Ans. (a) Viral interference Ref. Ananthanarayan 8/e, p 438, 9/e, p 439 Viral interference "Interference in which infection of a cell by one virus inhibits simultaneous or subsequent infection by another virus." Most impoant mediator of interference is interferon. Interference produced by destruction of cell receptors is seen with myxoviruses and enterovirus. It is applied in the field in controlling poliomyelitis outbreaks by introducing into the population, the live attenuated poliovirus vaccine. Remember: Interference is Nongenetic interaction.