LOCALIZATION OF T-CELL AND B-CELL STIMULATING DOMAINS OF THE IMMUNODOMINANT 33-KDA PROTEIN OF ONCHOCERCA-VOLVULUS (OV33)

The localization of T and B cell epitopes on a well characterized 33-k Da protein of the filarial nematode Onchocerca volvulus (Ov33) was stu died using peripheral blood mononuclear cells (PBMC) and sera from a t otal of 52 onchocerciasis patients with the generalized form of infect ion, A proportion of the PBMC samples proliferated in response to reco mbinant Ov33-GST fusion protein and to fusion free Ov33-6xHis. Prolife rative responses of patient PBMC to seven truncated Ov33-6xHis polypep tides and to three synthetic peptides revealed at least one major and two minor T cell epitopes in the protein. The dominant T cell stimulat ing domain was localized between amino acids 113 and 143. ELISA studie s with the Ov33-GST fusion protein revealed that patient sera containe d Ov33-specific IgG1, IgG4, IgE, and IgM antibodies. Analysis of the I gG4 response with 10 truncated Ov33 polypeptides identified four B cel l stimulating domains in the N-terminal, central, and C-terminal regio n of the molecule. The B cell domain recognized by the majority of ser a was localized between amino acids 113 and 143, The data indicate tha t this region of the protein is the major T and B cell stimulating dom ain of Ov33 and might be relevant for vaccine development and for impr oved immundiagnosis of onchocerciasis. (C) 1997 Academic Press.