Fig. 4.

Immunoblot analysis of the serological responses in mice following immunization and challenge by tick bite. Whole-cell lysates of B. hermsii DAH (panels a-c) and B. hermsii LAK-3 (panels d-f) were tested with individual mouse serum samples (M1-M5) from each of the 6 groups of mice immunized with rVtp Type 5, rVtp Type 6, or only the adjuvant. Mice challenged with the strain producing the same Vtp as the vaccine were protected from infection, and showed no expansion of antibodies after challenge other than to the vaccine (the ~20 kDa protein) (panels b and f). Mice immunized with the heterologous rVtp (panels c and e) or only the adjuvant (panels a and d) became infected and showed an expanded antibody response after challenge, although the response was weaker in some animals (panel c). One mouse in the LAK-3 homologous challenge group (panel f) died before the final serum samples were collected. * indicates the mouse that was infected from the second challenge. (−) shows serum samples from non-immunized, uninfected mice. Molecular mass standards are shown in kDa