Inactivation of coronaviruses under irradiation by UVA-range light-emitting diodes

We report the results of the development of an experimental stand based on UVA light-emitting diodes (UVA LEDs) with radiation wavelengths of 385 and 395 nm for studying experimentally the inactivation of viruses of the coronavirus family, including SARS-CoV-2. Methodological grounds are presented for determining the inactivation dose that provides a predetermined decrease in the virus titre under the impact of UVA radiation. The effect of the diode radiation divergence on the virus photoinactivation process is investigated. It is shown that UVA LEDs can be used to reduce the virus titre by 4 orders of magnitude.

Virucidal Activity of Plant Extracts against African Swine Fever Virus

African swine fever is one of the most dangerous and fatal swine diseases, described for the first time roughly a hundred years ago. Even now, there is neither a commercially approved vaccine nor treatment available. The only way to hinder further spread of the disease is by culling the affected herds and applying prevention based mainly on proper biosecurity. Due togrowing awareness of the potential ASF threat among pig producers, disinfection processes are considered as one of the most important preventive measures. Currently, a variety of chemical compounds are applied for the disinfection of pig farms. Meanwhile, these chemicals may pose a potential risk, due to their toxic, irritant or corrosive effect. The aim of this study was to determine whether any plant-based natural compounds may show a virucidal effect against ASFV, and simultaneously be depleted of some of the side-effects typical for chemical compounds. Ideally, natural virucidal compounds should be safe for both humans and animals, biodegradable, easily available and inexpensive. Fourteen plant extracts were selected and screened for their virucidal effect against ASFV, using the suspension test inspired by the PN-EN 14675:2015 European Standard procedure. The results of our study showed that most of the tested plant extracts were ineffective against ASFV. Some extracts suspended in a hydroglycolic medium exhibited high virus titre reduction, but it was confirmed that the effect resulted from medium composition. However, a 1.05% peppermint extract showed high effectiveness against ASFV, reducing the virus titre by ≥4 log10, thus demonstrating that natural compounds used as virucidal agents could potentially be used in disinfection procedures, being both effective and harmless to humans and animals.

Pharmacokinetic and pharmacodynamic analysis of baloxavir marboxil, a novel cap-dependent endonuclease inhibitor, in a murine model of influenza virus infection

Background Baloxavir acid, the active form of the orally available prodrug baloxavir marboxil, is a novel cap-dependent endonuclease inhibitor of influenza virus. Baloxavir marboxil has been shown to rapidly reduce virus titres compared with oseltamivir in clinical studies. Objectives We investigated the relationship between pharmacokinetic (PK) parameters and antiviral activity of baloxavir acid based on virus titre reduction in lungs of infected mice. Methods BALB/c mice infected with a sub-lethal dose of influenza A(H1N1), A(H1N1)pdm09, A(H3N2) or type B virus were treated on day 5 with oral baloxavir marboxil (0.5–50 mg/kg q12h), subcutaneous baloxavir acid (0.25–8 mg/kg/day), oseltamivir phosphate (5 or 50 eq mg/kg q12h) or other antivirals for 1 day. Lung virus titres were assessed 24 h after initial antiviral dosing. PK testing was performed at up to 24 h post-dosing of baloxavir marboxil or baloxavir acid in A/WSN/33-infected mice and the PK/pharmacodynamic (PD) relationship was evaluated for baloxavir acid. Results Oral baloxavir marboxil administration showed dose-dependent virus titre reductions in lungs of mice infected with the different types/subtypes of influenza viruses 24 h post-dosing. Baloxavir marboxil at 15 mg/kg q12h resulted in ≥100-fold and ≥10-fold reductions in influenza A and B virus titres, respectively, compared with oseltamivir phosphate. PK/PD analysis showed that the plasma concentration at the end of the dosing interval (Cτ) or the plasma concentration at 24 h after initial dosing (C24) was the PK parameter predicting the virus titres at 24 h post-dosing of baloxavir acid. Conclusions PK/PD analysis of baloxavir acid based on virus titre reduction in this mouse model could be helpful in predicting and maximizing virological outcomes in clinical settings.

VALIDATION OF REAL-TIME REVERSE TRANSCRIPTION POLYMERASE CHAIN REACTION FOR INDIRECT ASSESSMENT OF FMD VIRUS TITRE

Procedure for validation of the method for indirect assessment of cultural FMD virus titre (T FMDV) in raw materials used for vaccine production with real time reverse transcription polymerase chain reaction (RT-PCRrt) based on determined amplifcation threshold cycle value (Ct) using linear regression model, TFMDV= –0.2956Ct+ 11.4650, is described in the paper. Testing results for 390 samples of cultural FMD virus were analyzed and basic validation characteristics of the proposed method: specifcity, accuracy, precision, limit of detection and limit of quantifcation, application scope and linearity, were defned. Validation results for the method for indirect assessment of FMD virus titre with RT-PCRrt met the acceptance criteria.

COMPARATIVE STUDIES OF FELINE VIRAL RHINOTRACHEITIS VIRUS FOR ITS REPLICATION PROPERTIES IN DIFFERENT CELL CULTURES

The results of comparative studies of feline viral rhinotracheitis virus for its culture properties in primary and continuous cell cultures of feline origin (FK, FK (subculture), CrFK, FS, CC-81, FC/Tg) are presented. It was found that viral rhinotracheitis virus replication, irrespective of the route of infection and the culture technique, was consistent and practically equal in susceptible cell cultures. The most pronounced cytopathic effect (more than 75% monolayer degeneration) was observed in all types of cell cultures in 48–72 hours of cultivation. However, the accumulation of feline viral rhinotracheitis virus Grand strain was highest when preliminary adsorption occurred within the specified period of time, monolayer cell cultures were infected with the virus at a dose of 5.5 lg TCID50/ml and roller bottle cultivated, and the рН of the medium was maintained at 7.0–7.4. Single freezing of the virus at a temperature of minus 60 degrees Celsius upon the completion of the cultivation cycle (during 60–72 hours) and its thawing were found to significantly increase the virus titre by 0.5 lg TCID50/ml.

Evaluation of immunochromatographic tests for the rapid detection of the emerging GII.17 norovirus in stool samples, January 2016

A novel GII.17 norovirus emerged in Asia in the winter of 2014/15. A worldwide spread is conceivable and norovirus diagnostic assays need to be evaluated to investigate if they adequately detect this emerging genotype. Seven immunochromatographic kits commercially available in Europe were evaluated on ten stool samples where GII.17 virus had been quantified by real-time reverse transcription-polymerase chain reaction. All the kits detected GII.17 with various sensitivities, partly depending on the virus titre.