August 2013 Our paper Whole-Genome Sequencing of Trypanosoma brucei Reveals Introgression between Subspecies That Is Associated with Virulence marks a departure for us into the genetics of trypanosomes associated with human disease. We describe an analysis of multuple Trypanosoma brucei strains that suggests that T. brucei gambiense and T. brucei rhodesiense are much closer than previously thought and we identify loci that might be associated with differences in pathology between different groups of trypanosome strains.
October 2012: Our paper Trypanotolerance in N'Dama x Boran crosses under natural trypanosome challenge: effect of test-year environment, gender, and breed composition, BMC Genetics 2012 shows that avoidance, resistance and tolerance of the indigenous Kenyan Boran cattle breed to infection with African trypanosomes can all be improved by crossing with West African N'Dama cattle even under field conditions in the Masai Mara where there is intense trypanosome transmission.
November 2012: Our paper Novel SNP Discovery in African Buffalo, Syncerus caffer, Using High-Throughput Sequencing. PLoS ONE 2012 7(11) describes a large set of SNP in African buffalo. African buffalo are infected with trypanosomes but show no signs of disease so provide a valuable genetic model of trypanotolerance. The new data can be queried to obtain sets of SNP suitable for PCR-RFLP assays or for SNP in genes or regions of interest from our Cape Buffalo SNP web page.
May 2011: Our consortium paper Genetic and expression analysis of cattle identifies candidate genes in pathways responding to Trypanosoma congolense infection published by PNAS. The paper describes two genes, ARHGAP15 and TICAM1, that appear to regulate the difference in response to infection between N'Dama and Boran cattle. This paper has been reported by the BBC World Service Science in Action and online at AllAfrica.com and the news service of the UN office for humanitarian affairs IRIN news. Watch this film: "Battling A Killer Cattle Disease", to learn more about this paper. More coverage on the background to this discovery is on ILRI blogsite
April 2011: The film unit at the International Livestock Research Institute (ILRI) has released a new film showing how to treat bovine trypanosomiasis
The Bovine Trypanosomiasis Consortium is a network of scientists in the UK, Africa and the USA studying how African cattle respond to infection with trypanosome parasites. Trypanosomiasis in cattle is caused by Trypanosoma congolense and Trypanosoma vivax and is similar to sleeping sickness in humans which is caused by Trypanosoma brucei ssp. Both human and cattle trypanosomes are transmitted by tsetse flies. There are many breeds of African cattle, some such as N'Dama, have been in Africa for thousands of years whilst other zebu breeds, such as Boran, have been introduced more recently from India. The indigenous African cattle do not suffer such severe symptoms of disease and are said to be trypanolerant. The Indian derived zebu breeds are much more susceptible to the disease but are preferred by farmers for plowing and haulage, which are essential to agriculture. By understanding how the genetic differences between these breeds regulate differences in their immune response we expect to be able to develop new ways of treating infected cattle or new ways of breeding cattle that tolerate infection whilst having the characteristics that the farmers need.
We have used microarrays to study how each of the 25,000 genes in a cow respond to infection. This information can show us which physiological systems are responding to infection. The genes that respond differently between the susceptible and resistant breeds are giving us clues to the how the resistant animals protect themselves.
Genome sequencing technology is improving very rapidly and the cost of sequencing a genome has fallen over 5000 fold in the last ten years. We have used this new technology to sequence the genomes of African N'Dama, Indian Sahiwal and the mixed African/Indian breed Boran. This data is enabling us to identify the individual differences between susceptible and resistant breeds. By combining this information with our knowledge of how genes respond to infection we expect to find some of the genetic differences that control the differences in response to infection.
Humans and some primates produce a protein called APOL1 that kills cattle trypanosomes. Baboons have an even more effective form of the protein that kills all African trypanosomes even the ones that infect humans. We are planning to try to insert a specially adapted version of the APOL1 gene into susceptible African cattle in order to find out if this gene can also make cattle resistant to trypanosomiasis.