The Genetics of Trypanotolerance in Cattle: A Review

Abstract

Trypanosomosis is a major recognized factor limiting livestock productivity. Control of the disease has explored the use of drugs, vector and the farming of trypanotolerant livestock in order to enhance productivity. However, there are documented difficulties with each of the methods. These include drug resistance, re-invasion of controlled areas by tsetse flies and the small population of the trypanotolerant cattle population. Hence the search for genes that will confer trypanosome-resistance and enhance productivity is imperative. Attempts to control trypanosomosis using molecular genetic techniques have continued over the years. In this brief review, the advances made towards an understanding of genetics involved in trypanotolerance will be highlighted. So far, the genome involved in the genetics of trypanotolerance in cattle and in mice, known as the quantitative trait loci (QTL), has been identified using microsattelites. Comparative studies of map data between cattle and mice in the principal QTL region of both species have revealed a region of homology of about 300,000 base pairs (bp) between cattle chromosome 7 and mouse chromosome 17 lying within the principal QTL in both species. This finding points to the possibility that the underlying genes in these two QTL could be the same in cattle and mice and may pave the way for the eventual identification of trypanotolerant genes. The identification of the genes would make it possible to use transgenic approaches that would incorporate resistance to trypanosomosis for control design. Keywords: Genetics, trypanotolerance, cattle Trop. Vet. Vol. 21 (2) 55-60 (2003)