Prospects for recombinant vaccines against Babesia bovis and related parasites

Abstract

Babesial parasites infect cattle in tropical and temperate regions of the world and cause significant morbidity and mortality. Discovery of protective antigens that could be used in a killed vaccine has been slow and to date there are few promising vaccine candidates for cattle Babesia. This review describes mechanisms of protective innate and adaptive immune responses to babesial parasites and different strategies to identify potentially protective protein antigens of B. bovis, B. bigemina, and B. divergens. Successful parasites often cause persistent infection, and this paper also discusses how B. bovis evades and regulates the immune response to promote survival of parasite and host. Development of successful non-living recombinant vaccines will depend on increased understanding of protective immune mechanisms and availability of parasite genomes.

Label-free detection of Babesia bovis infected red blood cells using impedance spectroscopy on a microfabricated flow cytometer

“…Members of the genus Babesia are transmitted by ixodid ticks to a broad variety of vertebrate hosts, including domestic and wild animals and some species infect humans . B. bovis parasites are endemic in many tropical and subtropical regions worldwide causing anaemia due to extensive haemolysis and other symptoms (Brown et al, 2006).…”

Attenuated vaccines for tropical theileriosis, babesiosis and heartwater: the continuing necessity

“…Calves are more resistant to disease than older cattle, and this age-linked resistance is thought to be the result of natural killer cell responses in the spleens of young animals [40]. The mechanism of acquired immunity seems to rely on the rapid activation of memory and effector CD4 + T helper cells that secrete IFN-g, thereby activating phagocytic cells and enhancing antibody production by B cells [39][40][41].…”

“…has been slow. Immunization with native or recombinant rhoptry-associated proteins (RAP-1), which are targeted immunogens for vaccine development of B. bovis and B bigemina, reduced parasitemia in infected cattle [40,42]. Immunization with the N-terminal region containing immuno-dominant T-cell epitopes of B. bovis imparted no protection, despite specific RAP-1 immunoglobulin G and CD4 + T-cell responses to challenge [41].…”

“…Immunization with the N-terminal region containing immuno-dominant T-cell epitopes of B. bovis imparted no protection, despite specific RAP-1 immunoglobulin G and CD4 + T-cell responses to challenge [41]. Because immuno-dominant antigens eliciting strong cellmediated immune responses failed to confer protective immunity, it has been suggested that identification of subdominant antigens might be important for an effective vaccine [39][40][41][42]. The annotation of the B. bovis genome sequence should enable effective antigens to be identified.…”

“…The annotation of the B. bovis genome sequence should enable effective antigens to be identified. A protective vaccine might need to include multiple antigens [39] and its formulation would require a better understanding of antigenic diversity, mechanisms used by Babesia to evade host immunity and the heterogeneity of the bovine major histocompatibility complex class II molecules [40,[42][43][44].…”