Pigs Are Vulnerable to Infection by Bird Flu Virus and Human

Multiple Choice

Pigs are vulnerable to infection by bird flu virus and human flu virus, both of which can be present in an individual pig at the same time. When both viruses infect a pig simultaneously, it is possible for genes from bird flu virus and human flu virus to be combined. If the human flu virus contributes a gene for Tamiflu resistance (Tamiflu is an antiviral drug) to the bird flu virus, and if this new virus is introduced to an environment lacking Tamiflu, then which of the following scenarios is most likely to occur?

A) The new virus will maintain its Tamiflu-resistance gene, in case of future exposure to Tamiflu.
B) The Tamiflu-resistance gene will undergo mutations that convert it into a gene that has a useful function in this environment.
C) If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.
D) If the Tamiflu-resistance gene confers no benefit in the current environment, and has no cost, the virus will increase in frequency.