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

Abstract

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.

Fig. 1

Antibody levels of D. immitis-infected dog serum (No. 1) against crude extract antigens of three intestinal nematodes, measured by ELISA. Asterisk represents the range of optical density of control group.

Fig. 2

Antibody levels of D. immitis-infected dog serum (No. 2) against crude extract antigens of three intestinal nematodes, measured by ELISA. Asterisk represents the range of optical density of control group.

Fig. 3

Antibody levels of D. immitis-infected dog serum (No. 1) against crude extract antigens of three intestinal nematodes, measured by ELISA. Asterisk represents the range of optical density of control group.

Fig. 4

Protein fractions of adult T. canis were separated by SDS-PAGE stained with Coomassie brilliant blue R-250 (A), and antigenic cross reactions between T. canis antigens and sera from dogs experimentally infected with D. immitis by immunoblotting (B). Lane 1-3: uninfected serum, lane 4-6: sera collected at the period of prepatent infection, lane 7-9: sera collected at the period of patent infection (lane 1, 4, 7: dog 1, land 2, 5, 8: dog 2, lane 3, 6, 9: dog 3).