Differences between N'Dama and Boran cattle in the ability of their peripheral blood leucocytes to bind antibody-coated trypanosomes

Current status of vaccination against African trypanosomiasis

Anti-trypanosomiasis vaccination still remains the best theoretical option in the fight against a disease that is continuously hovering between its wildlife reservoir and its reservoir in man and livestock. While antigentic variation of the parasite surface coat has been considered the major obstacle in the development of a functional vaccine, recent research into the biology of B cells has indicated that the problems might go further than that. This paper reviews past and current attempts to design both anti-trypanosome vaccines, as well as vaccines directed towards the inhibition of infection-associated pathology.

Innate and acquired resistance to African trypanosomiasis

The review discusses the current field status of human and bovine trypanosomiases, and focuses on the molecular basis of innate and acquired control of African trypanosomes in people, cattle, and Cape buffalo.

Detection of Trypanosoma congolense antibodies with indirect ELISAs using antigen-precoated microtitre plates

The study reports the performance of four indirect enzyme-linked immunosorbent assays (ELISAs) for antibody (AB) detection using microtitre plates which were precoated with native or heat/detergent denatured antigens (AGs) from Trypanosoma congolense (T.c.) and T. vivax (T.v.), and stored for between 1 to 206 days at +37 degrees C. Bovine serum samples were obtained by sequential bleeding of 3-months old T.c.-infected bulls and their uninfected cohorts, as well as by a single bleeding of uninfected adult cattle. The first day of AB detection, and observations on samples after this (defined as estimated ELISA sensitivity), depended on the cut-off value in the specific ELISAs. Cut-off values from pre- and early post-infection samples of individual animals demonstrated a seroconversion in all ELISAs on average after 10-15 days post-infection (dpi). The AB detection was delayed in the T.c. native and denatured AG-based ELISAs using cut-off points from uninfected cohort cattle (16.5 dpi, 19.3 dpi) and the adult cattle population (22.1 dpi, 25.0 dpi). The T.v. AG-based ELISAs however lacked crossreactiviy to T.c. ABs. The estimated sensitivity of each T.c. AG-based ELISA was above 96% throughout, but significantly lower for the T.c. native AG-based ELISA (91.1%) when the adult cattle derived cut-off point was used (p<0.01). The sensitivity of the phase contrast buffy coat technique was similar to the T.c. AG-based ELISAs, but significantly lower when the T.c. denatured AG-based ELISA was used at the adult cattle derived cut-off point (p<0.05). The implications of the results and future research aspects on ELISAs to detect trypanosomal ABs and AGs are discussed.

Potential of trypanotolerance as a contribution to sustainable livestock production in tsetse affected Africa

Tsetse transmitted trypanosomiasis is possibly the major constraint on livestock and agriculture development in Subsaharan Africa. Control of the disease has been based on vector control as well as on the use of trypanocidal drugs to treat or prevent infection in animals. Both control methods are effective but have proven not to be sustainable. Moreover, the development of a vaccine against trypanosomiasis is unlikely to be successful in the near future. On the other hand, trypanotolerant cattle, like the N'Dama can survive and produce in tsetse affected areas without interventions. This taurine breed has been indigenous to Africa for approximately 7,000 years and forms presently about 6% of the bovine population of Africa. Generally the N'Dama are kept in the rural areas by the small-scale farmer as a multi-purpose animal. Recent studies have defined management characteristics and assessed the production potential at the village level and under ranching conditions of N'Dama cattle exposed to various levels of tsetse challenge. Furthermore, experimental infections showed conclusively the superior resistance to the effects of infection of the N'Dama cattle when compared to zebu cattle and have confirmed that trypanotolerance is innate in N'Dama cattle. Studies have been conducted on development of protective humoral and cellular responses, the regulation of parasite multiplication and control of anaemia. These studies provided tools for identifying components of trypanotolerance. The ability to resist the development of anaemia in the face of infection, has shown to be correlated with the capacity to be productive; moreover, PCV values can serve as selection criterium for trypanotolerance. Subsequently, repeatabilities and heritabilities of trypanotolerance and performance traits were estimated.(ABSTRACT TRUNCATED AT 250 WORDS)