Broadly neutralizing antibodies for HIV treatment and cure approaches.

PURPOSE OF REVIEW: In recent years, clinical trials have explored broadly neutralizing antibodies (bNAbs) as treatment and cure of HIV. Here, we summarize the current knowledge, review the latest clinical studies, and reflect on the potential role of bNAbs in future applications in HIV treatment and cure strategies. RECENT FINDINGS: In most individuals who switch from standard antiretroviral therapy to bNAb treatment, combinations of at least two bNAbs effectively suppress viremia. However, sensitivity of archived proviruses to bNAb neutralization and maintaining adequate bNAb plasma levels are key determinants of the therapeutic effect. Combinations of bNAbs with injectable small-molecule antiretrovirals are being developed as long-acting treatment regimens that may require as little as two annual administrations to maintain virological suppression. Further, interventions that combine bNAbs with immune modulators or therapeutic vaccines are under investigation as HIV curative strategies. Interestingly, administration of bNAbs during the early or viremic stage of infection appears to enhance host immune responses against HIV. SUMMARY: While accurately predicting archived resistant mutations has been a significant challenge for bNAb-based treatments, combinations of potent bNAbs against nonoverlapping epitopes may help overcome this issue. As a result, multiple long-acting HIV treatment and cure strategies involving bNAbs are now being investigated.

Single cell analysis reveals a subset of cytotoxic-like plasmacytoid dendritic cells in people with HIV-1.

Human plasmacytoid dendritic cells (pDCs) play a central role in initiating and activating host immune responses during infection. To understand how the transcriptome of pDCs is impacted by HIV-1 infection and exogenous stimulation, we isolated pDCs from healthy controls, people with HIV-1 (PWH) before and during toll-like receptor 9 (TLR9) agonist treatment and performed single-cell (sc)-RNA sequencing. Our cluster analysis revealed four pDC clusters: pDC1, pDC2, cytotoxic-like pDC and an exhausted pDC cluster. The inducible cytotoxic-like pDC cluster is characterized by high expression of both antiviral and cytotoxic genes. Further analyses confirmed that cytotoxic-like pDCs are distinct from NK and T cells. Cell-cell communication analysis also demonstrated that cytotoxic-like pDCs exhibit similar incoming and outgoing cellular communicating signals as other pDCs. Thus, our study presents a detailed transcriptomic atlas of pDCs and provides new perspectives on the mechanisms of regulation and function of cytotoxic-like pDCs.

SARS-CoV-2 elicits robust adaptive immune responses regardless of disease severity.

BACKGROUND: The SARS-CoV-2 pandemic currently prevails worldwide. To understand the immunological signature of SARS-CoV-2 infections and aid the search and evaluation of new treatment modalities and vaccines, comprehensive characterization of adaptive immune responses towards SARS-CoV-2 is needed. METHODS: We included 203 recovered SARS-CoV-2 infected patients in Denmark between April 3rd and July 9th 2020, at least 14 days after COVID-19 symptom recovery. The participants had experienced a range of disease severities from asymptomatic to severe. We collected plasma, serum and PBMC's for analysis of SARS-CoV-2 specific antibody response by Meso Scale analysis including other coronavirus strains, ACE2 competition, IgA ELISA, pseudovirus neutralization capacity, and dextramer flow cytometry analysis of CD8+ T cells. The immunological outcomes were compared amongst severity groups within the cohort, and 10 pre-pandemic SARS-CoV-2 negative controls. FINDINGS: We report broad serological profiles within the cohort, detecting antibody binding to other human coronaviruses. 202(>99%) participants had SARS-CoV-2 specific antibodies, with SARS-CoV-2 neutralization and spike-ACE2 receptor interaction blocking observed in 193(95%) individuals. A significant positive correlation (r=0.7804) between spike-ACE2 blocking antibody titers and neutralization potency was observed. Further, SARS-CoV-2 specific CD8+ T-cell responses were clear and quantifiable in 95 of 106(90%) HLA-A2+ individuals. INTERPRETATION: The viral surface spike protein was identified as the dominant target for both neutralizing antibodies and CD8+ T-cell responses. Overall, the majority of patients had robust adaptive immune responses, regardless of their disease severity. FUNDING: This study was supported by the Danish Ministry for Research and Education (grant# 0238-00001B) and The Danish Innovation Fund (grant# 0208-00018B).

The Impact of IFNλ4 on the Adaptive Immune Response to SARS-CoV-2 Infection.

Genetic polymorphisms at the IFNL4 loci are known to influence the clinical outcome of several different infectious diseases. Best described is the association between the IFNL4 genotype and hepatitis C virus clearance. However, an influence of the IFNL4 genotype on the adaptive immune system was suggested by several studies but never investigated in humans. In this cross-sectional study, we have genotyped 201 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive participants for 3 IFNL4 polymorphisms (rs368234815, rs12979860, and rs117648444) and stratified them according to the IFNλ4 activity. Based on this stratification, we investigated the association between the IFNL4 genotype and the antibody as well as the CD8+ T cell response in the acute phase of the SARS-CoV-2 infection. We observed no differences in the genotype distribution compared with a Danish reference cohort or the 1,000 Genome Project, and we were not able to link the IFNL4 genotype to changes in either the antibody or CD8+ T cell responses of these patients.

SARS-CoV-2 persistence is associated with antigen-specific CD8 T-cell responses.

BACKGROUND: Upon SARS-CoV-2 infection, most individuals develop neutralizing antibodies and T-cell immunity. However, some individuals reportedly remain SARS-CoV-2 PCR positive by pharyngeal swabs weeks after recovery. Whether viral RNA in these persistent carriers is contagious and stimulates SARS-CoV-2-specific immune responses is unknown. METHODS: This cohort study was conducted between April 3rd-July 9th 2020, recruiting COVID-19 recovered individuals that were symptom-free for at least 14 days. We collected serum for SARS-CoV-2-specific total Ig, IgA and IgM detection by ELISA, pharyngeal swabs (two time points) for ddPCR and PBMCs for anti-SARS-CoV-2 CD8 T-cell dextramer analyses. FINDINGS: We enrolled 203 post-symptomatic participants with a previous RT-PCR-verified SARS-CoV-2 infection. At time point 1, a median of 23 days (range 15-44) after recovery, 26 individuals (12⋅8%) were PCR positive. At time point 2, 90 days (median, range 85-105) after recovery, 5 (5⋅3%) were positive. There was no difference in SARS-CoV-2 antibody levels between the PCR negative and positive group. The persistent PCR positive group however, had SARS-CoV-2-specific CD8 T-cell responses of significantly increased breadth and magnitude. Assisted contact tracing among persistent PCR positive individuals revealed zero new COVID-19 diagnoses among 757 close contacts. INTERPRETATION: Persistent pharyngeal SARS-CoV-2 PCR positivity in post-symptomatic individuals is associated with elevated cellular immune responses and thus, the viral RNA may represent replicating virus. However, transmission to close contacts was not observed indicating that persistent PCR positive individuals are not contagious at the post-symptomatic stage of the infection.

Efficacy of the TMPRSS2 inhibitor camostat mesilate in patients hospitalized with Covid-19-a double-blind randomized controlled trial.

BACKGROUND: The trans-membrane protease serine 2 (TMPRSS2) is essential for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cell entry and infection. Efficacy and safety of TMPRSS2 inhibitors in patients with coronavirus disease 2019 (Covid-19) have not been evaluated in randomized trials. METHODS: We conducted an investigator-initiated, double-blind, randomized, placebo-controlled multicenter trial in patients hospitalized with confirmed SARS-CoV-2 infection from April 4, to December 31, 2020. Within 48 h of admission, participants were randomly assigned in a 2:1 ratio to receive the TMPRSS2 inhibitor camostat mesilate 200 mg three times daily for 5 days or placebo. The primary outcome was time to discharge or clinical improvement measured as ≥2 points improvement on a 7-point ordinal scale. Other outcomes included 30-day mortality, safety and change in oropharyngeal viral load. FINDINGS: 137 patients were assigned to receive camostat mesilate and 68 to placebo. Median time to clinical improvement was 5 days (interquartile range [IQR], 3 to 7) in the camostat group and 5 days (IQR, 2 to 10) in the placebo group (P = 0·31). The hazard ratio for 30-day mortality in the camostat compared with the placebo group was 0·82 (95% confidence interval [CI], 0·24 to 2·79; P = 0·75). The frequency of adverse events was similar in the two groups. Median change in viral load from baseline to day 5 in the camostat group was -0·22 log10 copies/mL (p <0·05) and -0·82 log10 in the placebo group (P <0·05). INTERPRETATION: Under this protocol, camostat mesilate treatment was not associated with increased adverse events during hospitalization for Covid-19 and did not affect time to clinical improvement, progression to ICU admission or mortality. ClinicalTrials.gov Identifier: NCT04321096. EudraCT Number: 2020-001200-42.

Effects of 24-week Toll-like receptor 9 agonist treatment in HIV type 1+ individuals.

DESIGN: This was an exploratory, single-arm clinical trial that tested the immune enhancement effects of 24-weeks of Toll-like receptor 9 (TLR9) agonist (MGN1703; Lefitolimod; 60 mg × 2 weekly) therapy. METHODS: We enrolled HIV-1-infected individuals on suppressive combination antiretroviral therapy. Safety was assessed throughout the study. The primary outcome was reduction in total CD4 T-cell viral DNA levels. Secondary outcomes included safety, detailed immunological and virological analyses, and time to viral rebound (viral load > 5000 copies/ml) after randomization into an analytical treatment interruption (ATI). RESULTS: A total of 12 individuals completed the treatment phase and nine completed the ATI. Adverse events were limited and consistent with previous reports for MGN1703. Although the dosing regimen led to potent T-cell activation and increased HIV-1-specific T-cell responses, there were no cohort-wide changes in persistent virus (total CD4 T cells viral DNA; P = 0.34). No difference in time to rebound was observed between the ATI arms (log rank P = 0.25). One of nine ATI participants, despite harboring a large replication-competent reservoir, controlled viremia for 150 days via both HIV-1-specific cellular and antibody-mediated immune responses. CONCLUSION: A period of 24 weeks of MGN1703 treatment was safe and improved innate as well as HIV-1-specific adaptive immunity in HIV-1+ individuals. These findings support the incorporation of TLR9 agonism into combination HIV-1 cure strategies. TRIAL NAME AND REGISTRATION: TLR9 Enhancement of antiviral immunity in chronic HIV-1 infection: a phase 1B/2A trial; ClinicalTrials.gov NCT02443935.

The role of miR-29a in HIV-1 replication and latency.

The development of an effective HIV-1 eradication strategy relies upon a clear understanding of the cellular mechanisms involved in HIV-1 latency. Among such cellular processes, microRNA activities affect HIV-1 production by regulating viral transcripts as well as host cell HIV-1 dependency factors. miR-29a stands apart from other relevant microRNAs as a potential therapeutic target in HIV-1 eradication. In vitro experiments have shown that miR-29a binds to a sequence in the 3'UTR of viral transcripts and inhibits their expression. In vivo data revealed the existence of a cytokine-microRNA (i.e. IL-21/miR-29a) pathway that significantly impacts HIV-1 replication. Here we present and discuss evidence supporting the role of miR-29a in HIV-1 replication and latency. We also discuss potential clinical applications of miR-29a inhibitors and enhancers in HIV-1 eradication strategies.