Early neutralizing and glycoprotein B (gB)-specific antibody responses to human cytomegalovirus (HCMV) in immunocompetent individuals with distinct clinical presentations of primary HCMV infection

Background: Antibodies with functional anti-Human Cytomegalovirus (HCMV) ac tivity are likely to be involved in preventing virus dissemination and thus may contribute to minimize the clinical manifestations of infection. Objec tives: To investigate the role of humoral immunity in modulating the clinic al expression of primary Human Cytomegalovirus (HCMV) infection in immunoco mpetent persons. Study design: Neutralizing (NA) and glycoprotein B (gB)-sp ecific antibodies were quantitated in acute-phase and late-convalescence ph ase sera from 19 individuals who developed either HCMV mononucleosis (12) o r oligosymptomatic hepatitis (seven). Results: The levels of NA in sera dra wn early after infection were significantly lower in the former patients th an in the latter (P = 0.032). This difference was not related to either the total serum Ige levels and anti-HCMV IgGs avidity or to the presence of hi gher viral loads in blood, as assessed by detecting serum HCMV DNA by PCR, in patients experiencing mononucleosis. Increased NA titers were seen in al l available late-convalescence sera. In these sera, median NA levels were n ot significantly different among the study groups. Antibodies to HCMV gB of both IgG and IgM classes were detected in all acute-phase sera analyzed. M edian anti-gB IgG and IgM titers did not differ significantly between study groups. Likewise, the IgG subclass reactivity pattern against gB was found to be similar for both groups. Conclusions: The data revealed that an inte nse and early antibody response to gB developed in patients undergoing prim ary HCMV infection irrespective of the clinical manifestation of the diseas e. In contrast, a deficient NA response was observed in patients with HCMV mononucleosis versus that observed in patients displaying a milder form of disease-suggesting that the strength of NA response to HCMV generated early after infection might determine the severity of primary HCMV infection. (C ) 2000 Elsevier Science B.V. All rights reserved.