Efficiency of beef extract for the recovery of poliovirus from wastewater effluents

Wastewater-based surveillance as a tool for public health action: SARS-CoV-2 and beyond

Wastewater-based surveillance (WBS) has undergone dramatic advancement in the context of the coronavirus disease 2019 (COVID-19) pandemic. The power and potential of this platform technology were rapidly realized when it became evident that not only did WBS-measured SARS-CoV-2 RNA correlate strongly with COVID-19 clinical disease within monitored populations but also, in fact, it functioned as a leading indicator. Teams from across the globe rapidly innovated novel approaches by which wastewater could be collected from diverse sewersheds ranging from wastewater treatment plants (enabling community-level surveillance) to more granular locations including individual neighborhoods and high-risk buildings such as long-term care facilities (LTCF). Efficient processes enabled SARS-CoV-2 RNA extraction and concentration from the highly dilute wastewater matrix. Molecular and genomic tools to identify, quantify, and characterize SARS-CoV-2 and its various variants were adapted from clinical programs and applied to these mixed environmental systems. Novel data-sharing tools allowed this information to be mobilized and made immediately available to public health and government decision-makers and even the public, enabling evidence-informed decision-making based on local disease dynamics. WBS has since been recognized as a tool of transformative potential, providing near-real-time cost-effective, objective, comprehensive, and inclusive data on the changing prevalence of measured analytes across space and time in populations. However, as a consequence of rapid innovation from hundreds of teams simultaneously, tremendous heterogeneity currently exists in the SARS-CoV-2 WBS literature. This manuscript provides a state-of-the-art review of WBS as established with SARS-CoV-2 and details the current work underway expanding its scope to other infectious disease targets.

Concentration and detection of hepatitis A virus and its indicator from artificial seawater using zeolite

Hepatitis A virus (HAV) infection is the leading worldwide cause of acute viral hepatitis, and outbreaks caused by this virus often occur in fecal polluted waters. Rapid concentration and detection of viral contamination in water environments can prevent economic loss and can identify the source of contamination within a short time. However, conventional methods for virus concentration are often laborious, time consuming, and subject to clogging. Furthermore, most methods require a secondary concentration step to reduce the final volume of samples. We developed a method to concentrate HAV from seawater using zeolite in aid of rapid detection. In this method,artificial seawater was inoculated with HAV (7-8 log TCID50) and filtered with zeolite. The viruses were then eluted from zeolite with sodium dodecyl sulfate and detected via real-time PCR (qPCR). Zeolite was able to concentrate HAV from artificial seawater with ∼99% efficiency in less than 5min and was more efficient in seawater than in fresh water. The entire concentration and detection can be done in approximately 2h. Compared to existing methods, this method eliminated the need for a secondary concentration step as well as the necessity to modify the pH or salinity of the seawater during concentration, and was simple and inexpensive.

Entrainment of viruses from septic tank leach fields through a shallow, sandy soil aquifer

A study was conducted which focused on movement of naturally occurring human enteroviruses from a subsurface wastewater disposal system through a shallow aquifer. The potential for significant entrainment of virus particles was evidenced by their recovery at down-gradient distances of 67.05 m and from aquifer depths of 18 m. A significant negative correlation was observed between virus occurrence and the distance from the "septage" (leaching pool) source. Virus occurrence could not be statistically correlated with either total or fecal coliforms, indicating the limitations of current microbial water quality indicators for predicting the virological quality of groundwater.

Optimum pH levels for eluting enteroviruses from sludge solids with beef extract

This study demonstrates that elution of enteroviruses from a mixture of primary- and activated-sludge solids with beef extract at pH 9.2 +/- 0.2 may be less efficient than elution with beef extract at pH 7.2 +/- 0.2 and that elution of enteroviruses from extended-aeration-sludge solids with beef extract is at best no more efficient at pH 9.2 +/- 0.2 than at pH 7.2 +/- 0.2. Thus, the common practice of adjusting the pH of beef extract used for eluting enteroviruses from the natural neutral level of the elutant to alkaline levels is unnecessary and probably undesirable.

Enteroviruses in sludge: multiyear experience with four wastewater treatment plants

We describe our experience with the isolation of viruses from four treatment plants located in different geographic areas. Over a period of 3 years, 297 enteroviruses were isolated from 307 sludge samples. The highest frequency of viral isolation (92%), including multiple isolates from single samples, was obtained from a treatment plant serving the smallest population. Excluding the polioviruses, 22 different enterovirus serotypes were isolated. The methods used to isolate the viruses were relatively simple and included an elution procedure in which beef extract was used and a disinfection step. No concentration procedure was used. Of three cell culture systems used, the RD line of human rhabdomyosarcoma cells was by far the most useful for the isolation of echoviruses; BGM and HeLa cells were particularly useful for the isolation of group B coxsackieviruses. A seasonal effect on viral isolation rates from sludge was observed.

Public health considerations associated with molluscan aquaculture systems: Human viruses

The documentation of several recent outbreaks of human virus diseases associated with the consumption of shellfish has reiterated the threat posed by these agents to the shellfish industry. This article reviews pertinent outbreaks, identifies principal viral agents involved, and delineates systems which may be at greatest risk. The results of two recent laboratory studies which sought to define environmental factors that contribute to virus accumulation by shellfish are also discussed. First, the accumulation of environmentally significant levels of feces-associated and monodispersed poliovirus by oysters (Crassostrea virginica) and clams (Mercenaria mercenaria) was investigated. The results of this study suggested that virus accumulation by mollusks may not be significant when water column concentrations are below ⋍0.01 plaque-forming units (PFU) per milliliter. The second study focused on the relative contributions of undisturbed sediments versus those in the water column in the accumulation of viruses by epifaunal and infaunal shellfish (C. virginica and M. mercenaria). Viruses were found to be most efficiently accumulated when suspended in the water column.

Viral pollution of the rivers in Toyama City

Viral pollution of the river water in Toyama City was surveyed during the two-year period from July 1979 to July 1981, and the ecology of viruses in the river water is discussed. Virus isolation from the river water samples, or from the water squeezed from cotton pads that were immersed in the stream for 3 days, was carried out by the "filter adsorption/elution" method. River waters were found to be contaminated with various species of enteric viruses, that is, poliovirus, echovirus, coxsackievirus, adenovirus, and reovirus. Poliovirus was isolated during the period immediately after the oral administration of polio vaccine, and coxsackie B virus was frequently isolated all year around. The enterovirus concentration in the river water was significantly high with a maximum of five plaque-forming units of coxsackie B2 virus per 250 ml. The species and type distribution of enteroviruses isolated from the river water coincided well with that of viruses isolated from inhabitants of Toyama Prefecture, with the exception of reovirus which was the largest population of virus species in the river water.

Elution of viruses from coastal sediments

Enteric viruses were eluted from estuarine sediments by using four organic mixtures; these solutions, with or without various supplements, were compared by determining their abilities to desorb virus from sediments taken from shellfish-harvesting sites. The least effective eluents consisted of glycine buffer, milk preparations, and beef extract paste. When virus type and sediment composition were taken into consideration, higher percentages of virus recovery were achieved with isoelectric casein, powdered beef extract, and nutrient broth mixtures. In addition to the type of eluent used, variations in virus recovery were due to the pH of the eluent, the composition of the sediment, and the type of virus being extracted. No clear distinction between the values of protein and inorganic ion supplements could be made.

Concentration of simian rotavirus SA-11 from tap water by membrane filtration and organic flocculation

Simian rotavirus SA-11 was concentrated from tap water by adsorption to and elution from microporous filters, followed by organic flocculation. Two types of filters were compared for their ability to concentrate the virus. Both Zeta Plus 60S and Cox AA type M-780 filters were efficient for virus adsorption, but the efficiency of virus elution was higher with Zeta Plus than with Cox filters. Optimum conditions for virus recovery from Zeta Plus filters included an input water pH of 6.5 to 7.5 and the use of 3% beef extract (pH 9.0) for elution. Under these conditions, an average of 62 to 100% of the virus was recovered in the concentrate. Organic flocculation was used as a second-step concentration method, with average recoveries of 47 to 69%. When the two methods were used to concentrate small numbers (7 to 75 PFU/liter) of input rotavirus, an average of 75 +/- 40% recovery was achieved. With large volumes of input water, however, recovery was reduced to 16 +/- 7%.

Accumulation of sediment-associated viruses in shellfish

The present study focused on the importance of contaminated sediments in shellfish accumulation of human viruses. Epifaunal (Crassostrea virginica) and infaunal (Mercenaria mercenaria) shellfish, placed on or in cores, were exposed to either resuspended or undisturbed sediments containing bound poliovirus type 1 (LSc 2ab). Consistent bioaccumulation by oysters (four of five trials) was only noted when sediment-bound viruses occurred in the water column. Virus accumulation was observed in a single instance where sediments remained in an undisturbed state. While the incidence of bioaccumulation was higher with resuspended rather than undisturbed contaminated sediment, the actual concentration of accumulated viruses was not significantly different. The accumulation of viruses from oysters residing on uninoculated sediments. When clams were exposed to undisturbed, virus-contaminated sediments, two of five shellfish pools yielded viral isolates. Bioaccumulation of undisturbed sediments by these bivalves was considered marginal when related to the concentration of virus in contaminated sediments; they would only represent a significant threat when suspended in the water column. Arguments were advanced for water-column sampling in the region of the water-sediment interface to provide an accurate determination of the virological quality of shellfish harvesting waters.

Inefficient accumulation of low levels of monodispersed and feces-associated poliovirus in oysters

The accumulation of low levels (0.002 to 0.18 PFU/ml) of both feces-associated and monodispersed poliovirus by oysters (Crassostrea virginica or C. gigas) and clams (Mercenaria mercenaria) was investigated. These levels were chosen to duplicate the conditions present in light to moderately polluted waters. Experiments were performed in both small- and large-scale flowing seawater systems, developed to mimic the natural marine habitats of shellfish. Under these experimental conditions, viral accumulation by physiologically active shellfish was only noted when water column concentrations exceeded approximately 0.01 PFU/ml. Bioaccumulation increased with increasing concentrations of both monodispersed and feces-associated viruses. At virus concentrations below this level, viruses were seldom detected in either clams or oysters. Evidence indicated that the lack of accumulation was not the result of inefficient extraction or detection methods. The modified Cat-Floc-beef extract procedure used in the experiment was found to be capable of detecting as few as 1.5 to 2.0 PFU per shellfish. Evidence is presented to indicate that an uptake-depuration equilibrium was present at virus exposure levels of 0.10 PFU/ml, but not at 0.01 PFU/ml. The results suggested that viral accumulation by shellfish may not be efficient at water column concentrations below congruent to 0.01 PFU/ml.

Techniques for virus detection in aquatic sediments

Laboratory experiments have been undertaken to study the adsorption-desorption of poliovirus to and from marine and freshwater sediments. It was observed that marine sediments retained 99% of added virus, whereas, freshwater sediments adsorbed approximately 40% of the added virus. Ten eluents were investigated for their ability to desorb viruses from a marine sediment. It was found that virus elution from the marine sediment was relatively low and ranged from less than 1% to 44%. Two eluents, urea-lysine and TCA-glycine at pH 9.0, were found to be the most efficient among the eluents tested. Viruses were more easily released from freshwater than from marine sediments. When urea-lysine, beef extract and purified casein were used as eluents, the overall virus recovery ranged from 8% to 22% for the marine sediment and from 23% to 59% for the freshwater sediments. The urea-lysine methods was used for the detection of indigenous enteroviruses in sediments from a closed shellfish bed. Enteroviruses were recovered with concentrations up to 708 TCID50/50 g of sediment.

Virus removal during groundwater recharge: effects of infiltration rate on adsorption of poliovirus to soil

Studies were conducted to determine the influence of infiltration rate on poliovirus removal during groundwater recharge with tertiary-treated wastewater effluents. Experiments were conducted at a uniquely designed, field-situated test recharge basin facility through which some 62,000 m3 of sewage had been previously applied. Recharge at high infiltration rates (75 to 100 cm/h) resulted in the movement of considerable numbers of seeded poliovirus to the groundwater. Moderately reduced infiltration rates (6 cm/h) affected significantly improved virus removal. Very low infiltration rates (0.5 to 1.0 cm/h), achieved by partial clogging of the test basin, yielded the greatest virus removal efficiencies.

Concentration of seeded simian rotavirus SA-11 from potable waters by using talc-celite layers and hydroextraction

There is mounting evidence for the waterborne transmission of diarrhea caused by rotaviruses. As a result, proper techniques are required for their recovery from samples of incriminated water. The combined efficiency of the talc-Celite technique and polyethylene glycol 6000 hydroextraction was, therefore, tested for this purpose, using Simian rotavirus SA-11 and MA-104 cells. Conditioning of the dechlorinated tap water samples was carried out by pH adjustment to 6.0 and the addition of Earle balanced salt solution to a final concentration of 1:100. Passage of a 1-liter volume of such a conditioned sample through a layer containing a mixture of talc (300 mg) and Celite 503 (100 mg) led to the adsorption of nearly 93% of the added SA-11 plaque-forming units. For the recovery of the layer-adsorbed virus, 3% beef extract and 1x tryptose phosphate broth were found to be superior to a variety of other eluents tested. When we tested 100-liter sample volumes, layers containing 1.2 g of talc and 0.4 g of Celite were employed. Virus elution was carried out with 100 ml of tryptose phosphate broth. The eluate was concentrated 10-fold by overnight (4 degrees C) hydroextraction with polyethylene glycol. With a total input virus of 7.0 x 10(5) and 1.4 x 10(2) plaque-forming units, the recoveries were about 71 and 59%, respectively.

Adsorption of enteroviruses to soil cores and their subsequent elution by artificial rainwater

The adsorption and elution of a variety of human enteroviruses in a highly permeable, sandy soil was studied by using cores (43 by 125 mm) collected from an operating recharge basin on Long Island. Viruses studied included field and reference strains of polioviruses types 1 and 3 and reference strains of coxsackie virus B3 and echovirus types 1 and 6. Viruses suspended in treated sewage effluent were allowed to percolate through soil cores, and the filtrate was assayed for unadsorbed viruses. To determine the likelihood of desorption and mobilization, soil-bound viruses were subjected to a rinse with either treated sewage effluent or simulated rainwater which reflected the anion, cation, and pH characteristics of a typical northeastern United States rainfall. The results demonstrated that all polioviruses tested, including both reference and field strains, adsorbed extremely well to cores. Adsorption was somewhat reduced when clean, unconditioned soils were used. Soil-bound poliovirus strain LSc was not significantly mobilized by flooding columns with either a sewage effluent or rainwater rinse. One virus was mobilized by both types of rinses. The amount of viruses mobilized by rainwater rinses ranged from 24 to 66%. Variable adsorption-elution results were observed with other enteroviruses. Two guanidine-resistant mutants of poliovirus LSc demonstrated a soil adsorption-elution profile different from that of the parent strain. The data support the conclusion that soil adsorption-elution behavior is strain dependent and that poliovirus, particularly strain LSc, represents an inappropriate model.

Modified procedure for the recovery of naturally accumulated poliovirus from oysters

Methods were compared for their ability to recover poliovirus from oysters (Crassostrea gigas) which had been allowed to accumulate virus via normal filtration activities. Clarification procedures included glycine-NaCl and polyelectrolyte extraction methods followed by a variety of acid precipitation concentration methods. Polyelectrolyte flocculation followed by a beef extract-supplemented acid precipitation carried out at pH 3.5 yielded the most efficient recoveries. Direct assay of homogenates was found to be an unreliable method for determining the initial virus concentration in "naturally infected" oysters.