Just as in higher life forms, viral genetic material is subject to change by mutation. Lack of a corrective replication “proofreading” mechanism results in a very high incidence of spontaneous mutations in RNA viruses, in turn greatly increasing the genotypic variability within each species (“viral qua- sispecies”). Furthermore, a potential for recombination of genetic material is also inherent in the replication process, not only material from different viruses but also from host cell and virus. This factor plays a major role in viral tumor induction and genetic engineering. Functional modifications arising from interactions between different viral species in mixed infec- tions—e.g., phenotype mixing, interference, and complementation—have nothing to do with genetic changes.

Sayfa 389Kitabı okudu

Medical Microbiology Kolektif