Isolation and Detection Methods of Viruses from Drinking Water
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At A Glance
Over 786 million people lack even basic drink water across the globe, with upwards of 1.8 million deaths annually attributed. Furthermore, it is suggested that approximately 20-30% of the ground water in the United States are contaminated with viruses.
In addressing this issue, researchers at Colorado State University have developed an isolation and detection method for viruses and other pathogens from large quantities of water (or other aqueous media). The technology developed here employs charged resins to isolate viral particles from liquid sources such as water, milk, juices, and even homogenized food. With current detection methods being time intensive and expensive, there is an acute need for the detection of viruses in water samples that can be conducted directly in the field.
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Reference No.: 09-058
Drinking water can become contaminated with enteric viruses and pose a significant health risk to people. These viruses enter source waterways through the direct or indirect discharge of treated and untreated human and animal waste into rivers, streams, and estuaries. In general, waterborne human enteric viruses pose a greater health risk than enteric bacteria due to the low infectious dose, which may be as little as one virion1.
Waterborne enteric viruses replicate in the gastrointestinal tract and are shed in the feces of infected individuals. Most enteric viruses are morphologically similar, and consist of an icosahedral-shaped, non-enveloped capsid, which surrounds a single-stranded RNA (e.g. Norwalk-like virus) or double stranded DNA (e.g. adenovirus) molecule. Noroviruses and Hepatitis A are the most common enteric viruses transmitted by water2. Other common waterborne viruses include rotaviruses, echoviruses, coxsackieviruses and adenoviruses.
Several of these viruses can be found on the Drinking Water Contaminant Candidate List as issued by the Environmental Protection Agency.
Anion exchange has traditionally been used in water purification methodologies, as a way to decrease the amount of nitrates, sulphates, and other negatively charged ions in water. And since anion exchange resins are effective at removing negatively charged ions in water, it stood to reason that these resins would also be effective at removing microorganisms, such as viruses which have a strong net negative surface charge.
Anionic resin beads are added to a sample liquid and suspended within the liquid. While in suspension the anionic beads complex with negatively charged virus particles or other pathogens. As water passes through the resin, the viruses will be exchanged for, and trade positions with the loosely held chloride or hydroxyl ions on the resin. This has the effect of concentrating the viruses on the resin. The complexed beads are then removed from the liquid, effecting the isolation of the virus. Detection techniques can then be performed directly on the complexed beads without resorting to additional steps to elute the virus or other pathogen from the bead.
Furthermore, the methodology can be employed for the detection of bacteriophages where the bacteriophage serves as a surrogate for the presence of a pathogen or other contaminant, such as an enteric virus, or as an indicator of water quality.
- Anion exchange resin is very effective at isolating virus surrogates from water and other liquids.
- Allows for direct analysis of the presence of target viruses without the need for elution
- Ability to remove viruses/pathogens from large water samples (up to 60 liters)
- Greater sensitivity in the detection of microbial contaminants than other methods
- Recreational water sampling (e.g., public health agency testing methodology)
- Water sampling for biodefense testing
- food industry (e.g., testing of water, juices, and milk can be tested for the presence of enteric viruses)
- Testing conducted directly in the field
Pérez-Méndez A, Chandler JC, Bisha B, Goodridge LD. Concentration of enteric viruses from tap water using an anion exchange resin-based method. J Virol Methods. 2014 Sep;206:95-8. doi: 10.1016/j.jviromet.2014.05.025. Epub 2014 Jun 6. PMID: 24911889.
Pérez-Méndez A, Chandler JC, Bisha B, Goodridge LD. Evaluation of an anion exchange resin-based method for concentration of F-RNA coliphages (enteric virus indicators) from water samples. J Virol Methods. 2014 Aug;204:109-15. doi: 10.1016/j.jviromet.2014.03.024. Epub 2014 Apr 18. PMID: 24747586.
- Girones, R, et al., Wat. Sci. Technol. (1993) 27, 235-241
- Koopmans M, and Duizer E., Int J Food Microbiol. (2004) 90(1):23-41