
Are infectious diseases caused by novel entities, viruses that have rapidly evolved into more pathogenic forms, or viruses that have crossed species divides and become more virulent in their alternative host? These questions and how new diseases such as AIDS emerged have prompted...

New viral diseases are emerging continuously. Viruses adapt to new environments at astounding rates. Genetic variability of viruses jeopardizes vaccine efficacy. For many viruses mutants resistant to antiviral agents or host immune responses arise readily, for example, with HIV...