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Epstein-Barr virus (EBV) DNA loads in peripheral blood mononuclear cells (PBMCs), plasma, and saliva, as well as infectivity of the virus in saliva, were evaluated in 20 patients for 6 months after the onset of infectious mononucleosis (IM). All patients displayed sustained high EBV DNA loads in the saliva, associated with a persistent infectivity of saliva at day 180. EBV DNA load in PBMCs decreased significantly from day 0 to day 180 (in spite of a viral rebound between day 30 and day 90 in 90% of the patients), and EBV DNA rapidly disappeared from plasma. These data show that patients with IM remain highly infectious during convalescence.

A patient with chronic T cell lymphocytic leukaemia developed a monoclonal immunoglobulin (IgG3 kappa = 14 g/l) which was in part cryoprecipitable. At the same time, a subclinical CMV infection occurred which was associated with a neutropenia and thrombocytopenia, and which led to a rise in anti-CMV antibodies. The F(ab')2 fragment of IgG3 kappa, obtained by enzymatic cleavage, was examined for several antiviral activities and it was found to have a strong anti-CMV activity using the immunofluorescence test with anti-kappa conjugate. This is one of the few examples of a cryoglobulin with specific antiviral activity. The leukaemia, possibly together with immunosuppressive therapy, may have been responsible for the uncontrolled proliferation of the clone producing the cryoimmunoglobulin.

Cytomegalovirus (CMV) was isolated in cell cultures derived from 2 of 11 nasopharyngeal carcinoma (NPC) biopsy specimens from North African patients. All these cases were Epstein-Barr virus (EBV)-associated NPC. Morphologic cytopathic changes and viral replication not associated with EBV were observed after 2 months in culture. Virus identification was achieved by immunofluorescence studies, and cell culture antigens were tested by the use of complement fixation and indirect hemagglutination. All these NPC patients had been infected by herpes simplex virus, varicella-zoster virus, and CMV, but the antibody titers determined by complement fixation and immunofluorescence were normal. CMV, which is not associated with this cancer, could nevertheless favor carcinogenesis in facilitating fusion between epithelial cells and EBV-positive lymphocytes.