Animal Molecular Breeding 2024, Vol.14, No.1, 10-18 http://animalscipublisher.com/index.php/amb 14 By analyzing genomic data from thousands of chickens, the researchers identified several genetic markers significantly associated with avian influenza resistance. Among them, a region located on chicken chromosome 4 was found to be particularly associated with virus resistance. Further studies indicated that a gene named "MX1" in this region plays a key role in avian influenza virus infection, and that the level of expression of the MX1 gene, which is involved in the cellular antiviral response, directly influences the resistance of chickens to avian influenza (Tan et al., 2024). Domestic researchers further explored the adaptive evolution of the MX gene and its association with avian influenza resistance. The results of the study showed that specific variations in the chicken MX protein at amino acid position 631 were decisive for its antiviral activity. This implies that certain genetic variants may enhance or attenuate the antiviral capacity of chicken MX protein and have a direct impact on avian influenza resistance (Figure 2). Figure 2 Performance of MX1 gene in key roles of avian influenza virus infection Marek's disease is another serious threat to poultry production, mainly affecting chickens. It is a cancer caused by a virus that can lead to extremely high mortality in chickens. Research on resistance to Marek's disease is important to reduce economic losses and improve poultry productivity (Cai et al., 2023). In a GWAS study on Marek's disease resistance, scientists succeeded in identifying several genetic markers associated with Marek's disease resistance. Among these markers, a specific region on chicken chromosome 1 caught the researchers' special attention. Within this region, a gene called "MDV1" is believed to be the key to MHL resistance. This gene is involved in the chicken's immune response, particularly in recognizing and destroying virus-infected cells. Marek's disease virus is able to multiply on duck embryo fibroblasts, chicken kidney cells and produce typical foci on chick embryo chorioallantoic membrane. Due to the high resistance of the virus, it can survive in feces and bedding for up to 4 months at room temperature, thus increasing the risk of disease transmission. In newly fledged chicks, "MDV" has a pronounced pathogenicity that may lead to immunosuppression, neurological signs, retinopathy or tumor formation, especially lymphocytic tumors in various organs such as nerves, muscles, lungs, liver and kidneys (Figure 3). 3.2 Key genetic markers and genes identified Identifying key genetic markers and genes in genome-wide association studies is a critical step in achieving genetic resolution of disease resistance. Through association analysis of large-scale genotype data, researchers can identify key genetic markers and genes associated with specific disease resistance. These key genetic markers and genes are often the main genetic factors affecting disease resistance in poultry, which is important for understanding the genetic basis of disease resistance and for genetic improvement.
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