[Virus quantification in peripheral blood as a reflection of the clinical course]

Quantitative determination of viral nucleic acid in peripheral blood appears to be important for nearly all viral infections with a chronic and reactivating course, as this provides relevant information on the clinical consequences, the level of infectivity and the response to antiviral treatment or other interventions. The practical application of this principle in clinical virology has benefited from the availability of new techniques, particularly those in which amplification of viral nucleic acid can be followed in real time. In addition, the potential value of quantitative virology was clearly demonstrated by the experience gained from viral load monitoring in HIV-infected patients. This approach will probably be widely applicable in clinical microbiology in general.