D Antigenic Variation

Question 1

how can influenza and HIV cause repeated infections

Answer 1

they have ability to evade adaptive immune system

Question 2

how is a second infection prevented

Answer 2

once infected by particular serotype of influenza a, will have antibodies, memory cells T cells. will not get sick again

Question 3

define structural plasticity

Answer 3

viral species that can tolerate many aa substitutions in their structural proteins and remain infectious. in influenza virus changes occur in 2 ways

Question 4

antigenic drift

Answer 4

influenza RDRP does not have proofreading ability. overtime virions accumulating changes allowing them to escape immune system are replicated. said to be sleeted by immune system

Question 5

give e.g. of antigenic drift

Answer 5

after 3 years HA1 eptitote of current virus that would have originally bound neutralizing antibodies have changed. significant portion of pop becomes susceptible to antigenic ally drifted virus

Question 6

antigenic shift

Answer 6

major change in spike proteins due to acquisition of gene segments that encode antigenically diff proteins

Question 7

how can antigenic shift occur in influenza

Answer 7

genome is segmented

Question 8

e.g. of antigenic shift

Answer 8

pig can be infected by avian and human influenza viruses. during assembly new combo of 8 segments are possible. produces visions that infect humans that have diff NA/HA serotype. new serotype infect everyone. if strain is deadly and contagious pandemic occurs