ANTIBODY RESPONSES OF YOUNG INFANTS TO NATURALLY OCCURRING VIRAL INFECTIONS
A fourfold rise in neutralizing antibodies was demonstrated for 45% of infants 1 through 6 months of age compared to 63% of older children or adults from whom an adenovirus or an enterovirus was recovered. This difference appeared to be related to severity of illness rather than to age, as there was no significant difference between young infants and older patients when only clinically severe illnesses were analyzed. The isolation of virus from more than one specimen increased the probability of a significant response in either age group. Infants with minor symptoms had a low frequency of significant fourfold antibody responses after virus isolation, but this was not significantly different from older children with minor symptoms. Failure to develop an increase in antibody titer could not be related to the presence of maternal antibodies.