A Study On The Polymorphism Of MHC Class I Genes And Their Relatedness To The Susceptibility To Influenza In Tiger (Panthera Tigris)

Tiger(Panthera tigris) is one of the most concerned endangered species, so ex situ conservation is the universal strategy for tiger protection. Since the reoccurrence of influenza H5N1 in HongKong, this virus has broken out worldwide and not only hit the poultry industry heavily but also infected some species of mammals. In 2002 and 2004, tigers in China and Thailand were infected by avian influenza virus and a big mount of them died of infection. The avian influenza virus became a new pathogen that threatened the exist of tiger. There is a close relatedness between the MHC class I gene and the resistance/susceptibility to virosis. In this paper, the polymorphism of MHC class I gene of tigers, which feed in the same condition but some was infected and some not, and the relatedness between the polymorphism and the susceptibility of tiger to avian influenza were studied, and some reference were provided for the genetic management of tiger. In this study, three expressed genes, TLA-B, FLA-Z-a and FLA-Z-b, were found. Then, by using the PCR-SSCP and DNA sequencing and analyzing, we found that, in the population of 41 tigers, the TLA-B gene had only one allele and no polymorphism;the FLA-Z-b gene had three alleles, of which the frequency was 0.4390, 0.4390 and 0.1220 respectively, and the heterozygosity of this gene was 0.878, which diverged from the Hardy-Weinberg Balance significantly (P<0.05). The distribution of alleles of locus TLA-B and FLA-Z-b did not show differences between the healthy group and the infected group, suggesting that the TLA-B gene and FLA-Z-b gene can not show the resistance to avian influenza virus which they were supposed to so that the tigers are in danger on the pressure of avian influenza. The polymorphism of MHC class I gene was low and the tiger was susceptive to virosis. Allele of low frequency was to loss easily in the reproduction process so that the susceptibility to virosis would be enhanced. Therefore, it should be pay more attention to protect the allele of low frequency in genetic management.