title: Prospects for vaccination against pathogenic African trypanosomes.
abstract: African trypanosomes cause human and animal African trypanosomiases, which are chronic, debilitating and often fatal diseases of people and livestock in sub-Saharan Africa. The extracellular protozoan parasites are exemplars of antigenic variation. They direct host-protective B-cell and T-cell immune responses towards hypervariable components of their variable surface glycoprotein coat and evade immune elimination by generating new surface coat antigenic variants at a rate that supersedes immune destruction. This results in recurring waves of parasitemia, tissue invasion and escalating immunopathology in trypanosomiasis-susceptible hosts. Here, we discuss the possibility that host control of African trypanosomes might be improved by immunization with conserved VSG peptides and invariant surface glycoproteins. Infection-induced T-cell recall responses to these typically poorly expressed or nonimmunogenic parasite components induce tissue phagocytes to produce microbicidal materials that kill trypanosomes. Preliminary data that support this immune-enhancing vaccine strategy are discussed, as are host and parasite interactions that might downregulate the protective responses. These include infection-induced immunosuppression and increasing virulence of infecting parasites over time.
authors.affiliation: Department of Veterinary and Animal Sciences, University of Massachusetts-Amherst, Amherst, MA, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Black
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Mansfield
mesh_terms: D017954:Africa South of the Sahara; D000818:Animals; D000940:Antigenic Variation / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D018512:Parasitemia; D016052:Protozoan Vaccines / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D014345:Trypanosoma / Q000276:immunology*; D014353:Trypanosomiasis, African / Q000469:parasitology / Q000517:prevention & control*; D014611:Vaccination
chemical_list: D016052:Protozoan Vaccines
keywords: parasite; tools and techniques; trypanosoma spp; vaccination