Kabi, M. | bioRxiv Science

bioRxiv2026

A novel High-Throughput Ligase-Independent Mapping method to detect Viral Integration Sites

Integrated DNA elements are central to virology, functional genomics, and gene therapy, but current insertion-site mapping methods often rely on restriction digestion, ligation, or complex sequencing workflows that introduce bias and limit recovery. Here, we present Terminal Mapping, a high-throughput method that identifies host-insert junctions without restriction enzymes or DNA ligation. The workflow combines linear amplification from a known terminal sequence, enrichment of single-stranded products, terminal transferase-mediated poly-A tailing, and PCR amplification for Illumina or Oxford Nanopore sequencing. Applied to Jurkat T cells transduced with HIV-1- and SIVmac251-derived vectors, Terminal Mapping recovered more HIV-1 insertion sites than inverse PCR, reproduced known integration biases, and showed improved robustness with long-read sequencing. It revealed shared but quantitatively distinct HIV-1 and SIVmac251 hotspots, as well as substantial differences between Jurkat cell sources. Comparison of 5' and 3' LTR-derived reads also provided an internal control for unintegrated viral DNA. Terminal Mapping therefore offers a rapid and flexible platform for profiling integrated genetic elements across vectors and cellular contexts.

genomics↗

bioRxiv2020

A stronger transcription regulatory circuit of HIV-1C drives rapid establishment of latency with implications for the direct involvement of Tat

The magnitude of transcription factor binding site variation emerging in HIV-1C, especially the addition of NF-{kappa}B motifs by sequence duplication, makes the examination of transcriptional silence challenging. How can HIV-1 establish and maintain latency despite having a strong LTR? We constructed panels of sub-genomic reporter viral vectors with varying copy numbers of NF-{kappa}B motifs (0 to 4 copies) and examined the profile of latency establishment in Jurkat cells. We found surprisingly that the stronger the viral promoter, the faster the latency establishment. Importantly, at the time of commitment to latency and subsequent points, Tat levels in the cell were not limiting. Using highly sensitive strategies, we demonstrate the presence of Tat in the latent cell, recruited to the latent LTR. Our data allude, for the first time, to Tat establishing a negative feedback loop during the late phases of viral infection, leading to the rapid silencing of the viral promoter. ImportanceOver the past 10-15 years, HIV-1C has been evolving rapidly towards gaining stronger transcriptional activity by sequence duplication of major transcription factor binding sites. The duplication of NF-{kappa}B motifs is unique and exclusive for HIV-1C, a property not shared with any of the other eight HIV-1 genetic families. What mechanism(s) does HIV-1C employ to establish and maintain transcriptional silence despite the presence of a strong promoter and a concomitant strong, positive transcriptional feedback is the primary question we attempted to address in the present manuscript. The role Tat plays in latency reversal is well established. Our work with the most common HIV-1 subtype C (HIV-1C) offers crucial leads towards Tat possessing a dual-role in serving both as transcriptional activator and repressor at different phases of the viral infection of the cell. The leads we offer through the present work have significant implications for HIV-1 cure research.

microbiology↗