Retrovirus sequences in a leukemic gibbon and its contact: evidence for partial provirus in the nonleukemic gibbon.

Integrated viral DNA sequences were detected in tissues from two gibbon apes, a leukemic gibbon (6G-1) from whose leukocytes a distinct strain of gibbon ape leukemia virus (GaLVH) was isolated, and gibbon 6G-4, a contact of 6G-1 from the same colony that had uremia and cachexia of unknown origin. Although 6G-4 had no detectable neoplasia or viral proteins, its serum contained persistent antibody against GaLV antigens. Whereas DNA from most of the tissues of 6G-1 contained GaLV provirus, DNA from only three tissues (kidney, spleen, and liver) from 6G-4 showed detectable viral sequences, and the extent of hybridization in each case was lower than with 6G-1. After cleavage with BamHI, two virus-specific DNA fragments were detected in tissues of 6G-1. Only one of these fragments was detected in the positive tissues of 6G-4. The results indicate that: (i) 6G-4 was exposed to and infected by GaLV; (ii) early target sites for infection of gibbon by GaLV may be limited to a few tissues; and (iii) infection can be contained by integration of only partial provirus in a few tissues.