Vaccination with recombinant filarial paramyosin induces partial immunity to Brugia malayi infection in jirds

Vaccination with irradiated infective larvae induces partial protective immunity to infection with the filarial nematode Brugia malayi in jirds. Prior studies have shown that such immunization stimulates a much stronger antibody response to recombinant and native filarial paramyosin than that seen after normal infection. To determine whether vaccination with recombinant paramyosin could induce protective immunity to larval challenge, jirds were immunized with either B. malayi paramyosin and maltose binding protein (BM5-MBP) (fusion protein of B. malayi paramyosin and maltose- binding protein), MBP alone, or recombinant Dirofilaria immitis paramyosin. Animals were challenged with 100 infective larvae s.c. 8 wk after the second immunization. Necropsies were performed 16 wk after challenge. Vaccination with BM5-MBP induced significant protective immunity; adult worm recoveries, worm lengths, and blood microfilaria counts were reduced in the BM5-MBP group relative to the MBP control group. The reductions in adult worm recoveries (43%) and female worm lengths (10%) were statistically significant (p < 0.05). Interestingly, protective immunity was not induced by immunization with D. immitis paramyosin. Additional studies are needed to identify mechanisms involved in protective immunity induced by BM5-MBP and to understand the differential activity of the two closely related recombinant paramyosin proteins in this model.