We know that genetic diversity within species or a population is beneficial for numerous reasons, including reduced incidence of the expression of harmful or lethal mutations. In livestock production however, there also are benefits to breeding for uniformity and selecting for specific traits, leading to extensive use of selected sire lines.
The resulting lack of genetic diversity could leave animals more susceptible to viral diseases, according to results of research at the University of Utah. Jason Kubinak, PhD, a postdoctoral fellow at University of Utah School of Medicine, led the study, which used mice to compare genetically similar and genetically diverse groups. The study was funded by the National Science Foundation and National Institutes of Health, and the report was recently published in the British journal Proceedings of the Royal Society B.
For the study, the researchers used seven different strains of a mouse species, Mus musculus, which they exposed to the “Friend virus complex,” which is a combination of a mouse leukemia virus named Friend virus and “spleen focus-forming virus,” regularly used to study viral infection. They conducted several tests, exposing various combinations of the mouse strains to the virus and monitoring virus replication and virulence within each group.
“We found there was a significant increase in viral replication and disease severity when a virus was passed through mice of the same breed,” Kubinak says in a university release. “But the virus exposed to different mouse breeds was unable to increase its reproduction or cause more severe disease.”
Previous research has demonstrated this effect in plants and insects, but this is the first study to show that genetic variation within a vertebrate species inhibits replication of a virus and severity of disease.
Potts says the theory is that the Friend virus complex, with a small genetic blueprint, mutates rapidly, and variations in genes are favored that allow the virus to do well in mouse A. But the virus then infects mouse B, and traits that helped it in mouse A may hurt it in mouse B. The researchers now are attempting to identify genetic changes in the virus as it tried to adapt to mice with diverse genes.
The Utah researchers suggest the results of the study could have implications for livestock production, indicating that greater genetic diversity within herds could reduce disease incidence and severity, thus improving productivity.
Read more from the University of Utah.