Molecular biology in the study of retroviruses and herpesviruses

Molecular biology has long been used as a tool for basic research in virology. Its medical use is recent and has been supported both by numerous technical improvements and the discovery of new human viruses. This is illustrated by the emergence of human immunodeficiency virus (HIV)-1, HIV-2, human T-cell leukemia virus (HTLV)-I/II, and human herpesviruses (HHV) 6, 7 and 8. Polymerase chain reaction (PCR) gave a major boost to an extended use of molecular biology techniques. This resulted in a better knowledge of human viral infections as illustrated by studies on HIV and HHV-8. New viruses have been characterized. Molecular markers have permitted analysis of virus transmission cases, classification of genetic variants and detection of mixed infections. The quantitation of viral load has led to a better understanding of chronic infections and reactivations. As a tool for diagnosis, molecular biology is not yet considered as a universal alternative to classical procedures such as serology and antigen detection. However, major improvements in molecular biology techniques might question current diagnosis strategies in the very near future. (C) 1998 Elsevier, Paris.