New Method Using a Positively Charged Microporous Filter and Ultrafiltration for Concentration of Viruses from Tap Water

Abstract

The methods used to concentrate enteric viruses from water have remained largely unchanged for nearly 30 years, with the most common technique being the use of 1MDS Virozorb filters followed by organic flocculation for secondary concentration. Recently, a few studies have investigated alternatives; however, many of these methods are impractical for use in the field or share some of the limitations of this traditional method. In the present study, the NanoCeram virus sampler, an electropositive pleated microporous filter composed of microglass filaments coated with nanoalumina fibers, was evaluated. Test viruses were first concentrated by passage of 20 liters of seeded water through the filter (average filter retention efficiency was >99.8%), and then the viruses were recovered using various salt-based or proteinaceous eluting solutions. A 1.0% sodium polyphosphate solution with 0.05 M glycine was determined to be the most effective. The recovered viruses were then further concentrated using Centricon Plus-70 centrifugal ultrafilters to a final volume of 3.3 (؎0.3 [standard deviation]) ml; this volume compares quite favorably to that of previously described methods, such as organic flocculation (ϳ15 to 40 ml). The overall virus recovery efficiencies were 66% for poliovirus 1, 83% for echovirus 1, 77% for coxsackievirus B5, 14% for adenovirus 2, and 56% for MS2 coliphage. In addition, this method appears to be compatible with both cell culture and PCR assays. This new approach for the recovery of viruses from water is therefore a viable alternative to currently used methods when small volumes of final concentrate are an advantage.

Field-based evaluation of a male-specific (F+) RNA coliphage concentration method

“…Dilution of the RNA from most of the FRNA coliphage spiked samples improved the Ct of the RT-PCR assays, and allowed for the detection of FRNA coliphages even in samples in which the IAC was positive in undiluted RNA. This finding was consistent with numerous reports indicating that PCR inhibitors are co-purified with nucleic acid isolation procedures, and these inhibitors may differentially impact the molecular detection outcome for various targets (Abbaszadegan et al, 1999;Ikner et al, 2011Ikner et al, , 2012Jones et al, 2009;Lambertini et al, 2008). Our previous studies suggest that the altered detection of FRNA coliphages are not related to differential adsorption to the anion exchange resin or RNA extraction efficiency (Perez-Mendez et al, 2014b).…”

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. II. Total Culturable Virus Assay

“…The 58% recovery from groundwater using the culture procedure is similar to that reported by others using tap water 23,24 . The mean recovery from the LFB samples of 111% with a coefficient of variation (CV) of 100% also met the method performance acceptance criteria even though they are higher than that observed for PE samples during the ICR.…”

Transfer Efficiency of Bacteria and Viruses from Porous and Nonporous Fomites to Fingers under Different Relative Humidity Conditions

“…PV-1 propagation and plaque-forming assays were conducted as described previously (39,40). Briefly, PV-1 was propagated on buffalo green monkey kidney (BGM) (ATCC CCL-81; American Type Culture Collection, Manassas, VA) cell line monolayers with minimal essential media (MEM) containing 5% calf serum (HyClone Laboratories, Logan, UT) at an incubation temperature of 37°C with 5% CO 2 .…”

“…The plates were incubated at 37°C for 18 Ϯ 2 h. B. thuringiensis spore samples were heat shocked at 81 Ϯ 2°C for 10 min prior to spread plating to stimulate germination. The MS2 plaque assay was conducted using the double-agar overlay method and TSA (EMD Chemicals Inc., Gibbstown, NJ) (39,43). PV-1 titrations were performed using 10-fold-serial-dilution plaque-forming assays as described previously (39,40).…”