Immune Response To Neospora Caninum Native Antigens And Recombinant Proteins Formulated With Immune Stimulating Complexes In Heifers

HECKER YP; VERNA A; CÓCERES V; IDÁRRAGA S; LEUNDA MR; CANO D; PEREYRA S; ODEÓN AC; CAMPERO CM; MOORE DP

Buenos Aires

Congreso; Proceedings 23rd International Conference of the World Association for Advancement of Veterinary Parasitology; 2011

The aim of this study was to compare the immune responses to live Neospora caninum tachyzoites, native antigens and recombinant proteins formulated with immune stimulating complexes (ISCOMs) in seronegative pregnant heifers. To prepare the either the live tachyzoites or the native antigens, the Nc6 strain was used. Twenty seronegative pregnant heifers were involved: 4 were inoculated intravenously with 1x108 live tachyzoites (Group A); 4 were inoculated with native antigens obtained from tachyzoites (750ug/dose) formulated with ISCOMs (Group B); 4 were inoculated with a mix of four recombinant proteins (SAG1, PIs, Hsp20, GRA7 (30ug of each protein/dose)) also formulated with ISCOMs (Group C); 3 received ISCOMMATRIX(Group D) and 3 were controls receiving PBS (Group E); all these last four groups were inoculated twice by subcutaneous via with interval of 21 days previous mating. The recombinant proteins were engineered to be expressed in Escherichia coli and purified in nickel resine. The animals were bled weekly to assess immune parameters. After vaccination and mating, the animals will be challenged using Nc1 strain at day 70 of gestation. The humoral immune response was evaluated by indirect fluorescence antibody test (IFAT). Whole blood samples were stimulated to asses IFN-ã production by using a commercial ELISA. The cellular immune response will be also evaluated by flow cytometry. Preliminary serological results showed that in week 2 after first dose, there were Neospora specific antibodies developed in animals from Groups A and B but antibody responses were higher in Group A compared with Group B. However, after the seconddose, the animals in group A antibody titles ranged between 3200 to 6400 as the animals of group B. Therefore, after second dose, antibody titers developed by the group A and B were similar. On the other hand, the animals in group C did not develop antibodies. The other experimental groups did not show titles to IFAT. Currently, cellular immune response is being characterized. After euthanasia, tissues will be obtained for further histological and PCR analysis.