Immune response to Neospora caninum native antigens formulated with immune stimulating complexes in calves

MOORE DP; ECHAIDE I; VERNA A; LEUNDA MR; CANO A; PEREYRA S; ZAMORANO PI; ODEÓN AC; CAMPERO CM

VETERINARY PARASITOLOGY

ELSEVIER SCIENCE BV

Año: 2011 vol. 175 p. 245 - 251

0304-4017

The aim of this study was to compare the immune responses to live Neospora caninum tachyzoites and N. caninum native antigens formulated with immune stimulating complexes matrix (ISCOM-matrix) in calves. Fifteen calves were used in this study: 3 were intravenously inoculated with 1×108 live tachyzoites (Group A), 3 were inoculated twice with N. caninum native antigens formulated with ISCOMs (Group B); 3 with N. caninum native antigens in phosphate-buffered saline (PBS) (Group C); 3 received ISCOM-matrix (ISCOMs without antigen) (Group D) and 3 were negative controls receiving PBS (Group E). The last four groups were inoculated subcutaneously. The specific total IgG and its subtypes were analyzed by an indirect enzyme-linked immunosorbent assays (ELISAs) and by Western blot. IFN-gamma levels in plasma were quantified using a commercial kit. All calves were challenged intravenously with 1×108 live tachyzoites at week 11 after receiving the first dose. Parasitemia was assessed in plasma samples by semi-nested PCR. Neospora-specific antibodies were detected in animals from Groups A and B in the week 2 after inoculation. The ELISA OD values were higher in Group B compared with Group A from weeks 6 to 11 (P < 0.05). Analysis of the subisotype specific antibodies in experimentally infected calves revealed a predominant IgG2 response; however, a predominant IgG1 response was observed in animals inoculated with N. caninum native antigens formulated with ISCOMmatrix. Control calves remained seronegative until challenge infection. The pattern of bands by Western blot was similar when testing sera from animals in Groups A and B. The levels of IFN-gamma production after respective immunization schedules were similar between Groups A and B. Neospora-DNA was detected in plasma samples shortly after intravenous challenge in calves from all groups including those receiving the experimental vaccine formulation. The duration of the parasitemia was similar in all groups.