Background: Women with naturally acquired serum antibodies to cytomegalovirus (CMV) are usually protected against both frequent secondary infection and giving birth to infants severely affected by intrauterine CMV infection.
Objective: To determine the feasibility of using a live attenuated strain of CMV (Towne) to achieve immunity similar to that provided by wild-type infection, we evaluated a new lot of the Towne strain of CMV in 3 open label trials involving 68 men, 63 women of childbearing age and 13 children, respectively.
Results: Mild local reactions occurred among approximately one-third of subjects. There were no systemic reactions. All 45 subjects tested developed lymphoproliferative responses to CMV. CD8+ class I-restricted cytotoxic T cell responses specific for CMV antigens were detected in three of four subjects and persisted for 6 months. Neutralizing titers were maximal at 2 to 4 months postimmunization, were dose-dependent and were comparable to those induced by natural infection.
Conclusion: These results support further evaluation of the Towne strain of CMV in women at risk for acquiring CMV infection during pregnancy or among children transmitting CMV to pregnant women.