China
Africa
Explore chapters and articles related to this topic
Ecology
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
In their authoritative review at that early time, Snowdon and Cliver (1989) accepted that “small, round coliphages, especially those containing RNA, appear to offer some potential as indicators or indices of the presence of enteroviruses” and that the “RNA coliphages can and do replicate in host E. coli cells in the environment outside the intestines.”
Indicators of microbial quality *
Published in Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse, Routledge Handbook of Water and Health, 2015
Bacteriophages (or, phages) are viruses that infect bacteria. They are closely associated with their bacterial hosts, and so may be found in the same settings. Unlike their bacterial hosts, there is some evidence that they are often present in greater quantities, are more environmentally persistent, and may be better models of virus fate and transport in the environment than bacterial indicators. Bacteriodes fragilis phages, Salmonella phages, and E. coli phages (coliphages) have all been proposed as indicators of fecal contamination. Of the phages that have been studied, F-pilus-specific (F+) coliphages with RNA genomes (sometimes known as “male-specific” coliphages) have received the most attention (Sobsey et al. 1995). Less is known about F+DNA coliphages and somatic coliphages as fecal and viral indicators, though somatic coliphages may be more common in feces as well as more stable in the environment (Jofre 2003). F+RNA coliphages infect E. coli and potentially other members of the coliform group. They have been used in microbial source tracking applications (Love and Sobsey 2007; Lee et al. 2011), although their associations to health outcomes in humans have not been well characterized.
Smartphone technology facilitates point-of-care nucleic acid diagnosis: a beginner’s guide
Published in Critical Reviews in Clinical Laboratory Sciences, 2021
Vinoth Kumar Rajendran, Padmavathy Bakthavathsalam, Peter L. Bergquist, Anwar Sunna
A smartphone system for imaging and counting of coliphages using an in-gel LAMP assay was described by Huang et al. [106]. Viral particles were immobilized with LAMP reagents in a polyethylene glycol hydrogel, and the viral RNAs were amplified through a LAMP reaction. Individual viral particles produced one amplicon dot because of the restrictive effect of the hydrogel matrix, and the dots were imaged using the smartphone. The digital counting of in-gel LAMP allowed detection of 1 plaque forming unit/mL of coliphage. Significantly, the assay demonstrated a high level of tolerance toward inhibitors naturally present in wastewater, a situation in which PCR was completely inhibited. The in-gel LAMP results correlated well with plaque assay counts (R2 = 0.984, p < .05) and achieved a sensitivity similar to PCR. Droplet-based digital detection platforms using a smartphone camera have been developed for the generation and detection of millions of droplets. Damhorst et al. [107] developed a reverse transcriptase loop-mediated isothermal amplification droplet detection platform on a smartphone to assay HIV-spiked whole blood samples. The silicon microchip platform showed amplification of three viruses in 60 nL droplets that corresponded to a whole blood concentration of 670 virus particles/µL. The smartphone acted as a microscope to image the droplets in each chamber and the results were processed using a MATLAB (matrix laboratory) code to provide quantitative detection of HIV-positive individuals [107].
Control of Salmonella Enteritidis on food contact surfaces with bacteriophage PVP-SE2
Published in Biofouling, 2018
Catarina Milho, Maria Daniela Silva, Luís Melo, Sílvio Santos, Joana Azeredo, Sanna Sillankorva
The treatment with phage PVP-SE2 of adhered and biofilm cells grown in both polystyrene and SS was shown to be more effective at 22 °C than at refrigerated temperatures. This result was expected owing to the closer optimal growth conditions in which Salmonella maintains a quite active metabolism when compared to 4 °C. It is generally accepted that cell growth and temperature conditions have a major effect on phage replication. For instance, the replication of coliphage FRNA at lower than optimal cell growth temperature conditions is slower and can even cease because of the lower expression of F pili and adsorption inhibition (Knolle and Orskov 1967; Woody and Cliver 1995). Similar results have also been reported for phages of Listeria (Tokman et al. 2016) and Pseudomonas fluorescens (Sillankorva et al. 2004) where incubation at refrigeration temperatures resulted in an increase in the latent period, a reduction in phage burst size and overall lower killing efficacy.
Biological challenges of phage therapy and proposed solutions: a literature review
Published in Expert Review of Anti-infective Therapy, 2019
Katherine M Caflisch, Gina A Suh, Robin Patel
Perhaps the most obvious eukaryotic niche in which to examine the impact of therapeutic phage is innate and adaptive immune systems. For more than 50 years, phages (particularly, coliphage ΦX174) have upheld a role in clinical practice in the diagnosis of primary and secondary immunodeficiencies and continue to be utilized in this way today [124]. As a neoantigen, ΦX174 is processed only via presentation by T to B cells of the humoral immune system, such that an inability to develop cell-mediated immunity against the phage indicates immunodeficiency.