Virus excretion and neutralizing antibody response in saliva in human cytomegalovirus infection

The local secretory immune mechanism in infants with cytomegalovirus infection was studied by a measurement of neutralizing antibody in saliva. Neutralizing antibodies were determined by the microculture plaque assay in 65 saliva specimens including 54 samples from cytomegalovirus-infected subjects and 11 from seronegative controls. In addition, cytomegalovirus isolation from saliva or urine or both and antibody determination in serum and saliva were simultaneously performed on seven infants with cytomegalovirus excretion over long periods. Results obtained were as follows. (i) Neutralizing antibodies were detected in 41 (76%) of 54 saliva specimens obtained from infected subjects but in none of the 11 seronegative controls. (ii) Neutralizing antibodies in saliva were of low titer but persistently detectable in all but one of the seven infants. No relationship was recognized between the cessation of virus excretion and the development of neutralizing antibodies in saliva. (iii) Virus-neutralizing activity was specifically found in the immunoglobulin A fraction of pooled saliva by diethylaminoethyl cellulose chromatography.