Cloning and Characterizing the MHC DRB exon ii of the Big Brown Bat (Eptesicus fuscus)

Abstract

The Major Histocompatibility Complex (MHC) refers to a multi-gene family that encodes for a set of protein products known as cell-surface glycoproteins. The MHC is of vital importance to immune system function, as its cell-surface glycoproteins are responsible for binding detrimental parasitic antigens and presenting them to T-lymphocytes. These cells are then able to implement a cascade of events which trigger an immune system response. In vertebrates, these protein products are encoded by two distinct groups of MHC genes, Class I and Class II. Because the MHC is a multi-gene family, it is possible that the genes encoding for its protein products exist at multiple loci.

Class II genes, which are responsible for the recognition of non-self antigens, are divided into three distinct regions: DR, DP, and DQ, and into six sub-regions. Divisions are based upon whether the gene encodes for the alpha or beta chain region of the protein. While Class I and Class II MHC genes are highly polymorphic on the levels of nucleotide and translated protein product, the specialized expression of MHC Class II genes (presenting antigens that are derived from the exterior environment) has distinguished this group as an ideal gene family for studying selection patterns.

We set out to characterize the DRB exon ii region of the big brown bat, Eptesicus fuscus and to expand understanding of the MHC in bats. Characterization involved amplification of the desired DRB exon using primers that have been employed in previous research. Furthermore, because MHC DRB exon ii encodes for a protein product that is known to contain the beta chain of the Antigen Binding Site (ABS), which interacts directly with pathogens, characterization of this exon would elucidate sites corresponding to this ABS region.