CHARACTERIZATION OF CANINE HUMORAL IMMUNE-RESPONSES TO OUTER SURFACE PROTEIN SUBUNIT VACCINES AND TO NATURAL INFECTION BY LYME-DISEASE SPIROCHETES

Canine antibody responses to Lyme disease subunit vaccines and to natu ral borrelial infection were investigated. Vaccines were formulated wi th QS21 and outer surface proteins A (OspA) and B (OspB) derived from Borrelia burgdorferi B31. Vaccines containing QS21 and the lipoprotein s gave 4-fold higher IgG1 and 8-fold higher IgG2 antibody responses th an without QS21. Antisera to lipidated OspA or OspB vaccines containin g QS21 had high antiborrelial activity against isolates B31 and CA-2-8 7, similar to those with a vaccine containing both OspA and OspB. Only the combination vaccine induced antiborrelial activity against hetero logous isolates 24008 Fr and Borrelia garinii G25. Nonlipidated OspA- and OspB-based vaccines with QS21 elicited lower antibody and antiborr elial activity than did lipidated OspA and OspB vaccines; 49% of natur ally exposed dogs had low titers to OspA or OspB. Thus, vaccines using lipidated OspA, OspB, and QS21 could induce higher antiborrelial acti vity than did natural exposure.