Objective To investigate the effect of initiation codon mutation within tva receptor gene (tva c.3G>A) on Qingyuan partridge chicken resistance to infection by avian leukosis virus subgroup K (ALV-K).

Method The tva c.3G>A mutation site within Qingyuan partridge chicken lines was genotyped by using direct sequencing method. The infection of RCASBP(K)-EGFP fluorescent reporter virus and ALV-K GD1601 virus to chicken embryo fibroblasts (CEFs) with different genotypes of tva c.3G>A mutation site were detected by flow cytometry and RT-qPCR, respectively. The infection of ALV-K GD1601 virus to Qingyuan partridge chicks with different genotypes of tva c.3G>A mutation site were detected by RT-qPCR.

Result The genotyping results of tva c.3G>A mutation site showed that the heterozygous mutant genotype tva c.3G>A and the homozygous mutant genotype tva c.3A/A existed in Qingyuan partridge chicken lines K and M, with the frequencies of 0.183 and 0.133 for tva c.3G/A, 0.116 and 0.033 for tva c.3A/A, respectively. The results of flow cytometry and RT-qPCR showed that the tva c.3G>A mutation site wild-type tva c.3G/G CEFs were susceptible to infection of both RCASBP(K)-EGFP and ALV-K GD1601 virus, while the homozygous mutant genetype tva c.3A/A CEFs were effectively resistant to infection of RCASBP(K)-EGFP and ALV-K GD1601 viruses, demonstating that tva c.3G>A mutation caused Qingyuan partridge chicken resistance to infection of ALV-K in vitro. The results of ALV-K challenge test indicated that tva c.3G>A mutation led to Qingyuan partridge chicks resistance to infection of ALV-K in vivo.

Conclusion The tva c.3G>A mutation confers Qingyuan partridge chicken resistance to infection of ALV-K both in vitro and in vivo, indicating that it can be used as a genetic marker for ALV-K resistance selection in Qingyuan partridge chicken.