Final answer:
Swine flu can undergo genetic changes known as antigenic drift and antigenic shift. Antigenic drift involves small genetic variations due to point mutations, while antigenic shift involves significant changes through gene reassortment that can lead to highly virulent strains. Antigenic shift is linked with major influenza pandemics. option 1
Step-by-step explanation:
Swine flu, like other strains of the influenza virus, can undergo major genetic changes through two different processes: antigenic drift and antigenic shift. Antigenic drift refers to the minor changes that occur because of point mutations in the spike proteins, specifically hemagglutinin (H) and neuraminidase (N), which can result in slight antigenic variations over time. Conversely, antigenic shift is a more significant change that involves the reassortment of genes for these spike proteins when two different influenza viruses infect the same host cell. This can lead to the emergence of a new virus with a unique combination of surface proteins from the original viruses, potentially leading to the development of highly virulent strains against which the population has little to no immunity.
Historically, several of the most important influenza pandemics have been associated with antigenic shifts, wherein these new, novel variants of the virus were so different from previous strains that the immune systems of individuals who were previously infected by other influenza strains were unlikely to recognize and effectively fight off the new variant. The potential for these new variants to spread widely and cause significant illness highlights the importance of continual surveillance by organizations like the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC).