Polymorphism of the bovine DRB, DQA, DQB, DYA, DOB and DIB genes was investigated using restriction fragment length polymorphism (RFLP) analysis, isoelectric focusing (IEF), class II serology and polymerase chain reaction (PCR) based typing techniques. The simultaneous application of multiple typing techniques and the characterization of multiple genes resulted in a greatly enhanced picture of the bovine class II regions. Thirty-eight class IIa (DR-DQ) and 5 class IIb (DYA-DOB-DIB) haplotypes were defined. It was found that IEF types were associated with DRB3 polymorphism defined by DRB3 PCR-RFLP and DRB3 microsatellite PCR. Serologically defined polymorphism was associated with distinct molecular/IEF motifs and, therefore, DR and DQ specificities could be tentatively distinguished. Although the DR and DQ genes are tightly linked, neither DR nor DQ typing defined all of the class IIa region polymorphism. Furthermore, even the most powerful DRB3 typing technique, DRB3 PCR-RFLP, failed to detect all expressed DRB3 polymorphism. All detected DRB3 polymorphism could, however, be distinguished with a combination of two molecular techniques: DRB3 PCR-RFLP and DRB3 microsatellite PCR. RFLP typing with transmembrane probes detected significantly less polymorphism than typing with cDNA or exon probes. However, the transmembrane probes were useful because they were locus specific. The presence of only 5 of 12 possible class IIb haplotypes was unexpected and indicates that the DYA, DOB and DIB genes are tightly linked.
Previous studies on expressed bovine MHC class II polymorphism using one-dimensional isoelectric focusing (1D-IEF) allowed the identification of at least 12 allelic variants of the DRB3 gene. So far, only limited data have been available on the expression of other class II genes. The present study involved biochemical analysis of bovine MHC class II molecules using a set of monoclonal antibodies presupposed to be bovine DR and DQ reactive. After essential modification of the standard electrophoresis conditions used for 1D-IEF typing of bovine DR products, biochemical polymorphism was observed for non-DR molecules, revealing polymorphic sets of basic and acidic focusing bands. Because of the extensive DNA polymorphism described for bovine DQA and DQB genes, and the apparent similarity with the focusing pattern of human DQ products, these molecules were considered to be the bovine DQ homologues. The definition of the DQ-associated banding patterns was made possible by using two half-sib sire families. Four different DQA-like patterns and nine DQB-like patterns were detected. Segregation of the DQ types was supported by serological class I and class II typing. These results show that it is now possible to discriminate between expressed bovine DR and DQ polymorphism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.