Microbiology Practice Exam 2026 – Comprehensive All-in-One Guide for Exam Success!

The emergence of new strains of the flu virus is primarily attributed to antigenic shifts. This process occurs when there is a significant change in the viral antigens, mainly the hemagglutinin and neuraminidase proteins found on the surface of the virus. Antigenic shifts predominantly happen through reassortment of the viral genome when two different influenza viruses infect the same host cell. This can lead to the formation of a new strain that significantly differs from previous strains, which can create challenges for the immune response developed from past infections or vaccinations.

In contrast, genetic drift refers to smaller, gradual mutations that occur over time as the virus replicates. These changes are often enough to allow the virus to evade some immune responses but do not result in the dramatic shifts seen with antigenic shifts. Mutation is a broader term that encompasses changes in the viral genetic material but does not specifically explain the emergence of new strains; it is part of the genetic drift process. Replication errors refer to mistakes made during the viral replication process, which can lead to mutations but are not the primary mechanism for the emergence of new strains.

Thus, the emergence of new influenza strains is fundamentally linked to antigenic shifts, highlighting the importance of genetic reassortment in viral evolution