The immunologic response of guinea pigs immunized with experimental formalin-inactivated EEE vaccines was studied. In whole sera obtained from guinea pigs immunized with either CETC or WCED vaccines, HI antibody was first detected on day 3, N antibody was present on day 7, and CF antibody reached a detectable level on day 10 after immunization. Antibody detected in the HI, CF, and N tests persisted through day 21 (day of ic challenge). Quantitatively higher levels of N antibody and greater resistance to ic challenge was found in guinea pigs immunized with CETC vaccine when compared with the WCED-immunized group of animals.
The fractionation studies on sera obtained as late as 10 days demonstrated that both HI and N antibody were found in association with 19S and 7S immunoglobulins. CF antibody was not detected in the guinea-pig sera until the 10th day of the immunization schedule, when it was found in association with the 7S fractions. All antibody activity present on day 21 and potentially associated with protection against an ic challenge was 7S in nature.
Present address: National Drug Co., Swiftwater, Pennsylvania.
Associate Professor of Biology, The Catholic University of America, Washington, D. C.