Functional polymorphisms in Toll-like receptor genes for innate immunity in farm animals

The exploitation of the genetic factors affecting the health status of farm animals represents an alternative approach to controlling the diseases caused by microbial pathogens. The determination of innate immunity based on the genotype of the germplasm cells is a constraint for specificity but becomes an advantage in breeding schemes. The structural deviations among Toll-like receptors (TLRs), as the most frequently studied innate immunity components, have been documented at all levels, i.e., interspecific, inter- and intravarietal, in the main farm species. The current computational methods facilitate the prediction of the functional consequences of the observed mutations. Subsequently, these predictions can be verified through immunological responsiveness and population-wide association studies. The frequency and haplotype grouping of individual polymorphisms are used to track the origin and selection coefficient as independent indicators of functional changes. The Toll-like receptor variants associated with mastitis and mycobacterial infection have been identified in cattle, consequently, the targeting of these proteins in breeding could contribute to disease control. The range of infections affected by TLR polymorphisms suggests that the improvement of innate resistance is feasible in more species. Thus, the traditional breeds and wild populations should be regarded as the resources of genetic variability accessible for these purposes.