Antiviral research最新文献

The flavivirus genus includes human pathogenic viruses such as Dengue (DENV), West Nile (WNV) and Zika virus (ZIKV) posing a global health threat due to limited treatment options. Host ion channels are crucial for various viral life cycle stages, but their potential as targets for antivirals is often not fully realized due to the lack of selective modulators. Here, we observe that treatment with ML2-SA1, an agonist for the human endolysosomal cation channel TRPML2, impairs ZIKV replication. Upon ML2-SA1 treatment, levels of intracellular genomes and number of released virus particles of two different ZIKV isolates were significantly reduced and cells displayed enlarged vesicular structures and multivesicular bodies with ZIKV envelope protein accumulation. However, no increased ZIKV degradation in lysosomal compartments was observed. Rather, the antiviral effect of ML2-SA1 seemed to manifest by the compound’s negative impact on genome replication. Moreover, ML2-SA1 treatment also led to intracellular cholesterol accumulation. ZIKV and many other viruses including the Orthohepevirus Hepatitis E virus (HEV) rely on the endolysosomal system and are affected by intracellular cholesterol levels to complete their life cycle. Since we observed that ML2-SA1 also negatively impacted HEV infections in vitro, this compound may harbor a broader antiviral potential through perturbing the intracellular cholesterol distribution. Besides indicating that TRPML2 may be a promising target for combatting viral infections, we uncover a tentative connection between this protein and cholesterol distribution within the context of infectious diseases.

We compared the duration of fever in children infected with A(H1N1)pdm09, A(H3N2), or influenza B viruses following treatment with baloxavir marboxil (baloxavir) or neuraminidase inhibitors (NAIs) (oseltamivir, zanamivir, or laninamivir). This observational study was conducted at 10 outpatient clinics across 9 prefectures in Japan during the 2012–2013 and 2019–2020 influenza seasons. Patients with influenza rapid antigen test positive were treated with one of four anti-influenza drugs. The type/subtype of influenza viruses were identified from MDCK or MDCK SIAT1 cell-grown samples using two-step real-time PCR. Daily self-reported body temperature after treatment were used to evaluate the duration of fever by treatment group and various underlying factors. Among 1742 patients <19 years old analyzed, 452 (26.0%) were A(H1N1)pdm09, 827 (48.0%) A(H3N2), and 463 (26.0%) influenza B virus infections. Among fours treatment groups, baloxavir showed a shorter median duration of fever compared to oseltamivir in univariate analysis for A(H1N1)pdm09 virus infections (baloxavir, 22.0 h versus oseltamivir, 26.7 h, P < 0.05; laninamivir, 25.5 h, and zanamivir, 25.0 h). However, this difference was not significant in multivariable analyses. For A(H3N2) virus infections, there were no statistically significant differences observed (20.3, 21.0, 22.0, and 19.0 h) uni- and multivariable analyses. For influenza B, baloxavir shortened the fever duration by approximately 15 h than NAIs (20.3, 35.0, 34.3, and 34.1 h), as supported by uni- and multivariable analyses. Baloxavir seems to have comparable clinical effectiveness with NAIs on influenza A but can be more effective for treating pediatric influenza B virus infections than NAIs.

Herpes simplex virus type 1 (HSV-1), a neurotropic DNA virus, establishes latency in neural tissues, with reactivation causing severe consequences like encephalitis. Emerging evidence links HSV-1 infection to chronic neuroinflammation and neurodegenerative diseases. Microglia, the central nervous system's (CNS) immune sentinels, express diverse receptors, including α7 nicotinic acetylcholine receptors (α7 nAChRs), critical for immune regulation. Recent studies suggest α7 nAChR activation protects against viral infections. Here, we show that α7 nAChR agonists, choline and PNU-282987, significantly inhibit HSV-1 replication in microglial BV2 cells. Notably, this inhibition is independent of the traditional ionotropic nAChR signaling pathway. mRNA profiling revealed that choline stimulates the expression of antiviral factors, IL-1β and Nos2, and down-regulates the apoptosis genes and type A Lamins in BV2 cells. These findings suggest a novel mechanism by which microglial α7 nAChRs restrict viral infections by regulating innate immune responses.

Emergence of drug resistance is rare after use of letermovir (LMV) as prophylaxis for post-transplant cytomegalovirus (CMV) infection. In a recent study involving renal transplant recipients, no known LMV resistance mutations were detected in those receiving LMV prophylaxis. However, uncharacterized viral amino acid substitutions were detected in LMV recipients by deep sequencing in viral subpopulations of 5%–7%, at codons previously associated with drug resistance: UL56 S229Y (n = 1), UL56 M329I (n = 9) and UL89 D344Y (n = 5). Phenotypic analysis of these mutations in a cloned laboratory CMV strain showed that S229Y conferred a 2-fold increase in LMV EC50, M329I conferred no LMV resistance, and D344Y knocked out viral viability that was restored after the nonviable clone was reverted to wild type D344. As in previous CMV antiviral trials, the detection of nonviable mutations, even in multiple study subjects, raises strong suspicion of genotyping artifacts and encourages the use of replicate testing for authentication of atypical mutation readouts. The non-viability of UL89 D344Y also confirms the biologically important locus of the D344E substitution that confers resistance to benzimidazole CMV terminase complex inhibitors, but does not feature prominently in LMV resistance.

Human interferon α2 (IFNα2) is a cytokine with broad-spectrum antiviral activity, and its engineered forms are widely used to treat viral infections. However, IFNα2 may trigger proinflammatory responses and underlying side effects during treatment. Trefoil factor 2 (TFF2) is a secreted protein with anti-inflammatory properties. Here, we explored whether coupling IFNα2 to TFF2 in a two-in-one fusion form could combine the beneficial effects of both molecules on viral infections toward a more desirable treatment outcome. We engineered two forms of human IFNα2 and TFF2 fusion proteins, IFNα2-TFF2-Fc (ITF) and TFF2-IFNα2-Fc (TIF), and examined their properties in vitro in comparison to IFNα2 and TFF2 alone. RNA-Seq was further used to explore such comparison on dynamic gene regulation at transriptomic level. These in vitro assessments collectively indicated that TIF largely retained the antiviral activity of IFNα2 while being a weaker inflammation inducer, consistent with the presence of TFF2 activity. We further demonstrated the superiority of TIF over IFNα2 or TFF2 alone in treating influenza infection using a mouse infection model. Together, our study provided evidence supporting that, by possessing antiviral activity conferred by IFNα2 with complementation from TFF2 in suppressing the inflammatory side effects, the fusion proteins, particularly TIF, represent more effective agents against influenza and other respiratory viral infections than IFNα2 or TFF2 alone. It implies that merging two molecules with complementary functions holds potential for developing novel therapeutics against viral infections.

Bacillus spp. has been considered a promising source for identifying new antimicrobial substances, including anti-viral candidates. Here, we successfully isolated a number of bacteria strains from aged dry citrus peel (Chenpi). Of note, the culture supernatant of a new isolate named Bacillus subtilis LjM2 demonstrated strong inhibition of influenza A virus (IAV) infection in multiple experimental systems in vitro and in vivo. In addition, the anti-viral effect of LjM2 was attributed to its direct lysis of viral particles. Further analysis showed that a protease which we named CPAVM1 isolated from the culture supernatant of LjM2 was the key component responsible for its anti-viral function. Importantly, the therapeutic effect of CPAVM1 was still significant when applied 12 hours after IAV infection of experimental mice. Moreover, we found that the CPAVM1 protease cleaved multiple IAV proteins via targeting basic amino acid Arg or Lys. Furthermore, this study reveals the molecular structure and catalytic mechanism of CPAVM1 protease. During catalysis, Tyr75, Tyr77, and Tyr102 are important active sites. Therefore, the present work identified a special protease CPAVM1 secreted by a new strain of Bacillus subtilis LjM2 against influenza A virus infection via direct cleavage of critical viral proteins, thus facilitates future biotechnological applications of Bacillus subtilis LjM2 and the protease CPAVM1.

The underlying threat of new Zika virus (ZIKV) outbreaks remains, as no vaccines or therapies have yet been developed. In vitro research has shown that glycolysis is a key factor to enable sustained ZIKV replication in neuroprogenitors. However, neither in vivo nor clinical investigation of glycolytic modulators as potential therapeutics for ZIKV-related fetal abnormalities has been conducted. Accordingly, we tested the therapeutic potential of metabolic modulators in relevant in vitro systems comprising two pools of neuroprogenitors (NPCs), which resemble early and late stages of pregnancy. Effective doses of metabolic modulators [3.0 μM] dimethyl fumarate (DMF), [3.2 mM] dichloroacetate (DCA), and [6.3 μM] VER-246608 were determined for these cells by their effect on lactate release, pyruvate dehydrogenase (PDH) activity and cell survival. The drugs were used in a 24h pre-treatment and kept throughout ZIKV infection of NPCs. Drug effects and ZIKV replication were assessed at 24- and 56-h post-infection. In early NPCs treated with DMF, DCA and VER-246608, there was a significant reduction in the extracellular release of ZIKV potentially by PDH-mediated increased mitochondrial oxidation of glucose. Out of the three drugs, only DCA was observed to reduce viral replication in late NPCs treated with DCA. Altogether, our findings suggest that reduction of anaerobic glycolysis could be of therapeutic potential against ZIKV-related fetal abnormalities and that clinical translation should consider the use of specific glycolytic modulators over different trimesters.

There are no approved vaccines or therapeutics for Lassa virus (LASV) infections. To identify compounds with anti-LASV activity, we conducted a cell-based screening campaign at biosafety level 4 and tested almost 60,000 compounds for activity against an infectious reporter LASV. Hits from this screen included several structurally related macrocycles. The most potent, Mac128, had a sub-micromolar EC₅₀ against the reporter virus, inhibited wild-type clade IV LASV, and reduced viral titers by 4 orders of magnitude. Mechanistic studies suggested that Mac128 inhibited viral replication at the level of the polymerase.

Hepatitis E is an underestimated disease, leading to estimated 20 million infections and up to 70,000 deaths annually. Infections are mostly asymptomatic, but can reach mortality rates up to 25% in pregnant women or become chronic in immunocompromised patients. Hepatitis E virus (HEV) infection have been associated with a range of extrahepatic manifestations, including a spectrum of neurological symptoms. Current therapy options are limited to non-specific antivirals like ribavirin, but recently, repurposed viral polymerase inhibitors like sofosbuvir and NITD008 were described to inhibit HEV replication. Here, we evaluated the efficacy of these drugs in various neuronal-derived cell lines to determine their potency outside the liver. Our findings indicate that both drugs, especially sofosbuvir, exhibited reduced efficacy in neuronal cells compared to hepatic cells. These results should be taken into account in the development of direct-acting antivirals for HEV and their potency at extrahepatic replication sites.

The SARS-CoV-2 pandemic has bolstered unprecedented research efforts to better understand the pathogenesis of coronavirus (CoV) infections and develop effective therapeutics. We here focus on non-structural protein nsp15, a hexameric component of the viral replication-transcription complex (RTC). Nsp15 possesses uridine-specific endoribonuclease (EndoU) activity for which some specific cleavage sites were recently identified in viral RNA. By preventing accumulation of viral dsRNA, EndoU helps the virus to evade RNA sensors of the innate immune response. The immune-evading property of nsp15 was firmly established in several CoV animal models and makes it a pertinent target for antiviral therapy. The search for nsp15 inhibitors typically proceeds via compound screenings and is aided by the rapidly evolving insight in the protein structure of nsp15. In this overview, we broadly cover this fascinating protein, starting with its structure, biochemical properties and functions in CoV immune evasion. Next, we summarize the reported studies in which compound screening or a more rational method was used to identify suitable leads for nsp15 inhibitor development. In this way, we hope to raise awareness on the relevance and druggability of this unique CoV protein.