Cross-reactivity between sera from dogs experimentally infected with Dirofilaria immitis and crude extract of Toxocara canis

This study was performed to investigate whethere there is cross-reactivity between Dirofilaria immitis and three intestinal nematodes of dogs. In ELISA, D. immitis-infected dog sera obtained at the 4th molting stage (9-11 weeks) and microfilaremic stage (25-30 weeks) were shown to be highly reactive with crude extract of T. canis. In immunoblotting, some antigenic fractions, 44, 57, 88, 100 kDa of crude extract of T. canis, were found to be positive reaction with sera of dogs infected with D. immitis. However, little or no cross-reaction were observed between sera of D. immitis-infected dogs and crude extract antigen of T. vulpis or A. caninum. These result suggest that there are partial cross reaction between sera of D. immitis-infected dogs and the antigen of T. canis.

Immunological Responses of Dogs Experimentally Infected with Dirofilaria immitis

Three dogs were experimentally infected with Dirofilaria immitis. All dogs were euthanised at 30, 36 and 37 weeks after inoculation of D. immitis for the recovery of adult worms. Three cases accounted to 42.91 % recovery of inoculated worms. Serum samples from dogs experimentally inoculated with D. immitis were analyzed by ELISA and immunoblotting methods. Antibody titers of dogs detected by ELISA peaked between 7 and 14 weeks then decreased between weeks 15 to 24 followed by another increase during weeks 25 to 30 and persisted throughout the remainde of the experiment period. Analysis of adult D. immitis protein stained with Coomassie brilliant blue R-250 indicated separately more than 10 bands, and the major bands were 22, 40, 46, 56, 70, 72 and 89 kDa. Antigenic identification of extracts antigens of adults D. immitis by immunoblotting analysis revealed several bands from pooled sera of patent infection (30 weeks after inoculation). The detected bands were 24, 70, 80 and 110 kDa, 22, 72 and 84 kDa, and 58 and 72 kDa in dogs 1, 2 and 3, respectively. Results of antibody titers reached high levels on the 4th molting stage after inoculation of infective larva (L3), and reinforced previous findings that high molecular weight regions are detected in young animals.

Detection of antibodies in cats infected with filarial parasites by the indirect immunofluorescence technique.

The indirect immunofluorescence technique in cats infected with filarial parasites, Brugia malayi, B. pahangi and D. repens were studied. The antibody level in infected microfilaraemic cats was higher than that in infected amicrofilaraemic cats and uninfected cats. Papain-treated whole microfilariae appeared to be more sensitive than the sonicated antigen. The comparative IFA titres using papain-treated and sonicated microfilarial antigen, in the serodiagnosis of filariasis is presented.