego viral diversity, what what is required?2 or more viruses

DNA viruses

Question Answer
Where does DNA replication of DNA virus occur?Nucleus; 1 exception - Poxviruses
What enzyme is required to transcribe DNA viruses?host RNA pol II; exception - Poxviruses
Indicate the hallmark of DNA viruses.Immedaite Early >> Early >> Late - Expression of viral genes and viral DNA synthesis occur in a defined reproducible pattern
Immediate early mRNA gives rise to what proteinsTRANSACTIVATORS that make new early mRNA
Early mRNA gives rise to what proteinsE proteins for DNA Synthesis >> Progeny DNA
Late mRNA from progeny DNA gives rise to what proteinsStructural proteins resulting in Progeny virus