Antibody responses to human cytomegalovirus-specific polypeptides studied by immunoblotting in relation to viral load during cytomegalovirus infection.

The humoral immune response to individual proteins of human cytomegalovirus (CMV) was studied by immunoblotting. CMV polypeptides present in an extract of CMV-infected fibroblasts in a late stage of infection were recognized by sera of healthy seropositive individuals and transplant recipients who suffered from a primary or secondary CMV infection. The results showed that the sera reacted with a maximum number of 18 polypeptides ranging in molecular weight from 28-235 kDa. In 60% or more of the healthy seropositives, polypeptides were recognized with an apparent molecular weight of 150, 98, 94, 58, 50, 44, 38, and 32 kDa. In the patient group, the most immunogenic polypeptides were those with an apparent molecular weight of 150, 104, 94, 66, 50, 38, and 32 kDa. A correlation was found between the antibody levels in sera from the healthy seropositives and the number of recognized polypeptides but no such relationship was seen in the transplant recipients. However, sera of patients with a high virus load during their secondary CMV infection, as detected by the CMV-antigenemia test, appeared to react less frequently and less intensely with the polypeptides than those with low viremia. A high number of antigen-positive leukocytes in the CMV-antigenemia test was related to a low frequency of polypeptides with molecular weights of 85, 76, 66, 44, 38, and 32 kDa recognized before transplantation.