Virology

Molecular techniques have become indispensable in viral diagnostics. Current applications include: (1) The detection of (unknown) viral infections in clinical samples. (2) Quantitative monitoring of viral load. (3) Genotyping of viral strains. (4) Detection of mutations in the viral genome that are associated with viral resistance. Proper sample acquisition and sample transport, as well as accurate DNA or RNA isolation are a prerequisite for reliable test results in molecular diagnostics of viral infections. In-house as well as commercial assays can be used for the amplification of viral DNA or RNA for the detection of viral infections and viral load monitoring. Many virus species consist of several subspecies, genotypes or variants. This molecular variation has to be taken into account when applying molecular diagnostics. More complicated diagnostics for genotyping or the detection of mutations related to therapy failure often rely on sequencing, although for some viral targets commercial assays are available. In this chapter, applications are described in which molecular methods have become the most important form of viral diagnostics. Molecular test results have a direct impact on patient management and as such, results have to be reliable, standardized and reproducible. Therefore, quality control and standardization are important issues!