Murine leukemia virus sequences a histocompatibility complex (viral integration/class I gene/TL region/cosmid library/gene expres

The studies reported here localize murine leukemia viral sequences to the TL region of the major histo- compatibility complex, H-2. We examined a battery of 38 cos- mids, isolated from two large genomic libraries constructed from C57BL/10 spleen DNA, that define 25 class I gene se- quences. The viral probes used hybridized with only four cos- mids, containing overlapping mouse sequences, that define four class I gene-related sequences in a region of 90 kilobases of DNA. The data show that two distinct viral envelope se- quences are contained in the cluster. One of these sequences is situated with its 3' end next to the 3' end of a class I sequence. The other sequence, which does not contain the entire viral