Question

Explain how a small mutation in a virus can have large implications for transmission using Chikungunya as an example. How did the E1-226A to E1-226V mutation influence the ability of the virus to infect mosquito vectors? How did this influence transmission?

Answer 1

A small mutation for example,in the envelope protein gene of the virus causes greater infectivity of virus in the midgut epithelial cells of Ae.albopictus but not in Ae.aegypti species.This mutation leads to enhanced viral transmission in one species of mosquitoes as mentioned earlier (Ae.albopictus)and confers the virus with evolutionary success when there occurs epidemics vectored by Ae.albopictus.With an increase in infectivity level,there also occurs efficient dissemination into mosquitos' secondary organs resulting in much more enhanced level of transmission to people.The mutation E1-226A to E1-226V increases the ability of the virus to infect the midgut eipthelial cells in one vector i.e Ae.albopictus but not in other i.e Ae.aegypti species.The virus with E1226V mutation are capable of infecting midgut epithelial cells 43 times more than the E1226A forms.Also,virus with E1226A undergo only one round of infection and cannot spread to neighbouring cells or disseminate while those with mutation have much more infectivity and enhanced dissemination and transmission to people.