Expression analyses and antiviral properties of the Beijing-You and White Leghorn myxovirus resistance gene with different amino acids at position 631.

Influenza is a topic of wide public concern, particularly because of the recent emergence of avian flu. The myxovirus resistance (Mx) protein has been shown to have an inhibitory effect on influenza virus and is therefore of great interest. This study examines the Mx protein in 8 local Chinese chicken breeds and 2 exotic chicken breeds. Amino acid 631, found in the Mx GTPase effector domain, was examined in 534 individuals by comparing PCR results, and individuals were separated into the A/A genotype or the G/G genotype, depending on whether amino acid 631 is an Asn or Ser. In the native breed, the frequency of G/G homozygotes is 0.780 (294/377). The Mx expression levels in tissues and chicken embryo fibroblast cells with different genotypes were also studied. The A/A individuals from Beijing-You and White Leghorn breeds had higher Mx expression levels than G/G individuals. The liver, heart, and spleen had higher expression levels than muscle or kidney. The A/A chicken embryo fibroblast cells had higher antiviral activity against vesicular stomatitis virus and Newcastle disease. We provide the first report examining the expression level and antiviral activity of different Mx alleles of nucleotide 2216(S631N) genotypes. This study lays a good foundation for correlative studies examining genotype and antiviral function.