- Highly conserved regions of the immunodominant major surface protein 2 of the genogroup II ehrlichial pathogen Anaplasma marginale are rich in naturally derived CD4+ T lymphocyte epitopes that elicit strong recall responses. Brown, W.C., McGuire, T.C., Zhu, D., Lewin, H.A., Sosnow, J., Palmer, G.H. J. Immunol. (2001)