[Conventional and molecular methods in diagnosis and monitoring of viral infection].

Laboratory diagnosis of viral infections comprises a spectre of methods and techniques with different sensitivity and specificity that are used in routine and research laboratory work. Modern laboratory procedures in virology can be divided in two groups: conventional and molecular methods. Although some of them are widely used, none deserves the title "gold standard" for its diagnostic and prognostic value. Viral isolation in cell culture is now considered a non-routine method. A virus can be detected and initially identified through observation of virus-induced characteristic morphology changes in inoculated cells. Although isolation is a highly specific method, it has many limitations.Today, the existence of other, more rapid and sensitive techniques, confines viral isolation onlyto research work. Conventional techniques also include: identification of viruses based on their morphology by electron microscopy (EM), viral antigen detection using the immunofluorescence (IF) or immunoenzyme methods (ELISA). All the above-mentioned conventional methods have lower sensitivity and unreliability as disadvantages when compared to modern, molecular methods. Serological diagnosis of viral infections is used very widely in routine laboratory work. Besides many advantages, such as rapidity, possibility of testing many samples at the same time, the ability to determine classes and types of antibodies as well as titres, serodiagnosis has many limitations. Recently, molecular methods have become more and more important in laboratory diagnosis of viral diseases. These methods are based on detection of viral nucleide acids by hybridisation with specific probes or amplification of the conserved regions of viral genome by PCR. These tecniques are especially useful for detection of latent infections and in determining the success of antiviral therapy.