Published online by Cambridge University Press: 19 October 2009
New technologies now enable virologists to study small genetic and antigenic differences between field isolates of animal viruses at a higher level of discrimination than has been possible using conventional serological techniques. The most important of the laboratory techniques revolve around the use of monoclonal antibodies, peptide mapping, fingerprinting of whole RNA virus genomes, RNA:RNA hybridization, ‘electropherotyping’ of virus RNA or polypeptides, restriction enzyme analysis of virus DNA genomes, cloning of genes and rapid sequencing of viral DNAs and RNAs, in the latter case using primer extension techniques (reviewed by Palese & Roizman, 1980). From a practical point of view, genetic and phenotypic heterogeneity among viruses may be of considerable importance in attempts to control certain virus diseases by chemo- or immunoprophylaxis.