Coamplification and Dispersion of Adjacent Human Endogenous Retroviral HERV-H and HERV-E Elements; Presence of Spliced Hybrid Transcripts in Normal Leukocytes

• Published in: Virology (New York, N.Y.) N.Y.), 1998-04, Vol.244 (1), p.219-229
• Main Authors: Lindeskog, Mats, Medstrand, Patrik, Cunningham, Andrew A., Blomberg, Jonas
• Format: Article
• Language: English
• Subjects: Alternative Splicing; Amino Acid Sequence; Animals; Base Sequence; Cell Line; DNA, Viral; Genome, Human; Humans; Leukocytes - virology; Molecular Sequence Data; Nucleic Acid Conformation; Polymerase Chain Reaction; Primates - virology; Retroviridae - genetics; RNA, Viral - chemistry; Tumor Cells, Cultured
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1006/viro.1998.9106

In an RT–PCR study of HERV-H spliced subgenomic transcripts, we found transcripts with HERV-H leader and protease-encoding sequences spliced to HERV-E integrase-encoding sequences in lymphocytes from healthy blood donors. In other cell types, including two T-cell leukemia cell lines, these transcripts were absent. The PCR fragments of the hybrid transcripts contained two open reading frames (ORFs). One was a hybrid HERV-H protease/HERV-E integrase ORF and the other was the HERV-E envelope surface glycoprotein ORF. Alternative splice products were also identified. The genomic DNA origin of the hybrid transcripts was shown to be a HERV-H element with a large 3′-end deletion, adjacent to a HERV-E element lacking the 5′-LTR. This hybrid structure was shown to be amplified and dispersed to six different human chromosomes. Thus, a relatively large part of full-length HERV-E elements (15–20%) is potentially under the transcriptional control of HERV-H LTRs. The HERV-H/HERV-E junction was present in multiple copies also in the chimpanzee and gorilla, but not in the orangutan or old world monkeys.