Evaluation of polymorphism loci associated with viral diseases in spangled Orloff chicken breed

The indigenous Russian Spangled Orloff chicken breed (Large Fowl) was for the first time studied by analyzing polymorphism in loci associated with viral diseases caused by Marek’s disease viruses (MDV), avian leukosis viruses (ALV), and avian influenza viruses. Samples for the analysis were collected at the farms of the All-Russian Poultry Research and Technological Institute (VNITIP), the All-Russian Institute of Farm Animal Genetics and Breeding (VNIIGRZh), and the Moscow Zoo. Assessed populations have a distinction in the frequency and range of allelic variants and as a consequence the frequencies of genotypes LEI0258. The highest level of polymorphism was found in microsatellite loci LEI0258 and Mx1 gene (VNIIGRZh population). The evaluation of polymorphism in genes Mxl (interferon-induced guanosine triphosphatase) and TVB (Tumor Virus В locus, cell receptors) showed, that the Mxl and TVB genotypes associated with resistance to avian influenza viruses and ALV, respectively, were not found in studied populations of Spangled Orloff chicken breed. The most homogeneous group for all studied loci is from the VNITIP population. These data are in good agreement with the results from the study of mtDNA polymorphism in the same samples. The observed polymorphism in nuclear and mitochondrial markers demonstrates that most representative population (about 700 individuals) of Spangled Orloff chicken breed from VNITIP during its long conservation breeding program has remained almost unchanged in the investigated molecular markers and is a source of valuable alleles 357 from microsatellite loci LEI0258 associated with Marek’s disease resistance. The observed frequency of the genotype 357/357 was 48%. The obtained data on the genetic homogeneity of Spangled Orloff chicken breed in all analyzed loci show the need for measures to maintain and increase the number of local groups of Orloffs with the aim of its further preservation.