TLR10 Senses HIV-1 Proteins and Significantly Enhances HIV-1 Infection

Toll-like receptors (TLRs) play a crucial role in innate immunity and provide a first line of host defense against invading pathogens. Of the identified human TLRs, TLR10 remains an orphan receptor whose ligands and functions are poorly understood. In the present study, we sought to evaluate the level of TLR10 expression in breast milk (BM) and explore its potential function in the context of HIV-1 infection. We evaluated HIV-1-infected (Nigerian: n = 40) and uninfected (Nigerian: n = 27; Canadian: n = 15) BM samples for TLR expression (i.e., TLR10, TLR2, and TLR1) and report here that HIV-1-infected BM from Nigerian women showed significantly higher levels of TLR10, TLR1, and TLR2 expression. Moreover, the level of TLR10 expression in HIV-1-infected BM was upregulated by over 100-fold compared to that from uninfected control women. In vitro studies using TZMbl cells demonstrated that TLR10 overexpression contributes to higher HIV-1 infection and proviral DNA integration. Conversely, TLR10 inhibition significantly decreased HIV-1 infection. Notably, HIV-1 gp41 was recognized as a TLR10 ligand, leading to the induction of IL-8 and NF-κBα activation. The identification of a TLR10 ligand and its involvement in HIV-1 infection enhances our current understanding of HIV-1 replication and may assist in the development of improved future therapeutic strategies

TLR10 Senses HIV-1 Proteins and Significantly Enhances HIV-1 Infection

Toll-like receptors (TLRs) play a crucial role in innate immunity and provide a first line of host defense against invading pathogens. Of the identified human TLRs, TLR10 remains an orphan receptor whose ligands and functions are poorly understood. In the present study, we sought to evaluate the level of TLR10 expression in breastmilk (BM) and explore its potential function in the context of HIV-1 infection. We evaluated HIV-1-infected (Nigerian: n = 40) and uninfected (Nigerian: n = 27; Canadian: n = 15) BM samples for TLR expression (i.e., TLR10, TLR2, and TLR1) and report here that HIV-1-infected BM from Nigerian women showed significantly higher levels of TLR10, TLR1, and TLR2 expression. Moreover, the level of TLR10 expression in HIV-1-infected BM was upregulated by over 100-fold compared to that from uninfected control women. In vitro studies using TZMbl cells demonstrated that TLR10 overexpression contributes to higher HIV-1 infection and proviral DNA integration. Conversely, TLR10 inhibition significantly decreased HIV-1 infection. Notably, HIV-1 gp41 was recognized as a TLR10 ligand, leading to the induction of IL-8 and NF-kBa activation. The identification of a TLR10 ligand and its involvement in HIV-1 infection enhances our current understanding of HIV-1 replication and may assist in the development of improved future therapeutic strategies

Expression profiling of human milk derived exosomal microRNAs and their targets in HIV‐1 infected mothers

Despite the use of antiretroviral therapy (ART) in HIV‐1 infected mothers approximately 5% of new HIV‐1 infections still occur in breastfed infants annually, which warrants for the development of novel strategies to prevent new HIV‐1 infections in infants. Human milk (HM) exosomes are highly enriched in microRNAs (miRNAs), which play an important role in neonatal immunity. Furthermore, HM exosomes from healthy donors are known to inhibit HIV‐1 infection and transmission; however, the effect of HIV‐1 on HM exosomal miRNA signatures remains unknown. In this study, we used nCounter NanoString technology and investigated miRNAs expression profiles in first week postpartum HM exosomes from HIV‐1 infected and uninfected control mothers (n = 36). Our results indicated that HIV‐1 perturbed the differential expression patterns of 19 miRNAs (13 upregulated and 6 downregulated) in HIV‐1 infected women compared to healthy controls. DIANA‐miR functional pathway analyses revealed that multiple biological pathways are involved including cell cycle, pathways in cancer, TGF‐β signaling, FoxO signaling, fatty acid biosynthesis, p53 signaling and apoptosis. Moreover, the receiver operating characteristics (ROC) curve analyses of miR‐630 and miR‐ 378g yielded areas under the ROC curves of 0.82 (95% CI 0.67 to 0.82) and 0.83 (95% CI 0.67 to 0.83), respectively highlighting their potential to serve as biomarkers to identify HIV‐1 infection in women. These data may contribute to the development of new therapeutic strategies in prevention of mother‐ to‐child transmission (MTCT) of HIV‐1

TRIM26 Facilitates HSV-2 Infection by Downregulating Antiviral Responses through the IRF3 Pathway

Herpes simplex virus type 2 (HSV-2) is the primary cause of genital herpes which results in significant morbidity and mortality, especially in women, worldwide. HSV-2 is transmitted primarily through infection of epithelial cells at skin and mucosal surfaces. Our earlier work to examine interactions between HSV-2 and vaginal epithelial cells demonstrated that infection of the human vaginal epithelial cell line (VK2) with HSV-2 resulted in increased expression of TRIM26, a negative regulator of the Type I interferon pathway. Given that upregulation of TRIM26 could negatively affect anti-viral pathways, we decided to further study the role of TRIM26 in HSV-2 infection and replication. To do this, we designed and generated two cell lines derived from VK2s with TRIM26 overexpressed (OE) and knocked out (KO). Both, along with wildtype (WT) VK2, were infected with HSV-2 and viral titres were measured in supernatants 24 h later. Our results showed significantly enhanced virus production by TRIM26 OE cells, but very little replication in TRIM26 KO cells. We next examined interferon-β production and expression of two distinct interferon stimulated genes (ISGs), MX1 and ISG15, in all three cell lines, prior to and following HSV-2 infection. The absence of TRIM26 (KO) significantly upregulated interferon-β production at baseline and even further after HSV-2 infection. TRIM26 KO cells also showed significant increase in the expression of MX1 and ISG15 before and after HSV-2 infection. Immunofluorescent staining indicated that overexpression of TRIM26 substantially decreased the nuclear localization of IRF3, the primary mediator of ISG activation, before and after HSV-2 infection. Taken together, our data indicate that HSV-2 utilizes host factor TRIM26 to evade anti-viral response and thereby increase its replication in vaginal epithelial cells

HepG2-NTCP Subclones Exhibiting High Susceptibility to Hepatitis B Virus Infection

HepG2 cells reconstituted with Hepatitis B virus (HBV) entry receptor sodium taurocholate co-transporting polypeptide (NTCP) are widely used as a convenient in vitro cell culture infection model for HBV replication studies. As such, it is pertinent that HBV infectivity is maintained at steady-state levels for an accurate interpretation of in vitro data. However, variations in the HBV infection efficiency due to imbalanced NTCP expression levels in the HepG2 cell line may affect experimental results. In this study, we performed single cell-cloning of HepG2-NTCP-A3 parental cells via limiting dilution and obtained multiple subclones with increased permissiveness to HBV. Specifically, one subclone (HepG2-NTCP-A3/C2) yielded more than four-fold higher HBV infection compared to the HepG2-NTCP-A3 parental clone. In addition, though HBV infectivity was universally reduced in the absence of polyethylene glycol (PEG), subclone C2 maintained relatively greater permissiveness under PEG-free conditions, suggesting the functional heterogeneity within parental HepG2-NTCP-A3 may be exploitable in developing a PEG-free HBV infection model. The increased viral production correlated with increased intracellular viral antigen expression as evidenced through HBcAg immunofluorescence staining. Further, these subclones were found to express different levels of NTCP, albeit with no remarkable morphology or cell growth differences. In conclusion, we isolated the subclones of HepG2-NTCP-A3 which support efficient HBV production and thus provide an improved in vitro HBV infection model

Regulation of Human T-Lymphotropic Virus Type I Latency and Reactivation by HBZ and Rex

<div><p>Human T lymphotropic virus type I (HTLV-I) infection is largely latent in infected persons. How HTLV-1 establishes latency and reactivates is unclear. Here we show that most HTLV-1-infected HeLa cells become senescent. By contrast, when NF-κB activity is blocked, senescence is averted, and infected cells continue to divide and chronically produce viral proteins. A small population of infected NF-κB-normal HeLa cells expresses low but detectable levels of Tax and Rex, albeit not Gag or Env. In these “latently” infected cells, HTLV-1 LTR trans-activation by Tax persists, but NF-κB trans-activation is attenuated due to inhibition by HBZ, the HTLV-1 antisense protein. Furthermore, Gag-Pol mRNA localizes primarily in the nuclei of these cells. Importantly, HBZ was found to inhibit Rex-mediated export of intron-containing mRNAs. Over-expression of Rex or shRNA-mediated silencing of HBZ led to viral reactivation. Importantly, strong NF-κB inhibition also reactivates HTLV-1. Hence, during HTLV-1 infection, when Tax/Rex expression is robust and dominant over HBZ, productive infection ensues with expression of structural proteins and NF-κB hyper-activation, which induces senescence. When Tax/Rex expression is muted and HBZ is dominant, latent infection is established with expression of regulatory (Tax/Rex/HBZ) but not structural proteins. HBZ maintains viral latency by down-regulating Tax-induced NF-κB activation and senescence, and by inhibiting Rex-mediated expression of viral structural proteins.</p></div

Genetic Diversity in Local and Exotic Avena sativa L. (Oat) Germplasm Using Multivariate Analysis

Avena sativa L., also known as Oat belongs to the Poaceae family, is one of the most significant crops that is grown for its seeds, fodder as well as for human consumption as oatmeal. In the current study, 236 genotypes of A. sativa were analysed for genetic diversity through agro-morphological and SDS-PAGE analysis. Cluster analysis based on agro-morphological characteristics grouped all the genotypes into nine clusters, whereas genotype numbers 537 and 728 were highly different from others. The seed yield production of cluster 9 genotypes was the highest per plant (38.2 ± 0.20 g), while cluster 2 genotypes produced maximum biomass per plant (122.5 ± 9.55 g) as compared to other clusters. In a principal component analysis where four variables were studied, and the observed total variations were 57.60%. Among the genotypes, a maximum grain yield of 38.2 g (each) was recorded for genotypes 22,350 and 728, followed by genotypes 737 and 22,390 (with 36.4 g and 35.6 g of seed productions, respectively). The SDS-PAGE analysis resulted in 13 bands and all the genotypes were grouped into seventeen clusters. At the extreme periphery of the dendrogram, genotype 537 and 22,332 were considered to be the most diverse genotypes. Our findings have implications for both understanding the diversity and relationships among these diverse genotypes of A. sativa and will provide a basis for obtaining the elite germplasm optimally adapted to local conditions. The selected genotypes based on agronomic performance may be potential breeding material to raise successful future cultivars

Characterizations of HeLa-G-derived cell lines productively (PIC, ΔN-IκBα/HTLV-1) or latently infected (LIC, HeLa-G/HTLV-1) by HTLV-1.

<p>(<b>A</b>) Immunoblot analyses of whole-cell lysates of HeLa-G/HTLV-1 clones 1, 2, and 3 (LIC); HeLa-G/ΔN-IκBα/HTLV-1 (ΔN-IκBα/HTLV-1, PIC) clones 1 and 2; and HeLa-G control. Antibodies used include p19, p24, Tax, Rex, Env, and β-actin (Actin). (<b>B & C</b>) LTR-Luc and E-selectin- Luc reporter activities in HTLV-1-infected cell lines analyzed in (<b>A</b>). Each reporter plasmid and the control Renilla-luciferase plasmid, pRL-TK, were transfected into HeLa-G cells, 3 LIC lines and 2 PIC lines as described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004040#s4" target="_blank"><b>Materials and Methods</b></a>. Relative luciferase activity after normalization is plotted.</p

Knockdown of HBZ expression or strong inhibition of NF-κB reactivates latent HTLV-1.

<p>(<b>A</b>) Knockdown of HBZ mRNA expression in latently infected cells (LICs). LIC clones were transduced with a lentiviral HBZ shRNA construct (open bars) or with a control vector (solid bars) as previously described <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004040#ppat.1004040-Satou1" target="_blank">[30]</a>. Transduced cells were selected in liquid medium containing 1 µg/ml puromycin. Knockdown of HBZ expression was confirmed by real-time PCR as detailed in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004040#s4" target="_blank"><b>Materials and Methods</b></a>. (<b>B</b>) Induction of p24 expression in latently infected cell (LIC) clones after HBZ knockdown. LIC clones 1–3 and their derivatives stably transduced with lentiviral HBZ shRNA were analyzed by immunoblotting for p24, Tax, Rex, and β-actin (Actin). (<b>C</b>) Strong inhibition of NF-κB reactivates HTLV-1 from latently infected cells. LIC clones were transduced with a lentiviral construct, LV-ΔN-IκBα, that expresses a degradation resistant super-repressor form of IκBα, ΔN-IκBα. Transduced cells were selected as in (A) and analyzed by immunoblotting for the indicated proteins.</p