Poster Presentation International Veterinary Immunology Symposium 2016

Different susceptibility between two porcine MX1 genotypes against porcine reproductive and respiratory syndrome virus infection (#139)

Takeya Morozumi 1 , Michihiro Takagi 2 , Hiroshi Iseki 2 , Akiko Sakuma 3 , Mitsuru Nakajo 3 , Daisuke Toki 1 , Ayumi Mikawa 1 , Hiroki Shinkai 4 , Takato Takenouchi 4 , Hiroshi Kitani 4 , Hirohide Uenishi 4
  1. Institute of Japan Association for Techno-innovation in Agriculture, Forestry and Fisheries, Tsukuba, IBARAKI, Japan
  2. National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
  3. Miyagi Livestock Experimental Station, Osaki, Miyagi, Japan
  4. Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan

Porcine reproductive and respiratory syndrome (PRRS) is one of the most important diseases that cause huge economic losses in pig industry around the world. The etiological agent, PRRS virus (PRRSV), has a positive-sense single-stranded RNA genome, which showed a high evolution rate and diversification, thereby the vaccine effect for virus control is restricted. On the other hand, although difference of susceptibility to PRRSV among pig lines was reported, the causative gene of the susceptibility was not identified to date.

 Myxovirus resistant gene 1 (Mx1) was discovered as the causative gene for influenza virus resistance in mouse, and the following studies revealed that the antiviral activity of human MXA exhibits not only to various member of negative-sense single-stranded RNA viruses, but also to classical swine fever virus a member of  positive-sense single-stranded RNA viruses. Hence, broad-spectrum antiviral activity of porcine MX1 was expected. While PRRSV infection induced the mRNA expression of porcine MX1, the anti-PRRSV activity of porcine MX1 was unknown.

One of porcine MX1 alleles (MX1c) has an 11 bp-deletion leading to a frameshift whereby 8 amino acids are altered and 23 amino acids are extended at the C-terminus of the protein compared to that of the major allele. MX1c was observed among various breeds of pigs with low frequency, and the anti-influenza virus activity of MX1c was significantly lower than that of the major type of porcine MX1. We evaluated relationship between porcine MX1 alleles and susceptibility to PRRSV by infection of the Japanese standard strain EDRD1. Macrophages with the major allele of MX1 showed a higher rate of cell death than those with MX1c. We will present results of in vivo studies by using animals with different alleles of MX1.