Genetic variation of the major histocompatibilty complex-B haplotypes in Nigerian local chicken populations

Abstract

To understand the genetic basis and mechanism underlying the differences in the level of immunity among and within chicken populations in Nigeria, it is important to start from the Major Histocompability Complex (MHC) region particularly as it serves as a reservoir for genes of the immune system. The B-complex of chicken major histocompatibility complex, located on microchromosome 16, consists of gene classes responsible for immunity through antigen presentation to T cells. A highly polymorphic tandem repeat marker (LEI0258) located within the B-complex has been a marker of choice for genotyping to identify major histocompatibility complex-B haplotypes and to study the genetic diversity of chicken populations. This study was carried out to determine the genetic variations, at the LEI0258 locus, in three Nigerian local chicken populations; Normal feather, Frizzle feather and Naked neck. The allelic and genotypic profiles of each representative from each population were determined through polymerase chain reaction amplification of the repeat region. The genetic diversity parameters, analysis of molecular variance and evolutionary relationship were determined using GenAlex, FSTAT, Arlequin and POPTREEW, respectively. 76 % of the entire population was heterozygous at the LEI0258 locus. Analysis of molecular variance revealed that large proportion of the total variations across populations was due to variation between individuals (79 %), whereas variations among the populations and among individuals within populations only accounted for less than 1 % and 21 %, respectively. Using Anak Titan as an exotic outgroup, the evolutionary relationship among the Nigerian local chicken populations was studied and a Nei-based dendrogram showed two major clades separating the exotic population from the Nigerian local chicken populations. The identified diversity at the locus could be exploited for usage in further breeding programmes especially for disease resistance and fitness in locally adapted chicken populations in Nigerian.