1996
Workshop Report
BoLA class I genes
The main objective of the class I component of the workshop was
to analyse published and workshop submitted sequences with the
aim of assigning each to a defined locus. Previous workshops have
used serology and one-dimensional iso-electric focusing (1D-IEF)
to analyse class I expression ( Davies
et al. 1994a), but neither of these techniques has provided
conclusive evidence concerning the number of expressed genes.
Comparison of sequence data with results from serology and 1D-IEF
led to the conclusion that antisera used to define BoLA specificities
often recognise more than one gene product.
In other species, locus-specific sequences have been identified,
particularly in the 3' part of the gene ( Gussow
et al. 1987). Earlier studies focused on this area when
attempting to assign BoLA class I sequences to loci ( Ennis
et al. 1988), and it has been assumed that variations in
transmembrane (TM) region length reflect locus differences (Ellis
et al. 1992; Garber et al.
1994). Analysis of the published BoLA class I sequences
(Table 2; Ellis et al. 1992)
has shown that, with one exception, they all encode a TM region
of either 37 or 35 amino acids. KN104, an allele found exclusively
in the Bos indicus subspecies, appears to be unique in
having a predicted 36 amino acid TM region ( Bensaid
et al. 1991), and is therefore considered to be an atypical
allele.
Characterisation of transcribed class I sequences from a number
of individual animals has shown that the 35 amino acid TM region
group must include the products of more than one class I gene
( Ellis et al. 1996). If this
is also true of the 37 residue TM group then four or more class
I genes may be transcribed. However, the number of class I transcripts
detected varies between 1 and 3 in different haplotypes ( Garber
et al. 1994, Ellis et al.
1996).
Naming of sequences after the associated BoLA-A serological
specificity is difficult, since most haplotypes are assigned
a single specificity, despite expressing more than one class
I gene ( Ellis et al. 1996;
Russell et al. 1996). It
was therefore agreed that although rules for the naming of class
I alleles could be established, local names should continue
to be used for BoLA class I sequences (Table 2), and designation
of BoLA class I alleles and loci would be addressed at a future
meeting of the BoLA Nomenclature Committee.
