Influenza viruses A and B contain eight RNA strands and influenza virus C has seven strands.During antigenic drift,genes coding for glycoproteins recognized by the host immune system are mutated,whereas during antigenic shift,whole RNA strands can be swapped with those of another influenza virus,greatly increasing the virulence and transmissibility of the virus and minimizing the ability of the host's defenses to recognize it.Which of the following statements is true?

Question

Quizplus · Accepted Answer

Genetic drift creates a need for a new vaccine every year to keep up with the seasonal changes. If a genetic shift occurs, a new vaccine will be required since it creates a different and more virulent strain of the virus. Therefore, option A is the correct choice.

Option B is incorrect because the same vaccine is not effective against both strains if genetic shift occurs.

Option C is incorrect because a novel strain resulting from antigenic shift can be highly pathogenic and can cause a pandemic. Therefore, it is necessary to get vaccinated.

Option D is incorrect because the worst influenza pandemics in history, such as the Spanish flu of 1918, were caused by genetic shift.

Influenza Viruses a and B Contain Eight RNA Strands and Influenza