Identification of IgG2 specific antigens in three Mexican Anaplasma marginale strains.

摘要

In order to identify Anaplasma marginale antigens associated with immune response, 10 crossbred heifers were inoculated on three occasions with inactivated Mex-17 A. marginale initial bodies mixed with saponin or an oil-based adjuvant. The animals were also challenged with strain Mex-30 on day 164 and with the exception of two animals which died at challenge, all other immunized animals showed minimum clinical signs compared with control. At ELISA, positive antibody titres were observed in immunized whereas no titres were detected in controls. In vitro proliferation indexes (PI) for mononuclear cells cultured in the presence of extracts of the three strains were positive for all immunized bovines, whereas both all vaccinated and control animals developed PI after challenge inoculation. Western blot (WB) analysis of vaccinated 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 comigrated with a band of similar molecular weight of MSP-2. It is suggested that 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..