Bioscience Evidence 2024, Vol.14, No.1, 24-31 http://bioscipublisher.com/index.php/be 25 1 The Genetic Basis of Animal Disease Resistance 1.1 The genetic basis of resistance Resistance, as the ability of animals to counteract pathogen invasion, has a diverse genetic basis across different species (Ridha, 2023). Genetic diversity refers to the variety of genotypes and phenotypes present in animal populations, where some genotypes are resistant to diseases, while others are susceptible. This diversity provides a basis for natural selection within animal populations, allowing individuals with disease-resistant genotypes to have a better chance of surviving and reproducing under disease pressure, thereby promoting the transmission and accumulation of resistance genes. 1.2 The relationship between the host immune system and disease resistance The host immune system is an essential defense against pathogen invasion in animals, divided into innate and adaptive immunity. Innate immunity provides basic disease protection through nonspecific mechanisms, such as the phagocytic action of macrophages and the activity of natural killer cells. These mechanisms enable the host to quickly and effectively counter various types of pathogens. Adaptive immunity, on the other hand, offers more targeted disease protection through specific antigen recognition and immune memory mechanisms. Once exposed to a specific pathogen, the adaptive immune system produces specific antibodies or cell-mediated immune responses, enhancing resistance to that pathogen and forming immune memory, allowing for a quicker response upon re-exposure. 1.3 The association between immune genes and disease resistance Immune genes, which encode proteins related to the immune system, are closely associated with an animal's disease resistance due to their expression and functional variations. For example, in humans, the HLA gene family is an important component of the immune system, with different HLA genotypes associated with susceptibility or resistance to specific diseases. This association indicates that polymorphisms in immune genes play a key role in animal disease resistance. By regulating the degree and manner of the immune system's response, the polymorphism in immune genes affects the host's ability to resist various pathogens, thereby influencing the level of disease resistance in the entire population. Therefore, research on immune genes not only helps understand the mechanisms of disease resistance in animals but also provides an important genetic basis for breeding for disease resistance. 2 Application of GWAS Technology in the Study of Animal Disease Resistance 2.1 Principles and advantages of GWAS technology Genome-wide association studies (GWAS) are a technique for exploring the relationship between genes and traits by comparing large-scale genotype and phenotype data. The principle behind GWAS is to identify genetic markers associated with specific traits by finding association signals between genotypes and phenotypes (Uffelmann et al., 2021). A key advantage of GWAS technology is its ability to comprehensively screen the genome for disease-related variations without relying on prior hypotheses. The core of GWAS technology involves the analysis of large-scale single nucleotide polymorphisms (SNPs). Researchers first genotype the subjects to obtain individual genotype data at millions of SNP sites. Relevant phenotype data, such as the occurrence of a disease or its severity, are also collected. Statistical methods are then used to perform association analyses between these genotype and phenotype data, identifying SNP sites related to the traits of interest. Another advantage of GWAS technology is its high throughput and comprehensiveness. Traditional genetics research often requires hypothesis-driven analyses targeting specific genes or pathways, whereas GWAS can comprehensively screen for trait-related variations across the entire genome without prior hypotheses. This makes GWAS a powerful tool for discovering new genes related to diseases (Figure 1). 2.2 The history and development of GWAS in animal genetics research GWAS technology was initially applied in human genetics. With the advancement of sequencing technology and the increase in data volume, it has also been widely applied in animal genetics research. Through GWAS,
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