Egyptian cobra (Naja haje haje) venom phospholipase A2: a promising antiviral agent with potent virucidal activity against simian rotavirus and bovine coronavirus.

Viral infections are linked to a variety of human diseases. Despite the achievements made in drug and vaccine development, several viruses still lack preventive vaccines and efficient antiviral compounds. Thus, developing novel antiviral agents is of great concern, particularly the natural products that are promising candidates for such discoveries. In this study, we have purified an approximately 15 kDa basic phospholipase A2 (PLA2) enzyme from the Egyptian cobra Naja haje haje venom. The purified N. haje PLA2 showed a specific activity of 22 units/mg protein against 6 units/mg protein for the whole crude venom with 3.67-fold purification. The antiviral activity of purified N. haje PLA2 has been investigated in vitro against bovine coronavirus (BCoV) and simian rotavirus (RV SA-11). Our results showed that the CC50 of PLA2 were 33.6 and 29 µg/ml against MDBK and MA104 cell lines, respectively. Antiviral analysis of N. haje PLA2 showed an inhibition of BCoV and RV SA-11 infections with a therapeutic index equal to 33.6 and 16, respectively. Moreover, N. haje PLA2 decreased the BCoV and RV SA-11 titers by 4.25 log10 TCID50 and 2.5 log10 TCID50, respectively. Thus, this research suggests the potential antiviral activity of purified N. haje PLA2 against BCoV and RV SA-11 infections in vitro.

High-Sulfated Glycosaminoglycans Prevent Coronavirus Replication.

Coronaviruses (CoVs) are common among humans and many animals, causing respiratory or gastrointestinal diseases. Currently, only a few antiviral drugs against CoVs are available. Especially for SARS-CoV-2, new compounds for treatment of COVID-19 are urgently needed. In this study, we characterize the antiviral effects of two high-sulfated glycosaminoglycan (GAG) derivatives against SARS-CoV-2 and bovine coronaviruses (BCoV), which are both members of the Betacoronavirus genus. The investigated compounds are based on hyaluronan (HA) and chondroitin sulfate (CS) and exhibit a strong inhibitory effect against both CoVs. Yield assays were performed using BCoV-infected PT cells in the presence and absence of the compounds. While the high-sulfated HA (sHA3) led to an inhibition of viral growth early after infection, high-sulfated CS (sCS3) had a slightly smaller effect. Time of addition assays, where sHA3 and sCS3 were added to PT cells before, during or after infection, demonstrated an inhibitory effect during all phases of infection, whereas sHA3 showed a stronger effect even after virus absorbance. Furthermore, attachment analyses with prechilled PT cells revealed that virus attachment is not blocked. In addition, sHA3 and sCS3 inactivated BCoV by stable binding. Analysis by quantitative real-time RT PCR underlines the high potency of the inhibitors against BCoV, as well as B.1-lineage, Alpha and Beta SARS-CoV-2 viruses. Taken together, these results demonstrated that the two high-sulfated GAG derivatives exhibit low cytotoxicity and represent promising candidates for an anti-CoV therapy.

An automated room disinfection system using ozone is highly active against surrogates for SARS-CoV-2.

BACKGROUND: The presence of coronaviruses on surfaces in the patient environment is a potential source of indirect transmission. Manual cleaning and disinfection measures do not always achieve sufficient removal of surface contamination. This increases the importance of automated solutions in the context of final disinfection of rooms in the hospital setting. Ozone is a highly effective disinfectant which, combined with high humidity, is an effective agent against respiratory viruses. Current devices allow continuous nebulization for high room humidity as well as ozone production without any consumables. AIM: In the following study, the effectiveness of a fully automatic room decontamination system based on ozone was tested against bacteriophage Φ6 (phi 6) and bovine coronavirus L9, as surrogate viruses for the pandemic coronavirus SARS-CoV-2. METHODS: For this purpose, various surfaces (ceramic tile, stainless steel surface and furniture board) were soiled with the surrogate viruses and placed at two different levels in a gas-tight test room. After using the automatic decontamination device according to the manufacturer's instructions, the surrogate viruses were recovered from the surfaces and examined by quantitative cultures. Then, reduction factors were calculated. FINDINGS: The ozone-based room decontamination device achieved virucidal efficacy (reduction factor >4 log10) against both surrogate organisms regardless of the different surfaces and positions confirming a high activity under the used conditions. CONCLUSION: Ozone is highly active against SARS-CoV-2 surrogate organisms. Further investigations are necessary for a safe application and efficacy in practice as well as integration into routine processes.

New Acaciin-Loaded Self-Assembled Nanofibers as MPro Inhibitors Against BCV as a Surrogate Model for SARS-CoV-2.

BACKGROUND: SARS-COVID-2 has recently been one of the most life-threatening problems which urgently needs new therapeutic antiviral agents, especially those of herbal origin. PURPOSE: The study aimed to load acaciin (ACA) into the new self-assembled nanofibers (NFs) followed by investigating their possible antiviral effect against bovine coronavirus (BCV) as a surrogate model for SARS-COV-2. METHODS: ACA was identified using 1H-NMR and DEPT-Q 13C-NMR spectroscopy, the molecular docking study was performed using Autodock 4 and a modification of the traditional solvent injection method was applied for the synthesis of the biodegradable NFs. Different characterization techniques were used to inspect the formation of the NFs, which is followed by antiviral investigation against BCV as well as MTT assay using MDBK cells. RESULTS: Core/shell NFs, ranging between 80-330 nm with tiny thorn-like branches, were formed which attained an enhanced encapsulation efficiency (97.5 ± 0.53%, P<0.05) and a dual controlled release (a burst release of 65% at 1 h and a sustained release up to >24 h). The antiviral investigation of the formed NFs revealed a significant inhibition of 98.88 ± 0.16% (P<0.05) with IC50 of 12.6 µM against BCV cells. CONCLUSION: The results introduced a new, time/cost-saving strategy for the synthesis of biodegradable NFs without the need for electric current or hazardous cross-linking agents. Moreover, it provided an innovative avenue for the discovery of drugs of herbal origin for the fight against SARS-CoV-2 infection.

Application of Environment-Friendly Rhamnolipids against Transmission of Enveloped Viruses Like SARS-CoV2.

In the face of new emerging respiratory viruses, such as SARS-CoV2, vaccines and drug therapies are not immediately available to curb the spread of infection. Non-pharmaceutical interventions, such as mask-wearing and social distance, can slow the transmission. However, both mask and social distance have not prevented the spread of respiratory viruses SARS-CoV2 within the US. There is an urgent need to develop an intervention that could reduce the spread of respiratory viruses. The key to preventing transmission is to eliminate the emission of SARS-CoV2 from an infected person and stop the virus from propagating in the human population. Rhamnolipids are environmentally friendly surfactants that are less toxic than the synthetic surfactants. In this study, rhamnolipid products, 222B, were investigated as disinfectants against enveloped viruses, such as bovine coronavirus and herpes simplex virus 1 (HSV-1). The 222B at 0.009% and 0.0045% completely inactivated 6 and 4 log PFU/mL of HSV-1 in 5-10 min, respectively. 222B at or below 0.005% is also biologically safe. Moreover, 50 µL of 222B at 0.005% on ~1 cm2 mask fabrics or plastic surface can inactivate ~103 PFU HSV-1 in 3-5 min. These results suggest that 222B coated on masks or plastic surface can reduce the emission of SARS-CoV2 from an infected person and stop the spread of SARS-CoV2.

Antiviral activity of a novel mixture of natural antimicrobials, in vitro, and in a chicken infection model in vivo.

The aim of this study was to test in vitro the ability of a mixture of citrus extract, maltodextrin, sodium chloride, lactic acid and citric acid (AuraShield L) to inhibit the virulence of infectious bronchitis, Newcastle disease, avian influenza, porcine reproductive and respiratory syndrome (PRRS) and bovine coronavirus viruses. Secondly, in vivo, we have investigated its efficacy against infectious bronchitis using a broiler infection model. In vitro, these antimicrobials had expressed antiviral activity against all five viruses through all phases of the infection process of the host cells. In vivo, the antimicrobial mixture reduced the virus load in the tracheal and lung tissue and significantly reduced the clinical signs of infection and the mortality rate in the experimental group E2 receiving AuraShield L. All these effects were accompanied by a significant reduction in the levels of pro-inflammatory cytokines and an increase in IgA levels and short chain fatty acids (SCFAs) in both trachea and lungs. Our study demonstrated that mixtures of natural antimicrobials, such AuraShield L, can prevent in vitro viral infection of cell cultures. Secondly, in vivo, the efficiency of vaccination was improved by preventing secondary viral infections through a mechanism involving significant increases in SCFA production and increased IgA levels. As a consequence the clinical signs of secondary infections were significantly reduced resulting in recovered production performance and lower mortality rates in the experimental group E2.