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Frequent partial deletion of human adult T-cell leukemia virus type I proviruses in experimental transmission:
Abstract:
Human T-cell leukemia virus type I (HTLV I) propagated in human diploid fibroblast IMR90 was transmitted to human promyelocytic leukemia HL60 cells by coculture. Of 14 provirus-positive HL60 clones, five harbored only defective proviruses, five had defective proviruses in addition to full-sized HTLV I, and four had full-sized proviruses integrated in their chromosomes. The frequency of defective proviruses was unexpectedly high (41% of total proviruses). Analysis of the genomic structure of these defective proviruses revealed polarity of deletion, that is, preferred conservation of the 3' end of the proviral genome (pX and the 3' long terminal repeat). The implication of these findings are discussed with reference to the replication and pathogenesis of HTLV I.
Insights
Human T-cell leukemia virus type I (HTLV-I) infection of HL60 cells resulted in a high frequency of defective proviruses. These defective HTLV-I genomes showed a preference for retaining their 3' end, impacting viral replication and pathogenesis.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Human T-cell leukemia virus type I (HTLV-I) is a retrovirus associated with certain cancers.
- Understanding HTLV-I replication and genetic integrity is crucial for comprehending its pathogenesis.
Purpose of the Study:
- To investigate the characteristics of HTLV-I proviruses after transmission to human promyelocytic leukemia (HL60) cells.
- To determine the frequency and genomic structure of defective HTLV-I proviruses.
Main Methods:
- Coculture of HTLV-I-infected IMR90 fibroblasts with HL60 cells.
- Isolation and characterization of HTLV-I provirus-positive HL60 clones.
- Analysis of the genomic structure of integrated proviruses, focusing on deletions.
Main Results:
- Successful transmission of HTLV-I to HL60 cells via coculture.
- A high frequency (41%) of defective HTLV-I proviruses was observed among the 14 provirus-positive clones.
- Defective proviruses exhibited a deletion polarity, with preferential retention of the 3' end, including the pX region and 3' LTR.
Conclusions:
- The study reveals a significant prevalence of defective HTLV-I proviruses in infected HL60 cells.
- The observed deletion pattern suggests mechanisms influencing HTLV-I genome integrity during replication.
- These findings have implications for understanding HTLV-I replication dynamics and its role in disease development.