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Cell-mediated immune responses in 27 infants and children with cytomegalovirus (CMV) infection acquired between birth and 1 year of age were compared with responses in 13 children who had neonatal herpes simplex virus (HSV) infection. Infection was asymptomatic in 25 of 27 CMV-infected children; the 13 patients with HSV infection were all ill as newborns. The median age when studied was 46 months for children infected with CMV and 24 months for those infected with HSV. We measured lymphocyte transformation responses (LTRs) to CMV antigens in the former group and to HSV type 1 (HSV-1) (and in six cases to HSV-2) in the latter group, with the results expressed as a stimulation index. Based on the results in seropositive and seronegative adult control subjects, stimulation indexes of greater than or equal to 3 were considered indicative of a positive LTR. Among the CMV-infected children, a positive LTR was observed in 0 to 13 assays performed before 1 year of age, 3 of 8 assays performed between 1 and 4 years of age, and 9 of 15 assays performed over 4 years of age. In contrast, a positive LTR to HSV-1 was seen in 15 to 18 assays performed in children under 1 year of age and in 14 of 16 assays performed in survivors of neonatal HSV infection older than 1 year. Six HSV-2-infected patients were tested simultaneously 13 times with HSV-1 and HSV-2 antigens. Those patients under 6 months of age responded similarly to each antigen, whereas those who were older had significantly higher LTRs to HSV-2. Children with CMV infection that was acquired early had persistently diminished specific LTRs. In contrast, after neonatal HSV infection, LTRs to HSV were present even in infancy and became more specific for the infecting type with increasing age.

Congenital or perinatally acquired human cytomegalovirus (CMV) infections in children may be symptomatic or asymptomatic. In this study, we characterized the electrophoretic properties of CMV-infected cell polypeptides immune-precipitated by sera from children with different types of CMV infections from birth to 4 years of age. Sodium dodecyl sulfate-polyacrylamide gel analysis of immune precipitates formed with radiolabeled extracts of cells infected with CMV strain AD169 showed the following. (i) Electrophoretic profiles of CMV polypeptides immune-precipitated by sera from children with perinatal and congenital infections were similar. At least 11 polypeptides with apparent molecular weights of 150,000, 140,000, 110,000, 100,000, 74,000, 66,000, 50,000, 49,000, 34,000, 25,000, and 20,000 were precipitated. Antibody titer in anticomplement immunofluorescence tests and virus titer in urine correlated with the intensity of polypeptide profiles in autoradiograms. (ii) The initial immune response of children with symptomatic congenital infections was delayed as compared to that of children with asymptomatic congenital and perinatal CMV infections. Sera obtained serially from symptomatic children for years after birth continued to precipitate CMV polypeptides, whereas sera from children with subclinical congenital infections precipitated lesser amounts over time. (iii) Immune precipitates obtained with sera from CMV-infected patients and with monoclonal antibodies to CMV contained polypeptides with comparable electrophoretic and immunological properties.

Use of an antigen consisting of purified isolated nuclei from a mixture of human cytomegalovirus-infected and uninfected fibroblasts in a 2:1 ratio is a simple and reliable method for eliminating nonspecific fluorescence associated with the presence of Fc-immunoglobulin G receptors in the cytoplasm of infected cells. The specificity obtained with this antigen on 100 normal human sera was 99, 100, and 98% when compared with microneutralization, anticomplement immunofluorescence, and conventional indirect fluorescent-antibody assays, respectively. Also, 95% of the antibody titers obtained with the nuclear antigen had a perfect correlation with or were within a fourfold-dilution difference of the antibody levels obtained by anticomplement immunofluorescence and the conventional indirect fluorescent-antibody test.

Immunoglobulin M (IgM) antibodies were detected by a commercially available enzyme-Linked Immunosorbent Assay (ELISA) in 36 of 49 (73%) pregnant women with primary cytomegalovirus (CMV) infection. A positive ELISA-IgM result occurred in 10 of 13 patients (77%) assessed within 8 weeks of seroconversion. The sensitivity of the radioimmunoassay (RIA) to identify primary infection in pregnant women was comparable, 78% in general and 86% for women tested within 16 weeks of seroconversion. Of the 36 women with primary infection who had detectable IgM antibodies by ELISA, 25 (69%) were delivered of congenitally infected infants, whereas of the 13 with undetectable IgM antibodies, 7 (54%) transmitted the infection in utero. IgM antibodies were detected by ELISA in only 5 of 43 (11%) women who experienced a recurrence of CMV which either did or did not result in congenital infection. RIA was less likely to measure CMV-specific IgM in recurrent infection, inasmuch as 1 of 19 (5.2%) women with proven recurrent infection had detectable IgM antibody, giving RIA a better specificity for primary infection. Specific IgM antibodies were detected by ELISA in 42 of 61 (69%) babies congenitally infected with CMV and in 4 of 70 (5.7%) uninfected control newborn infants. The RIA was superior for diagnosis of congenital CMV infection, with a sensitivity of 89% and a specificity of 100%. The lower sensitivity of the ELISA-IgM occurred in the category of congenitally infected infants born to mothers with recurrent infection (43%), a group that is at the lowest risk of disease or to develop sequelae. This commercially available ELISA-IgM could be used in combination with a CMV-specific IgG test for monitoring women during pregnancy for primary infection.

Paired sera from 150 pregnant women and 387 umbilical cord sera were tested for BK virus (BKV) antibodies. The hemagglutination inhibition, neutralization, and indirect immunofluorescence tests were employed for the detection of antibodies. Treatment of serum with anti-gamma Fc and tests of immunoglobulin M (IgM) fractions for antibodies were utilized as required to detect and validate the presence of virus-specific IgM. The BKV antibody prevalence in the sera collected at the time of the first prenatal visit was 75% by hemagglutination inhibition and 91% by neutralization tests. A total of 95% of the women had antibodies by at least one of the three serological tests. Five of 100 women with normal pregnancies exhibited BKV activity during pregnancy as evidenced by a greater than fourfold rise in BKV hemagglutination inhibition antibody titers and acquisition of BKV-specific IgM. The antibody rise occurred in the younger women and appeared to be a result of reactivation of the virus rather than of primary infection. Two instances of possible recent BKV infections were identified. BKV-specific IgM was not detected in any of the 387 umbilical cord sera which included three specimens from infants born to mothers with definite or probable BKV activity during pregnancy and 50 specimens with IgM levels of > 20 mg/100 ml. The results indicate that few women in the child-bearing age are nonimmune to BKV and that, although reactivation of infection occurs in pregnancy, congenital transmission of the virus either does not occur or is rare.