Diagnosis and prognostic markers of HCMV infection

Human cytomegalovirus (HCMV) infections are frequently observed as well in immunocompetent as in immunocompromised patients. Diagnostic techniques for HCMV detection have greatly improved during the recent years. Detection of HCMV by culture has been bettered by centrifugating samples in a shell vial and by using monoclonal antibody to the immediate early antigen. Detection of antigens in leucocytes was facilitated by using whole blood instead of leucocytes separated by dextran sedimentation. Detection of HCMV recently sharpened by using molecular biology methods mainly based on the detection of the genome. Under certain circumstances, and especially in pregnant women, diagnosis of HCMV infection is essentially based on the detection of IgG and IgM antibodies. However, as IgM antibody is not a marker of primary infection, complementary tests are needed to help in the datation of the infection. Among them, the measurement of IgG avidity greatly improved the diagnosis of primary infections. In immunocompromised patients, very sensitive techniques are needed to diagnose HCMV infections. Detection of antigenemia and HCMV DNA are the methods of choice for an early detection of the infection. Diagnosis of HCMV-organ diseases largely depends on the infected organ and the presence of HCMV in the organ is, sometimes, difficult to interpret. Today, diagnosis of congenital infections is possible by detecting HCMV in the amniotic fluid. However, in order to reliably detect HCMV, amniocentesis must be performed after 21 week's gestation and at least 6 weeks after seroconversion. As all HCMV infections do not induce disease, prognostic markers are needed, as well in immunocompromised patients as in fetuses. Many studies were conducted in immunocompromised patients to find prognostic markers of HCMV infection in order to introduce preemptive therapy when needed. It seems that quantitative determination of HCMV DNA could be very useful to predict HCMV disease. Qualitative determination of mRNA could also be useful as a prognostic marker of HCMV disease. Determination of viral genotypes is more controversial. As for the infected fetuses, little was published about the prediction of sequelae. Some factors, such as viral load in amniotic fluid or in fetal blood or level of IgM antibody in fetal blood, may be predictive of sequelae, but these data require further studies.