Reference strand mediated conformation analysis resolves HLA-DRB1 typing ambiguities when matching for unrelated bone marrow transplantation

Reference strand conformational analysis (RSCA) is a valuable tool in identifying MHC-DRB sequences in three species of Aotus monkeys

The Aotus monkey has been of great value in the pre-clinical study of malaria vaccine candidates. Several components of this primate's immune system have been studied and they display great similarity to their human counterparts. Cloning and sequencing studies have revealed extensive sequence polymorphisms in Aotus MHC-DRB with very high similarities to several human allelic lineages, grouping at least nine distinct MHC-DRB lineages. As the efficacy of peptide vaccines in this animal model may be strongly influenced by exon 2 MHC-DRB polymorphism, the availability of a reliable and rapid MHC-DRB typing method for three species of Aotus (Aotus nancymaae, Aotus vociferans and Aotus nigriceps) is necessary. Reference strand conformational analysis (RSCA) was used here for differentiating the distinctive Aotus MHC-DRB sequences' mobility using five fluorescently labelled references proved to be very useful for resolving closely related sequences, establishing the number of sequences transcribed in a particular monkey and their identity. The RSCA method's reliability in terms of identifying Aotus MHC-DRB sequences will facilitate evaluating individual responsiveness to vaccines and prompt studies associating susceptibility/resistance to infectious agents or auto-immune disease, for which Aotus monkeys may be considered to be an appropriate animal model.

Frequency and distribution of alleles of canine MHC-II DLA-DQB1, DLA-DQA1 and DLA-DRB1 in 25 representative American Kennel Club breeds

The frequency and distribution of dog leucocyte antigens (DLA) class II -DQA1, -DQB1 and -DRB1 alleles were determined for 25 American Kennel Club (AKC) registered dog breeds, representing 360 dogs from each of the seven major performance categories. Six to twenty-eight (average n=11) dogs were studied per group, with the exception of the Akita dog (n=94). All dogs were unrelated with no common grandparents based on AKC pedigree records (F-value <0.125). DLA class II allelic diversity was broad across breeds; 31/61 published DLA-DRB1 alleles, 11/18 published DLA-DQA1 alleles and 31/47 published DLA-DQB1 alleles were found among the 25 breeds. However, allelic diversity was severely limited within a breed. Seventeen of the DLA-DRB1 alleles were each found in only a single breed, and only seven alleles were shared by seven or more breeds. DLA-DRB1*00101 and DLA-DRB1*01501 were shared by 16 and 19 breeds, respectively. DLA-DQA1*00101 and DLA-DQA1*00601 alleles were shared by many breeds. The Rough Collie (DLA-DQA1*00901), English Setter (DLA-DQA1*00101) and Scottish Terrier (DLA-DQA1*00101) were monoallelic for DLA-DQA1. Eleven DLA-DQB1 alleles were each found only in a single breed and only seven alleles were shared by six or more breeds. DLA-DQB1*00201 and DLA-DQB1*02301 were shared by 17 and 18 breeds, respectively. Forty per cent of dogs typed were homozygous at DLA-DRB1, 52% at DLA-DQA1 and 44% at DLA-DQB1. Nine new DLA class II alleles were identified; three for DRB1 and six for DQB1. Comparison of our study of North American purebred dogs to previous European DLA surveys showed a similar use of common alleles consistent with known founder effects. However, more alleles were detected in European breeds, compared to their North American descendents, indicating that additional DLA class II diversity was lost when European breeds were established in North America.

Two sets of HLA Class II DRB and DQB1 alleles co-segregate among family members in a single maternal haplotype

HLA class II typing by sequence specific oligonucleotide probes (SSOP) on the family of a Burkit's Lymphoma patient produced hybridization patterns indicating the presence of two DRB1, and two linked DQB1 genes on the same maternal chromosome. DRB and DQB1 exon 2 amplification products associated with the novel maternal haplotype were identified by DNA typing techniques: These products corresponded to DRB1*0101, DRB1*1501, DRB5*01, DQB1*0501 and DQB1*0602 alleles. These alleles were seen to co-segregate among siblings sharing the same maternal haplotype. The patient, his mother and two of his siblings each appeared to possess elements of three DRB1, DQA1 and DQB1 genes. HLA DNA typing results indicated that a DNA sequence of approximately 100 Kb, spanning the region between, and including, DRB1 and DQB1 genes was inserted into the maternal haplotype. Serological typing on EBV transformed B lymphocytes obtained from the patient's mother showed three expressed DRB1 antigens. Serology on EBV transformed patient's cells also indicated multiple DRB1 antigen expression. The expression of three DRB1 and DQB1 genes on the cells of this patient would make it virtually impossible to obtain a suitably matched unrelated stem cell donor.