mutation

Question 1

why is there a mutation?

Answer 1

most of the viruses have single stranded genomes —> no complementary strand to be used as a template to check for mis-match

Question 2

RNA viruses are more prone to accumulate mutation compared to DNA viruses. why?

Answer 2

• viral enzymes used for the replication of the viral genome do not have proof reading mechanism
• ie : HIV reverses transcriptase which is a RNA dependent DNA polymerase and influenza virus RNA dependent RNA polymerase
• also RNA polymerase does not have proof reading mechanism

Question 3

what is antigenic drift?

Answer 3

• random mutations that cause a gradual change in the hemagglutinin and neuraminidase antigens (in influenza)

Question 4

what is antigenic shift?

Answer 4

• influenza obtains a new genome segment from an influenza virus capable of infecting other animals (genetic reassortment)
• it causes a sudden and major change