Characterization of a polymorphic heat shock protein 70 gene in swine outside the SLA major histocompatibility complex.

To characterize a hitherto unidentified swine Hsp70 gene, a cDNA library was prepared from total RNA isolated from swine lymphocytes and heat-shocked at 42 degrees C for 2 h. One positive clone with a 2.6 kb insert was found. Its sequencing revealed a maximum homology with the human inducible Hsp70B' gene. The genomic polymorphism of this insert was investigated by restriction fragment length polymorphism (RFLP) in an informative family for the major histocompatibility complex SLA. Digestion with PvuII generated 8 bands which were common to both parents, and for the male two extra bands at 0.69 and 0.64 kb. After digestion with PstI, there was also an extra band at 1.6 kb for the male in addition to the seven bands common to both parents. The eleven offsprings' RFLP patterns exhibited all the common parental bands, but four piglets displayed the male's specific bands in addition. All the polymorphic bands belonged to the same locus and segregated independently of SLA. Restriction mapping of the Hsp70 gene indicated the absence of introns, and showed that the polymorphic PstI site was located upstream of the gene's 5' coding region, and the PvuII site inside its coding region.