[Virological studies on the feto-maternal tissues infected with rubella virus]

In studies on the congenital rubella syndrome, trans-placental rubella virus (RV) infection was investigated in vitro with human chorionic, decidual and fetal tissues obtained by artificial abortion from RV-infected pregnant women showing high hemagglutination-inhibiting and complement-fixing RV antibodies (1:512 and 1:16). RV was isolated from both chorionic (CR) and the fetal cells (FR) derived from RV-infected pregnant woman and the neutralization test disclosed that their antigenicity and biological properties were similar to that of the standard RV strain, M-33. These CR and FR cells showed a constant release of RV ranging from 2 to 4 log10 FFU (focus forming unit)/0.1ml into the culture media. Moreover, positive staining by immunofluorescent technique (IF) over 70 days seems to indicate RV persistent infection in these cells. However, decidual cells derived from RV-infected pregnant woman gave negative results in the RV release and IF staining. The above evidence strongly indicates that the chorionic cells are easily infected and converted to the RV-carrier. One possible mode of trans-placental RV infection is via an initial infection of the chorionic cells followed by the establishment of persistent RV infection.