Three hundred and twenty-two single sera from children (newborn to 9 years old), young adults (18-20 years of age), pregnant women and theircord sera, and elderly people (more than 70 years old) were tested for antibodies specific to enteric adenoviruses (species 40 and 41) using neutralization test. All sera were also tested for specific antibodices to common antigen of adenovirus by enzyme immunoassay. The rate of acquisition of antibodies to Ad 40 and/or 41 increased with age. Sera of children from 1 to 6 months old, and from 37 to 48 months of age, revealed antibodies to Ad 40 and/or 41 in 20.0% and 50.0% of samples, respectively. Forty eight percent of sera collected from young adults showed positive antibodies to Ad 40 and/or 41 and the positive rate was as low as 10.0% among aged people. Nineteen percent of paired sera from patients with acute gastroenteritis showed a significant rise in antibodies to Ad 40 and/or 41. Forty two percent of the same paired sera showed significant rise of antibodies specific to rotavirus by enzyme immunoassay. All sera tested reacted positively to common antigen of adenoviruses when determined by enzyme imunoassay.
Thirty-four stool specimens, collected from patients with acute gastroenteritis and shown to contain adenovirus by electron microscopy, were divided into three groups by different dates and soures collected. Fourteen stool specimens (Group 1) were inoculated onto 293, HEp-2, and human embryonic kidney cell cultures. Of 14 specimens exmined, nine induced cytopathic effect (CPE) on primary inoculation in 293 cells. On serial passage of the progeny virus from three cell cultures, it was found that six of these isolates in three cell cultures acquired the ability to grow in cell at passages 2 and 3 materials. By use of DNA restriction enzyme analysis, and neutralization test, seven of 12 (58%) adenoviruses were identified as enteric adenoviruses 40 and 41 (Ad 40 and Ad 41). On further serial passage of the progeny virus from each passage of cell cultures to other cells, cytopathic effect became unclear or diminished after further subcultures. Of the specimens of group 1 to 3, co-cultivation of isolates and 293 cells were compared to conventional isolation assay. The former was more sensitive than the latter for isolation and subculture of enteric adenoviruses. The detection of enteric adenoviruses by use of DNA restriction enzyme analysis from primary infected 293 cells was more effective than that of direct isolation from stool specimens. Five specimens of three groups determined as Ad 41 showed three different migration patterns of DNA restriction analysis by using Sma I and Hind III in each assay. Seroconversion to homogeous virus antigen were demonstrated in all five paired serum samples from patients shedding adenoviruses. One of the patients showed a dual fnfection with Ad 1 and Ad 40 by serodiagnosis.