Viral Replication Research Articles

ISGylation by HERCs facilitates STING activation

Optimal activation of stimulator of interferon genes (STING) protein is crucial for host defenses against pathogens and avoiding detrimental effects. Various post-translational modifications control STING activity. However, the function of interferon (IFN)-stimulated gene (ISG) 15 modification (ISGylation) in controlling STING stability and activation is unclear. Here, we show that the E3 ISGylation ligases HECT domain- and RCC1-like domain-containing proteins (HERCs; HERC5 in humans and HERC6 in mice) facilitate STING activation by mediating ISGylation of STING at K150, preventing its K48-linked ubiquitination and degradation. Concordantly, Herc6 deficiency suppresses herpes simplex virus 1 infection-induced type I IFN responses and facilitates viral replication both invitro and invivo. Notably, severe acute respiratory syndrome coronavirus 2 protein papain-like protease cleaves HERC5-mediated ISGylation of STING, suppressing host antiviral responses. These data identify a mechanism by which HERCs-mediated ISGylation controls STING stability and activation and uncover the correlations and interactions of ISGylation and ubiquitination during STING activation.

Targeted isolation of antiviral cinnamoylphloroglucinol-terpene adducts from Cleistocalyx operculatus by building blocks-based molecular networking approach

The building blocks-based molecular network (BBMN) strategy was applied to the phytochemical investigation of Cleistocalyx operculatus, leading to the targeted isolation of eighteen novel cinnamoylphloroglucinol-terpene adducts (CPTAs) with diverse skeleton types (cleistoperones A–R, 1–18). Their structures including absolute configurations were determined by extensive spectroscopic methods, quantum chemical calculations, and single-crystal X-ray crystallographic experiments. Cleistoperone A (1), consisting of a cinnamoylphloroglucinol motif and two linear monoterpene moieties, represents an unprecedented macrocyclic CPTA, whose densely functionalized tricyclo[15.3.1.03,8]heneicosane bridge ring skeleton contains an enolizable β,β′-triketone system and two different kinds of stereogenic elements (including five point and three planar chiralities). Cleistoperones B and C (2 and 3) are two new skeletal CPTAs with an unusual coupling pattern between the (nor)monoterpene moiety and the cinnamoyl chain of the cinnamoylphloroglucinol unit. Cleistoperone D (4) possesses an unprecedented cage-like 6/6/6/4/6-fused heteropentacyclic scaffold. The plausible biosynthetic pathways for 1–18 were also proposed. Notably, compounds 1, 4, 7, 8, and 18 exhibited significant antiviral activity against respiratory syncytial virus (RSV). The most potent one, cleistoperone A (1) with IC50 value of 1.71 ± 0.61 μmol/L, could effectively inhibit virus replication via affecting the Akt/mTOR/p70S6K signaling pathway.

Corrigendum: A highly discriminatory RNA strand-specific assay to facilitate analysis of the role of cis-acting elements in foot-and-mouth disease virus replication.

Corrigendum: A highly discriminatory RNA strand-specific assay to facilitate analysis of the role of cis-acting elements in foot-and-mouth disease virus replication.

Matrine exhibits antiviral activities against PEDV by directly targeting Spike protein of the virus and inducing apoptosis via the MAPK signaling pathway

Porcine Epidemic Diarrhea Virus (PEDV) is a highly contagious virus that causes Porcine Epidemic Diarrhea (PED). This enteric disease results in high mortality rates in piglets, leading to significant financial losses in the pig industry. However, vaccines cannot provide sufficient protection against epidemic strains. Spike (S) protein exposed on the surface of virion mediates PEDV entry into cells. Our findings imply that matrine (MT), a naturally occurring alkaloid, inhibits PEDV infection targeting S protein of virions and biological process of cells. The GLY434 residue in the autodocking site of the S protein and MT conserved based on sequence comparison. This study provides a comprehensive analysis of viral attachment, entry, and virucidal effects to investigate how that MT inhibits virus replication. MT inhibits PEDV attachment and entry by targeting S protein. MT was added to cells before, during, or after infection, it exhibits anti-PEDV activities and viricidal effects. Network pharmacology focuses on addressing causal mechanisms rather than just treating symptoms. We identified the key genes and screened the cell apoptosis involved in the inhibition of MT on PEDV infection in network pharmacology. MT significantly promotes cell apoptosis in PEDV-infected cells to inhibit PEDV infection by activating the MAPK signaling pathway. Collectively, we provide the biological foundations for the development of single components of traditional Chinese medicine to inhibit PEDV infection and spread.

In silico study: molecular docking of SARS-Cov-2 endoribonuclease on active compounds of Gmelina arborea Roxb. bark

Infection by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) triggers COVID-19 disease of the respiratory tract similar to pneumonia. The virus encodes four structural proteins and 16 non-structural proteins (nsp), one of which includes nsp15 or endoribonuclease (NendoU). NendoU plays an important role in viral replication and transcription and reduces the stimulation of immune cell responses. Active compounds in Gmelina arborea Roxb. bark have antioxidant properties that can inhibit the NendoU activity of SARS-CoV-2. This study aims to analyze the potential of compounds from Gmelina arborea Roxb. bark in inhibiting SARS-CoV-2 NendoU within in silico using the YASARA structure application. Balnophonin is the best test ligand based on binding ΔG value, dissociation constant (Kd), prediction of physicochemical characteristics, pharmacokinetics, and toxicity. Therefore, balanophonin can be developed as an effective alternative drug to inhibit SARS CoV-2 NendoU.

Guanylate-binding protein 1 inhibits inflammatory factors produced by H5N1 virus through Its GTPase activity

The combination of inflammatory factors resulting from an influenza A virus infection is one of the main causes of death in host animals. Studies have shown that guinea pig guanosine monophosphate binding protein 1 (guanylate-binding protein 1, gGBP1) can downregulate cytokine production induced by the influenza virus. Therefore, exploring the innate immune defense mechanism of GBP1 in the process of H5N1 influenza virus infection has important implications for understanding the pathogenic mechanism, disease prevention, and the control of influenza A virus infections. We found that, in addition to inhibiting the early replication of influenza virus, gGBP1 also inhibited the production of CCL2 and CXCL10 cytokines induced by the influenza virus as well as the proliferation of mononuclear macrophages induced by these cytokines. These findings further confirmed that gGBP1 inhibited the production of cytokines through its GTPase activity and cell proliferation through its C-terminal α-helix structure. This study revealed the effect of gGBP1 on the production of cellular inflammatory factors during influenza virus infection and determined the key amino acid residues that assist in the inhibitory processes mediated by gGBP1.

Genetic diversity of murine norovirus populations less susceptible to chlorine.

High genetic diversity in RNA viruses contributes to their rapid adaptation to environmental stresses, including disinfection. Insufficient disinfection can occur because of the emergence of viruses that are less susceptible to disinfection. However, understanding regarding the mechanisms underlying the alteration of viral susceptibility to disinfectants is limited. Here, we performed an experimental adaptation of murine norovirus (MNV) using chlorine to understand the genetic characteristics of virus populations adapted to chlorine disinfection. Several MNV populations exposed to an initial free chlorine concentration of 50 ppm exhibited reduced susceptibility, particularly after the fifth and tenth passages. A dominant mutation identified using whole-genome sequencing did not explain the reduced susceptibility of the MNV populations to chlorine. Conversely, MNV populations with less susceptibility to chlorine, which appeared under higher chlorine stress, were accompanied by significantly lower synonymous nucleotide diversity (πS) in the major capsid protein (VP1). The nonsynonymous nucleotide diversity (πN) in VP1 in the less-susceptible populations was higher than that in the susceptible populations, although the difference was not significant. Therefore, the ability of MNV populations to adapt to chlorine was associated with the change in nucleotide diversity in VP1, which may lead to viral aggregate formation and reduction in chlorine exposure. Moreover, the appearance of some nonsynonymous mutations can also contribute to the alteration in chlorine susceptibility by influencing the efficiency of viral replication. This study highlights the importance of understanding the genetic characteristics of virus populations under disinfection, which can contribute to the development of effective disinfection strategies and prevent the development of virus populations less susceptible to disinfectants.

Exploring the Antiviral Potential of Natural Compounds against Influenza: A Combined Computational and Experimental Approach.

The influenza A virus nonstructural protein 1 (NS1), which is crucial for viral replication and immune evasion, has been identified as a significant drug target with substantial potential to contribute to the fight against influenza. The emergence of drug-resistant influenza A virus strains highlights the urgent need for novel therapeutics. This study proposes a combined theoretical criterion for the virtual screening of molecular libraries to identify candidate NS1 inhibitors. By applying the criterion to the ZINC Natural Product database, followed by ligand-based virtual screening and molecular docking, we proposed the most promising candidate as a potential NS1 inhibitor. Subsequently, the selected natural compound was experimentally evaluated, revealing measurable virus replication inhibition activity in cell culture. This approach offers a promising avenue for developing novel anti-influenza agents targeting the NS1 protein.

The nucleoside analog 4'-fluorouridine suppresses the replication of multiple enteroviruses by targeting 3D polymerase.

Human enteroviruses are the major pathogens causing hand-foot-and-mouth disease in infants and young children throughout the world, and infection with enterovirus is also associated with severe complications, such as aseptic meningitis and myocarditis. However, there are no antiviral drugs available to treat enteroviruses infection at present. In this study, we found that 4'-fluorouridine (4'-FlU), a nucleoside analog with low cytotoxicity, exhibited broad-spectrum activity against infections of multiple enteroviruses with EC50 values at low micromolar levels, including coxsackievirus A10 (CV-A10), CV-A16, CV-A6, CV-A7, CV-B3, enterovirus A71 (EV-A71), EV-A89, EV-D68, and echovirus 6. With further investigation, the results indicated that 4'-FlU directly interacted with the RNA-dependent RNA polymerase of enterovirus, the 3D pol, and impaired the polymerase activity of 3D pol, hence inhibiting viral RNA synthesis and significantly suppressing viral replication. Our findings suggest that 4'-FlU could be promisingly developed as a broad-spectrum direct-acting antiviral agent for anti-enteroviruses therapy.

Metabolic and immune status of Pacific white shrimp Penaeus vannamei concerning farming conditions

Biomarkers for monitoring shrimp health have been proposed but scarcely evaluated at the farm level. We analyzed several indicators of energy status in shrimp under farming conditions concerning stocking densities (100 m-2 with biofloc, 15 and 7 m-2). The influence of the year's season (temperature) was also analyzed, and, finally, an unfortunate event of White spot syndrome virus (WSSV) infection occurred on the 7 m-2 farms, adding another condition. At shrimp sampling from ponds, the effect of acute handling stress was also analyzed for indicators typically affected by such procedure with a 3- and 10-fold increase in glucose and lactate levels in hemolymph, respectively, regardless of density. This response was partially blunted at lower temperatures and WSSV incidence. Increased levels of protein in the hepatopancreas, adenylic energy charge (AEC) in both hepatopancreas and muscle and phosphagens in muscle were observed in shrimp from the 100 m-2 farms, suggesting a better nutritional and energetic status in shrimp cultured at high density with biofloc technology. Shrimp with WSSV presented lower hemocyanin levels in hemolymph, most likely associated with its role in the immune response. In WSSV-infected shrimp, the stress response regarding glucose increase was blunted, whereas a stress-induced increase in triglycerides (TG) levels in hemolymph was observed only with WSSV. Increased TG levels in those shrimp hepatopancreas could indicate a switch from carbohydrate to lipid-based metabolism associated with the preferential use of carbohydrates (Warburg effect) for virus replication in the early infection state.

Structure-Based Virtual Screening of Antiviral Compounds Targeting the Norovirus RdRp Protein

Background: Human noroviruses (NV) are the primary etiological organisms causing acute gastroenteritis around the world, causing severe morbidity and imposing a significant economic burden. The RNA-dependent RNA polymerase (RdRp) is essential for viral replication and could be a promising target for anti-NV therapeutics. Despite the discovery of a few NV RdRp inhibitors, the majority of these pharmaceuticals have demonstrated limited efficacy in inhibiting viral replication in cellular models.Methods: In this study, computational screening of antiviral compounds was conducted targeting the NV RdRp protein. The assessment was based on binding poses and the key residues of RdRp involved in interactions with compounds.Results: The compounds namely, Ribavirin, BMS806, Dihydromyricetin, R7935788, and LY2784544 were found to bind the RdRp protein with high affinity. Notably, these compounds displayed significantly lower binding affinities compared to the positive control, PPNDS. In addition, these compounds exhibited many RdRp protein binding residues that were also present in the PPNDS.Conclusion: The results presented here suggest that these compounds have the potential to be used as inhibitors of NV RdRp in the development of antiviral medications. Nevertheless, due to the computational nature of this study, it is imperative to do experimental validation.Keywords: Noroviruses; RdRp; Virtual screening; Antiviral Compounds

Ayurvedic and Chinese Herbs against Coronaviruses.

COVID-19 is a viral disease that infects the lower airways, causing severe acute respiratory syndrome (SARS) and fatal pneumonia. The ripple effect of the COVID-19 outbreak has created serious problems in the healthcare systems of many countries and had far-reaching consequences for the global economy. Thus, effective control measures should be implemented for this coronavirus infection in the future. The ongoing episode of the SARS-CoV-2 sickness, COVID-19, in China, and the subsequent irregular spread of contamination to different nations, has alarmed the clinical and academic community primarily due to the deadly nature of this disease. Being a newly identified virus in the viral classification and having the highest mutation rate, rapid therapeutics are not readily available for treating this ailment, leading to the widespread of the disease and causing social issues for affected individuals. Evidence of Ayurveda and traditional Chinese medicine (TCM) has been found in ancient civilizations, such as those of the Hindus, Babylonians, Hebrews, and Arabs. Although TCM and Ayurvedic herbs do not promise to be very effective treatments for this pandemic, they can reduce infectivity and virulence by enhancing immunity and showing effectiveness in rehabilitation after COVID-19 disease. Thus, they could be used as sources of inhibitor molecules for certain phenomena, such as viral replication, attachment to the host, 3CL protease inhibition, 3a ion channel inhibitors, and reverse transcription inhibition. Medicinal plants from TCM and Ayurveda and their biologically active phytoconstituents can effectively modulate the targets and pathways relevant to inflammation and immune responses in human bodies. The present review analyzes the role of certain TCM and Ayurvedic medicinal plants in healing COVID-19 infection. Medicinal plants such as Glycyrrhiza glabra (licorice), Curcuma longa (turmeric), and Zingiber officinale (ginger) are regarded as the main antiviral herbs. Their extracts and individual bioactive compounds could be used as potential substances for developing remedies to prevent or cure the coronavirus disease. Generally, antiviral phytochemicals obtained from natural sources are considered potent candidates for fighting COVID-19 infection and rehabilitation after it.

Molecular mechanism of infectious spleen and kidney necrosis virus in manipulating the hypoxia-inducible factor pathway to augment virus replication

ABSTRACT Infectious spleen and kidney necrosis virus (ISKNV), a member of the genus Megalocytivirus in the family Iridoviridae, can infect over 50 fish species and cause significant economic losses in Asia. Our previous study showed that hypoxia triggers the hypoxia-inducible factor pathway (HIF-pathway), leading to increased replication of ISKNV through promoting the upregulation of viral hypoxic response genes like orf077r. This study delved into the molecular mechanism of how ISKNV manipulates the HIF-pathway to enhance its replication. In vitro and in vivo experiments confirmed that ISKNV infection activated the HIF-pathway, which in turn promoted ISKNV replication. These findings suggest that ISKNV actively manipulates the HIF-pathway. Co-immunoprecipitation experiments revealed that the ISKNV-encoded protein VP077R interacts with the Von Hippel−Lindau (VHL) protein at the HIF-binding region, competitively inhibiting the interaction of HIF-1α with VHL. This prevents HIF degradation and activates the HIF-pathway. Furthermore, VP077R interacts with factor-inhibiting HIF (FIH), recruiting FIH and S-phase kinase-associated protein 1 (Skp1) to form an FIH – VP077R – Skp1 complex. This complex promotes FIH protein degradation via ubiquitination, further activating the HIF-pathway. These findings indicated that ISKNV takes over the HIF-pathway by releasing two “brakes” on this pathway (VHL and FIH) via VP077R, facilitating virus replication. We speculate that hypoxia initiates a positive feedback loop between ISKNV VP077R and the HIF pathway, leading to the outbreak of ISKNV disease. This work offers valuable insights into the complex interactions between the environment, host, and virus.

External Guide Sequence Effectively Suppresses the Gene Expression and Replication of Herpes Simplex Virus 2.

Ribonuclease P (RNase P) complexed with an external guide sequence (EGS) represents a promising nucleic acid-based gene targeting approach for gene expression knock-down and modulation. The RNase P-EGS strategy is unique as an EGS can be designed to basepair any mRNA sequence and recruit intracellular RNase P for hydrolysis of the target mRNA. In this study, we provide the first direct evidence that the RNase P-based approach effectively blocks the gene expression and replication of herpes simplex virus 2 (HSV-2), the causative agent of genital herpes. We constructed EGSs to target the mRNA encoding HSV-2 single-stranded DNA binding protein ICP8, which is essential for viral DNA genome replication and growth. In HSV-2 infected cells expressing a functional EGS, ICP8 levels were reduced by 85%, and viral growth decreased by 3000 folds. On the contrary, ICP8 expression and viral growth exhibited no substantial differences between cells expressing no EGS and those expressing a disabled EGS with mutations precluding RNase P recognition. The anti-ICP8 EGS is specific in targeting ICP8 because it only affects ICP8 expression but does not affect the expression of the other viral immediate-early and early genes examined. This study shows the effective and specific anti-HSV-2 activity of the RNase P-EGS approach and demonstrates the potential of EGS RNAs for anti-HSV-2 applications.

Development of an effective single-chain variable fragment recognizing a novel epitope in the hepatitis C virus E2 protein that restricts virus entry into hepatocytes.

Previously, we reported a neutralizing monoclonal antibody, A8A11, raised against a novel conserved epitope within the hepatitis C virus (HCV) E2 protein, that could significantly reduce HCV replication. Here, we report the nucleotide sequence of A8A11 and demonstrate the efficacy of a single-chain variable fragment (scFv) protein that mimics the antibody, inhibits the binding of an HCV virus-like particle to hepatocytes, and reduces viral RNA replication in a cell culture system. More importantly, scFv A8A11 was found to effectively restrict the increase of viral RNA levels in the serum of HCV-infected chimeric mice harbouring human hepatocytes. These results suggest a promising approach to neutralizing-antibody-based therapeutic interventions against HCV infection.

Compounds based on Adamantyl-Substituted Amino Acids and Peptides as Potential Antiviral Drugs Acting as Viroporin Inhibitors.

The discussion has revolved around the derivatives of amino acids and peptides containing carbocycles and their potential antiviral activity in vitro against influenza A, hepatitis C viruses, and coronavirus. Studies conducted on cell cultures reveal that aminoadamantane amino acid derivatives exhibit the capacity to hinder the replication of viruses containing viroporins. Furthermore, certain compounds demonstrate potent virucidal activity with respect to influenza A/H5N1 and hepatitis C virus particles. A conceptual framework for viroporin inhibitors has been introduced, incorporating carbocyclic motifs as membranotropic carriers in the structure, alongside a functional segment comprised of amino acids and peptides. These components correspond to the interaction with the inner surface of the channel's pore or another target protein.

SARS-CoV-2 strains bearing Omicron BA.1 spike replicate in C57BL/6 mice.

SARS-CoV-2, the cause of the COVID pandemic, is an RNA virus with a high propensity to mutate. Successive virus variants, including variants of concern (VOC), have emerged with increased transmission or immune escape. The original pandemic virus and early variants replicated poorly, if at all, in mice at least partly due to a mismatch between the receptor binding domain on the viral spike protein and the murine angiotensin converting enzyme 2 (ACE2). Omicron VOC emerged in late 2021 harboring > 50 new mutations, 35 of them in the spike protein. This variant resulted in a very large wave of infections, even in the face of prior immunity, albeit being inherently less severe than earlier variants. Reflecting the lower severity reported in humans, Omicron displayed attenuated infection in hamsters and also in the K18-hACE2 mouse model. K18-hACE2 mice express both the human ACE2 as well as the endogenous mouse ACE2. Here we infected hACE2 knock-in mice that express only human ACE2 and no murine ACE2, or C57BL/6 wildtype mice with SARS-CoV-2 D614G (first-wave isolate), Delta or Omicron BA.1 variants and assessed infectivity and downstream innate immune responses. While replication of SARS-CoV-2 Omicron was lower in the lungs of hACE2 knock-in mice compared with SARS-CoV-2 D614G and VOC Delta, it replicated more efficiently than the earlier variants in C57BL/6 wildtype mice. This opens the opportunity to test the effect of host genetics on SARS-CoV-2 infections in wildtype mice. As a proof of principle, we tested Omicron infection in mice lacking expression of the interferon-alpha receptor-1 (IFNAR1). In these mice we found that loss of type I IFN receptor signaling resulted in higher viral loads in the lungs were detected. Finally, using a chimeric virus of first wave SARS-CoV-2 harboring the Omicron spike protein, we show that Omicron spike increase infection of C57BL/6 wildtype mice, but non-spike genes of Omicron confer attenuation of viral replication. Since this chimeric virus efficiently infected C57BL/6 wildtype mice, and replicated in their lungs, our findings illustrate a pathway for genetic mapping of virushost interactions during SARS-CoV-2 infection.

Прогнозування РНК, siRNA з подальшим визначенням імунологічної відповіді запропонованої вакцини (Vac534) проти COVID-19

Despite the decline in Coronavirus infections, care must be taken to avoid new mutations that allow the virus to escape vaccination and treatment. Viral RNA is responsible for virus replication and assembly in the host cell. Aim. The goal of this work was to predict the RNA secondary structure of the vaccination we developed before (Vac534). In addition, the degree of RNA overlaps while translating into ribosomes, refolding, and evaluating the protein immune response are all considered. Methods. Different immunobioinformatics tools and servers were utilized for analysis. RNA folding was executed through the application of RNAstructure 6.4 and RNAfold software. The unique sequence context led to the emergence of potential RNA structures at the site where ribosome binding occurs. A new method, C-IMMSIM, which relies on immune cell epitope prediction, was employed to gain fresh insights into comprehending the immune system. Results. А high probability of ≥ 99% is shown between nucleotides with the stability of loops and motifs of the RNA 2D structure. The predicted siRNA sequences, which were located in three places, were used to calculate total energy, self-folding, and a free end with a high accessibility score. RNA translation into the ribosome is required to determine the optimum direction of translation. The short docking fragment of 24 nucleotides of RNA (Vac534) generated six robust binds with MPRO at high energy. Conclusions. The immunological evaluation of the vaccination is critical for stimulating immune cells and detecting interleukins and cytokine production. This study is viewed as a step toward developing Coronavirus treatments. The number of loops and motifs is increasing, with a probability of above 99% for most sequences. The predicted siRNA sequences, which were located in three places, were used to calculate total energy, self-folding, and a free end with a high accessibility score.

Antiviral Activity of Low-Molecular-Weight Fluorinated Compounds Against Influenza A (H1N1) Virus

Influenza A virus takes a stable position in annual acute respiratory disease outbreaks during the autumn-winter period. Antiviral drugs for influenza infection help significantly ease the course of the disease and prevent complications, but there is still no drug to which none of the circulating strains would be resistant. Therefore, the search for new effective drugs against influenza A virus is constantly being conducted, in particular among fluorine-containing organic compounds, taking into account the special properties of fluorine. The goal of the study is to investigate the activity of a group of low-molecular-weight fluorinated compounds against the influenza A (H1N1) virus and to determine the potential mechanism of their action using in silico methods. Methods. Five fluorinated compounds designated as 10S-45, 10S-46, 10S-47, 10S-48 and 10S-49 were studied. In vitro experiments were performed using MDCK cell culture, A/FM/1/47 strain of influenza A (H1N1) virus, and oseltamivir phosphate as a reference drug. The cytotoxic effect on cell culture was determined using the MTT test. Antiviral effect was investigated by post-exposure incubation of compound solutions with cells, and visualization of results was performed using crystal violet dye. The possibility of the interaction of compounds with the cap-binding domain (CBD) of the PB2 subunit of the RNA-dependent RNA polymerase (RdRp) of the virus was evaluated using molecular dynamics simulation. Results. It was established that the studied compounds have a moderate cytotoxic effect on MDCK cell culture: the calculated CC50 values are in the range of 471─577 μg/mL for 10S-45, 10S-46, 10S-47 and 10S-48. Substance 10S-49 is almost 2 times less toxic compared to the rest, but it also has no effect on the influenza virus. Compounds 10S-45, 10S-46 and 10S-48 demonstrate antiviral activity in the range of 12─78 % inhibition of viral reproduction with an inverse dose-dependent effect. Substance 10S-47 showed a relatively stable inhibition of viral reproduction in the range of 63─69 % at all tested concentrations, which is similar to the results of the reference drug. According to the results of the selectivity index calculation, compound 10S-48 has the highest value, and 10S-47 has the lowest one, for the rest of the substances, this indicator is acceptable, but low, compared to the reference drug. For in silico studies, all possible spatial forms of the compounds presented as a mixture of diastereoisomers were generated: 4 stereoisomers each for 10S-45 and 10S-46, as well as 3 for 10S-47. According to the results of molecular docking of substances to the active center of CBD, 10S-45 has the lowest calculated affinity, and 10S-47 has the highest. Accordingly, compound 10S-45 showed no tendency to form ordered interactions with CBD. The 10S-47/CBD complex was not characterized by the presence of stable orientational bonds between receptor and ligand, similar to 10S-48/CBD. However, compound 10S-46 showed a generally stable interaction with CBD, albeit with a period of conformational instability. Conclusions. All studied compounds (except for 10S-49) demonstrate an antiviral effect in vitro against the influenza A (H1N1) virus. Based on the results of the in silico analysis of their interactions with CBD PB2, compound 10S-46 is highly likely to be an inhibitor of the cap-binding activity of RdRp.

Clinical efficacy and safety of Xuanfei Touxie Fang as a complementary medicine in the treatment of SARS-CoV-2 Omicron variant: A retrospective study

IntroductionTo explore the clinical efficacy and safety of Xuanfei Touxie Fang (XFTXF) as a complementary medicine in the treatment of SARS-CoV-2 Omicron variant. MethodsA retrospective study of 317 patients with ordinary symptoms admitted to our hospital from December 2022 to February 2023 were divided into the observation group (n = 224) and the control group (n = 93). The observation group was treated with Xuanfei Touxie Fang combined with conventional treatment and the control group treated with conventional treatment alone. Recovery time of symptoms, length of hospital stay, clinical cure rate and recovery rate of chest CT manifestations were compared between the two groups. ResultsThe time to recover from fever (median: 1 vs 3 days) and the length of hospital stay (median: 7 vs 9 days) of the observation group after treatment were significantly shorter than the control group. The difference was statistically significant (P < 0.05). The clinical cure rate (68.3% vs 54.84 %) and the recovery rate of chest CT manifestations (87.95% vs 66.67 %) of the observation group after treatment were higher than the control group. The difference was statistically significant (P < 0.05). There was no adverse reactions during the treatment for two groups. The difference was no statistically significant (P > 0.05). DiscussionNumerous studies have demonstrated that Xuanfei Touxie Fang, which is frequently used in respiratory diseases, has anti-coronavirus effects by inhibiting viral replication, release, penetration, and RNA synthesis. Therefore, we treated COVID-19 with it and evaluated its safety and effectiveness. ConclusionsXuanfei Touxie Fang as a complementary medicine has a significant effect in the treatment of COVID-19, which can reduce the duration of fever and the length of hospital stay, improve the clinical cure rate and recovery rate of chest CT manifestations.