Evaluation of positively charged alumina nanofibre cartridge filters for the primary concentration of noroviruses,adenoviruses and male‐specific coliphages from seawater

Aim: To evaluate the electropositive, alumina nanofibre (NanoCeram) cartridge filter as a primary concentration method for recovering adenovirus, norovirus and male‐specific coliphages from natural seawater. Methods and Results: Viruses were concentrated from 40 l of natural seawater using a NanoCeram cartridge filter and eluted from the filter either by soaking the filter in eluent or by recirculating the eluent continuously through the filter using a peristaltic pump. The elution solution consisted of 3% beef extract and 0·1 mol l^?1 of glycine. The method using a peristaltic pump was more effective in removing the viruses from the filter. High recoveries of norovirus and male‐specific coliphages (>96%) but not adenovirus (<3%) were observed from seawater. High adsorption to the filter was observed for adenovirus and male‐specific coliphages (>98%). The adsorption and recovery of adenovirus and male‐specific coliphages were also determined for fresh finished water and source water. Conclusion: The NanoCeram cartridge filter was an effective primary concentration method for the concentration of norovirus and male‐specific coliphages from natural seawater, but not for adenovirus, in spite of the high adsorption of adenovirus to the filter. Significance and Impact of the Study: This study demonstrates that NanoCeram cartridge filter is an effective primary method for concentrating noroviruses and male‐specific coliphages from seawater, thereby simplifying collection and processing of water samples for virus recovery.     

A Small Volume Procedure for Viral Concentration from Water

Small-scale concentration of viruses (sample volumes 1-10 L, here simulated with spiked 100 ml water samples) is an efficient, cost-effective way to identify optimal parameters for virus concentration. Viruses can be concentrated from water using filtration (electropositive, electronegative, glass wool or size exclusion), followed by secondary concentration with beef extract to release viruses from filter surfaces, and finally tertiary concentration resulting in a 5-30 ml volume virus concentrate. In order to identify optimal concentration procedures, two different electropositive filters were evaluated (a glass/cellulose filter [1MDS] and a nano-alumina/glass filter [NanoCeram]), as well as different secondary concentration techniques; the celite technique where three different celite particle sizes were evaluated (fine, medium and large) followed by comparing this technique with that of the established organic flocculation method. Various elution additives were also evaluated for their ability to enhance the release of adenovirus (AdV) particles from filter surfaces. Fine particle celite recovered similar levels of AdV40 and 41 to that of the established organic flocculation method when viral spikes were added during secondary concentration. The glass/cellulose filter recovered higher levels of both, AdV40 and 41, compared to that of a nano-alumina/glass fiber filter. Although not statistically significant, the addition of 0.1% sodium polyphosphate amended beef extract eluant recovered 10% more AdV particles compared to unamended beef extract.     

Water potential changes in faecal matter and Escherichia coli survival

Aims: This study investigated the influence of a range of evaporation rates (2·0, 5·3 and 7·4 mm day⁻¹) on degradation of E. coli (ATCC Strain 25922) inoculated in canine faeces. Methods and Results: Experiments were carried out in an environmental chamber and a first order exponential decay function (Chick’s Law) was used to estimate degradation rates. We estimated die-off coefficients using linear regression. Die-off rates were −0·07, −0·22 and −0·23 h⁻¹, respectively, for evaporation rates of 2·0, 5·3 and 7·4 mm day⁻¹ (P = 0·000+, for each model). Nearly complete die-off was found within 15–60 h (7·4–2·0 mm day⁻¹ evaporation rates), which corresponds with a water potential of approximately −22·4 MPa. Conclusions: This study indicates that canine faeces need not be desiccated to achieve complete loss of indicator organisms. Water potential, which is a combination of osmotic and matric potential, is a key stress that increases as evaporation removes water from the faecal matrix and increases concentration of the remaining faecal solution. Evaporation may remove populations of indicator organisms in faeces relatively quickly, even though faeces are not completely dehydrated. Significance and Impact of the Study: This research may be used as the foundation for studies more closely resembling real-world evaporation conditions including diurnal fluctuations, rewetting and freezing.     

A closed system for the filtration of Mycobacterium bovis liquid cultures using disposable capsule filters

A filtration system was designed to sterilize large volumes of Mycobacterium bovis BCG Tokyo culture safely, needed to purify protein antigens for immunodiagnosis of bovine tuberculosis. A closed system consists of culture bottles connected to three disposable filter capsules of decreasing pore size in series : a depth prefilter over a 1·2 μm filter ; a 0·8 μm prefilter over a 0·45 μm filter ; and a 0·2 μm sterile filter. Low air pressure (3 psi) forces liquid from below the bacillary pellicle. The system features a stainless steel clamp to hold rubber stoppers on the culture bottles, pleated filters to exclude bacillary clumps, a quick disconnector to minimize aerosols, and a closed system with plastic disposable filters that can be autoclaved as a unit without dismantling.     

Detection of Noroviruses in Tap Water in Japan by Means of a New Method for Concentrating Enteric Viruses in Large Volumes of Freshwater

A virus concentration method using a cation-coated filter was developed for large-volume freshwater applications. Poliovirus type 1 (LSc 2ab Sabin strain) inoculated into 40 ml of MilliQ (ultrapure) water was adsorbed effectively to a negatively charged filter (Millipore HA, 0.45-μm pore size) coated with aluminum ions, 99% (range, 81 to 114%) of which were recovered by elution with 1.0 mM NaOH (pH 10.8) following an acid rinse with 0.5 mM H₂SO₄ (pH 3.0). More than 80% poliovirus recovery yields were obtained from 500-ml, 1,000-ml, and 10-liter MilliQ water samples and from tap water samples. This method, followed by TaqMan PCR detection, was applied to determine the presence of noroviruses in tap water in Tokyo, Japan. In a 14-month survey, 4 (4.1%) and 7 (7.1%) of 98 tap water samples (100 to 532 liters) contained a detectable amount of noroviruses of genotype 1 and genotype 2, respectively. This method was proved to be useful for surveying the occurrence of enteric viruses, including noroviruses, in large volumes of freshwater.     

The use of copper and silver in carbon point-of-use filters for the suppression of Legionella throughput in domestic water systems

Aims: To evaluate throughput of seeded Legionella pneumophila bacteria in domestic point‐of‐use filters. Methods and Results: The filters were challenged with tap water seeded with Leg. pneumophila. After multiple challenge events (4·25 × 10¹¹ CFU per filter), the levels of Legionella were lower in the effluent from the filter containing both copper and silver (mean 4·48 × 10³ CFU ml^?1) than in the effluent from the filter containing copper only (1·26 × 10⁴ CFU ml^?1; P < 0·001). After a single challenge event of approx. 5 × 10⁹ CFU L. pneumophila per filter, there was no significant difference between the levels of Legionella in the effluents from a carbon filter containing copper and a carbon filter with no metals (mean 6·87 × 10² and 6·89 × 10² CFU ml^?1, respectively; P = 0·985). Conclusions: Legionella was detected in filter effluent up to 6 weeks after being challenged, indicating that while filters may reduce the levels during an initial contamination event, the exposure is extended as the accumulated bacteria slough off over time. Significance and Impact of the Study: This study has provided an understanding of the response of Legionella to the use of silver and copper in domestic point‐of‐use carbon filters.     

Hepatitis E virus‐based evaluation of a virion concentration method and detection of enteric viruses in environmental samples by multiplex nested RT‐PCR

Aims: The prevalence of enteric viruses in drinking and river water samples collected from Pune, India was assessed. During an outbreak of HEV in a small town near pune, water samples were screened for enteric viruses. Methods and Results: The water samples were subjected to adsorption–elution‐based virus concentration protocol followed by multiplex nested PCR. Among 64 Mutha river samples, 49 (76·56%) were positive for Hepatitis A Virus, 36 (56·25%) were positive for Rotavirus, 33 (51·56%) were positive for Enterovirus and 16 (25%) were positive for Hepatitis E Virus RNA. Only enterovirus RNA was detected in 2/662 (0·3%) drinking water samples, and the samples from the city’s water reservoir tested negative for all four viruses. HEV RNA was detected in three out of four river water samples during HEV outbreak and partial sequences from patients and water sample were identical. Conclusions: The study suggests absence of enteric viruses both in the source and in the purified water samples from Pune city, not allowing evaluation of the purification system and documents high prevalence of enteric viruses in river water, posing threat to the community. Significance and Impact of the Study: The rapid, sensitive and relatively inexpensive protocol developed for virological evaluation of water seems extremely useful and should be adapted for evaluating viral contamination of water for human consumption. This will lead to development of adequate control measures thereby reducing disease burden because of enteric viruses.     

Evaluation of methodology for detection of human adenoviruses in wastewater,drinking water,stream water and recreational waters

Aims: This study evaluates dialysis filtration and a range of PCR detection methods for identification and quantification of human adenoviruses in a range of environmental waters. Methods and Results: Adenovirus was concentrated from large volumes (50–200 l) of environmental and potable water by hollow fibre microfiltration using commercial dialysis filters. By this method, an acceptable recovery of a seeded control bacteriophage MS2 from seawater (median 95·5%, range 36–98%, n = 5), stream water (median 84·7%, range 23–94%, n = 5) and storm water (median 59·5%, range 6·3–112%, n = 5) was achieved. Adenovirus detection using integrated cell culture PCR (ICC‐PCR), direct PCR, nested PCR, real‐time quantitative PCR (qPCR) and adenovirus group F‐specific direct PCR was tested with PCR products sequenced for confirmation. Adenovirus was routinely detected from all water types by most methods, with ICC‐PCR more sensitive than direct‐nested PCR or qPCR. Group F adenovirus dominated in wastewater samples but was detected very infrequently in environmental waters. Conclusions and Implications: Human adenoviruses (HAdv) proved relatively common in environmental and potable waters when assessed using an efficient concentration method and sensitive detection method. ICC‐PCR proved most sensitive, could be used semiquantitatively and demonstrated virus infectivity but was time consuming and expensive. qPCR provided quantitative results but was c. ten‐fold less sensitive than the best methods.     

Detection of noroviruses in tap water in Japan by means of a new method for concentrating enteric viruses in large volumes of freshwater

A virus concentration method using a cation-coated filter was developed for large-volume freshwater applications. Poliovirus type 1 (LSc 2ab Sabin strain) inoculated into 40 ml of MilliQ (ultrapure) water was adsorbed effectively to a negatively charged filter (Millipore HA, 0.45- micro m pore size) coated with aluminum ions, 99% (range, 81 to 114%) of which were recovered by elution with 1.0 mM NaOH (pH 10.8) following an acid rinse with 0.5 mM H(2)SO(4) (pH 3.0). More than 80% poliovirus recovery yields were obtained from 500-ml, 1,000-ml, and 10-liter MilliQ water samples and from tap water samples. This method, followed by TaqMan PCR detection, was applied to determine the presence of noroviruses in tap water in Tokyo, Japan. In a 14-month survey, 4 (4.1%) and 7 (7.1%) of 98 tap water samples (100 to 532 liters) contained a detectable amount of noroviruses of genotype 1 and genotype 2, respectively. This method was proved to be useful for surveying the occurrence of enteric viruses, including noroviruses, in large volumes of freshwater.     

Detection and molecular characterization of enteric viruses in environmental samples in Monastir,Tunisia between January 2003 and April 2007

Aims: A prospective study was performed to characterize the main human enteric viruses able to persist in sewage samples and in shellfish tissues, and to establish the correlation between environmental strains and viral infantile diarrhoea observed in the same area during the same period. Methods and Results: A total of 250 sewage (raw and treated) and 60 shellfish samples were collected between January 2003 and April 2007 in Monastir region, Tunisia. Group A rotavirus (RVA) was detected in 80 (32%) sewage samples, norovirus (NoV) in 11 (4·4%) and enteric adenovirus (AdV) in 1 (0·4%). Among 60 shellfish samples collected near sewage effluents, one was contaminated by NoV (1·6%). Conclusion: Our data represent the first documentation in Tunisia, combining gastroenteritis viruses circulating in the environment and in clinical isolates. We observed a correlation between environmental strains and those found in children suffering from gastroenteritis during the same period study. This suggests the existence of a relationship between water contamination and paediatric diarrhoea. Significance and Impact of the Study: Our results address the potential health risks associated with transmission of human enteric viruses through water‐related environmental routes. The research findings will aid in elucidating the molecular epidemiology and circulation of enteric viruses in Tunisia and in Africa, where data are rare.     

Characterization and flocculation properties of biopolymeric flocculant (glycosaminoglycan) produced by Cellulomonas sp. Okoh

Aims

Bioflocculant production potential of an actinobacteria isolated from a freshwater environment was evaluated and the bioflocculant characterized.

Methods and Results

16S rDNA nucleotide sequence and BLAST analysis was used to identify the actinobacteria and fermentation conditions, and nutritional requirements were evaluated for optimal bioflocculant production. Chemical analyses, FTIR, 1H NMR spectrometry and SEM imaging of the purified bioflocculant were carried out. The 16S rDNA nucleotide sequences showed 93% similarities to three Cellulomonas species (strain 794, Cellulomonas flavigena DSM 20109 and Cellulomonas flavigena NCIMB 8073), and the sequences was deposited in GenBank as Cellulomonas sp. Okoh (accession number HQ537132 ). Bioflocculant was optimally produced at an initial pH 7, incubation temperature 30°C, agitation speed of 160 rpm and an inoculum size of 2% (vol/vol) of cell density 1·5 × 10⁸ cfu ml^?1. Glucose (88·09% flocculating activity; yield: 4·04 ± 0·33 g l^?1), (NH₄)₂NO₃ (82·74% flocculating activity; yield: 4·47 ± 0·55 g l^?1) and MgCl₂ (90·40% flocculating activity; yield: 4·41 g l^?1) were the preferred nutritional source. Bioflocculant chemical analyses showed carbohydrate, protein and uronic acids in the proportion of 28·9, 19·3 and 18·7% in CPB and 31·4, 18·7 and 32·1% in PPB, respectively. FTIR and 1H NMR indicated the presence of carboxyl, hydroxyl and amino groups amongst others typical of glycosaminoglycan. SEM imaging revealed horizontal pleats of membranous sheets closely packed.

Conclusion

Cellulomonas sp. produces bioflocculant predominantly composed of glycosaminoglycan polysaccharides with high flocculation activity.

Significance and Impact of the Study

High flocculation activity suggests suitability for industrial applications; hence, it may serve to replace the hazardous flocculant used in water treatment.     

Assessment of adenovirus,hepatitis A virus and rotavirus presence in environmental samples in Florianopolis,South Brazil

Aims: To assess the presence of human adenovirus (HAdV), hepatitis A (HAV) virus and rotavirus A (RV‐A) in environmental samples from the Southern region of Brazil and to provide viral contamination data for further epidemiological studies and governmental actions. Methods and Results: Water samples from various sources (seawater, lagoon brackish water, urban wastewater, drinking water sources‐with and without chlorination and water derived from a polluted creek) and oysters of two growing areas were analysed by enzymatic amplification (nested PCR and RT‐PCR), quantification of HAdV genome (qPCR) and viral viability assay by integrated cell culture‐PCR (ICC‐PCR). From June 2007 to May 2008 in a total of 84 water samples, 54 (64·2%) were positive for HAdV, 16 (19%) for RV‐A and 7 (8·3%) for HAV. Viability assays showed nonpositive samples for HAV; though, infectious viruses were confirmed for RV‐A (12·5%) and HAdV (88·8%). Oyster samples by PCR were positive for HAdV (87·5%) and RV‐A (8·3%), but none for HAV. Quantitative PCR in oysters showed means loads in genomic copies (gc) of 9·1 × 10⁴ gc g^?1 (oyster farm south) and 1·5 × 10⁵ gc g^?1 (oyster farm north) and in waters ranging from 2·16 × 10⁶ (lagoon water) to 1·33 × 10⁷ gc l^?1 (untreated drinking water). Conclusions: This study has shown a widespread distribution of the analysed viruses in this particular region with high loads of HAdV in the environment which suggests the relevance of evaluating these viruses as positive indicators of viral contamination of water. Significance and Impact of the Study: The environmental approach in this study provides data concerning the prevalence, viability and quantification of enteric viruses in environmental waters and oysters in the South region of Brazil and has indicated that their presence might pose a risk to population in contact with the environmental samples searched.     

Use of zero-valent iron biosand filters to reduce Escherichia coli O157:H12 in irrigation water applied to spinach plants in a field setting

Aims:  Zero‐valent iron (ZVI) filters may provide an efficient method to mitigate the contamination of produce crops through irrigation water. Methods:  A field‐scale system was utilized to evaluate the effectiveness of a biosand filter (S), a biosand filter with ZVI incorporated (ZVI) and a control (C, no treatment) in decontaminating irrigation water. An inoculum of c. 8·5 log CFU 100 ml^?1 of Escherichia coli O157:H12 was introduced to all three column treatments in 20‐l doses. Filtered waters were subsequently overhead irrigated to ‘Tyee’ spinach plants. Water, spinach plant and soil samples were obtained on days 0, 1, 4, 6, 8, 10, 13 and 15 and analysed for E. coli O157:H12 populations. Results:  ZVI filters inactivated c. 6 log CFU 100 ml^?1E. coli O157:H12 during filtration on day 0, significantly (P < 0·05) more than S filter (0·49 CFU 100 ml^?1) when compared to control on day 0 (8·3 log CFU 100 ml^?1). On day 0, spinach plants irrigated with ZVI‐filtered water had significantly lower E. coli O157 counts (0·13 log CFU g^?1) than spinach irrigated with either S‐filtered (4·37 log CFU g^?1) or control (5·23 log CFU g^?1) water. Soils irrigated with ZVI‐filtered water contained E. coli O157:H12 populations below the detection limit (2 log CFU g^?1), while those irrigated with S‐filtered water (3·56 log CFU g^?1) were significantly lower than those irrigated with control (4·64 log CFU g^?1). Conclusions:  ZVI biosand filters were more effective in reducing E. coli O157:H12 populations in irrigation water than sand filters. Significance and Impact of the Study:  Zero‐valent ion treatment may be a cost‐effective mitigation step to help small farmers reduce risk of foodborne E. coli infections associated with contamination of leafy greens.     

Comparison of culture and PCR for the detection of Brucella melitensis in blood and lymphoid tissues of serologically positive and negative slaughtered sheep

Aims: To compare the culture and PCR methods for detection of Brucella melitensis in blood and lymphoid tissue samples obtained from slaughtered sheep (n = 162) testing positive/negative in serological tests (Rose Bengal test and serum agglutination test). Methods and Results: Of 162 sheep examined, 45 were positive and 117 negative in serological tests. A PCR assay based on a pair of Br. melitensis‐specific primers was used to detect DNA in blood and lymphoid tissue. Brucella melitensis was isolated from 1·2% (2/162) and 17·2% (28/162) of the blood and lymphoid tissue samples respectively. Positive PCR products with a molecular size of 731 bp were obtained from 27·7% (45/162) of blood and 29·0% (47/162) of lymphoid tissue samples. Conclusions: The species‐specific PCR assay detected a higher number of Br. melitensis DNA both from serologically positive (P < 0·01 in blood PCR, P < 0·001 in tissue PCR) and serologically negative (P < 0·001 in both blood PCR and tissue PCR) sheep compared with classical bacteriological culture methods. Significance and Impact of the Study: The results emphasize the importance of using more than one type of diagnostic technique for the detection of animals positive for brucellosis, especially with epidemiological purposes.     

Abscisic acid introduced into the transpiration stream accumulates in the guard-cell apoplast and causes stomatal closure

Petioles of water‐sufficient intact Vicia faba L. plants were infused with 1 µm abscisic acid (ABA) to simulate the import of root‐source ABA. This protocol permitted quantitative ABA delivery, up to 300 pmol ABA over 60 min, to the leaf without ambiguities associated with perturbations in plant–water status. The ABA concentrations in whole‐leaf samples and in apoplastic sap increased with the amount infused; ABA degradation was not detected. The ABA concentration in apoplastic sap was consistent with uptake of imported ABA into the leaf symplast, but this interpretation is qualified. Our focus was quantitative cellular compartmentation of imported ABA in guard cells. Unlike when leaves are stressed, the guard‐cell symplast ABA content did not increase because of ABA infusion (P = 0·48; 3·0 ± 0·5 versus 4·0 ± 1·2 fg guard‐cell‐pair^?1). However, the guard‐cell apoplast ABA content increased linearly (R² = 0·98) from ?0·2 ± 0·5 to 3·1 ± 1·3 fg guard‐cell‐pair^?1 (≈ 3·1 µm ) and was inversely related to leaf conductance (R² = 0·82). Apparently, xylem ABA accumulates in the guard‐cell wall as a result of evaporation of the apoplast solution. This mechanism provides for integrating transpiration rate and ABA concentration in the xylem solution.     

Occurrence of adenovirus and other enteric viruses in limited-contact freshwater recreational areas and bathing waters

Aims: The goal of this study was to characterize enteric virus concentrations and their infectivity in a variety of limited‐contact recreation and bathing waters, including Great Lakes beaches, inland lakes, rivers, and an effluent‐dominated urban waterway. Additionally, we evaluated associations between point sources of human faecal pollution and enterovirus and adenovirus presence and concentrations. Methods and Results: Quantitative polymerase chain reaction (qPCR) and two cell culture lines were used to identify and quantify viruses in water samples. The presence of human adenoviruses F was strongly associated with effluent‐dominated waters (odds ratio 6·1, confidence interval 2·3, 15·7), as was adenovirus concentration; though, neither enterovirus presence nor concentration was associated with an effluent source. Samples with high concentrations of qPCR targets all tested positive by cell culture on both cell lines, although qPCR target concentrations were not correlated with culture values. Conclusions: Adenovirus was strongly associated with point sources of human faecal pollution while enterovirus was not, indicating that adenovirus measured by qPCR is a better target than enterovirus for identifying wastewater discharges in recreational freshwaters. Significance and Impact of the Study: The development of monitoring for enteric human viral pathogens at recreational waters should include adenovirus testing. Further research is needed to interpret the results of qPCR testing in relationship to the presence of infectious viruses using cell culture.     

Sensory adaptation and the regulation of meal size in the Australian plague locust, Chortoicetes terminifera

Adults of Chortoicetes terminifera consumed larger meals of sucrose solution, applied as drops directly to their mouthparts, than of water. Meal size increased with increasing sucrose concentration up to 0·5 M but meals of 1·0 M sucrose were of lower volume. Locusts fed so that there was a short interval between each successive drop of sugar solution consumed greater volumes than those fed continuously, which indicates that sensory adaptation plays a part in bringing about the termination of meals of sugar solutions. Meals of water were not increased in size by discontinuous application.     

Most probable number methodology for quantifying dilute concentrations and fluxes of Salmonella in surface waters

Aims: To better understand and manage the fate and transport of Salmonella in agricultural watersheds, we developed a culture‐based, five tube–four dilution most probable number (MPN) method for enumerating dilute densities of Salmonella in environmental waters. Methods and Results: The MPN method was a combination of a filtration technique for large sample volumes of environmental water, standard selective media for Salmonella and a TaqMan confirmation step. This method has determined the density of Salmonella in 20‐l samples of pond inflow and outflow streams as low as 0·1 MPN l^?1 and a low 95% confidence level 0·015 MPN l^?1. Salmonella densities ranged from not detectable to 0·55 MPN l^?1 for pond inflow samples and from not detectable to 3·4 MPN l^?1 for pond outflow samples. Salmonella densities of pond inflow samples were associated with densities of Escherichia coli and faecal enterococci that indicated stream contamination with faeces and with nondetectable pond outflow densities of the faecal indicator bacteria. The MPN methodology was extended to flux determinations by integrating with volumetric measurements of pond inflow (mean flux of 2·5 l s^?1) and outflow (mean flux of 5·6 l s^?1). Fluxes of Salmonella ranged from 100 to greater than 10⁴ MPN h^?1. Conclusions: This is a culture‐based method that can detect small numbers of Salmonella in environmental waters of watersheds containing animal husbandry and wildlife. Significance and Impact of the Study: Applying this method to environmental waters will improve our understanding of the transport and fate of Salmonella in agricultural watersheds, and can be the basis of valuable collections of environmental Salmonella.     

Hollow-fiber ultrafiltration of Cryptosporidium parvum oocysts from a wide variety of 10-L surface water samples

An optimized hollow-fiber ultrafiltration system (50 000 MWCO) was developed to concentrate Cryptosporidium oocysts from 10-L samples of environmental water. Seeded experiments were conducted using a number of surface-water samples from the southwestern U.S.A. and source water from four water districts with histories of poor oocyst recovery. Ultrafiltration produced a mean recovery of 47.9% from 19 water samples (55.3% from 39 individual tests). We also compared oocyst recoveries using the hollow-fiber ultrafiltration system with those using the Envirochek filter. In limited comparison tests, the hollow-fiber ultrafiltration system produced recoveries similar to those of the Envirochek filter (hollow fiber, 74.1% (SD = 2.8); Envirochek, 71.9% (SD = 5.2)) in low-turbidity (3.9 NTU) samples and performed better than the Envirochek filter in high-turbidity (159.0 NTU) samples (hollow fiber, 27.5%; Envirochek, 0.4%). These results indicate that hollow-fiber ultrafiltration can efficiently recover oocysts from a wide variety of surface waters and may be a cost-effective alternative for concentrating Cryptosporidium from water, given the reusable nature of the filter.     

Concentration of viruses from environmental waters using nanoalumina fiber filters

Human viral contamination in drinking and recreational water may persist for extensive periods of time and cause a significant health risk concern. The aim of this study is to evaluate a viral recovery method using a new electropositive charged nanoalumina filter and to compare results with the widely used negatively charged HAWP filter by Millipore Inc. The recovery of infectious recombinant adenovirus type 5 (rAd5) was tested using the Fluorescence-Activated Cell Sorting (FACS) assay, in parallel with viral genomes recovery assay by quantitative PCR (qPCR). The mean infectivity recoveries were 82-91% by nanoalumina filters eluted with 3% beef extract (BE, pH6.0), and 78-90% by HAWP filters eluted with 3% BE (pH 9.0), respectively, from 1 L of environmental samples seeded with 1pfu/mL rAd5. The mean genome recoveries were 16-35% by nanoalumina filters eluted with BE (pH 6.0), and 29-66% by HAWP filters eluted with NaOH (pH 10.8) from different types of water, respectively. Water quality, concentration of viruses, filters, and elution buffers are factors that determine the viral recovery efficiencies. The nanoalumina filters also had higher filtration rates than HAWP filters for large volumes of environmental water samples (up to10 L), thus, have an advantage in concentrating infectious viruses from environments without pre-filtration, adjusting pH or adding multivalent cations.