Infectious Virus Tracking by Fluorescent Live Cell Imaging in Primary Cells.

To successfully infect a cell, HIV-1 has to overcome several host barriers while exploiting cellular cofactors. HIV-1 infection is highly inefficient with the great majority of viral particles not being able to successfully integrate into the target cell genome. Nonproductive HIV-1 particles are degraded or accumulated in cellular compartments. Thus, it becomes hard to distinguish between viral behaviors that lead to effectively infecting the cell from the ones that do not by using traditional methods. Here, we describe the infectious virus tracking method that detects and quantifies individual fluorescent viral particles over time and links viral particle behavior to its infectivity. This method employs live-cell imaging at ultra-low MOIs to detect the outcome of infection for every HIV-1 particle.

Structure of HIV-1 RRE stem-loop II identifies two conformational states of the high-affinity Rev binding site.

During HIV infection, specific RNA-protein interaction between the Rev response element (RRE) and viral Rev protein is required for nuclear export of intron-containing viral mRNA transcripts. Rev initially binds the high-affinity site in stem-loop II, which promotes oligomerization of additional Rev proteins on RRE. Here, we present the crystal structure of RRE stem-loop II in distinct closed and open conformations. The high-affinity Rev-binding site is located within the three-way junction rather than the predicted stem IIB. The closed and open conformers differ in their non-canonical interactions within the three-way junction, and only the open conformation has the widened major groove conducive to initial Rev interaction. Rev binding assays show that RRE stem-loop II has high- and low-affinity binding sites, each of which binds a Rev dimer. We propose a binding model, wherein Rev-binding sites on RRE are sequentially created through structural rearrangements induced by Rev-RRE interactions.

The association between single-nucleotide polymorphisms within type 1 interferon pathway genes and human immunodeficiency virus type 1 viral load in antiretroviral-naïve participants.

BACKGROUND: Human genetic contribution to HIV progression remains inadequately explained. The type 1 interferon (IFN) pathway is important for host control of HIV and variation in type 1 IFN genes may contribute to disease progression. This study assessed the impact of variations at the gene and pathway level of type 1 IFN on HIV-1 viral load (VL). METHODS: Two cohorts of antiretroviral (ART) naïve participants living with HIV (PLWH) with either early (START) or advanced infection (FIRST) were analysed separately. Type 1 IFN genes (n = 17) and receptor subunits (IFNAR1, IFNAR2) were examined for both cumulated type 1 IFN pathway analysis and individual gene analysis. SKAT-O was applied to detect associations between the genotype and HIV-1 study entry viral load (log10 transformed) as a proxy for set point VL; P-values were corrected using Bonferroni (P < 0.0025). RESULTS: The analyses among those with early infection included 2429 individuals from five continents. The median study entry HIV VL was 14,623 (IQR 3460-45100) copies/mL. Across 673 SNPs within 19 type 1 IFN genes, no significant association with study entry VL was detected. Conversely, examining individual genes in START showed a borderline significant association between IFNW1, and study entry VL (P = 0.0025). This significance remained after separate adjustments for age, CD4+ T-cell count, CD4+/CD8+ T-cell ratio and recent infection. When controlling for population structure using linear mixed effects models (LME), in addition to principal components used in the main model, this was no longer significant (p = 0.0244). In subgroup analyses stratified by geographical region, the association between IFNW1 and study entry VL was only observed among African participants, although, the association was not significant when controlling for population structure using LME. Of the 17 SNPs within the IFNW1 region, only rs79876898 (A > G) was associated with study entry VL (p = 0.0020, beta = 0.32; G associated with higher study entry VL than A) in single SNP association analyses. The findings were not reproduced in FIRST participants. CONCLUSION: Across 19 type 1 IFN genes, only IFNW1 was associated with HIV-1 study entry VL in a cohort of ART-naïve individuals in early stages of their infection, however, this was no longer significant in sensitivity analyses that controlled for population structures using LME.

Designing boosting immunogens for HIV-1 vaccine development.

Inducing HIV-1 broadly neutralizing antibodies (bnAbs) through vaccination poses exceptional challenges. In this issue of Cell Host & Microbe, Wiehe and colleagues report the elicitation of affinity-matured bnAbs in knock-in mice through boosting immunogen vaccination, which selects for key improbable mutations.

Comparison of feline and human immunodeficiency virus reverse transcriptase enzymes through chemical screening and computational analysis.

Feline immunodeficiency virus (FIV) is a common infection found in domesticated and wild cats worldwide. Despite the wealth of therapeutic understanding of the disease in humans, considerably less information exists regarding the treatment of the disease in felines. Current treatment relies on drugs developed for the related human immunodeficiency virus (HIV) and includes compounds of the popular non-nucleotide reverse transcriptase (NNRTI) class. This is despite FIV-RT being only 67% similar to HIV-1 RT at the enzyme level, increasing to 88% for the allosteric pocket targeted by NNRTIs. The goal of this project was to try to quantify how well the more extensive pharmacological knowledge available for human disease translates to felines. To this end we screened known NNRTIs and 10 diverse pyrimidine analogs identified virtually. We use this chemo-centric probe approach to (a) assess the similarity between the two related RT targets based on the observed experimental inhibition values, (b) try to identify more potent inhibitors at FIV, and (c) gain a better appreciation of the structure-activity relationships (SAR). We found the correlation between IC50s at the two targets to be strong (r2 = 0.87) and identified compound 1 as the most potent inhibitor of FIV with IC50 of 0.030 µM ± 0.009. This compared to FIV IC50 values of 0.22 ± 0.17 µM, 0.040 ± 0.010 µM and >160 µM for known anti HIV-1 RT drugs Efavirenz, Rilpivirine, and Nevirapine, respectively. This knowledge, along with an understanding of the structural origin that give rise to any differences could improve the way HIV drugs are repurposed for FIV.

Assessment of swallowability and acceptability of scored darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) fixed-dose combination (FDC) tablets in HIV-1-infected children aged ≥6 to <12 years, using matching placebo tablets: A randomized study.

BACKGROUND: Darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) fixed-dose combination (FDC) was developed as a once-daily, complete antiretroviral (ARV) regimen therapy to address the need for simplified protease inhibitor-based ARV regimens. This study assessed the swallowability and acceptability for long-term use of scored placebo tablets matching the D/C/F/TAF FDC tablets in children living with HIV-1. METHODS: This study (NCT04006704) was a Phase 1, open-label, randomized, single-dose, 2-period, 2-sequence crossover study in children living with HIV-1, aged ≥6 to <12 years and weighing ≥25 to <40 kg, on a stable ARV regimen for ≥3 months. Participants were asked to swallow whole (size, 21 × 11 × 7 mm) and split matching placebo D/C/F/TAF tablets. Swallowability of the matching placebo D/C/F/TAF tablets (primary endpoint) was assessed by observers. Acceptability of taking matching placebo D/C/F/TAF tablets and current ARVs was evaluated by participants using a 3-point questionnaire. Participants rated the acceptability for long-term daily use of the placebo D/C/F/TAF tablets, and observers assessed how easily caregivers could split a scored tablet by hand, using 3-point questionnaires. RESULTS: Among the 24 participants who enrolled and completed the study, 95.8% (23/24) were able to swallow the whole and split matching placebo D/C/F/TAF tablets after 1 or 2 attempts. Most participants (>70%) rated the acceptability of tablets for long-term daily use as acceptable or good to take. Breaking the tablets was considered easy or OK by 79.2% (19/24) of caregivers. CONCLUSION: Scored D/C/F/TAF FDC tablets are swallowable - with whole favoured over split - and considered at least acceptable for long-term daily intake in children living with HIV-1 aged ≥6 to <12 years. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04006704.

Large-volume RT-LAMP enables extraction-free amplification of HIV RNA from fingerstick plasma.

BACKGROUND: Point-of-care (POC) nucleic acid amplification tests (NAAT) can significantly expand testing coverage, which is critical for infectious disease diagnostics and monitoring. The development of various isothermal amplification techniques greatly simplifies NAATs, but the cumbersome nucleic acid extraction step remains a bottleneck for the POC. Alternatively, extraction-free amplification, where crude samples are directly added into the assay, substantially simplifies the workflow. However, sample dilution is often needed in extraction-free amplification to reduce assay inhibition from sample matrices. Since NAATs are typically run at small volumes around 20 µL, the input sample quantity is therefore limited, resulting in an inevitable sensitivity loss. RESULTS: Here we explore the potential to perform isothermal amplification in larger reaction volumes to accommodate larger sample quantities, thereby improving sensitivity in extraction-free amplification. We demonstrated the approach by developing large-volume reverse transcription loop-mediated isothermal amplification (RT-LAMP) for HIV RNA detection from fingerstick plasma. We found that LAMP at reaction volumes up to 1 mL maintained the same performance. We then identified plasma dilution conditions needed to maintain the limit of detection in RT-LAMP. Subsequently, using inactivated HIV virus, we showed the successful detection of 24 HIV RNA copies in a 500 µL RT-LAMP reaction in the presence of 20 µL plasma (fingerstick volumes), translating to a viral load of 1200 copies per mL. To reduce the increased reagent cost with expanded reaction volumes, we further identified lower-cost reagents with maintained assay performance. Moreover, we showed that large-volume LAMP, compared to 20 µL reactions, could tolerate higher concentrations of various inhibitors in the sample, such as albumin and GuSCN. SIGNIFICANCE AND NOVELTY: NAATs are conventionally conducted at small reaction volumes. Here we demonstrated that LAMP can be run at large reaction volumes (over 100 µL) with maintained assay performance, allowing sample inhibition to be mitigated while accommodating larger sample quantities. The same strategy of expanding reaction volumes could be applied to other isothermal amplification methods and various POC applications, to streamline test workflows and/or improve assay sensitivity.

Replication competent HIV-guided CRISPR screen identifies antiviral factors including targets of the accessory protein Nef.

Innate antiviral factors are essential for effective defense against viral pathogens. However, the identity of major restriction mechanisms remains elusive. Current approaches to discover antiviral factors usually focus on the initial steps of viral replication and are limited to a single round of infection. Here, we engineered libraries of >1500 replication-competent HIV-1 constructs each expressing a single gRNAs to target >500 cellular genes for virus-driven discovery of antiviral factors. Passaging in CD4+ T cells robustly enriched HIV-1 encoding sgRNAs against GRN, CIITA, EHMT2, CEACAM3, CC2D1B and RHOA by >50-fold. Using an HIV-1 library lacking the accessory nef gene, we identified IFI16 as a Nef target. Functional analyses in cell lines and primary CD4+ T cells support that the HIV-driven CRISPR screen identified restriction factors targeting virus entry, transcription, release and infectivity. Our HIV-guided CRISPR technique enables sensitive discovery of physiologically relevant cellular defense factors throughout the entire viral replication cycle.

Inhibition of caspase pathways limits CD4+ T cell loss and restores host anti-retroviral function in HIV-1 infected humanized mice with augmented lymphoid tissue.

The study of HIV infection and pathogenicity in physical reservoirs requires a biologically relevant model. The human immune system (HIS) mouse is an established model of HIV infection, but defects in immune tissue reconstitution remain a challenge for examining pathology in tissues. We utilized exogenous injection of the human recombinant FMS-like tyrosine kinase 3 ligand (rFLT-3 L) into the hematopoietic stem cell (HSC) cord blood HIS mouse model to significantly expand the total area of lymph node (LN) and the number of circulating human T cells. The results enabled visualization and quantification of HIV infectivity, CD4 T cell depletion and other measures of pathogenesis in the secondary lymphoid tissues of the spleen and LN. Treatment with the Caspase-1/4 inhibitor VX-765 limited CD4+ T cell loss in the spleen and reduced viral load in both the spleen and axillary LN. In situ hybridization further demonstrated a decrease in viral RNA in both the spleen and LN. Transcriptomic analysis revealed that in vivo inhibition of caspase-1/4 led to an upregulation in host HIV restriction factors including SAMHD1 and APOBEC3A. These findings highlight the use of rFLT-3 L to augment human immune system characteristics in HIS mice to support investigations of HIV pathogenesis and test host directed therapies, though further refinements are needed to further augment LN architecture and cellular populations. The results further provide in vivo evidence of the potential to target inflammasome pathways as an avenue of host-directed therapy to limit immune dysfunction and virus replication in tissue compartments of HIV+ persons.

Porphyrins with combinations of 4-carboxyphenyl and 4-hydroxyphenyl substituents in meso-positions as anti-HIV-1 agents.

A series of 4-carboxyphenyl/4-hydroxyphenyl meso-substituted porphyrins were synthesized, purified, and characterized. The compounds exhibited anti-HIV-1 activities, in vitro, under both non-photodynamic (non-PDT) and photodynamic (PDT) conditions. Specifically, the porphyrins inhibited HIV-1 virus entry, with c-PB2(OH)2 and PB(OH)3 showing significant anti-HIV-1 activity. All of the porphyrins inhibited HIV-1 subtype B and C virus entry under PDT conditions. Our study demonstrated that the compounds bearing combinations of 4-carboxyphenyl/4-hydroxyphenyl moieties were not toxic even at higher concentrations, as compared to the reference porphyrins 5,10,15,20-tetra-(4-carboxyphenyl)porphyrin (TCPP) and 5,10,15,20-tetra-(4-hydroxyphenyl)porphyrin (THPP), under PDT conditions. This study underscores the promising potential of these compounds as HIV entry inhibitors in both non-PDT and PDT scenarios.

A unified classification system for HIV-1 5' long terminal repeats.

The HIV-1 provirus mainly consists of internal coding region flanked by 1 long terminal repeats (LTRs) at each terminus. The LTRs play important roles in HIV-1 reverse transcription, integration, and transcription. However, despite of the significant study advances of the internal coding regions of HIV-1 by using definite reference classification, there are no systematic and phylogenetic classifications for HIV-1 5' LTRs, which hinders our elaboration on 5' LTR and a better understanding of the viral origin, spread and therapy. Here, by analyzing all available resources of 5' LTR sequences in public databases following 4 recognized principles for the reference classification, 83 representatives and 14 consensus sequences were identified as representatives of 2 groups, 6 subtypes, 6 sub-subtypes, and 9 CRFs. To test the reliability of the supplemented classification system, the constructed references were applied to identify the 5' LTR assignment of the 22 clinical isolates in China. The results revealed that 16 out of 22 tested strains showed a consistent subtype classification with the previous LTR-independent classification system. However, 6 strains, for which recombination events within 5' LTR were demonstrated, unexpectedly showed a different subtype classification, leading a significant change of binding sites for important transcription factors including SP1, p53, and NF-κB. The binding change of these transcriptional factors would probably affect the transcriptional activity of 5' LTR. This study supplemented a unified classification system for HIV-1 5' LTRs, which will facilitate HIV-1 characterization and be helpful for both basic and clinical research fields.

A specific natural killer cells phenotypic signature associated to long term elite control of HIV infection.

Elite controllers (ECs) are an exceptional group of people living with HIV (PLWH) that control HIV replication without therapy. Among the mechanisms involved in this ability, natural killer (NK)-cells have recently gained much attention. We performed an in-deep phenotypic analysis of NK-cells to search for surrogate markers associated with the long term spontaneous control of HIV. Forty-seven PLWH (22 long-term EC [PLWH-long-term elite controllers (LTECs)], 15 noncontrollers receiving antiretroviral treatment [ART] [PLWH-onART], and 10 noncontrollers cART-naïve [PLWH-offART]), and 20 uninfected controls were included. NK-cells homeostasis was analyzed by spectral flow cytometry using a panel of 15 different markers. Data were analyzed using FCSExpress and R software for unsupervised multidimensional analysis. Six different subsets of NK-cells were defined on the basis of CD16 and CD56 expression, and the multidimensional analysis revealed the existence of 68 different NK-cells clusters based on the expression levels of the 15 different markers. PLWH-offART presented the highest disturbance of NK-cells homeostasis and this was not completely restored by long-term ART. Interestingly, long term spontaneous control of HIV (PLWH-LTEC group) was associated with a specific profile of NK-cells homeostasis disturbance, characterized by an increase of CD16dimCD56dim subset when compared to uninfected controls (UC) group and also to offART and onART groups (p < 0.0001 for the global comparison), an increase of clusters C16 and C26 when compared to UC and onART groups (adjusted p-value < 0.05 for both comparisons), and a decrease of clusters C10 and C20 when compared to all the other groups (adjusted p-value < 0.05 for all comparisons). These findings may provide clues to elucidate markers of innate immunity with a relevant role in the long-term control of HIV.

Lamivudine plus dolutegravir as a switch strategy in children: three case reports.

Lamivudine (3TC)/dolutegravir (DTG) single tablet regimen (STR) has shown long-term efficacy and tolerability in people living with HIV (PLWH). Dolutegravir has been approved for use in children, while data on the efficacy of 3TC plus DTG in maintaining virological suppression in this population are still under evaluation. In this case series, we describe three children with perinatally acquired HIV who maintained virological suppression after switching antiretroviral therapy to DTG/3TC. We present three case reports of three children enrolled in the Italian Register for HIV Infection in Children: a 9-year-old boy, a 10-year-old girl, and a 2-year-old girl with perinatally acquired HIV who immediately started antiretroviral therapy with a three-drug regimen upon diagnosis, which occurred at delivery, after 6 months of life, and after 2 years of life, respectively. They achieved and maintain virological suppression after 1, 6, and 7 months of therapy, respectively; then a switch strategy was performed with a two-drug regimen with DTG/3TC STR at the age of 7 years for the first child and at the age of 9 years for the second, while the third was switched to a DTG plus 3TC not STR, owing to weight requirements, at the age of 2 years and 10 months. All children maintained virological suppression at last follow-up visit (January 2024), showing an excellent growth curve and maintaining good adherence and tolerability to DTG plus 3TC. A two-drug regimen with DTG/3TC demonstrated efficacy in maintaining virological suppression in a switch strategy in these children, with important advantages such as better tolerability and comfort of taking a single tablet once daily.

PRESTIGIO RING "a 59-year-old man with multidrug resistant HIV-1 infection failing a regimen including dolutegravir, rilpivirine, atazanavir/cobicistat: successful treatment tailoring based on genotypic and phenotypic resistance tests".

Management of virological failure in heavily treatment-experienced people with multidrug-resistant (MDR) HIV infection is a serious clinical challenge. New drugs with novel mechanisms of action have recently been approved, and their use has improved the outcome of subjects with limited treatment options (LTO). In this setting, the choice of antiretroviral therapy (ART) should be tailored based on the pattern of resistance, treatment history and patients' individual characteristics. While genotypic resistance testing is the reference method for analysing residual drug susceptibility, phenotypic resistance testing can provide additional support when facing LTO. Herein, we present the case of a patient with MDR HIV-1 infection on virological failure enrolled in the PRESTIGIO Registry. The salvage ART regimen, which included drugs with novel mechanisms of action (MoA), was tailored to the patient's clinical characteristics and on the resistance pattern explored with genotypic and phenotypic investigation, allowing the achievement of viro-immunological success. The use of recently approved drugs with novel MoA, combined with an optimized background regimen, may also achieve virological suppression in people with LTO.

Contemporary HIV-1 consensus Env with AI-assisted redesigned hypervariable loops promote antibody binding.

An effective HIV-1 vaccine must elicit broadly neutralizing antibodies (bnAbs) against highly diverse Envelope glycoproteins (Env). Since Env with the longest hypervariable (HV) loops is more resistant to the cognate bnAbs than Env with shorter HV loops, we redesigned hypervariable loops for updated Env consensus sequences of subtypes B and C and CRF01_AE. Using modeling with AlphaFold2, we reduced the length of V1, V2, and V5 HV loops while maintaining the integrity of the Env structure and glycan shield, and modified the V4 HV loop. Spacers are designed to limit strain-specific targeting. All updated Env are infectious as pseudoviruses. Preliminary structural characterization suggests that the modified HV loops have a limited impact on Env's conformation. Binding assays show improved binding to modified subtype B and CRF01_AE Env but not to subtype C Env. Neutralization assays show increases in sensitivity to bnAbs, although not always consistently across clades. Strikingly, the HV loop modification renders the resistant CRF01_AE Env sensitive to 10-1074 despite the absence of a glycan at N332.

Characteristics of drug resistance mutations in ART-experienced HIV-1 patients with low-level viremia in Zhengzhou City, China.

Although most people living with HIV (PLWH) receiving antiretroviral therapy (ART) achieve continuous viral suppression, some show detectable HIV RNA as low-level viremia (LLV) (50-999 copies/mL). Drug resistance mutations (DRMs) in PLWH with LLV is of particular concern as which may lead to treatment failure. In this study, we investigated the prevalence of LLV and LLV-associated DRMs in PLWH in Zhengzhou City, China. Of 3616 ART-experienced PLWH in a long-term follow-up cohort from Jan 2022 to Aug 2023, 120 were identified as having LLV. Of these PLWH with LLV, we obtained partial pol and integrase sequences from 104 (70 from HIV-1 RNA and 34 from proviral DNA) individuals. DRMs were identified in 44 individuals. Subtyping analysis indicated that the top three subtypes were B (48.08%, 50/104), CRF07_BC (31.73%, 33/104), and CRF01_AE (15.38%, 16/104). The proportions of nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors (PIs), and integrase strand transfer inhibitors (INSTIs) associated DRMs were 23.83% (24/104), 35.58% (37/104), 5.77% (6/104), and 3.85% (4/104), respectively, which contributed to an overall prevalence of 42.31% (44/104). When analyzed by individual DRMs, the most common mutation(s) were V184 (18.27%, 19/104), followed by V179 (11.54%, 12/104), K103 (9.62%, 10/104), Y181 (9.62%, 10/104), M41 (7.69%, 8/104), and K65R (7.69%, 8/104). The prevalence of DRMs in ART-experienced PLWH with LLV is high in Zhengzhou City and continuous surveillance can facilitate early intervention and provision of effective treatment.

A mathematical model for HIV dynamics with multiple infections: implications for immune escape.

Multiple infections enable the recombination of different strains, which may contribute to viral diversity. How multiple infections affect the competition dynamics between the two types of strains, the wild and the immune escape mutant, remains poorly understood. This study develops a novel mathematical model that includes the two strains, two modes of viral infection, and multiple infections. For the representative double-infection case, the reproductive numbers are derived and global stabilities of equilibria are obtained via the Lyapunov direct method and theory of limiting systems. Numerical simulations indicate similar viral dynamics regardless of multiplicities of infections though the competition between the two strains would be the fiercest in the case of quadruple infections. Through sensitivity analysis, we evaluate the effect of parameters on the set-point viral loads in the presence and absence of multiple infections. The model with multiple infections predict that there exists a threshold for cytotoxic T lymphocytes (CTLs) to minimize the overall viral load. Weak or strong CTLs immune response can result in high overall viral load. If the strength of CTLs maintains at an intermediate level, the fitness cost of the mutant is likely to have a significant impact on the evolutionary dynamics of mutant viruses. We further investigate how multiple infections alter the viral dynamics during the combination antiretroviral therapy (cART). The results show that viral loads may be underestimated during cART if multiple-infection is not taken into account.

HIV-1 with gag processing defects activates cGAS sensing.

BACKGROUND: Detection of viruses by host pattern recognition receptors induces the expression of type I interferon (IFN) and IFN-stimulated genes (ISGs), which suppress viral replication. Numerous studies have described HIV-1 as a poor activator of innate immunity in vitro. The exact role that the viral capsid plays in this immune evasion is not fully understood. RESULTS: To better understand the role of the HIV-1 capsid in sensing we tested the effect of making HIV-1 by co-expressing a truncated Gag that encodes the first 107 amino acids of capsid fused with luciferase or GFP, alongside wild type Gag-pol. We found that unlike wild type HIV-1, viral particles produced with a mixture of wild type and truncated Gag fused to luciferase or GFP induced a potent IFN response in THP-1 cells and macrophages. Innate immune activation by Gag-fusion HIV-1 was dependent on reverse transcription and DNA sensor cGAS, suggesting activation of an IFN response by viral DNA. Further investigation revealed incorporation of the Gag-luciferase/GFP fusion proteins into viral particles that correlated with subtle defects in wild type Gag cleavage and a diminished capacity to saturate restriction factor TRIM5α, likely due to aberrant particle formation. We propose that expression of the Gag fusion protein disturbs the correct cleavage and maturation of wild type Gag, yielding viral particles that are unable to effectively shield viral DNA from detection by innate sensors including cGAS. CONCLUSIONS: These data highlight the crucial role of capsid in innate evasion and support growing literature that disruption of Gag cleavage and capsid formation induces a viral DNA- and cGAS-dependent innate immune response. Together these data demonstrate a protective role for capsid and suggest that antiviral activity of capsid-targeting antivirals may benefit from enhanced innate and adaptive immunity in vivo.

HIV immunological non-responders are characterized by extensive immunosenescence and impaired lymphocyte cytokine production capacity.

Introduction: Immunological non-responders (INR) are people living with HIV (PLHIV) who fail to fully restore CD4+ T-cell counts despite complete viral suppression with antiretroviral therapy (ART). INR are at higher risk for non-HIV related morbidity and mortality. Previous research suggest persistent qualitative defects. Methods: The 2000HIV study (clinical trials NTC03994835) enrolled 1895 PLHIV, divided in a discovery and validation cohort. PLHIV with CD4 T-cell count <350 cells/mm3 after ≥2 years of suppressive ART were defined as INR and were compared to immunological responders (IR) with CD4 T-cell count >500 cells/mm3. Logistic and rank based regression were used to analyze clinical data, extensive innate and adaptive immunophenotyping, and ex vivo monocyte and lymphocyte cytokine production after stimulation with various stimuli. Results: The discovery cohort consisted of 62 INR and 1224 IR, the validation cohort of 26 INR and 243 IR. INR were older, had more advanced HIV disease before starting ART and had more frequently a history of non-AIDS related malignancy. INR had lower absolute CD4+ T-cell numbers in all subsets. Activated (HLA-DR+, CD38+) and exhausted (PD1+) subpopulations were proportionally increased in CD4 T-cells. Monocyte and granulocyte immunophenotypes were comparable. INR lymphocytes produced less IL-22, IFN-γ, IL-10 and IL-17 to stimuli. In contrast, monocyte cytokine production did not differ. The proportions of CD4+CD38+HLA-DR+ and CD4+PD1+ subpopulations showed an inversed correlation to lymphocyte cytokine production. Conclusions: INR compared to IR have hyperactivated and exhausted CD4+ T-cells in combination with lymphocyte functional impairment, while innate immune responses were comparable. Our data provide a rationale to consider the use of anti-PD1 therapy in INR.