Rare LEDGF/p75 genetic variants in white long-term nonprogressor HIV+ individuals

Association of single nucleotide polymorphisms in the lens epithelium-derived growth factor (LEDGF/p75) with HIV-1 infection outcomes in Brazilian HIV-1+ individuals

The lens epithelium-derived growth factor p75 (LEDGF/p75), coded by the PSIP1 gene, is an important host co-factor that interacts with HIV-1 integrase to target integration of viral cDNA into active genes. The aim of this study was to investigate the association of SNPs in the PSIP1 gene with disease outcome in HIV-1 infected patients. We performed a genetic association study in a cohort of 171 HIV-1 seropositive Brazilian individuals classified as rapid progressors (RP, n = 69), typical progressors (TP, n = 79) and long-term nonprogressors (LTNP, n = 23). The exonic SNP rs61744944 and 9 tag SNPs were genotyped. A group of 192 healthy subjects was analyzed to determine the frequency of SNPs and haplotypes in the general population. Linkage disequilibrium (LD) analyses indicated that the SNPs analyzed were not in high LD (r²<0.8). Logistic regression models suggested that patients carrying the T allele rs61744944 (472L) were more likely to develop a LTNP phenotype (OR = 4.98; p = 0.05) as compared to TP group. The same trend was observed when LTNPs were compared to the RP group (OR = 3.26). Results of haplotype analyses reinforced this association, since the OR values obtained for the haplotype carrying allele T at rs61744944 also reflected an association with LTNP status (OR = 6.05; p = 0.08 and OR = 3.44; p = 0.12 for comparisons to TP and RP, respectively). The rare missense variations Ile436Ser and Thr473Ile were not identified in the patients enrolled in this study. Gene expression analyses showed lower LEDGF/p75 mRNA levels in peripheral blood mononuclear cells obtained from HIV-1 infected individuals. However, these levels were not influenced by any of the SNPs investigated. In spite of the limited number of LTNPs, these data suggest that the PSIP1 gene could be associated with the outcome of HIV-1 infection. Further analyses of this gene may guide the identification of causative variants to help predict disease course.

Zinc finger endonuclease targeting PSIP1 inhibits HIV-1 integration

Genome editing using zinc finger nucleases (ZFNs) has been successfully applied to disrupt CCR5 or CXCR4 host factors and inhibit viral entry and infection. Gene therapy using ZFNs to modify the PSIP1 gene, which encodes the lens epithelium-derived growth factor (LEDGF) protein, might restrain an early step of the viral replication cycle at the integration level. ZFNs targeting the PSIP1 gene (ZFNLEDGF) were designed to specifically recognize the sequence after the integrase binding domain (IBD) of the LEDGF/p75 protein. ZFNLEDGF successfully recognized the target region of the PSIP1 gene in TZM-bl cells by heteroduplex formation and DNA sequence analysis. Gene editing induced a frameshift of the coding region and resulted in the abolishment of LEDGF expression at the mRNA and protein levels. Functional assays revealed that infection with the HIV-1 R5 BaL or X4 NL4-3 viral strains was impaired in LEDGF/p75 knockout cells regardless of entry tropism due to a blockade in HIV-1 proviral integration into the host genome. However, residual infection was detected in the LEDGF knockout cells. Indeed, LEDGF knockout restriction was overcome at a high multiplicity of infection, suggesting alternative mechanisms for HIV-1 genome integration rather than through LEDGF/p75. However, the observed residual integration was sensitive to the integrase inhibitor raltegravir. These results demonstrate that the described ZFNLEDGF effectively targets the PSIP1 gene, which is involved in the early steps of the viral replication cycle; thus, ZFNLEDGF may become a potential antiviral agent for restricting HIV-1 integration. Moreover, LEDGF knockout cells represent a potent tool for elucidating the role of HIV integration cofactors in virus replication.

Biobanking and translation of human genetics and genomics for infectious diseases

Biobanks are invaluable resources in genomic research of both the infectious diseases and their hosts. This article examines the role of biobanks in basic research of infectious disease genomics, as well as the relevance and applicability of biobanks in the translation of impending knowledge and the clinical uptake of knowledge of infectious diseases. Our research identifies potential fields of interaction between infectious disease genomics and biobanks, in line with global trends in the integration of genome-based knowledge into clinical practice. It also examines various networks and biobanks that specialize in infectious diseases (including HIV, HPV and Chlamydia trachomatis), and provides examples of successful research and clinical uptake stemming from these biobanks. Finally, it outlines key issues with respect to data privacy in infectious disease genomics, as well as the utility of adequately designed and maintained electronic health records. We maintain that the public should be able to easily access a clear and detailed outline of regulations and procedures for sample and data utilization by academic or commercial investigators, and also should be able to understand the precise roles of relevant governing bodies. This would ultimately facilitate uptake by researchers and clinics. As a result of the efforts and resources invested by several networks and consortia, there is an increasing awareness of the prospective uses of biobanks in advancing infectious disease genomic research, diagnostics and their clinical management.

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The role of biobanks in research of host genomic factors and infectious diseases.

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Examples of translation of HIV, HPV and Chlamydia research results into clinics.

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Lack of published overviews of infectious disease biobanks, result is low visibility.

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Regulations and sample utilization procedures should be more easily accessible.

Insights from host genomics into HIV infection and disease: Identification of host targets for drug development

HIV susceptibility and disease progression show a substantial degree of individual heterogeneity, ranging from fast progressors to long-term non progressors or elite controllers, that is, subjects that control infection in the absence of therapy. Recent years have seen a significant increase in understanding of the host genetic determinants of susceptibility to HIV infection and disease progression, driven in large part by candidate gene studies, genome-wide association studies, genome-wide transcriptome analyses, and large-scale functional screens. These studies have identified common variants in host loci that clearly influence disease progression, characterized the scale and dynamics of gene and protein expression changes in response to infection, and provided the first comprehensive catalogue of genes and pathways involved in viral replication. This review highlights the potential of host genomic influences in antiviral therapy by pointing to promising novel drug targets but also providing the basis of the identification and validation of host mechanisms that might be susceptible targets for novel antiviral therapies.

Characterization of rare lens epithelium-derived growth factor/p75 genetic variants identified in HIV-1 long-term nonprogressors

OBJECTIVE

Lens epithelium-derived growth factor (LEDGF)/p75 is a cellular binding partner of HIV-1 integrase and a crucial cofactor for HIV-1 replication. Here, we study two LEDGF/p75 exonic variants I436S and T473I, identified in HIV-1 long-term nonprogressors, together with Q472L.

METHODS

In-vitro binding assays, cell culture complementation, and functional rescue.

RESULTS

Binding affinities of wild-type, I436S, T473I, and Q472L LEDGF/p75 for HIV-1 integrase were comparable. All LEDGF/p75 variants bound equally well to LEDGF/p75 interacting partners JPO2 and PogZ. In addition, HIV-1 replication was evaluated in human somatic LEDGF/p75-knockout cells and LEDGF/p75-knockdown cells complemented with either wild-type LEDGF/p75 or the respective LEDGF/p75 variants. All variants rescued HIV-1 replication to wild-type levels, whereas LEDGF/p75 D366N, defective for interaction with HIV-1 integrase, did not.

CONCLUSION

Although identified in a cohort of long-term nonprogressors, our study did not indicate that the I436S or T473I mutation in LEDGF/p75 affects the interaction with HIV-1 integrase.

Characterization of LEDGF/p75 genetic variants and association with HIV-1 disease progression

Background

As Lens epithelium-derived growth factor (LEDGF/p75) is an important co-factor involved in HIV-1 integration, the LEDGF/p75-IN interaction is a promising target for the new class of allosteric HIV integrase inhibitors (LEDGINs). Few data are available on the genetic variability of LEDGF/p75 and the influence on HIV disease in vivo. This study evaluated the relation between LEDGF/p75 genetic variation, mRNA expression and HIV-1 disease progression in order to guide future clinical use of LEDGINs.

Methods

Samples were derived from a therapy-naïve cohort at Ghent University Hospital and a Spanish long-term-non-progressor cohort. High-resolution melting curve analysis and Sanger sequencing were used to identify all single nucleotide polymorphisms (SNPs) in the coding region, flanking intronic regions and full 3′UTR of LEDGF/p75. In addition, two intronic tagSNPs were screened based on previous indication of influencing HIV disease. LEDGF/p75 mRNA was quantified in patient peripheral blood mononuclear cells (PBMC) using RT-qPCR.

Results

325 samples were investigated from patients of Caucasian (n = 291) and African (n = 34) origin, including Elite (n = 49) and Viremic controllers (n = 62). 21 SNPs were identified, comprising five in the coding region and 16 in the non-coding regions and 3′UTR. The variants in the coding region were infrequent and had no major impact on protein structure according to SIFT and PolyPhen score. One intronic SNP (rs2737828) was significantly under-represented in Caucasian patients (P<0.0001) compared to healthy controls (HapMap). Two SNPs showed a non-significant trend towards association with slower disease progression but not with LEDGF/p75 expression. The observed variation in LEDGF/p75 expression was not correlated with disease progression.

Conclusions

LEDGF/p75 is a highly conserved protein. Two non-coding polymorphisms were identified indicating a correlation with disease outcome, but further research is needed to clarify phenotypic impact. The conserved coding region and the observed variation in LEDGF/p75 expression are important characteristics for clinical use of LEDGINs.

Small molecule inhibitors of the LEDGF site of human immunodeficiency virus integrase identified by fragment screening and structure based design

A fragment-based screen against human immunodeficiency virus type 1 (HIV) integrase led to a number of compounds that bound to the lens epithelium derived growth factor (LEDGF) binding site of the integrase catalytic core domain. We determined the crystallographic structures of complexes of the HIV integrase catalytic core domain for 10 of these compounds and quantitated the binding by surface plasmon resonance. We demonstrate that the compounds inhibit the interaction of LEDGF with HIV integrase in a proximity AlphaScreen assay, an assay for the LEDGF enhancement of HIV integrase strand transfer and in a cell based assay. The compounds identified represent a potential framework for the development of a new series of HIV integrase inhibitors that do not bind to the catalytic site of the enzyme.

HIV-1 infection and CCR5Δ32 homozygosis

HIV susceptibility shows a substantial degree of individual heterogeneity, much of which can be conferred by host genetic variation. Several polymorphisms in the CCR5 gene that influence HIV transmission and/or disease progression have highlighted the importance of this co-receptor in vivo. One of them, the CCR5Δ32 deletion, was the first host genetic factor with a demonstrated effect on HIV-1 disease and has been unequivocally associated with strong resistance against HIV-1 infection. Here, we review the CCR5Δ32 homozygous HIV-1 patients cases reported. The discovery of CCR5Δ32 was of key importance to demonstrate that host genetic factors could influence the course of HIV infection, providing insights into the mechanisms of control and a relevant proof of principle for the development of new therapeutic strategies.