Association of BoLA DRB3 alleles with variability in immune response among the crossbred cattle vaccinated for foot-and-mouth disease (FMD) G.R. Gowane a,⇑ , A.K. Sharma b , M. Sankar b , K. Narayanan b , Biswajit Das c , S. Subramaniam c , B. Pattnaik c a Central Sheep & Wool Research Institute, Avikanagar via Jaipur, Rajasthan 304 501, India b Temperate Animal Husbandry Division, Indian Veterinary Research Institute, Mukteshwar Nainital, UK 263 138, India c Project Directorate on Foot and Mouth Disease, Mukteshwar Nainital, UK 263 138, India article info Article history: Received 25 June 2012 Accepted 3 March 2013 Keywords: Bovine leukocyte antigen Vaccine genetics FMD Crossbred cattle abstract Polymorphism of bovine leukocyte antigen (BoLA) DRB3 gene is being intensively investigated for poten- tial association with economically important diseases of cattle. Accordingly, we investigated the associ- ation of DRB3 Exon 2 polymorphism as evidenced by the variation in the binding pockets with variability in immune response to inactivated trivalent (O, A and Asia1) foot and mouth disease virus (FMDV) vac- cine in a closed population of crossbred cattle. Antibody titer of P1.8 was set as the cut off value to dis- tinguish the protected (P1.8) and unprotected (<1.8) animals. Eleven different alleles of over 3% frequency were detected in the population. We found that DRB3 alleles / 0201, / 0801 and / 1501 always ranked high for protective immune response whereas alleles / 0701, / 1103 and / 1101 consistently ranked low for unprotected immune response for all the three serotypes. Rank correlation of DRB3 alleles among the three serotypes was positive, high in magnitude and statistically significant (P < 0.05). Logistic regres- sion analysis revealed that odds of protection from the vaccine were highest for all the three serotypes if allele / 1501 was present and strengthened the results of allele ranking. Predicted amino acid substitution in the peptide binding pockets revealed that all the important sites had high Wu–Kabat index. Similarly, specific residues in pockets were crucial for immune response to FMD vaccine. There were specific sub- stitutions in un-protected alleles such as absence of acidic amino acids substituted by basic amino acid at b71, presence of non-polar cysteine or basic histidine at b30 and presence of polar tyrosine at b37. From the observations, we hypothesize that the substitutions lead to unique conformational changes in the protein products of the studied alleles that would associate with the protective or unprotective antibody response to FMDV vaccine. The knowledge has potential implications in future selection programs if inte- grated with the complete BoLA haplotype details and production traits of the herd. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The bovine leukocyte antigen (BoLA) class II genes play a signif- icant role in the genetic control of immune responses. The main class II restriction elements are products of the DRB and DQA genes (Lewin et al., 1999). The main function of major histocompatibility complex (MHC) class II molecules is to present processed pathogen derived peptides to CD4 + T lymphocytes. MHC class II alleles are redundant and highly polymorphic, enhancing the repertoire of epitopes that an individual can recognize (Norimine and Brown, 2005). Only two class II proteins, DR and DQ are expressed in cattle, however, in the majority of haplotypes expressed by cattle, BoLA- DQ molecules are duplicated, permitting additional diversity through intrahaplotype and, potentially, interhaplotype pairing of DQA and DQB proteins. The DRA chain in both humans and cattle is monomorphic; therefore, polymorphism in DRB genes is the only source of diversity in DR molecules. In cattle, only the DRB3 gene is known to be functional. DRB3 exon 2 is highly polymorphic, with 119 alleles identified to date (http://www.ebi.ac.uk/ipd/MHC/ BoLA/). A subtle change in the nucleotide sequence of the MHC DRB3 gene can substantially substitute the coding amino acid and ultimately bring conformational changes in the binding groove so as to affect the efficiency of the protein to present the antigen efficiently for further processing. This gene has been extensively studied for its association with several disease resistance traits such as tick resistance (Stear et al., 1984), resistance to mastitis (Sharif et al., 1998; Kulberg et al., 2007; Rupp et al., 2007; Duangjinda et al., 2009), bovine leukemia virus (Juliarena et al., 2008) and response to a simple FMDV peptide vaccine (García-Bri- ones et al., 2000; Baxter et al., 2010) in cattle. Genetic variability in response to vaccination is likely to become an even more signifi- cant factor in designing ideal ‘‘safe, synthetic’’ vaccines (Glass et al., 2011). The genes identified might also be important for 0034-5288/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.rvsc.2013.03.001 ⇑ Corresponding author. Tel.: +91 7597288789; fax: +91 1437220163. E-mail address: gopalgowane@gmail.com (G.R. Gowane). Research in Veterinary Science 95 (2013) 156–163 Contents lists available at SciVerse ScienceDirect Research in Veterinary Science journal homepage: www.elsevier.com/locate/rvsc