One virus particle prevents multiplication of second virus, this phenomena is:

Ans. is 'a' i.e., Viral interferenceInterference denotes inhibition of growth of one virus in a host cell when it is simultaneously infected with another virus. Interferon is the most important mediator of interference. Auto interference is another type of interference, in which a high multiplicity of infection inhibits production of infectious progeny. In contrast, mixed infections sometimes increase the yield of one virus and produce well-marked cytopathic effects in the cell lines. This phenomenon is called enhancement.