[Objective] To investigate the polymorphism of the thirteenth exon of MxA gene in 4 species of horse. [Method] The thirteenth exon of MxA gene fragments were amplified from genomic DNA of Sanhe horse, Xinihe horse, Wushen horse and Baerhu horse with the primers designed according to the MxA sequence announced in GenBank; the polymorphism of MxA gene was detected by PCR-SSCP and the products were sequenced. [Result] The polymorphism of the thirteenth exon of MxA gene appeared only in Wushen horse, the 2 081 nt of which mutated from guanine (G) to adenine (A) and the corresponding amino acid of which changed from glutamate (Glu) to alanine (Ala). [Conclusion] The study provided a basis for exploring the antiviral effect of MxA protein.
