Immune Response of Hosts and Prospects of Vaccine Development against African Trypanosomes: The Review

Abstract

African trypanosomiasis, a parasitic infection caused by flagellated extracellular parasites that survive in the tissue fluids and the bloodstream, encompasses a number of diseases affecting both humans and animals. Although hosts acquire infection principally via the bite of infected tsetse flies, other haematophagus insects like Tabanids and Stomoxysspecies also transmit trypanosomiasis mechanically. African trypanosomes are exposed to the host immune system from the time of infection. Antigenic variation is the immune evasion strategy that has evolved in African trypanosomes. Currently, there are no effective vaccines against African trypanosomiasis, neither for humans nor for livestock. Initially, vaccine trials against African trypanosomiasis, started targeting the surface coat of the parasite. In principle, this surface protein would be an idea vaccine candidate, if it were not for the antigenic variation strategy that the parasites have cunningly evolved. While a vaccine against African trypanosomiasis is not an immediate prospect, but there are several promising avenues for immunological exploration, namely, trypanosomes attenuated in in vitro and in vivo culture systems, genetic engineering, cross-reacting subcellular fractions, variant antigen types and metacyclic antigen. . It is likely, if any one of these areas is rewarding, that the resulting vaccine will be more successfully exploited, at least initially, in trypanotolerant animals. Since discovery of more efficacious drug is slow and the development of resistance of the existing drug, vaccination is viewed as the most promising sustainable method of controlling African trypanosomiasis.

Keywords: Immune Response, Vaccine, Trypanosomes