Safe and effective liver-directed AAV-mediated homology-independent targeted integration in mouse models of inherited diseases.

Liver-directed adeno-associated viral (AAV) vector-mediated homology-independent targeted integration (AAV-HITI) by CRISPR-Cas9 at the highly transcribed albumin locus is under investigation to provide sustained transgene expression following neonatal treatment. We show that targeting the 3' end of the albumin locus results in productive integration in about 15% of mouse hepatocytes achieving therapeutic levels of systemic proteins in two mouse models of inherited diseases. We demonstrate that full-length HITI donor DNA is preferentially integrated upon nuclease cleavage and that, despite partial AAV genome integrations in the target locus, no gross chromosomal rearrangements or insertions/deletions at off-target sites are found. In line with this, no evidence of hepatocellular carcinoma is observed within the 1-year follow-up. Finally, AAV-HITI is effective at vector doses considered safe if directly translated to humans providing therapeutic efficacy in the adult liver in addition to newborn. Overall, our data support the development of this liver-directed AAV-based knockin strategy.

HPV, HBV, and HIV-1 Viral Integration Site Mapping: A Streamlined Workflow from NGS to Genomic Insights of Carcinogenesis.

Viral integration within the host genome plays a pivotal role in carcinogenesis. Various disruptive mechanisms are involved, leading to genomic instability, mutations, and DNA damage. With next-generation sequencing (NGS), we can now precisely identify viral and host genomic breakpoints and chimeric sequences, which are useful for integration site analysis. In this study, we evaluated a commercial hybrid capture NGS panel specifically designed for detecting three key viruses: HPV, HBV, and HIV-1. We also tested workflows for Viral Hybrid Capture (VHC) and Viral Integration Site (VIS) analysis, leveraging customized viral databases in CLC Microbial Genomics. By analyzing sequenced data from virally infected cancer cell lines (including SiHa, HeLa, CaSki, C-33A, DoTc2, 2A3, SCC154 for HPV; 3B2, SNU-182 for HBV; and ACH-2 for HIV-1), we precisely pinpointed viral integration sites. The workflow also highlighted disrupted and neighboring human genes that may play a crucial role in tumor development. Our results included informative virus-host read mappings, genomic breakpoints, and integration circular plots. These visual representations enhance our understanding of the integration process. In conclusion, our seamless end-to-end workflow bridges the gap in understanding viral contributions to cancer development, paving the way for improved diagnostics and treatment strategies.

Identification of transcriptionally-active human papillomavirus integrants through nanopore sequencing reveals viable targets for gene therapy against cervical cancer.

Integration of the human papillomavirus (HPV) genome into the cellular genome is a key event that leads to constitutive expression of viral oncoprotein E6/E7 and drives the progression of cervical cancer. However, HPV integration patterns differ on a case-by-case basis among related malignancies. Next-generation sequencing technologies still face challenges for interrogating HPV integration sites. In this study, utilizing Nanopore long-read sequencing, we identified 452 and 108 potential integration sites from the cervical cancer cell lines (CaSki and HeLa) and five tissue samples, respectively. Based on long Nanopore chimeric reads, we were able to analyze the methylation status of the HPV long control region (LCR), which controls oncogene E6/E7 expression, and to identify transcriptionally-active integrants among the numerous integrants. As a proof of concept, we identified an active HPV integrant in between RUNX2 and CLIC5 on chromosome 6 in the CaSki cell line, which was supported by ATAC-seq, H3K27Ac ChIP-seq, and RNA-seq analysis. Knockout of the active HPV integrant, by the CRISPR/Cas9 system, dramatically crippled cell proliferation and induced cell senescence. In conclusion, identifying transcriptionally-active HPV integrants with Nanopore sequencing can provide viable targets for gene therapy against HPV-associated cancers.

ViroISDC: a method for calling integration sites of hepatitis B virus based on feature encoding.

BACKGROUND: Hepatitis B virus (HBV) integrates into human chromosomes and can lead to genomic instability and hepatocarcinogenesis. Current tools for HBV integration site detection lack accuracy and stability. RESULTS: This study proposes a deep learning-based method, named ViroISDC, for detecting integration sites. ViroISDC generates corresponding grammar rules and encodes the characteristics of the language data to predict integration sites accurately. Compared with Lumpy, Pindel, Seeksv, and SurVirus, ViroISDC exhibits better overall performance and is less sensitive to sequencing depth and integration sequence length, displaying good reliability, stability, and generality. Further downstream analysis of integrated sites detected by ViroISDC reveals the integration patterns and features of HBV. It is observed that HBV integration exhibits specific chromosomal preferences and tends to integrate into cancerous tissue. Moreover, HBV integration frequency was higher in males than females, and high-frequency integration sites were more likely to be present on hepatocarcinogenesis- and anti-cancer-related genes, validating the reliability of the ViroISDC. CONCLUSIONS: ViroISDC pipeline exhibits superior precision, stability, and reliability across various datasets when compared to similar software. It is invaluable in exploring HBV infection in the human body, holding significant implications for the diagnosis, treatment, and prognosis assessment of HCC.

HPV oncogenes expressed from only one of multiple integrated HPV DNA copies drive clonal cell expansion in cervical cancer.

The integration of HPV DNA into human chromosomes plays a pivotal role in the onset of papillomavirus-related cancers. HPV DNA integration often occurs by linearizing the viral DNA in the E1/E2 region, resulting in the loss of a critical viral early polyadenylation signal (PAS), which is essential for the polyadenylation of the E6E7 bicistronic transcripts and for the expression of the viral E6 and E7 oncogenes. Here, we provide compelling evidence that, despite the presence of numerous integrated viral DNA copies, virus-host fusion transcripts originate from only a single integrated HPV DNA in HPV16 and HPV18 cervical cancers and cervical cancer-derived cell lines. The host genomic elements neighboring the integrated HPV DNA are critical for the efficient expression of the viral oncogenes that leads to clonal cell expansion. The fusion RNAs that are produced use a host RNA polyadenylation signal downstream of the integration site, and almost all involve splicing to host sequences. In cell culture, siRNAs specifically targeting the host portion of the virus-host fusion transcripts effectively silenced viral E6 and E7 expression. This, in turn, inhibited cell growth and promoted cell senescence in HPV16+ CaSki and HPV18+ HeLa cells. Showing that HPV E6 and E7 expression from a single integration site is instrumental in clonal cell expansion sheds new light on the mechanisms of HPV-induced carcinogenesis and could be used for the development of precision medicine tailored to combat HPV-related malignancies. IMPORTANCE: Persistent oncogenic HPV infections lead to viral DNA integration into the human genome and the development of cervical, anogenital, and oropharyngeal cancers. The expression of the viral E6 and E7 oncogenes plays a key role in cell transformation and tumorigenesis. However, how E6 and E7 could be expressed from the integrated viral DNA which often lacks a viral polyadenylation signal in the cancer cells remains unknown. By analyzing the integrated HPV DNA sites and expressed HPV RNAs in cervical cancer tissues and cell lines, we show that HPV oncogenes are expressed from only one of multiple chromosomal HPV DNA integrated copies. A host polyadenylation signal downstream of the integrated viral DNA is used for polyadenylation and stabilization of the virus-host chimeric RNAs, making the oncogenic transcripts targetable by siRNAs. This observation provides further understanding of the tumorigenic mechanism of HPV integration and suggests possible therapeutic strategies for the development of precision medicine for HPV cancers.

Multi-omics panoramic analysis of HBV integration, transcriptional regulation, and epigenetic modifications in PLC/PRF/5 cell line.

The clearance or transcriptional silencing of integrated HBV DNA is crucial for achieving a functional cure in patients with chronic hepatitis B and reducing the risk of hepatocellular carcinoma development. The PLC/PRF/5 cell line is commonly used as an in vitro model for studying HBV integration. In this study, we employed a range of multi-omics techniques to gain a panoramic understanding of the characteristics of HBV integration in PLC/PRF/5 cells and to reveal the transcriptional regulatory mechanisms of integrated HBV DNA. Transcriptome long-read sequencing (ONT) was conducted to analyze and characterize the transcriptional activity of different HBV DNA integration sites in PLC/PRF/5 cells. Additionally, we collected data related to epigenetic regulation, including whole-genome bisulfite sequencing (WGBS), histone chromatin immunoprecipitation sequencing (ChIP-seq), and assays for transposase-accessible chromatin using sequencing (ATAC-seq), to explore the potential mechanisms involved in the transcriptional regulation of integrated HBV DNA. Long-read RNA sequencing analysis revealed significant transcriptional differences at various integration sites in the PLC/PRF/5 cell line, with higher HBV DNA transcription levels at integration sites on chr11, chr13, and the chr13/chr5 fusion chromosome t (13:5). Combining long-read DNA and RNA sequencing results, we found that transcription of integrated HBV DNA generally starts downstream of the SP1, SP2, or XP promoters. ATAC-seq data confirmed that chromatin accessibility has limited influence on the transcription of integrated HBV DNA in the PLC/PRF/5 cell line. Analysis of WGBS data showed that the methylation intensity of integrated HBV DNA was highly negatively correlated with its transcription level (r = -0.8929, p = 0.0123). After AzaD treatment, the transcription level of integrated HBV DNA significantly increased, especially for the integration chr17, which had the highest level of methylation. Through ChIP-seq data, we observed the association between histone modification of H3K4me3 and H3K9me3 with the transcription of integrated HBV DNA. Our findings suggest that the SP1, SP2 and XP in integrated HBV DNA, methylation level of surrounding host chromosome, and histone modifications affect the transcription of integrated HBV DNA in PLC/PRF/5 cells. This provides important clues for future studies on the expression and regulatory mechanisms of integrated HBV.

HBV integrations reshaping genomic structures promote hepatocellular carcinoma.

OBJECTIVE: Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), mostly characterised by HBV integrations, is prevalent worldwide. Previous HBV studies mainly focused on a few hotspot integrations. However, the oncogenic role of the other HBV integrations remains unclear. This study aimed to elucidate HBV integration-induced tumourigenesis further. DESIGN: Here, we illuminated the genomic structures encompassing HBV integrations in 124 HCCs across ages using whole genome sequencing and Nanopore long reads. We classified a repertoire of integration patterns featured by complex genomic rearrangement. We also conducted a clustered regularly interspaced short palindromic repeat (CRISPR)-based gain-of-function genetic screen in mouse hepatocytes. We individually activated each candidate gene in the mouse model to uncover HBV integration-mediated oncogenic aberration that elicits tumourigenesis in mice. RESULTS: These HBV-mediated rearrangements are significantly enriched in a bridge-fusion-bridge pattern and interchromosomal translocations, and frequently led to a wide range of aberrations including driver copy number variations in chr 4q, 5p (TERT), 6q, 8p, 16q, 9p (CDKN2A/B), 17p (TP53) and 13q (RB1), and particularly, ultra-early amplifications in chr8q. Integrated HBV frequently contains complex structures correlated with the translocation distance. Paired breakpoints within each integration event usually exhibit different microhomology, likely mediated by different DNA repair mechanisms. HBV-mediated rearrangements significantly correlated with young age, higher HBV DNA level and TP53 mutations but were less prevalent in the patients subjected to prior antiviral therapies. Finally, we recapitulated the TONSL and TMEM65 amplification in chr8q led by HBV integration using CRISPR/Cas9 editing and demonstrated their tumourigenic potentials. CONCLUSION: HBV integrations extensively reshape genomic structures and promote hepatocarcinogenesis (graphical abstract), which may occur early in a patient's life.

Detección e integración del virus del papiloma humano de alto riesgo en lesiones pre-neoplásicas en mujeres del sur de Chile: un estudio transversal / High-risk human papillomavirus detection and integration in preneoplastic lesions among women in Southern Chile: a cross-sectional study

INTRODUCCIÓN: El virus del papiloma humano de alto riesgo (VPH-AR) es responsable del cáncer de cuello uterino y sus lesiones preneoplásicas. Los genotipos VPH16 y VPH18 son los más frecuentes en este cáncer. La integración del VPH-AR en el genoma de la célula hospedera es crucial en la carcinogénesis cervical, pero la etapa en que ocurre en la población chilena es incierta. OBJETIVO: Evaluar la integración de VPH16 y VPH18 en lesiones pre-neoplásicas de cuello uterino. MÉTODOS: Se analizaron 108 muestras de raspados cervicales. El VPH se genotipificó mediante reacción de polimerasa en cadena (RPC) e hibridación no radiactiva. La integración de VPH16 y VPH18 se determinó por presencia del gen E2 mediante RPC. RESULTADOS: VPH16 y VPH18 se detectaron en 36,1% y 12,0% de las muestras, respectivamente. El VPH16 se integró en 23,1% de los casos de VPH16, mientras que VPH18 se integró en 100% de las muestras positivas para este genotipo. CONCLUSIONES: La integración VPH-AR es un evento temprano en la carcinogénesis cervical que ocurre en casi la mitad de las lesiones pre-neoplásicas y es más frecuente en VPH18 que en VPH16. La evaluación de la integración VPH-AR puede ser una herramienta útil para detectar el virus en la población chilena.

BACKGROUND: High-risk Human Papillomaviruses (HR-HPVs) are the etiological agents of cervical cancer and its preneoplastic lesions. HPV16 and 18 are the most frequent HR-HPV genotypes detected in cervical cancer. HR-HPV genome integration into the host cell is an important event in the carcinogenic process. However, it remains uncertain which stage of cervical carcinogenesis HPV16 and 18 integration occurs in the Chilean population. AIM: The goal of this study was to evaluate HPV16 and HPV18 integration in preneoplastic lesions of the cervix. METHODS: DNA was extracted from 108 cervical scrape samples with preneoplastic lesions. HPV was genotyped using PCR and non-radioactive hybridization. The integration status of HPV16 and HPV 18 was determined by evaluating the E2 gene presence through PCR. RESULTS: HPV16 and HPV18 tested positive in 36.1% and 12.0% of samples, respectively. HPV16 was found integrated in 23.1% of HPV 16 cases, while HPV 18 in 100% of samples positive for this viral genotype. CONCLUSIONS: HR-HPV integration is an early event in cervical carcinogenesis, occurring in nearly half of preneoplastic lesions and being more frequent in HPV18 than in HPV16. The evaluation of HR-HPV integration can be utilized as a complementary tool for detecting HPV in the Chilean population.

Long-read sequencing reveals the structural complexity of genomic integration of HPV DNA in cervical cancer cell lines.

BACKGROUND: Cervical cancer (CC) causes more than 311,000 deaths annually worldwide. The integration of human papillomavirus (HPV) is a crucial genetic event that contributes to cervical carcinogenesis. Despite HPV DNA integration is known to disrupt the genomic architecture of both the host and viral genomes in CC, the complexity of this process remains largely unexplored. RESULTS: In this study, we conducted whole-genome sequencing (WGS) at 55-65X coverage utilizing the PacBio long-read sequencing platform in SiHa and HeLa cells, followed by comprehensive analyses of the sequence data to elucidate the complexity of HPV integration. Firstly, our results demonstrated that PacBio long-read sequencing effectively identifies HPV integration breakpoints with comparable accuracy to targeted-capture Next-generation sequencing (NGS) methods. Secondly, we constructed detailed models of complex integrated genome structures that included both the HPV genome and nearby regions of the human genome by utilizing PacBio long-read WGS. Thirdly, our sequencing results revealed the occurrence of a wide variety of genome-wide structural variations (SVs) in SiHa and HeLa cells. Additionally, our analysis further revealed a potential correlation between changes in gene expression levels and SVs on chromosome 13 in the genome of SiHa cells. CONCLUSIONS: Using PacBio long-read sequencing, we have successfully constructed complex models illustrating HPV integrated genome structures in SiHa and HeLa cells. This accomplishment serves as a compelling demonstration of the valuable capabilities of long-read sequencing in detecting and characterizing HPV genomic integration structures within human cells. Furthermore, these findings offer critical insights into the complex process of HPV16 and HPV18 integration and their potential contribution to the development of cervical cancer.

Viral integration promotes SV40T-induced immortalization by disturbing the expression of DNA/chromosome- and ECM-associated functional genes.

Lentivirus containing simian virus 40 large T antigen (SV40T) is routinely used to induce cell immortalization. However, the roles of viral integration itself in this progress is still controversial. Here, we transformed primary mouse embryonic fibroblasts (MEFs) with SV40T lentivirus and studied the roles of viral integration in the immortalization using RNA sequencing (RNA-seq) and whole genome sequencing (WGS). During the immortalization, differentially expressed genes (DGEs) are enriched in viral infection and several diverse activities. However, DEGs between immortalized and aging cells are significantly enriched in DNA/chromosome- and extracellular matrix (ECM)-associated activities. Gene regulatory network (GRN) analysis shows that although p53 is a key regulatory factor, many other transcription factors also play critical roles in the process, like STAT1. Of these DEGs, 32 genes have viral integration in their coding and/or regulatory regions. Our findings suggest that viral integration may promote SV40T-mediated immortalization by disturbing the expression of DNA/chromosome- and ECM-associated genes.

Prevalent and Disseminated Recombinant and Wild-Type Adeno-Associated Virus Integration in Macaques and Humans.

Integration of naturally occurring adeno-associated viruses (AAV; wild-type AAV [wtAAV]) and those used in gene therapy (recombinant AAV [rAAV]) into host genomic DNA has been documented for over two decades. Results from mouse and dog studies have raised concerns of insertional mutagenesis and clonal expansion following AAV exposure, particularly in the context of gene therapy. This study aimed to characterize the genomic location, abundance, and expansion of wtAAV and rAAV integrations in macaque and human genomes. Using an unbiased, next-generation sequencing-based approach, we identified the genome-wide integration loci in tissue samples (primarily liver) in 168 nonhuman primates (NHPs) and 85 humans naïve to rAAV exposure and 86 NHPs treated with rAAV in preclinical studies. Our results suggest that rAAV and wtAAV integrations exhibit similar, broad distribution patterns across species, with a higher frequency in genomic regions highly vulnerable to DNA damage or close to highly transcribed genes. rAAV exhibited a higher abundance of unique integration loci, whereas wtAAV integration loci were associated with greater clonal expansion. This expansive and detailed characterization of AAV integration in NHPs and humans provides key translational insights, with important implications for the safety of rAAV as a gene therapy vector.

The analysis of HPV integration sites based on nanopore sequencing and the profiling changes along the course of photodynamic therapy.

OBJECTIVE: To detect the HPV genotype and integration sites in patients with high-risk HPV infection at different stages of photodynamic therapy using nanopore technology and to evaluate the treatment effect. METHODS: Four patients with HPV infection were selected and subjected to photodynamic therapy, and cervical exfoliated cell was sampled at before treatment, after three courses of treatment and six courses of treatment, their viral abundance and insertion sites were analyzed by nanopore technology, and pathological examinations were performed before and after treatment. In this study, we developed a novel assay that combined viral sequence enrichment and Nanopore sequencing for identification of HPV genotype and integration sites at once. The assay has obvious advantages over qPCR or NGS-based methods, as it has better sensitivity after viral sequences enrichment and can generate long-reads (kb to Mb) for better detection rate of structure variations, moreover, fast turn-around time for real-time viral sequencing and analysis. RESULTS: The pathological grade was reduced in all four patients after photodynamic therapy. Virus has been cleared in two cases after treatment, the virus amount reduced after treatment but not completely cleared in one case, and two type viruses were cleared and one type virus persisted after treatment in the last patient with multiple infection. Viral abundance and the number of integration sites were positively correlated. Gene enrichment analysis showed complete viral clearance in 1 patient and 3 patients required follow-up. CONCLUSION: Nanopore sequencing can effectively monitor the abundance of HPV viruses and integration sites to show the presence status of viruses, and combined with the results of gene enrichment analysis, the treatment effect can be dynamically assessed.

Characterization of integrated Marek's disease virus genomes supports a model of integration by homology-directed recombination and telomere-loop-driven excision.

IMPORTANCE: Marek's disease virus (MDV) is a ubiquitous chicken pathogen that inflicts a large economic burden on the poultry industry, despite worldwide vaccination programs. MDV is only partially controlled by available vaccines, and the virus retains the ability to replicate and spread between vaccinated birds. Following an initial infection, MDV enters a latent state and integrates into host telomeres and this may be a prerequisite for malignant transformation, which is usually fatal. To understand the mechanism that underlies the dynamic relationship between integrated-latent and reactivated MDV, we have characterized integrated MDV (iMDV) genomes and their associated telomeres. This revealed a single orientation among iMDV genomes and the loss of some terminal sequences that is consistent with integration by homology-directed recombination and excision via a telomere-loop-mediated process.

Unraveling the palindromic and nonpalindromic motifs of retroviral integration site sequences by statistical mixture models.

A weak palindromic nucleotide motif is the hallmark of retroviral integration site alignments. Given that the majority of target sequences are not palindromic, the current model explains the symmetry by an overlap of the nonpalindromic motif present on one of the half-sites of the sequences. Here, we show that the implementation of multicomponent mixture models allows for different interpretations consistent with the existence of both palindromic and nonpalindromic submotifs in the sets of integration site sequences. We further show that the weak palindromic motifs result from freely combined site-specific submotifs restricted to only a few positions proximal to the site of integration. The submotifs are formed by either palindrome-forming nucleotide preference or nucleotide exclusion. Using the mixture models, we also identify HIV-1-favored palindromic sequences in Alu repeats serving as local hotspots for integration. The application of the novel statistical approach provides deeper insight into the selection of retroviral integration sites and may prove to be a valuable tool in the analysis of any type of DNA motifs.

Mitochondrial DNA is a target of HBV integration.

Hepatitis B virus (HBV) may integrate into the genome of infected cells and contribute to hepatocarcinogenesis. However, the role of HBV integration in hepatocellular carcinoma (HCC) development remains unclear. In this study, we apply a high-throughput HBV integration sequencing approach that allows sensitive identification of HBV integration sites and enumeration of integration clones. We identify 3339 HBV integration sites in paired tumour and non-tumour tissue samples from 7 patients with HCC. We detect 2107 clonally expanded integrations (1817 in tumour and 290 in non-tumour tissues), and a significant enrichment of clonal HBV integrations in mitochondrial DNA (mtDNA) preferentially occurring in the oxidative phosphorylation genes (OXPHOS) and D-loop region. We also find that HBV RNA sequences are imported into the mitochondria of hepatoma cells with the involvement of polynucleotide phosphorylase (PNPASE), and that HBV RNA might have a role in the process of HBV integration into mtDNA. Our results suggest a potential mechanism by which HBV integration may contribute to HCC development.

Oncogenic virus integration: Moving toward clinical applications.

The majority of oncogenic viruses are capable of integrating into the host genome, posing significant challenges to clinical control. Recent conceptual and technological advances, however, offer promising clinical applications. Here, we summarize the advances in our understanding of oncogenic viral integration, their clinical relevance, and the future perspectives.

HPV integration generates a cellular super-enhancer which functions as ecDNA to regulate genome-wide transcription.

Human papillomavirus (HPV) integration is a critical step in cervical cancer development; however, the oncogenic mechanism at the genome-wide transcriptional level is still poorly understood. In this study, we employed integrative analysis on multi-omics data of six HPV-positive and three HPV-negative cell lines. Through HPV integration detection, super-enhancer (SE) identification, SE-associated gene expression and extrachromosomal DNA (ecDNA) investigation, we aimed to explore the genome-wide transcriptional influence of HPV integration. We identified seven high-ranking cellular SEs generated by HPV integration in total (the HPV breakpoint-induced cellular SEs, BP-cSEs), leading to intra-chromosomal and inter-chromosomal regulation of chromosomal genes. The pathway analysis revealed that the dysregulated chromosomal genes were correlated to cancer-related pathways. Importantly, we demonstrated that BP-cSEs existed in the HPV-human hybrid ecDNAs, explaining the above transcriptional alterations. Our results suggest that HPV integration generates cellular SEs that function as ecDNA to regulate unconstrained transcription, expanding the tumorigenic mechanism of HPV integration and providing insights for developing new diagnostic and therapeutic strategies.

Genomic profiling of HIV-1 integration in microglia cells links viral integration to the topologically associated domains.

HIV-1 encounters the hierarchically organized host chromatin to stably integrate and persist in anatomically distinct latent reservoirs. The contribution of genome organization in HIV-1 infection has been largely understudied across different HIV-1 targets. Here, we determine HIV-1 integration sites (ISs), associate them with chromatin and expression signatures at different genomic scales in a microglia cell model, and profile them together with the primary T cell reservoir. HIV-1 insertions into introns of actively transcribed genes with IS hotspots in genic and super-enhancers, characteristic of blood cells, are maintained in the microglia cell model. Genome organization analysis reveals dynamic CCCTC-binding factor (CTCF) clusters in cells with active and repressed HIV-1 transcription, whereas CTCF removal impairs viral integration. We identify CTCF-enriched topologically associated domain (TAD) boundaries with signatures of transcriptionally active chromatin as HIV-1 integration determinants in microglia and CD4+ T cells, highlighting the importance of host genome organization in HIV-1 infection.

VIS Atlas: A Database of Virus Integration Sites in Human Genome from NGS Data to Explore Integration Patterns.

Integration of oncogenic DNA viruses into the human genome is a key step in most virus-induced carcinogenesis. Here, we constructed a virus integration site (VIS) Atlas database, an extensive collection of integration breakpoints for three most prevalent oncoviruses, human papillomavirus, hepatitis B virus, and Epstein-Barr virus based on the next-generation sequencing (NGS) data, literature, and experimental data. There are 63,179 breakpoints and 47,411 junctional sequences with full annotations deposited in the VIS Atlas database, comprising 47 virus genotypes and 17 disease types. The VIS Atlas database provides (1) a genome browser for NGS breakpoint quality check, visualization of VISs, and the local genomic context; (2) a novel platform to discover integration patterns; and (3) a statistics interface for a comprehensive investigation of genotype-specific integration features. Data collected in the VIS Atlas aid to provide insights into virus pathogenic mechanisms and the development of novel antitumor drugs. The VIS Atlas database is available at https://www.vis-atlas.tech/.

Antiretroviral APOBEC3 cytidine deaminases alter HIV-1 provirus integration site profiles.

APOBEC3 (A3) proteins are host-encoded deoxycytidine deaminases that provide an innate immune barrier to retroviral infection, notably against HIV-1. Low levels of deamination are believed to contribute to the genetic evolution of HIV-1, while intense catalytic activity of these proteins can induce catastrophic hypermutation in proviral DNA leading to near-total HIV-1 restriction. So far, little is known about how A3 cytosine deaminases might impact HIV-1 proviral DNA integration sites in human chromosomal DNA. Using a deep sequencing approach, we analyze the influence of catalytic active and inactive APOBEC3F and APOBEC3G on HIV-1 integration site selections. Here we show that DNA editing is detected at the extremities of the long terminal repeat regions of the virus. Both catalytic active and non-catalytic A3 mutants decrease insertions into gene coding sequences and increase integration sites into SINE elements, oncogenes and transcription-silencing non-B DNA features. Our data implicates A3 as a host factor influencing HIV-1 integration site selection and also promotes what appears to be a more latent expression profile.