Identificación de antígenos IgG2 específicos en tres cepas mexicanas de Anaplasma marginale

In order to identify Anaplasma marginale antigens associated with protection, susceptible animals were inoculated on three occasions with inactivated Mex-17 A. marginale initial bodies mixed with saponin or an oil-based adjuvant. Animals were challenge inoculated with strain Mex-30 on d 164. With the exception of two animals which died at challenge, all other immunized animals showed minimum clinical signs compared with control animals. At ELISA, positive antibody titers were observed in immunized whereas no titers were detected in controls. In vitro proliferation indexes (PI) for mononuclear cells cultured in the presence of extracts of the three strains were positive (³2.0) for all immunized bovines, whereas all both vaccinated an control animals developed PI after challenge inoculation. Western blot (WB) analysis of vaccinates sera showed recognition of antigens in a range between 15 to 209 kDa, of which eleven were specifically recognized by IgG2 in Mex-17 and Mex-30 strains. Additionally, a 52 kDa protein was observed in the Mex-15 extract by the sera of immunized and protected bovines. Two- dimension WB analysis of Mex-17 showed an additional 37 kDa protein that co-migrated with a band of similar molecular weight of MSP-2. Our results indicate that these eleven IgG2 specific proteins are associated with an immunoprotective response induced by vaccination. Four of these proteins correspond to previously characterized major-surface proteins and seven are novel antigens previously unreported for their immunoprotective properties.