BOLA Gene Polymorphism and Determination of Disease Severity and Susceptibility: Review

Abstract

Major histocompatibility complex is the gene complex that exists in all vertebrae like humans (HLA), dogs (DLA), bovine (BLA), ovine (OLA), swine (SLA), and equine (ELA). MHC possesses three regions (I, II, III) that control major specific immune responses and contain variety of genes which influence growth, development, reproduction, odor, and olfaction. Measuring levels of polymorphism of these genes can provide indirect measures of the immunological fitness of populations. As humans and mice, cattle have three MHC gene classes (class I, II, and III). Both BoLA class I and II play a role in antigen presentation, however the function of BoLA class III has been releated with components of the complement system. BoLA class II region is extra separated into class IIa and class IIb. In this gene, the genetic polymorphism of class II α and β genes occurs predominantly in exon 2 encoding the antigen binding site. The BoLa-A locus has 32 serologically defined alleles and minimum four further putative alleles in addition to a high frequency of null alleles. With association allele hold DRB3.2*8 (DRB3*1201) and DRB3.2*16 (DRB3*1501) genes are associated with mastitis susceptibility, and DRB3.2*22 (DRB3*1101), DRB3.2*23 (DRB3*2703) and DRB3.2*24 (DRB3*0101) with mastitis resistance. The A8 specificity and the EIAY sequence are significant markers of resistance, while the serine residue is a marker of susceptibility to dermatophlosis. According to the report 2004, BoLA-DRB3 alleles with the amino acid residues Glu, Arg, and valine (Val) at positions 74, 77, and 78, respectively, give resistance to tumor development by BLV infection. On the other hand, HaeIII CC and HaeIII BC genotypes were actually associated with resistance to FMD in contrast, the HaeIII AA genotype was associated with susceptibility to FMD. Another report on infected Egyptian buffaloes with serotype O FMDV genotype AA for FMD resistance while genotype AC for susceptibility to FMD.