Scientists have identified two genes which may help the fight against African animal trypanosomiasis, a sleeping sickness transmitted by tsetse fly
The finding would help save the livelihoods of many farmers as an estimated three million dairy and meat-producing cattle die from the disease, which is locally known as nagana.
"The two genes discovered in this research could provide a way for cattle breeders to identify animals that are best at resisting disease," said International Livestock Research Institute (ILRI) geneticist Steve Kemp.
Researchers have used a range of genetic approaches, including analysing differences in genetic activity in the tissues of cattle breeds after animals were experimentally infected with the parasites.
While zebus, the humped cattle breeds was susceptible to disease-causing trypanosome parasites, a humpless West African breed called N'Dama was not seriously affected. Using microarrays, the researchers identified a suite of genes that were switched on or off after infection.
After resequencing the two genes integral to fighting infections – ARHGAP15 which regulates neutrophil function, and TICAM1 which regulates dendritic cell migration – scientists identified the disease-resistant alleles in the West African breed.
Though the N'Damas weren't particularly good at plowing fields or producing milk, researchers hope to create cattle breeds that are disease-resistant and commercially productive by crossing the two alleles with zebus species.
Using genetic engineering, an approach still in its early days, Kemp said he hoped the disease-resistant breed would be produced in four or five years.
The annual economic impact of nagana in terms of sick, wasting cattle and farming productivity losses has been estimated to be from US$4 billion to $5 billion.
