HCMV infection is associated with persistent and recurrent virus shedding through saliva. Besides isolating HCMV from patient's saliva, it can also be isolated from the urine. HCMV in laboratory cultures displays slow cellular replication, restricted cell trophism, limited cell to cell infection, and the presence of virulent virus within the cell. These in vitro properties of HCMV may reflect limited pathogenicity in the normal human host. Cellular immune responses of HCMV are very important because the immediate early genes of HCMV are the immunodominant target of the virus-specific cytotoxic T-lymphocytes ( CTLs) which react against the immediate early proteins of CMV (p72). This is a specific in vivo response and not a generalized dysregulation of the MHC antigen response generally seen in other DNA virus infections.
The disease manifestations of HCMV in patients could include infectious mononucleosis, pneumonia, hepatitis, CNS involvement (Guillain-Barré syndrome) aseptic meningitis, and immunologic abnormalities.
Congenital infections of HCMV in children include CNS involvement and maldevelopment. Primary infection of HCVM during pregnancy is rare, but not uncommon. HCMV infection in allograft recipients could lead to graft rejection.
Some of the HCMV patient symptoms include prolonged fever, leukopenia, thrombocytopenia, atypical lymphocytosis, and elevated hepatic transaminase. HCMV infection in bone marrow allograft recipients has to be diagnosed and the patient watched closely because 80% of such patients develop pneumonia.
The secondary infection of HCMV in HIV infected patients suggests that HCMV may pose an increased risk for the development of AIDS.
Because of the above manifestations, diagnosis of HCMV infection and close monitoring of a reactive viral state in clinical patients is critical. The HCMV specific IgM antibody responses and detection of HCMV in clinical specimens of the patient require the use of highly specific reagents such as monoclonal antibodies, special culture techniques (shell viral assay), and quantitation of viral DNA by PCR methods.
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