Techniques of molecular biology in morphological diagnosis of DNA and RNA viruses.

Recognition of virus structure and biology as well as the increasingly more complete understanding of pathogenesis in infectious diseases have been possible due to the rapid development of the molecular biology techniques. In the recent few years, most of the studies employing those techniques in diagnosis of infectious diseases concerned the detection of novel viruses, clarification of the virus role in diseases of unknown aetiology and determination of the effect of virus mutants on the course of the infection. The pathogenetic mechanisms of chronic infections, oncogenesis and fibrogenesis are continued to be studied. This paper presents the advantages of using in situ hybridisation in the microscopical diagnosis of viruses. Moreover, principal techniques of amplifying the level of virus detection (in situ PCR and its variants, Immunomax) have been described. Direct application of the Immunomax technique in combination with the in situ hybridisation and with immunocytochemistry have been illustrated with our own studies on tissue expression of selected DNA viruses (HBV and HCMV).