Adaptation of Ugandan cattle to East Coast fever: landscape genomics analysis

Researchers have investigated the genetics of tolerance to theileriosis in indigenous cattle from Uganda.

They first produced a map showing the areas of Uganda where the disease is most prevalent. The map is the result of a novel method compiling epidemiological data collected from 823 indigenous cattle along with their location. Using an environmental genomics approach – which combines the probability of being bitten by a tick (Rhipicephalus appendiculatus), the risk of infection by the parasite (Theileria parva parva) and the genetic characteristics of cattle populations – the researchers were able to identify the genes potentially involved in resisting theileriosis. Their findings are reported in Frontiers in Genetics.

The method developed by the team aims to help local veterinarians – who took part in the study as well – to see where the riskiest areas are. Farmers’ associations will also be able to make better choices about which breeds to raise, depending on their region. For the researchers, the study furthermore shows the importance of preventing indigenous breeds from crossing with other breeds, particularly European ones. Zebu breeds that migrated from India to Africa around 4,000 years ago are resistant to the disease vector, whereas imported breeds die just a few months after infection.

“Our study shows that the cross-breeding carried out in Africa in the last few years – pushed by European corporations with the promise of higher yields in terms of milk and meat – is a mistake based on a short-term approach. Diluting indigenous breeds reduces the cattle’s resistance to this disease,” says Elia Vajana, post-doctoral researcher at École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland and first author of the journal article.

In particular, the study documents the role played by two genes (PRKG1 and SLA2) in the disease resistance process. As a result, the study could be a first step towards implementing breeding programmes that exploit this disease resistance process.

The publication is based on a research programme carried out by EPFL as part of NextGen, a European research project that began in 2010 (FP7). According to Stéphane Joost, who works in EPFL’s Laboratory of Geographic Information Systems (LASIG) and is the corresponding author: “The study involved large amounts of environmental data produced by meteorological stations and satellites, and large amounts of genetic and health data collected on the ground as part of the NextGen project. Extensive IT resources were also used to develop the statistical models and produce the results. This field of ‘Geocomputational Molecular Ecology’ combines some of the unique environmental engineering skills that we have developed here at EPFL.”

Article: Combining Landscape Genomics and Ecological Modelling to Investigate Local Adaptation of Indigenous Ugandan Cattle to East Coast Fever by Elia Vajana, Mario Barbato, Licia Colli, Marco Milanesi, Estelle Rochat, Enrico Fabrizi, Christopher Mukasa, Marcello Del Corvo, Charles Masembe, Vincent B. Muwanika, Fredrick Kabi, Tad Stewart Sonstegard, Heather Jay Huson, Riccardo Negrini, The NextGen Consortium, Stéphane Joost and Paolo Ajmone-Marsan published in Frontiers in Genetics (2018) 9:385, doi: 10.3389/fgene.2018.00385

[SOURCE: École Polytechnique Fédérale de Lausanne (EPFL)]