Comparison of agar and agarose preparations for mengovirus plaque formation

Isolation of Enterococcus Bacteriophages from Municipal Wastewater Samples Using an Enrichment Step

Municipal wastewater, as an aggregate mixture of household and industrial effluents, harbors a highly diverse population of bacteria and their associated bacteriophages. Accordingly, it is a commonly used source of bacteriophages against many human-associated bacterial pathogens. Here, we describe a method for bacteriophage isolation from municipal wastewater with several optional enrichment and concentration steps.

Potential Antiviral Properties of Industrially Important Marine Algal Polysaccharides and Their Significance in Fighting a Future Viral Pandemic

Over the decades, the world has witnessed diverse virus associated pandemics. The significant inhibitory effects of marine sulfated polysaccharides against SARS-CoV-2 shows its therapeutic potential in future biomedical applications and drug development. Algal polysaccharides exhibited significant role in antimicrobial, antitumor, antioxidative, antiviral, anticoagulant, antihepatotoxic and immunomodulating activities. Owing to their health benefits, the sulfated polysaccharides from marine algae are a great deal of interest globally. Algal polysaccharides such as agar, alginate, carrageenans, porphyran, fucoidan, laminaran and ulvans are investigated for their nutraceutical potential at different stages of infection processes, structural diversity, complexity and mechanism of action. In this review, we focus on the recent antiviral studies of the marine algae-based polysaccharides and their potential towards antiviral medicines.

Different Behavior of Enteric Bacteria and Viruses in Clay and Sandy Soils after Biofertilization with Swine Digestate

Enteric pathogens from biofertilizer can accumulate in the soil, subsequently contaminating water and crops. We evaluated the survival, percolation and leaching of model enteric pathogens in clay and sandy soils after biofertilization with swine digestate: PhiX-174, mengovirus (vMC0), Salmonella enterica Typhimurium and Escherichia coli O157:H7 were used as biomarkers. The survival of vMC0 and PhiX-174 in clay soil was significantly lower than in sandy soil (iT90 values of 10.520 ± 0.600 vs. 21.270 ± 1.100 and 12.040 ± 0.010 vs. 43.470 ± 1.300, respectively) and PhiX-174 showed faster percolation and leaching in sandy soil than clay soil (iT90 values of 0.46 and 2.43, respectively). S. enterica Typhimurium was percolated and inactivated more slowly than E. coli O157:H7 (iT90 values of 9.340 ± 0.200 vs. 6.620 ± 0.500 and 11.900 ± 0.900 vs. 10.750 ± 0.900 in clay and sandy soils, respectively), such that E. coli O157:H7 was transferred more quickly to the deeper layers of both soils evaluated (percolation). Our findings suggest that E. coli O157:H7 may serve as a useful microbial biomarker of depth contamination and leaching in clay and sandy soil and that bacteriophage could be used as an indicator of enteric pathogen persistence. Our study contributes to development of predictive models for enteric pathogen behavior in soils, and for potential water and food contamination associated with biofertilization, useful for risk management and mitigation in swine digestate recycling.

Propidium Monoazide Integrated with qPCR Enables the Detection and Enumeration of Infectious Enteric RNA and DNA Viruses in Clam and Fermented Sausages

The increase of foodborne viral outbreaks highlights the need for a rapid and sensitive method for the prediction of viral infectivity in food samples. This study assesses the use of propidium monoazide (PMA) coupled with real-time PCR methods (RT-qPCR or qPCR for RNA or DNA viruses, respectively) in the determination of viral infectivity in complex animal-related food matrices. Clam and Spanish fermented sausage (“chorizo”) samples were spiked with infectious and heat-inactivated human adenovirus-2 (HAdV-2) and mengovirus (vMC₀). PMA-qPCR/RT-qPCR discriminated infective virus particles, with significant reductions (>2.7 log₁₀ or 99.7%). Additionally, infectious HAdV-2 and vMC₀ were quantified by plaque assay (in plaque forming units, PFU), and compared with those in virus genomes copies (GCs) quantified by PMA-qPCR/RT-qPCR. A consistent correlation (R² > 0.92) was showed between PFU and GCs along serial 10-fold dilutions in both DNA and RNA virus and in both food matrices. This study shows the use of PMA coupled to qPCR/RT-qPCR as a promising alternative for prediction of viral infectivity in food samples in comparison to more expensive and time-consuming methods and for those viruses that are not able to grow under available cell culture techniques.

Propidium Monoazide Coupled with PCR Predicts Infectivity of Enteric Viruses in Swine Manure and Biofertilized Soil

The use of propidium monoazide (PMA) coupled with real-time PCR (RT-qPCR or qPCR for RNA or DNA viruses, respectively) was assessed to discriminate infectious enteric viruses in swine raw manure, swine effluent from anaerobic biodigester (AB) and biofertilized soils. Those samples were spiked either with infectious and heat-inactivated human adenovirus-2 (HAdV-2) or mengovirus (vMC0), and PMA-qPCR/RT-qPCR allowed discriminating inactivated viruses from the infective particles, with significant reductions (>99.9%). Then, the procedure was further assayed to evaluate the presence and stability of two non-cultivable viruses (porcine adenovirus and rotavirus A) in natural samples (swine raw manure, swine effluent from AB and biofertilized soils); it demonstrated viral inactivation during the storage period at 23 °C. As a result, the combination of PMA coupled to real-time PCR can be a promising alternative for prediction of viral infectivity in comparison to more labour-intensive and costly techniques such as animal or tissue-culture infectivity methods, and for those viruses that do not have currently available cell culture techniques.

A comparative study of agar overlay and standard tissue culture methods for isolation of enteroviruses

A study was made of the isolation of enteroviruses from 62 cerebrospinal fluids and 141 autopsy specimens with standard fluid monolayer tissue culture methods and tissue cultures under agar overlay with and without added MgCl2 (0.025M). Sixteen virus isolations were made only by the overlay method, two only by the standard technique, and six by both procedures. Additional studies were carried out on 975 diagnostic specimens of various types with standard tissue culture methods and with primary rhesus kidney cells under agar overlay containing 0.025M MgCl2. Seventeen virus isolations were made only by the overlay procedure, 20 only by the standard tissue culture method, and 75 by both techniques. Since there were instances in which either the agar overlay or the standard method alone succeeded in isolating a virus, use of both types of procedures would be desirable to isolate as many enteroviruses as possible from clinical specimens.