Molecular Epidemiological Survey On Marek’s Disease And Meq Gene Analysis In Chia-nan Area Of Taiwan

Marek’s disease(MD) is one of the most contagious oncogenic lymphotropic diseases in chicken caused by Marek’s disease virus. It mainly causes tumors of various kinds of tissues and organs. The use of MDV live vaccines since 1970 has greatly reduced the economic losses from Marek’s disease. However, MDV has been frequently occurring virulent MDV may account for the repeated outbreaks of MD. Vaccines with greater efficacy are needed to protect against MDV. At present, MD is a serious threat to poultry, so the analysis of the current popular MD virulence and characteristics can be a base for monitoring and control of the disease.This study intends to polymerase chain reaction(PCR) to do a molecular epidemiology investigation of Marek’s disease on local chicken of 80-90 days of age in South-western Taiwan and use Meg Align program within the DNASTAR to compare and analyze the Meq nucleotide and amino acid respectively and sequence by using the built-in clastal W. Then construct a phylogenetic tree with the use of 6 MEGA software.The results are as follows:1. Test the South-western Taiwan native feather pulp samples in south region of 80-90 days of age by using the method of PCR. According to the test, the positive rate of 80-90 days of age of native wild poisonous is-1.48%-10.23%(4.38%) and batch wild positive rate is18.75%(3/16).By PCR detection to distinguish Marek’s three serotype of the virus, we can infer that 90% of native field in South-western Taiwan area are using Marek’s virus immune serum type 1 vaccine, 25% of the native field using serum type 1 and type three. There are two chicken farms found Marek’s and Avian leukosis mixed infection.2. Using DNASTAR Meg Align program, respectively compare and sequence Meq gene nucleotide and amino acid with the use of the built-in clastal W method, construct a phylogenetic tree with the 6 MEGA software with the Neighbor-Joining method. The result shows, the nucleotide sequence similarity with foreign 23 strains ranges from 94.4% to 100%,the amino acid sequence similarity 97.6%-100%. From the analysis of the nucleotide and amino phylogenetic tree acid related, it is found that the seedlings are independent and no clinical symptoms of wild strain belongs to a small branch; while China’s strain is relatively unstable and China’s strong strains and separated wild strains in Taiwan tend to be similarwith the wild strains in America; Vaccine strains and Russian strains are in the same branch.From the Meq virus gene sequence differences as well as the analysis of the phylogenetic tree,it can be concluded that Taiwan and China strong poison strains are of close relatives, and its virulence and pathogenicity are as equal as that of strong strains in China.