Figure 3.

Vaccine-induced protection in gerbils immunized with BmHAT followed by three trickle booster infections with B malayi L3 were determined by three different approaches. (A) Adult worms recovered from the organs of vaccinated gerbils were counted to determine the percent protection compared to trickle infection only group (B) Protective responses in vaccinated gerbils were assessed by a micropore chamber challenge method (C) Presence of protective antibodies in the serum of vaccinated gerbils were determined by evaluating the ability of these antibodies to participate in the killing of B malayi L3 in an ADCC assay. BmHAT prime boost group was used as the positive control and pVAX-1/adjuvant controls were used as the negative controls. *P<0.05, **P<0.01 and ***P<0.001 compared to negative controls and ⁺⁺⁺P<0.001 compared to L3 trickle infection only group. (D–F) B. malayi L3 were observed under the microscope 48 hours after the ADCC assay. Larvae present in wells containing control gerbil serum were coiled and moving without any cells adhered to them (D), while those L3s from the wells that contained serum from vaccinated gerbils were straight and dead with cells adhered to the larval surface (E&F). Photographs taken at 100X magnification.