VARIABLE NUMBER OF PIG MHC CLASS-I GENES IN DIFFERENT SEROLOGICALLY DEFINED HAPLOTYPES IDENTIFIED BY A 3'-UNTRANSLATED REGION PROBE

To estimate the number of porcine class I major histocompatibility gen es, a short class I cDNA probe from the 3'-untranslated region was dev eloped to be used in restriction fragment length polymorphism analysis . Six clones isolated from a pig spleen cDNA library were sequenced fr om their 3'-untranslated region. Three different transcripts were iden tified, one probably derived from the class I PD7 locus and two showin g highest homology to the PD1 and the PD14 genes, respectively. Class I typing was performed both by restriction fragment length polymorphis m and serology. Segregation of class I haplotypes was followed in one three-generation family (European Wild Boar x Large White: Swedish Yor kshire) and in six two-generation families (Duroc, Yorkshire and Chest er White), for a total of 266 pigs. Twenty different class I haplotype s were identified either with restriction fragment length polymorphism and/or serological typing. Furthermore, previously unpublished serolo gical haplotypes H62, H67 and H68 were identified. Two to seven polymo rphic and three monomorphic fragments were detected in different restr iction fragment length. polymorphism haplotypes indicating that the nu mber of class I genes in the investigated haplotypes varies.