Question

Which description of antigenic drift and antigenic shift in the influenza virus is incorrectly matched?

- Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans
- Antigenic shift: May result in a pandemic outbreak due to widespread lack of immunity
- Antigenic drift: A host vaccinated against an influenza strain before antigenic drift may lack effective immunity and be susceptible to infection
- Antigenic drift: Spontaneous mutation leads to a minor change in HA or NA spikes
- Antigenic shift: Often leads to viral strains with new features such as increased infectivity or expanded host range.

Answer 1

The incorrectly matched description is that antigenic drift involves re-assortment and a species jump to humans; this actually describes antigenic shift.

Step-by-step explanation:

The incorrect match in the description of antigenic drift and antigenic shift in influenza viruses is the statement about antigenic drift often involving re-assortment of viral strains in an animal host followed by a "species jump" to humans. In fact, it is antigenic shift that typically involves this re-assortment and can result in new strains with features such as increased infectivity or an expanded host range. On the contrary, antigenic drift is a form of slight antigenic variation that occurs because of point mutations in the genes that encode surface proteins hemagglutinin (H) and neuraminidase (N), leading to minor changes in these spike proteins. When a host vaccinated against an influenza strain before antigenic drift occurs, they may lack effective immunity against the new drifted strain and become susceptible to infection. On the other hand, antigenic shift can result in a major change that may lead to a pandemic outbreak due to the widespread lack of immunity against this new variant.