EXPRESSION OF AN ONCHOCERCA-VOLVULUS OV33 HOMOLOG IN DIROFILARIA-IMMITIS - POTENTIAL IN IMMUNODIAGNOSIS OF HEARTWORM INFECTION

In this study, the expression of an Onchocerca volvulus Ov33 homolog w as demonstrated in Dirofilaria immitis. Rabbit antiserum raised agains t a recombinant fusion protein of O. volvulus, MBP/OvD 5B (Ov33), was found to react with a 31-33 kDa glycoprotein (DiT33) of adult worms of D. immitis. An antibody response to MBP/OvD 5B was observed in dogs, as early as II weeks post infection with infective larvae of D. immiti s, and in dogs with occult infection. Cats both experimentally and nat urally infected with D. immitis also reacted strongly with the recombi nant antigen. In contrast, sera from dogs receiving chemically-abbrevi ated infection or from animals harbouring a variety of other helminths failed to react. These data suggest that antibody responses generated by DiT33 may have potential in immunodiagnosis of heartworm infection in cats and dogs.