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Nirmatrelvir is an M pro inhibitor active against SARS-CoV-2 and is given with ritonavir, a pharmacokinetic enhancer. In this double-blind, placebo-controlled trial, nirmatrelvir plus ritonavir, when given within 5 days after symptom onset to patients at high risk for disease progression, decreased the risk of Covid-19–related hospitalization or death by 87.8%.

In a phase 2 trial, outpatients with Covid-19 who received a single infusion of a 2800-mg dose of the neutralizing antibody LY-CoV555 had a greater reduction from baseline in viral load than those who received placebo. Hospitalization was less frequent among antibody-treated patients (1.6% vs. 6.3%).

Human immunodeficiency virus (HIV)-1-specific broadly neutralizing monoclonal antibodies are currently under development to treat and prevent HIV-1 infection. We performed a single-center, randomized, double-blind, dose-escalation, placebo-controlled trial of a single administration of the HIV-1 V3-glycan-specific antibody PGT121 at 3, 10 and 30 mg kg –1 in HIV-uninfected adults and HIV-infected adults on antiretroviral therapy (ART), as well as a multicenter, open-label trial of one infusion of PGT121 at 30 mg kg –1 in viremic HIV-infected adults not on ART (no. NCT02960581). The primary endpoints were safety and tolerability, pharmacokinetics (PK) and antiviral activity in viremic HIV-infected adults not on ART. The secondary endpoints were changes in anti-PGT121 antibody titers and CD4 +  T-cell count, and development of HIV-1 sequence variations associated with PGT121 resistance. Among 48 participants enrolled, no treatment-related serious adverse events, potential immune-mediated diseases or Grade 3 or higher adverse events were reported. The most common reactions among PGT121 recipients were intravenous/injection site tenderness, pain and headache. Absolute and relative CD4 +  T-cell counts did not change following PGT121 infusion in HIV-infected participants. Neutralizing anti-drug antibodies were not elicited. PGT121 reduced plasma HIV RNA levels by a median of 1.77 log in viremic participants, with a viral load nadir at a median of 8.5 days. Two individuals with low baseline viral loads experienced ART-free viral suppression for ≥168 days following antibody infusion, and rebound viruses in these individuals demonstrated full or partial PGT121 sensitivity. The trial met the prespecified endpoints. These data suggest that further investigation of the potential of antibody-based therapeutic strategies for long-term suppression of HIV is warranted, including in individuals off ART and with low viral load. A single dose of a broadly neutralizing, HIV-specific antibody transiently reduces viral load in plasma, and in some individuals is associated with durable virus suppression in the absence of antiretroviral therapy.

Expression of the programmed death 1 (PD-1) receptor and its ligands are implicated in the T cell exhaustion phenotype which contributes to the persistence of several chronic viral infections, including human hepatitis C virus (HCV). The antiviral potential of BMS-936558 (MDX-1106) - a fully human anti-PD-1 monoclonal immunoglobulin-G4 that blocks ligand binding - was explored in a proof-of-concept, placebo-controlled single-ascending-dose study in patients (N = 54) with chronic HCV infection. Interferon-alfa treatment-experienced patients (n = 42) were randomized 5∶1 to receive a single infusion of BMS-936558 (0.03, 0.1, 0.3, 1.0, 3.0 mg/kg [n = 5 each] or 10 mg/kg [n = 10]) or of placebo (n = 7). An additional 12 HCV treatment-naïve patients were randomized to receive 10 mg/kg BMS-936558 (n = 10) or placebo (n = 2). Patients were followed for 85 days post-dose. Five patients who received BMS-936558 (0.1 [n = 1] or 10 mg/kg) and one placebo patient achieved the primary study endpoint of a reduction in HCV RNA ≥0.5 log10 IU/mL on at least 2 consecutive visits; 3 (10 mg/kg) achieved a >4 log10 reduction. Two patients (10 mg/kg) achieved HCV RNA below the lower limit of quantitation (25 IU/mL), one of whom (a prior null-responder) remained RNA-undetectable 1 year post-study. Transient reductions in CD4(+), CD8(+) and CD19(+) cells, including both naïve and memory CD4(+) and CD8(+) subsets, were observed at Day 2 without evidence of immune deficit. No clinically relevant changes in immunoglobulin subsets or treatment-related trends in circulating cytokines were noted. BMS-936558 exhibited dose-related exposure increases, with a half-life of 20-24 days. BMS-936558 was mostly well tolerated. One patient (10 mg/kg) experienced an asymptomatic grade 4 ALT elevation coincident with the onset of a 4-log viral load reduction. Six patients exhibited immune-related adverse events of mild-to-moderate intensity, including two cases of hyperthyroidism consistent with autoimmune thyroiditis. Further investigation of PD-1 pathway blockade in chronic viral disease is warranted. ClinicalTrials.gov NCT00703469.

In a phase 3 trial involving 1035 outpatients who were at increased risk for severe Covid-19, those who received two monoclonal antibodies targeting SARS-CoV-2 had a significant reduction in the viral load and a significantly lower incidence of progression to severe illness than those who received placebo.

An anti–SARS-CoV-2 antibody cocktail was given to patients within 3 days after PCR confirmation of Covid-19. In patients who were antibody-negative at baseline, treatment was associated with rapid viral clearance and potentially with a less frequent need for medical attention. The effect was less marked among patients who were antibody-positive at baseline.

In this international trial involving 371 patients with highly drug-resistant HIV-1 infection, fostemsavir reduced the HIV-1 RNA level by 0.79 log 10 copies per milliliter during the first 8 days of treatment. At week 48, more than half the patients treated with fostemsavir and an optimized background regimen had a virologic response.

This phase 3, placebo-controlled platform trial evaluated a single infusion of casirivimab and imdevimab (REGEN-COV) at 2400-mg and 1200-mg doses in outpatients with acute SARS-CoV-2 infection. The incidence of Covid-19–related hospitalization was lower and recovery was faster among patients who received the antibody combination than among those who received placebo.

A novel coronavirus—severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—emerged in humans in Wuhan, China, in December 2019 and has since disseminated globally 1 , 2 . As of April 16, 2020, the confirmed case count of coronavirus disease 2019 (COVID-19) had surpassed 2 million. Based on full-genome sequence analysis, SARS-CoV-2 shows high homology to SARS-related coronaviruses identified in horseshoe bats 1 , 2 . Here we show the establishment and characterization of expandable intestinal organoids derived from horseshoe bats of the Rhinolophus sinicus species that can recapitulate bat intestinal epithelium. These bat enteroids are fully susceptible to SARS-CoV-2 infection and sustain robust viral replication. Development of gastrointestinal symptoms in some patients with COVID-19 and detection of viral RNA in fecal specimens suggest that SARS-CoV-2 might cause enteric, in addition to respiratory, infection 3 , 4 . Here we demonstrate active replication of SARS-CoV-2 in human intestinal organoids and isolation of infectious virus from the stool specimen of a patient with diarrheal COVID-19. Collectively, we established the first expandable organoid culture system of bat intestinal epithelium and present evidence that SARS-CoV-2 can infect bat intestinal cells. The robust SARS-CoV-2 replication in human intestinal organoids suggests that the human intestinal tract might be a transmission route of SARS-CoV-2. Bat and human intestinal organoids can support replication of SARS-CoV-2, enabling further characterization of the virus lifecycle and investigation of potential mechanisms of enteric infection in COVID-19.

Coronavirus disease 2019 (COVID-19) has rapidly become a global pandemic and no antiviral drug or vaccine is yet available for the treatment of this disease 1 – 3 . Several clinical studies are ongoing to evaluate the efficacy of repurposed drugs that have demonstrated antiviral efficacy in vitro. Among these candidates, hydroxychloroquine (HCQ) has been given to thousands of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—the virus that causes COVID-19—worldwide but there is no definitive evidence that HCQ is effective for treating COVID-19 4 – 7 . Here we evaluated the antiviral activity of HCQ both in vitro and in SARS-CoV-2-infected macaques. HCQ showed antiviral activity in African green monkey kidney cells (Vero E6) but not in a model of reconstituted human airway epithelium. In macaques, we tested different treatment strategies in comparison to a placebo treatment, before and after peak viral load, alone or in combination with azithromycin (AZTH). Neither HCQ nor the combination of HCQ and AZTH showed a significant effect on viral load in any of the analysed tissues. When the drug was used as a pre-exposure prophylaxis treatment, HCQ did not confer protection against infection with SARS-CoV-2. Our findings do not support the use of HCQ, either alone or in combination with AZTH, as an antiviral drug for the treatment of COVID-19 in humans. Hydroxychloroquine did not confer protection against SARS-CoV-2 infection or reduce the viral load after infection in macaques; these findings do not support the use of hydroxychloroquine as an antiviral drug treatment of COVID-19 in humans.