Cytomegalovirus infection in guinea pigs. II. Transplacental and horizontal transmission.

Transplacental transmission of cytomegalovirus (CMV) was demonstrated in guinea pigs, but transmission only occurred during acute primary maternal infection. Infectious CMV was isolated from 27 of 44 placental tissues and nine of 37 fetal tissues (including brain, lung, and kidney) tested five to 24 days after maternal infection. Fetal infection occurred at different stages of gestation ranging from 28 to 60 days. No virus was detected in the tissues of 43 fetuses examined that were taken from pregnant guinea pigs that had been infected for greater than 30 days. The maternal animals had significant levels of circulating neutralizing antibody concurrent with infectious CMV in the salivary glands at the time of sacrifice. Contact infection was accomplished when infected and uninfected animals of either the same sex or oppsite sexes were paired and housed together for one to three months. Among the seven male contact guinea pigs housed with infected females, five showed virus in their salivary glands, and all seven showed rises in titer of antibody; five of the females became pregnant. In contrast, when infected and uninfected animals of the same sex were paired and housed together, only one of 13 contact animals had virus in the salivary gland, and four of 13 had rises in titer of antibody. Thus sexual contact appeared to be more efficient than environmental contact in the spread of CMV infection.