Pepper mild mottle virus: A plant pathogen with a greater purpose in (waste)water treatment development and public health management

Respiratory Virus Season Surveillance in the United States Using Wastewater Metrics, 2023-2024

Wastewater measurements represent an entire contributing population and can be available within 24 h. Enhanced information about disease occurrence can improve population health through better timing of policies and interventions. We aimed to infer seasonal occurrence patterns for common respiratory viruses alongside transmission dynamics for SARS-CoV-2 across the USA using wastewater samples. We used wastewater RNA concentrations of influenza A and B (IAV/IBV), respiratory syncytial virus (RSV), human metapneumovirus (HMPV), and SARS-CoV-2 from 175 treatment plants (July 2023-June 2024). For IAV, IBV, RSV, and HMPV, we determined epidemic onset, offset, peak, and duration at national and subnational scales. For SARS-CoV-2, we categorized wastewater measurements based on recent wastewater levels and trends. Epidemic onset occurred in November for IAV and RSV which aligned with prepandemic norms. Onset occurred in January for IBV and April for HMPV which were later than expected according to historical data. Duration was longer for IAV and shorter for IBV, RSV, and HMPV than expected based on historical data. Epidemic peak dates were consistent with prepandemic norms for all viruses. Peak dates for influenza and RSV coincided with high, upward trending SARS-CoV-2 RNA concentrations, suggesting potential co-occurrence of SARS-CoV-2 with these viruses.

Advantages and disadvantages of current human enteric virus surrogates in soils and aquifers

Groundwater is one of the main sources of drinking water, thus, human enteric viruses in groundwater could pose safety risks. Many enteric viruses enter drinking water sources through irrigation or recharge of contaminated water. It is therefore advised to test the potential transport risk with harmless surrogates before wastewater or recycled water is used for irrigation or groundwater recharge. An ideal virus surrogate should be able to mimic the particle size, the surface properties and the inactivation rate of its target virus and should be easy to detect. Particle size should be the first consideration when selecting a suitable virus surrogate in soil and aquifer. The natural bacteriophages could only mimic the viruses that are inherently similar to themselves, and there is only a limited number of readily available bacteriophages. Therefore, once a certain bacteriophage is chosen for study, its particle size, surface properties and inactivation rate are set and unmodifiable for the experiment. Fluorescent microspheres <200 nm could surrogate target viruses in fast-flow subsurface systems, where inactivation can be neglected. However, the current detection limit of fluorescent nanospheres cannot support the detection of small-sized fluorescent microspheres (∼20 nm) through porous media without macropores. Newly emerging DNA tracers not only allow controlling the size and surface properties, but also offer a low detection limit (ideally 1 copy of DNA). Investigating new types of DNA tracers that could either simulate or mimic the inactivation rate of target viruses could widen the use of virus surrogates to study groundwater contamination and drinking water supply safety.

Detection of human enteric viral genes in a non-native winter crane fly, Trichocera maculipennis (Diptera) in the sewage treatment facilities at Antarctic stations

BACKGROUND

The Antarctic environment is susceptible to the introduction of non-native species due to its unique ecosystem, which has evolved under geographical isolation and extreme climatic conditions over an extended period. The recent introduction of the non-native winter crane fly, Trichocera maculipennis, to maritime Antarctica may pose a potential threat to the Antarctic ecosystem. In this study, we evaluated the possibility of the mechanical transmission of viruses by T. maculipennis.

METHODS

We assessed the potential for the mechanical transmission of viruses using next-generation sequencing (NGS), quantitative PCR (qPCR), and virus isolation methods from T. maculipennis (Tm)-related samples (Tm body-wash fluid and Tm body-ground samples) collected from habitats and sewage treatment facilities located at three research stations in Antarctica.

RESULTS

Virome analysis detected the genomic fragments of human adenovirus (AdV) and human endogenous retrovirus (HERV) in Tm-related samples. These viruses are commonly found in human feces. In addition, plant viruses, such as pepper mild mottle virus (PMMoV) and cucumber green mottle mosaic virus (CGMMV), both known indicators of enteric viruses, were identified in all Tm-related samples, likely originating from wastewater. However, the low quantities of AdV and HERV genomes detected in Tm-related samples through qPCR, coupled with the non-viability of AdV in virus isolation tests, indicate that T. maculipennis has limited potential for mechanical transmission under the conditions in the studies.

CONCLUSIONS

Our study represents the first evaluation of the potential risk of non-native species serving as vectors for viral pathogens in Antarctica. Although the viruses detected were in relatively low quantities and non-viable, this study highlights the importance of further evaluating the risks associated with non-native species, particularly as the likelihood of their introduction increases to Antarctica due to climate change and increased human activity.

Alterations of the gut microbiome in HIV infection highlight human anelloviruses as potential predictors of immune recovery

BACKGROUND

HIV-1 infection is characterized by a massive depletion of mucosal CD4 T cells that triggers a cascade of events ultimately linking gut microbial dysbiosis to HIV-1 disease progression and pathogenesis. The association between HIV infection and the enteric virome composition is less characterized, although viruses are an essential component of the gut ecosystem. Here, we performed a cross-sectional analysis of the fecal viral (eukaryotic viruses and bacteriophages) and bacterial microbiome in people with HIV (PWH) and in HIV-negative individuals. To gain further insight into the association between the gut microbiome composition, HIV-associated immunodeficiency, and immune recovery, we carried out a longitudinal study including 14 PWH who initiated antiretroviral therapy (ART) and were followed for 24 months with samplings performed at baseline (before ART) and at 2, 6, 12, and 24 months post-ART initiation.

RESULTS

Our data revealed a striking expansion in the abundance and prevalence of several human virus genomic sequences (Anelloviridae, Adenoviridae, and Papillomaviridae) in stool samples of PWH with severe immunodeficiency (CD4 < 200). We also noted a decreased abundance of sequences belonging to two plant viruses from the Tobamovirus genus, a reduction in bacterial alpha diversity, and a decrease in Inoviridae bacteriophage sequences. Short-term ART (24 months) was linked to a significant decrease in human Anelloviridae sequences. Remarkably, the detection of Anellovirus sequences at baseline independently predicted poor immune recovery, as did low CD4 T cell counts. The bacterial and bacteriophage populations were unique to each PWH with individualized trajectories; we found no discernable pattern of clustering after 24 months on ART.

CONCLUSION

Advanced HIV-1 infection was associated with marked alterations in the virome composition, in particular a remarkable expansion of human anelloviruses, with a gradual restoration after ART initiation. In addition to CD4 T cell counts, anellovirus sequence detection might be useful to predict and monitor immune recovery. This study confirms data on the bacteriome and expands our knowledge on the viral component of the gut microbiome in HIV-1 infection. Video Abstract.

Human pathogen nucleic acids in wastewater solids from 191 wastewater treatment plants in the United States

We measured concentrations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants, influenza A and B viruses, respiratory syncytial virus, human metapneumovirus, enterovirus D68, human parainfluenza types 1, 2, 3, 4a, and 4b in aggregate, norovirus genotype II, rotavirus, Candida auris, hepatitis A virus, human adenovirus, mpox virus, H5 influenza A virus, and pepper mild mottle virus nucleic acids in wastewater solids prospectively at 191 wastewater treatment plants in 40 states across the United States plus Washington DC. Measurements were made two to seven times per week from 1 January 2022 to 30 June 2024, depending on wastewater treatment plant staff availability. Measurements were made using droplet digital (reverse-transcription-) polymerase chain reaction (ddRT-PCR) following best practices for making environmental molecular biology measurements. These data can be used to better understand disease occurrence in communities contributing to the wastewater.

Indicator and pathogenic virus removal in bench scale soil aquifer treatment

The demonstration of enteric virus removal for indirect potable reuse of advanced purified water is necessary to ensure safe water reclamation practices. This study evaluated the efficacy of soil treatment in reducing concentrations of Pepper Mild Mottle Virus (PMMoV), Hepatitis A (HAV), and Norovirus (NoV) gene markers through bench scale unsaturated soil columns. Three different infiltration rates were evaluated to determine their impact on viral gene marker removal. The concentrations of viral markers in the column influent and effluent samples were measured through RNA extraction and then RT-qPCR, and the log reduction values (LRVs) were calculated to quantify the effectiveness of removal across the columns. The LRVs achieved for PMMoV were 2.80 ± 0.36, 2.91 ± 0.48, and 2.72 ± 0.32 for infiltration rates of 4.9 mm/h, 9.4 mm/h, and 14.0 mm/h, respectively. A one-way ANOVA indicated no statistically significant differences in LRVs among the various infiltration rates (p-value = 0.329). All samples measured for HAV were below the detection limit both in the influent and effluent of the soil columns. While NoV GI and GII markers were measurable in the soil column influent, they were removed to below the detection limit in the effluent. The use of half the Limit-of-Detection (LoD) for effluent values enabled the estimation of log removals, which were calculated as 1.42 ± 0.07, 1.64 ± 0.29, and 1.74 ± 0.18 for NoV GI and 1.14 ± 0.19, 1.58 ± 0.21, and 1.87 ± 0.41 for NoV GII at infiltration rates of 4.9 mm/h, 9.4 mm/h, and 14.0 mm/h. This highlights the efficacy of soil treatment in reducing virus gene marker concentrations at various infiltration rates, and that spreading basins employed for reclaimed water recharge to ground water aquifers are an effective method for reducing the presence of viral contaminants in indirect potable reuse systems.

Engineered Resistance to Tobamoviruses

Tobacco mosaic virus (TMV) was the first virus to be studied in detail and, for many years, TMV and other tobamoviruses, particularly tomato mosaic virus (ToMV) and tobamoviruses infecting pepper (Capsicum spp.), were serious crop pathogens. By the end of the twentieth and for the first decade of the twenty-first century, tobamoviruses were under some degree of control due to introgression of resistance genes into commercial tomato and pepper lines. However, tobamoviruses remained important models for molecular biology, biotechnology and bio-nanotechnology. Recently, tobamoviruses have again become serious crop pathogens due to the advent of tomato brown rugose fruit virus, which overcomes tomato resistance against TMV and ToMV, and the slow but apparently inexorable worldwide spread of cucumber green mottle mosaic virus, which threatens all cucurbit crops. This review discusses a range of mainly molecular biology-based approaches for protecting crops against tobamoviruses. These include cross-protection (using mild tobamovirus strains to 'immunize' plants against severe strains), expressing viral gene products in transgenic plants to inhibit the viral infection cycle, inducing RNA silencing against tobamoviruses by expressing virus-derived RNA sequences in planta or by direct application of double-stranded RNA molecules to non-engineered plants, gene editing of host susceptibility factors, and the transfer and optimization of natural resistance genes.

A multi-marker assessment of sewage contamination in streams using human-associated indicator bacteria, human-specific viruses, and pharmaceuticals

Human sewage contaminates waterways, delivering excess nutrients, pathogens, chemicals, and other toxic contaminants. Contaminants and various sewage indicators are measured to monitor and assess water quality, but these analytes vary in their representation of sewage contamination and the inferences about water quality they support. We measured the occurrence and concentration of multiple microbiological (n = 21) and chemical (n = 106) markers at two urban stream locations in Milwaukee, Wisconsin, USA over two years. Five-day composite water samples (n = 98) were collected biweekly, and sewage influent samples (n = 25) were collected monthly at a Milwaukee, WI water reclamation facility. We found the vast majority of markers were not sensitive enough to detect sewage contamination. To compare analytes for monitoring applications, five consistently detected human sewage indicators were used to evaluate temporal patterns of sewage contamination, including microbiological (pepper mild mottle virus, human Bacteroides, human Lachnospiraceae) and chemical (acetaminophen, metformin) markers. The proportion of human sewage in each stream was estimated using the mean influent concentration from the water reclamation facility and the mean concentration of all stream samples for each sewage indicator marker. Estimates of instream sewage pollution varied by marker, differing by up to two orders of magnitude, but four of the five sewage markers characterized Underwood Creek (mean proportions of human sewage ranged 0.0025 % - 0.075 %) as less polluted than Menomonee River (proportions ranged 0.013 % - 0.14 %) by an order of magnitude more. Chemical markers correlated with each other and yielded higher estimates of sewage pollution than microbial markers, which exhibited greater temporal variability. Transport, attenuation, and degradation processes can influence chemical and microbial markers differently and cause variation in human sewage estimates. Given the range of potential human and ecological health effects of human sewage contamination, robust characterization of sewage contamination that uses multiple lines of evidence supports monitoring and research applications.

Pepper mild mottle virus intended for use as a process indicator for drinking water treatment: Present forms and quantitative relations to norovirus and rotavirus in surface water

Pepper mild mottle virus (PMMoV) has been proposed as a potential indicator of human enteric viruses in environmental water and for viral removal during drinking water treatment. To investigate the occurrence and present forms of PMMoV and quantitative relations to norovirus GII and rotavirus A (RVA) in surface waters, 147 source water samples were collected from 21 drinking water treatment plants (DWTPs) in Japan between January 2018 and January 2021, and the concentrations of viruses in suspended and dissolved fractions were measured using real-time RT-PCR. PMMoV was detected in 81-100 % of samples in each sample month and observed concentrations ranged from 3.0 to 7.0 log10 copies/L. The concentrations of PMMoV were higher in dissolved fraction compared to suspended fractions, while different partitioning was observed for NoV GII depending on seasons. The concentrations of PMMoV were basically higher than those of norovirus GII (1.9-5.3 log10 copies/L) and RVA (1.9-6.6 log10 copies/L), while in 18 samples, RVA presented higher concentrations than PMMoV. Partial regions of VP7, VP4, and VP6 of the RVA in the 18 samples were amplified using nested PCR, and the genotypes were determined using an amplicon-based next-generation sequencing approach. We found that these source water samples included not only human RVA but also various animal RVA and high genetic diversity due to the existence of animal RVA was associated with a higher RVA concentration than PMMoV. Our findings suggest that PMMoV can be used as an indicator of norovirus GII and human RVA in drinking water sources and that the indicator performance should be evaluated by comparing to zoonotic viruses as well as human viruses.

Virus surrogates throughout a full-scale advanced water reuse system

Water reuse as an alternative water supply is increasing throughout the world due to water stress and scarcity; however, there are no standard practices for monitoring virus pathogens in such systems. This study aimed to identify suitable surrogates for virus fate, transport, and removal throughout a water reuse scheme. Various microbial targets (11 viruses, two phage, and three bacteria) were monitored using molecular and culture methods across all treatment stages in a wastewater reclamation facility and advanced water treatment facility. Criteria were established for identifying suitable surrogates, which included reliable detection, observable fate and transport, calculable log-reduction values (LRVs), correlations with other targets, and various morphological types. In total, five viruses (PMMoV, AiV, GII NoV, AdV, FRNA GII) met these stringent criteria and were suggested as potential virus surrogates. These surrogates enabled successful comparison of assigned versus actual LRVs throughout a water reuse scheme. Results suggest that virus pathogens are effectively removed throughout water reuse treatment and the suggested surrogates can be utilized for monitoring treatment performance and ensuring public health safety. This study provides a framework that water utilities across the world can reference for establishing virus monitoring practices.

Bioinformatics-based screening tool identifies a wide variety of human and zoonotic viruses in Trujillo-Peru wastewater

Peru was one of the most affected countries during the COVID-19 pandemic. Moreover, multiple other viral diseases (enteric, respiratory, bloodborne, and vector-borne) are endemic and rising. According to Peru's Ministry of Health, various health facilities in the country were reallocated for the COVID-19 pandemic, thereby leading to reduced action to curb other diseases. Many viral diseases in the area are under-reported and not recognized. The One Health approach, in addition to clinical testing, incorporates environmental surveillance for detection of infectious disease outbreaks. The purpose of this work is to use a screening tool that is based on molecular methods, high throughput sequencing and bioinformatics analysis of wastewater samples to identify virus-related diseases circulating in Trujillo-Peru. To demonstrate the effectiveness of the tool, we collected nine untreated wastewater samples from the Covicorti wastewater utility in Trujillo-Peru on October 22, 2022. High throughput metagenomic sequencing followed by bioinformatic analysis was used to assess the viral diversity of the samples. Our results revealed the presence of sequences associated with multiple human and zoonotic viruses including Orthopoxvirus, Hepatovirus, Rhadinovirus, Parechovirus, Mamastrovirus, Enterovirus, Varicellovirus, Norovirus, Kobuvirus, Bocaparvovirus, Simplexvirus, Spumavirus, Orthohepevirus, Cardiovirus, Molliscipoxvirus, Salivirus, Parapoxvirus, Gammaretrovirus, Alphavirus, Lymphocryptovirus, Erythroparvovirus, Sapovirus, Cosavirus, Deltaretrovirus, Roseolovirus, Flavivirus, Betacoronavirus, Rubivirus, Lentivirus, Betapolyomavirus, Rotavirus, Hepacivirus, Alphacoronavirus, Mastadenovirus, Cytomegalovirus and Alphapapillomavirus. For confirmation purposes, we tested the samples for the presence of selective viruses belonging to the genera detected above. PCR based molecular methods confirmed the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), monkeypox virus (MPXV), noroviruses GI and GII (NoVGI and NoVGII), and rotavirus A (RoA) in our samples. Furthermore, publicly available clinical data for selected viruses confirm our findings. Wastewater or other environmental media surveillance, combined with bioinformatics methods, has the potential to serve as a systematic screening tool for the identification of human or zoonotic viruses that may cause disease. The results of this method can guide further clinical surveillance efforts and allocation of resources. Incorporation of this bioinformatic-based screening tool by public health officials in Peru and other Latin American countries will help manage endemic and emerging diseases that could save human lives and resources.

Campus source to sink wastewater surveillance of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)

Wastewater-based surveillance (WBS) offers an aggregate, and cost-effective approach for tracking infectious disease outbreak prevalence within communities, that provides data on community health complementary to individual clinical testing. This study reports on a 16-month WBS initiative on a university campus in England, UK, assessing the presence of SARS-CoV-2 in sewers from large buildings, downstream sewer locations, raw wastewater, partially treated and treated effluents. Key findings include the detection of the Alpha (B.1.1.7) variant in wastewater, with 70 % of confirmed campus cases correlating with positive wastewater samples. Notably, ammonium nitrogen (NH4-N) levels showed a positive correlation (ρ = 0.543, p < 0.01) with virus levels at the large building scale, a relationship not observed at the sewer or wastewater treatment works (WWTW) levels due to dilution. The WWTW was compliant to wastewater standards, but the secondary treatment processes were not efficient for virus removal as SARS-CoV-2 was consistently detected in treated discharges. Tools developed through WBS can also be used to enhance traditional environmental monitoring of aquatic systems. This study provides a detailed source-to-sink evaluation, emphasizing the critical need for the widespread application and improvement of WBS. It showcases WBS utility and reinforces the ongoing challenges posed by viruses to receiving water quality.

Human norovirus (HuNoV) GII RNA in wastewater solids at 145 United States wastewater treatment plants: comparison to positivity rates of clinical specimens and modeled estimates of HuNoV GII shedders

BACKGROUND

Human norovirus (HuNoV) is a leading cause of disease globally, yet actual incidence is unknown. HuNoV infections are not reportable in the United States, and surveillance is limited to tracking severe illnesses or outbreaks. Wastewater monitoring for HuNoV has been done previously and results indicate it is present in wastewater influent and concentrations are associated with HuNoV infections in the communities contributing to wastewater. However, work has mostly been limited to monthly samples of liquid wastewater at one or a few wastewater treatment plants (WWTPs).

OBJECTIVE

The objectives of this study are to investigate whether HuNoV GII preferentially adsorbs to wastewater solids, investigate concentrations of HuNoV GII in wastewater solids in wastewater treatment plants across the county, and explore how those relate to clinical measures of disease occurrence. In addition, we aim to develop and apply a mass-balance model that predicts the fraction of individuals shedding HuNoV in their stool based on measured concentrations in wastewater solids.

METHODS

We measured HuNoV GII RNA in matched wastewater solids and liquid influent in 7 samples from a WWTP. We also applied the HuNoV GII assay to measure viral RNA in over 6000 wastewater solids samples from 145 WWTPs from across the United States daily to three times per week for up to five months. Measurements were made using digital droplet RT-PCR.

RESULTS

HuNoV GII RNA preferentially adsorbs to wastewater solids where it is present at 1000 times the concentration in influent. Concentrations of HuNoV GII RNA correlate positively with clinical HuNoV positivity rates. Model output of the fraction of individuals shedding HuNoV is variable and uncertain, but consistent with indirect estimates of symptomatic HuNoV infections in the United States.

IMPACT STATEMENT

Illness caused by HuNoV is not reportable in the United States so there is limited data on disease occurrence. Wastewater monitoring can provide information about the community spread of HuNoV. Data from wastewater can be available within 24 h of sample receipt at a laboratory. Wastewater is agnostic to whether individuals seek medical care, are symptomatic, and the severity of illness. Knowledge gleaned from wastewater may be used by public health professionals to make recommendations on hand washing, surface disinfection, or other behaviors to reduce transmission of HuNoV, or medical doctors to inform clinical decision making.

Observations of Respiratory Syncytial Virus (RSV) Nucleic Acids in Wastewater Solids Across the United States in the 2022-2023 Season: Relationships with RSV Infection Positivity and Hospitalization Rates

Respiratory syncytial virus (RSV) is a leading cause of respiratory illness and hospitalization, but clinical surveillance detects only a minority of cases. Wastewater surveillance could determine the onset and extent of RSV circulation in the absence of sensitive case detection, but to date, studies of RSV in wastewater are few. We measured RSV RNA concentrations in wastewater solids from 176 sites during the 2022-2023 RSV season and compared those to publicly available RSV infection positivity and hospitalization rates. Concentrations ranged from undetectable to 107 copies per gram. RSV RNA concentration aggregated at state and national levels correlated with infection positivity and hospitalization rates. RSV season onset was determined using both wastewater and clinical positivity rates using independent algorithms for 14 states where both data were available at the start of the RSV season. In 4 of 14 states, wastewater and clinical surveillance identified RSV season onset during the same week; in 3 states, wastewater onset preceded clinical onset, and in 7 states, wastewater onset occurred after clinical onset. Wastewater concentrations generally peaked in the same week as hospitalization rates but after case positivity rates peaked. Differences in onset and peaks in wastewater versus clinical data may reflect inherent differences in the surveillance approaches.

Evaluation of virus removal in membrane bioreactor (MBR) and conventional activated sludge (CAS) processes based on long-term monitoring at two wastewater treatment plants

The membrane bioreactor (MBR) process always offers better wastewater treatment than conventional activated sludge (CAS) treatment. However, the difference in their efficacy of virus reduction remains unknown. To investigate this, we monitored virus concentrations before and after MBR and CAS processes over 2 years. Concentrations of norovirus genotypes I and II (NoV GI and GII), aichivirus (AiV), F-specific RNA phage genotypes I, II, and III (GI-, GII-, and GIII-FRNAPHs), and pepper mild mottle virus (PMMoV) were measured by a quantitative polymerase chain reaction (qPCR) method at two municipal wastewater treatment plants (WWTPs A and B) in Japan. Virus concentration datasets containing left-censored data were estimated by using both maximum likelihood estimation (MLE) and robust regression on order statistics (rROS) approaches. PMMoV was the most prevalent at both WWTPs, with median concentrations of 7.5 to 8.8 log10 copies/L before treatment. Log10 removal values (LRVs) of all viruses based on means and standard deviations of concentrations before and after treatment were consistently higher following MBR than following CAS. We used NoV GII as a model pathogen in a quantitative microbial risk assessment of the treated water, and we estimated the additional reductions required following MBR and CAS processes to meet the guideline of 10-6 DALYs pppy for safe wastewater reuse.

Polyethylenimine mediated recovery of SARS-CoV-2 and total viral RNA: Impact of aqueous conditions on behaviour and recovery

Wastewater-based epidemiology (WBE) is an emerging, practical surveillance tool for monitoring community levels of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, SC2). However, a paucity of data exists regarding SARS-CoV-2 and viral biomarker behaviour in aqueous and wastewater environments. Therefore, there is a pressing need to develop efficient and robust methods that both improve method sensitivity and reduce time and cost. We present a novel method for SARS-CoV-2, Human Coronavirus 229E (229E), and Pepper Mild Mottle Virus (PMMoV) recovery utilizing surface charge-based attraction via the branched cationic polymer, polyethylenimine (PEI). Initially, dose-optimization experiments demonstrated that low concentrations of PEI (0.001% w/v) proved most effective at flocculating suspended viruses and viral material, including additional unbound SC2 viral fragments and/or RNA from raw wastewater. A design-of-experiments (DOE) approach was used to optimize virus and/or viral material aggregation behaviour and recovery across varying aqueous conditions, revealing pH as a major influence on recoverability in this system, combinatorially due to both a reduction in viral material surface charge and increased protonation of PEI-bound amine groups. Overall, this method has shown great promise in significantly improving quantitative viral recovery, providing a straightforward and effective augmentation to standard centrifugation techniques.

A retrospective longitudinal study of adenovirus group F, norovirus GI and GII, rotavirus, and enterovirus nucleic acids in wastewater solids at two wastewater treatment plants: solid-liquid partitioning and relation to clinical testing data

Enteric infections are important causes of morbidity and mortality, yet clinical surveillance is limited. Wastewater-based epidemiology (WBE) has been used to study community circulation of individual enteric viruses and panels of respiratory diseases, but there is limited work studying the concurrent circulation of a suite of important enteric viruses. A retrospective WBE study was carried out at two wastewater treatment plants located in California, United States. Using digital droplet polymerase chain reaction (PCR), we measured concentrations of human adenovirus group F, enteroviruses, norovirus genogroups I and II, and rotavirus nucleic acids in wastewater solids two times per week for 26 months (n = 459 samples) between February 2021 and mid-April 2023. A novel probe-based PCR assay was developed and validated for adenovirus. We compared viral nucleic acid concentrations to positivity rates for viral infections from clinical specimens submitted to a local clinical laboratory to assess concordance between the data sets. We detected all viral targets in wastewater solids. At both wastewater treatment plants, human adenovirus group F and norovirus GII nucleic acids were detected at the highest concentrations (median concentrations greater than 105 copies/g), while rotavirus RNA was detected at the lowest concentrations (median on the order of 103 copies/g). Rotavirus, adenovirus group F, and norovirus nucleic acid concentrations were positively associated with clinical specimen positivity rates. Concentrations of tested viral nucleic acids exhibited complex associations with SARS-CoV-2 and other respiratory viral nucleic acids in wastewater, suggesting divergent transmission patterns.IMPORTANCEThis study provides evidence for the use of wastewater solids for the sensitive detection of enteric virus targets in wastewater-based epidemiology programs aimed to better understand the spread of enteric disease at a localized, community level without limitations associated with testing many individuals. Wastewater data can inform clinical, public health, and individual decision-making aimed to reduce the transmission of enteric disease.

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.

Evaluating endogenous viral targets as potential treatment monitoring surrogates for onsite non-potable water reuse

Onsite non-potable water reuse systems (ONWS) are decentralized systems that treat and repurpose locally collected waters (e.g. greywater or combined wastewater) for uses such as irrigation and flushing toilets. To ensure that treatment is meeting risk benchmarks, it is necessary to monitor the efficacy of pathogen removal. However, accurate assessment of pathogen reduction is hampered by their sporadic and low occurrence rates in source waters and concentrations in treated water that are generally below measurement detection limits. An alternative metric for evaluation of onsite water treatment is log reduction of a more abundant organism that can serve as a surrogate for the pathogen removal. Viruses endogenous to the decentralized system could serve as monitoring surrogates to verify that treatment meets the relevant viral log reduction targets. This study assesses eight candidate PCR targets representing potential monitoring surrogates from different viral classes to determine whether they could be used to verify the efficacy of treatment in onsite non-potable water reuse systems. Candidates tested include markers for Carjivirus (formerly CrAssphage), Pepper Mild Mottle Virus (PMMoV), Microviridae, and T4 Coliphage. We quantified these targets in untreated influent wastewater at three onsite non-potable water reuse systems, two that use greywater and one that uses combined wastewater. We also confirmed, using amplicon sequencing, that the widely used Carjivirus and PMMoV primers correctly target their respective regions of interest, and found sequence diversity within the amplicons including in the probe binding region. Ultimately, we found that the surrogates assessed are not abundant enough for end uses with higher exposure use and concomitant greater removal requirements (e.g., indoor non-potable uses), but may be effective for end uses where exposure risk is lower (e.g., irrigation).

Implementing an adaptive, two-tiered SARS-CoV-2 wastewater surveillance program on a university campus using passive sampling

Building-level wastewater-based surveillance (WBS) has been increasingly applied upstream from wastewater treatment plants to conduct targeted monitoring for SARS-CoV-2. In this study, a two-tiered, trigger-based wastewater surveillance program was developed on a university campus to monitor dormitory wastewater. The objective was to determine if passive sampling with cotton gauze as a sampling medium could be used to support institution-level public health action. Two nucleocapsid gene targets (N1 and N2) of SARS-CoV-2 as well as the endogenous fecal indicator pepper mild mottle virus (PMMoV) were quantified using RT-qPCR. >500 samples were analyzed during two contrasting surveillance periods. In the Fall of 2021 community viral burden was low and a tiered sampling network was able to isolate individual clinical cases at the building-scale. In the Winter of 2022 wastewater signals were quickly elevated by the emergence of the highly transmissible SARS-CoV-2 Omicron (B.1.1.529) variant. Prevalence of SARS-CoV-2 shifted surveillance objectives from isolating cases to monitoring trends, revealing both the benefits and limitations of a tiered surveillance design under different public health situations. Normalization of SARS-CoV-2 by PMMoV was not reflective of upstream population differences, suggesting saturation of the material occurred during the exposure period. The passive sampling method detected nearly all known clinical cases and in one instance was able to identify one pre-symptomatic individual days prior to confirmation by clinical test. Comparisons between campus samplers and municipal wastewater influent suggests that the spread of COVID-19 on the campus was similar to that of the broader community. The results demonstrate that passive sampling is an effective tool that can produce semi-quantitative data capable of tracking temporal trends to guide targeted public health decision-making at an institutional level. Practitioners of WBS can utilize these results to inform surveillance program designs that prioritize efficient resource use and rapid reporting.

QMRA of Ralstonia solanacearum in potato cultivation: Risks associated with irrigation water recycled through managed aquifer recharge

Agricultural aquifer storage recovery and transfer (ASTR) stores excess fresh water for later reuse in irrigation. Moreover, water quality improves because chemical pollutants and pathogens will be removed by degradation and attachment to the aquifer material. The source water may contain the bacterial plant pathogen Ralstonia solanacearum which causes plant infections and high yield losses. We used quantitative microbial risk assessment (QMRA) to investigate the removal of R. solanacearum during ASTR to predict infection risks of potato plants after irrigation with the recovered water. Laboratory experiments analyzed the ASTR treatment by investigating the bacterial die-off in the water phase and the removal by attachment to the aquifer sediment. Die-off in the water phase depends on the residence time and ranged between 1.3 and 2.7 log10 after 10 or 60 days water storage, respectively. A subpopulation of the bacteria persisted for a prolonged time at low concentrations which may pose a risk if the water is recovered too early. However, the natural aquifer sand filtration proofed to be highly effective in removing R. solanacearum by attachment which depends on the distance between injection and abstraction well. The high removal by attachment alone (18 log10 after 1 m) would reduce bacterial concentrations to negligible numbers. Upscaling to longer soil passages is discussed in the paper. Infection risks of potato plants were calculated using a dose-response model and ASTR treatment resulted in negligible infection risks of a single plant, but also when simulating the irrigation of a 5 ha potato field. This is the first QMRA that analyzed an agricultural ASTR and the fate of a plant pathogen focusing on plant health. QMRA is a useful (water) management tool to evaluate the treatment steps of water reclamation technologies with the aim to provide safe irrigation water and reduce risks disseminating plant diseases.

Challenges detecting SARS-CoV-2 in Costa Rican domestic wastewater and river water

This study presents the development of a SARS-CoV-2 detection method for domestic wastewater and river water in Costa Rica, a middle-income country in Central America. Over a three-year period (November to December 2020, July to November 2021, and June to October 2022), 80 composite wastewater samples (43 influent and 37 effluent) were collected from a Wastewater Treatment Plant (SJ-WWTP) located in San José, Costa Rica. Additionally, 36 river water samples were collected from the Torres River near the SJ-WWTP discharge site. A total of three protocols for SARS-CoV-2 viral concentration and RNA detection and quantification were analyzed. Two protocols using adsorption-elution with PEG precipitation (Protocol A and B, differing in the RNA extraction kit; n = 82) were used on wastewater samples frozen prior to concentration, while wastewater (n = 34) collected in 2022 were immediately concentrated using PEG precipitation. The percent recovery of Bovine coronavirus (BCoV) was highest using the Zymo Environ Water RNA (ZEW) kit with PEG precipitation executed on the same day as collection (mean 6.06 % ± 1.37 %). It was lowest when samples were frozen and thawed, and viruses were concentrated using adsorption-elution and PEG concentration methods using the PureLink™ Viral RNA/DNA Mini (PLV) kit (protocol A; mean 0.48 % ± 0.23 %). Pepper mild mottle virus and Bovine coronavirus were used as process controls to understand the suitability and potential impact of viral recovery on the detection/quantification of SARS-CoV-2 RNA. Overall, SARS-CoV-2 RNA was detected in influent and effluent wastewater samples collected in 2022 but not in earlier years when the method was not optimized. The burden of SARS-CoV-2 at the SJ-WWTP decreased from week 36 to week 43 of 2022, coinciding with a decline in the national COVID-19 prevalence rate. Developing comprehensive nationwide surveillance programs for wastewater-based epidemiology in low-middle-income countries involves significant technical and logistical challenges.

Reduction of SARS-CoV-2 by biological nutrient removal and disinfection processes in full-scale wastewater treatment plants

Detection of SARS-CoV-2 RNA in wastewater poses people's concerns regarding the potential risk in water bodies receiving wastewater treatment effluent, despite the infectious risk of SARS-CoV-2 in wastewater being speculated to be low. Unlike well-studied nonenveloped viruses, SARS-CoV-2 in wastewater is present abundantly in both solid and liquid fractions of wastewater. Reduction of SARS-CoV-2 in past studies were likely underestimated, as SARS-CoV-2 in influent wastewater were quantified in either solid or liquid fraction only. The objectives of this study were (i) to clarify the reduction in SARS-CoV-2 RNA during biological nutrient removal and disinfection processes in full-scale WWTPs, considering the SARS-CoV-2 present in both solid and liquid fractions of wastewater, and (ii) to evaluate applicability of pepper mild mottle virus (PMMoV) as a performance indicator for reduction of SARS-CoV-2 in WWTPs. Accordingly, large amount of SARS-CoV-2 RNA were partitioned in the solid fraction of influent wastewater for composite sampling than grab sampling. When SARS-CoV-2 RNA in the both solid and liquid fractions were considered, log reduction values (LRVs) of SARS-CoV-2 during step-feed multistage biological nitrogen removal (SM-BNR) and enhanced biological phosphorus removal (EBPR) processes ranged between>2.1-4.4 log and did not differ significantly from those in conventional activated sludge (CAS). The LRVs of SARS-CoV-2 RNA in disinfection processes by ozonation and chlorination did not differ significantly. PMMoV is a promising performance indicator to secure reduction of SARS-CoV-2 in WWTPs, because of its higher persistence in wastewater treatment processes and abundance at a detectable concentration even in the final effluent after disinfection.

Occurrence of human pathogenic viruses in drinking water and in its sources: A review

Since many waterborne diseases are caused by human pathogenic viruses, virus monitoring of drinking water (DW) and DW sources is crucial for public health. Therefore, the aim of this review was to describe the occurrence of human pathogenic viruses in DW and DW sources; the occurrence of two viruses proposed as novel indicators of human faecal contamination (Pepper mild mottle virus and Tobacco mosaic virus) was also reported. This research was focused on articles that assessed viral occurrence using molecular methods in the surface water used for DW production (SW-D), groundwater used for DW production (GW-D), DW and bottled-DW (BW). A total of 1544 studies published in the last 10 years were analysed, and 79 were ultimately included. In considering the detection methods, filtration is the most common concentration technique, while quantitative polymerase chain reaction is the most common quantification technique. Regarding virus occurrence in SW-D, GW-D, and DW, high percentages of positive samples were reported for adenovirus, polyomavirus and Pepper mild mottle virus. Viral genomes were frequently detected in SW-D and rarely in GW-D, suggesting that GW-D may be a safe DW source. Viral genomes were also detected in DW, posing a possible threat to human health. The lowest percentages of positive samples were found in Europe, while the highest were found in Asia and South America. Only three articles assessed viral occurrence in BW. This review highlights the lack of method standardization and the need for legislation updates.

Bayesian sequential approach to monitor COVID-19 variants through test positivity rate from wastewater

Deployment of clinical testing on a massive scale was an essential control measure for curtailing the burden of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and the magnitude of the COVID-19 (coronavirus disease 2019) pandemic during its waves. As the pandemic progressed, new preventive and surveillance mechanisms emerged. Implementation of vaccine programs, wastewater (WW) surveillance, and at-home COVID-19 antigen tests reduced the demand for mass SARS-CoV-2 testing. Unfortunately, reductions in testing and test reporting rates also reduced the availability of public health data to support decision-making. This paper proposes a sequential Bayesian approach to estimate the COVID-19 test positivity rate (TPR) using SARS-CoV-2 RNA concentrations measured in WW through an adaptive scheme incorporating changes in virus dynamics. The proposed modeling framework was applied to WW surveillance data from two WW treatment plants in California; the City of Davis and the University of California, Davis campus. TPR estimates are used to compute thresholds for WW data using the Centers for Disease Control and Prevention thresholds for low (<5% TPR), moderate (5%-8% TPR), substantial (8%-10% TPR), and high (>10% TPR) transmission. The effective reproductive number estimates are calculated using TPR estimates from the WW data. This approach provides insights into the dynamics of the virus evolution and an analytical framework that combines different data sources to continue monitoring COVID-19 trends. These results can provide public health guidance to reduce the burden of future outbreaks as new variants continue to emerge. IMPORTANCE We propose a statistical model to correlate WW with TPR to monitor COVID-19 trends and to help overcome the limitations of relying only on clinical case detection. We pose an adaptive scheme to model the nonautonomous nature of the prolonged COVID-19 pandemic. The TPR is modeled through a Bayesian sequential approach with a beta regression model using SARS-CoV-2 RNA concentrations measured in WW as a covariable. The resulting model allows us to compute TPR based on WW measurements and incorporates changes in viral transmission dynamics through an adaptive scheme.

Longitudinal and quantitative fecal shedding dynamics of SARS-CoV-2, pepper mild mottle virus, and crAssphage

Wastewater-based epidemiology (WBE) emerged during the coronavirus disease 2019 (COVID-19) pandemic as a scalable and broadly applicable method for community-level monitoring of infectious disease burden. The lack of high-resolution fecal shedding data for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) limits our ability to link WBE measurements to disease burden. In this study, we present longitudinal, quantitative fecal shedding data for SARS-CoV-2 RNA, as well as for the commonly used fecal indicators pepper mild mottle virus (PMMoV) RNA and crAss-like phage (crAssphage) DNA. The shedding trajectories from 48 SARS-CoV-2-infected individuals suggest a highly individualized, dynamic course of SARS-CoV-2 RNA fecal shedding. Of the individuals that provided at least three stool samples spanning more than 14 days, 77% had one or more samples that tested positive for SARS-CoV-2 RNA. We detected PMMoV RNA in at least one sample from all individuals and in 96% (352/367) of samples overall. CrAssphage DNA was detected in at least one sample from 80% (38/48) of individuals and was detected in 48% (179/371) of all samples. The geometric mean concentrations of PMMoV and crAssphage in stool across all individuals were 8.7 × 104 and 1.4 × 104 gene copies/milligram-dry weight, respectively, and crAssphage shedding was more consistent for individuals than PMMoV shedding. These results provide us with a missing link needed to connect laboratory WBE results with mechanistic models, and this will aid in more accurate estimates of COVID-19 burden in sewersheds. Additionally, the PMMoV and crAssphage data are critical for evaluating their utility as fecal strength normalizing measures and for source-tracking applications. IMPORTANCE This research represents a critical step in the advancement of wastewater monitoring for public health. To date, mechanistic materials balance modeling of wastewater-based epidemiology has relied on SARS-CoV-2 fecal shedding estimates from small-scale clinical reports or meta-analyses of research using a wide range of analytical methodologies. Additionally, previous SARS-CoV-2 fecal shedding data have not contained sufficient methodological information for building accurate materials balance models. Like SARS-CoV-2, fecal shedding of PMMoV and crAssphage has been understudied to date. The data presented here provide externally valid and longitudinal fecal shedding data for SARS-CoV-2, PMMoV, and crAssphage which can be directly applied to WBE models and ultimately increase the utility of WBE.

More than a Tripledemic: Influenza A Virus, Respiratory Syncytial Virus, SARS-CoV-2, and Human Metapneumovirus in Wastewater during Winter 2022-2023

Wastewater monitoring can provide insights into respiratory disease occurrence in communities that contribute to the wastewater system. Using daily measurements of RNA of influenza A (IAV), respiratory syncytial virus (RSV), and human metapneumovirus (HMPV), as well as SARS-CoV-2 in wastewater solids from eight publicly owned treatment works in the Greater San Francisco Bay Area of California between July 2022 and early July 2023, we identify a "tripledemic" when concentrations of IAV, RSV, and SARS-CoV-2 peaked at approximately the same time. HMPV was also widely circulating. We designed novel hydrolysis probe RT-PCR assays for different IAV subtype markers to discern that the dominant circulating IAV subtype was H3N2. We show that wastewater data can be used to identify the onset and offset of wastewater disease occurrence events. This information can provide insight into disease epidemiology and timely, localized information to inform hospital staffing and clinical decision making to respond to circulating viruses. Whereas RSV and IAV wastewater events were mostly regionally coherent, HMPV events displayed localized occurrence patterns.

Human viral nucleic acids concentrations in wastewater solids from Central and Coastal California USA

We measured concentrations of SARS-CoV-2, influenza A and B virus, respiratory syncytial virus (RSV), mpox virus, human metapneumovirus, norovirus GII, and pepper mild mottle virus nucleic acids in wastewater solids at twelve wastewater treatment plants in Central California, USA. Measurements were made daily for up to two years, depending on the wastewater treatment plant. Measurements were made using digital droplet (reverse-transcription-) polymerase chain reaction (RT-PCR) following best practices for making environmental molecular biology measurements. These data can be used to better understand disease occurrence in communities contributing to the wastewater.

Searching for a Reliable Viral Indicator of Faecal Pollution in Aquatic Environments

The disposal of sewage in significant quantities poses a health hazard to aquatic ecosystems. These effluents can contain a wide range of pathogens, making faecal contamination a leading source of waterborne diseases around the world. Yet monitoring bacteria or viruses in aquatic environments is time consuming and expensive. The standard indicators of faecal pollution all have limitations, including difficulty in determining the source due to lack of host specificity, poor connection with the presence of non-bacterial pathogens, or low environmental persistence. Innovative monitoring techniques are sorely needed to provide more accurate and targeted solutions. Viruses are a promising alternative to faecal indicator bacteria for monitoring, as they are more persistent in ambient water, more abundant in faeces, and are extremely host-specific. Given the range of viruses found in diverse contexts, it is not easy to find one "ideal" viral indicator of faecal pollution; however, several are of interest. In parallel, the ongoing development of molecular techniques coupled with metagenomics and bioinformatics should enable improved ways to detect faecal contamination using viruses. This review examines the evolution of faecal contamination monitoring with the following aims (i) to identify the characteristics of the main viral indicators of faecal contamination, including human enteric viruses, bacteriophages, CRESS and plant viruses, (ii) to assess how these have been used to monitor water pollution in recent years, (iii) to evaluate the reliability of recent detection methods of such viruses, and (iv) to tentatively determine which viruses may be most effective as markers of faecal pollution.

Comparative evaluation of advanced oxidation processes (AOPs) for reducing SARS-CoV-2 viral load from campus sewage water

Presence of SARS-CoV-2 in wastewater is a major concern as the wastewater meets rivers and other water bodies and is used by the population for various purposes. Hence it is very important to treat sewage water in an efficient manner in order to reduce the public health risk. In the present work, various advanced oxidation processes (AOPs) have been evaluated for disinfection of SARS-CoV-2 from sewage water collected from STP inlet of academic institutional residential. The sewage water was subjected to ten AOPs, which include Ozone (O3), Hydrodynamic cavitation (HC), Ultraviolet radiation (UV), and their hybrid combinations like HC/O3, HC/O3/H2O2, HC/H2O2, O3/UV, UV/H2O2, UV/H2O2/O3, and O3/H2O2 to reduce SARS-CoV-2 viral load. Further, AOP treated sewage water was subjected to total nucleic acid isolation followed by RT-qPCR for viral load estimation. The sewage water treatment techniques were evaluated based on their viral concentration-reducing efficiency. It was found that ozone and ozone-coupled hybrid AOPs showed the most promising result with more than 98 % SARS-CoV-2 viral load reducing efficiency from sewage water. Interestingly, the best six AOPs used in this study significantly reduced both the SARS-CoV-2 and PMMoV (faecal indicator) viral load and improved water quality in terms of increasing DO and decreasing TOC.

A new workflow for assigning removal credits to assess overall performance of managed aquifer recharge (MAR)

Pathogen removal in managed aquifer recharge (MAR) systems is dependent upon numerous operational, physicochemical water quality, and biological parameters. Due to the site-specific conditions affecting these parameters, guidelines for specifying pathogen removal have historically taken rather precautionary and conservative approaches in order to protect groundwater quality and public health. A literature review of regulated pathogens in MAR applications was conducted and compared to up-and-coming indicators and surrogates for pathogen assessment, all of which can be gathered into a toolbox from which regulators and operators alike can select appropriate pathogens for monitoring and optimization of MAR practices. Combined with improved knowledge of pathogen fate and transport obtained through lab- and pilot-scale studies and supported by modeling, this foundation can be used to select appropriate, site-specific pathogens for regarding a more efficient pathogen retention, ultimately protecting public health and reducing costs. This paper outlines a new 10 step-wise workflow for moving towards determining robust removal credits for pathogens based on risk management principles. This approach is tailored to local conditions while reducing overly conservative regulatory restrictions or insufficient safety contingencies. The workflow is intended to help enable the full potential of MAR as more planned water reuse systems are implemented in the coming years.

Metagenomic analyses of plant virus sequences in sewage water for plant viruses monitoring

Frequent monitoring of emerging viruses of agricultural crops is one of the most important missions for plant virologists. A fast and precise identification of potential harmful viruses may prevent the occurrence of serious epidemics. Nowadays, high-throughput sequencing (HTS) technologies became an accessible and powerful tool for this purpose. The major discussion of this strategy resides in the process of sample collection, which is usually laborious, costly and nonrepresentative. In this study, we assessed the use of sewage water samples for monitoring the widespread, numerous, and stable plant viruses using HTS analysis and RT-qPCR. Plant viruses belonged to 12 virus families were found, from which Virgaviridae, Solemoviridae, Tymoviridae, Alphaflexiviridae, Betaflexiviridae, Closteroviridae and Secoviridae were the most abundant ones with more than 20 species. Additionally, we detected one quarantine virus in Brazil and a new tobamovirus species. To assess the importance of the processed foods as virus release origins to sewage, we selected two viruses, the tobamovirus pepper mild mottle virus (PMMoV) and the carlavirus garlic common latent virus (GarCLV), to detect in processed food materials by RT-qPCR. PMMoV was detected in large amount in pepper-based processed foods and in sewage samples, while GarCLV was less frequent in dried and fresh garlic samples, and in the sewage samples. This suggested a high correlation of virus abundance in sewage and processed food sources. The potential use of sewage for a virus survey is discussed in this study.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40858-023-00575-8.

Pepper Mild Mottle Virus as a Potential Indicator of Fecal Contamination in Influents of Wastewater Treatment Plants in Riyadh, Saudi Arabia

Several indicators of fecal pollution in water resources are continuously monitored for their reliability and, of particular interest, their correlation to human enteric viruses-not justified by traditional bacterial indicators. Pepper mild mottle virus (PMMoV) has recently been proposed as a successful viral surrogate of human waterborne viruses; however, in Saudi Arabia there are no available data in terms of its prevalence and concentration in water bodies. The concentration of PMMoV in three different wastewater treatment plants (King Saud University (KSU), Manfoha (MN), and Embassy (EMB) wastewater treatment plants (WWTP)) was measured using qRT-PCR during a one-year period and compared to the human adenovirus (HAdV), which is highly persistent and considered an indicator for viral-mediated fecal contamination. PMMoV was found in ~94% of the entire wastewater samples (91.6-100%), with concentrations ranging from 62 to 3.5 × 107 genome copies/l (GC/l). However, HAdV was detected in 75% of raw water samples (~67-83%). The HAdV concentration ranged between 1.29 × 103 GC/L and 1.26 × 107 GC/L. Higher positive correlation between PMMoV and HAdV concentrations was detected at MN-WWTP (r = 0.6148) than at EMB-WWTP (r = 0.207). Despite the lack of PMMoV and HAdV seasonality, a higher positive correlation (r = 0.918) of PMMoV to HAdV was recorded at KSU-WWTP in comparison to EMB-WWTP (r = 0.6401) around the different seasons. Furthermore, meteorological factors showed no significant influence on PMMoV concentrations (p > 0.05), thus supporting the use of PMMoV as a possible fecal indicator of wastewater contamination and associated public health issues, particularly at MN-WWTP. However, a continuous monitoring of the PMMoV distribution pattern and concentration in other aquatic environments, as well as its correlation to other significant human enteric viruses, is essential for ensuring its reliability and reproducibility as a fecal pollution indicator.

Risk of Gastroenteritis from Swimming at a Wastewater-Impacted Tropical Beach Varies across Localized Scales

Population growth and changing climate are expected to increase human exposure to pathogens in tropical coastal waters. We examined microbiological water quality in three rivers within 2.3 km of each other that impact a Costa Rican beach and in the ocean outside their plumes during the rainy and dry seasons. We performed quantitative microbial risk assessment (QMRA) to predict the risk of gastroenteritis associated with swimming and the amount of pathogen reduction needed to achieve safe conditions. Recreational water quality criteria based on enterococci were exceeded in >90% of river samples but in only 13% of ocean samples. Multivariate analysis grouped microbial observations by subwatershed and season in river samples but only by subwatershed in the ocean. The modeled median risk from all pathogens in river samples was between 0.345 and 0.577, 10-fold above the U.S. Environmental Protection Agency (U.S. EPA) benchmark of 0.036 (36 illnesses/1,000 swimmers). Norovirus genogroup I (NoVGI) contributed most to risk, but adenoviruses raised risk above the threshold in the two most urban subwatersheds. The risk was greater in the dry compared to the rainy season, due largely to the greater frequency of NoVGI detection (100% versus 41%). Viral log10 reduction needed to ensure safe swimming conditions varied by subwatershed and season and was greatest in the dry season (3.8 to 4.1 dry; 2.7 to 3.2 rainy). QMRA that accounts for seasonal and local variability of water quality contributes to understanding the complex influences of hydrology, land use, and environment on human health risk in tropical coastal areas and can contribute to improved beach management. IMPORTANCE This holistic investigation of sanitary water quality at a Costa Rican beach assessed microbial source tracking (MST) marker genes, pathogens, and indicators of sewage. Such studies are still rare in tropical climates. Quantitative microbial risk assessment (QMRA) found that rivers impacting the beach consistently exceeded the U.S. EPA risk threshold for gastroenteritis of 36/1,000 swimmers. The study improves upon many QMRA studies by measuring specific pathogens, rather than relying on surrogates (indicator organisms or MST markers) or estimating pathogen concentrations from the literature. By analyzing microbial levels and estimating the risk of gastrointestinal illness in each river, we were able to discern differences in pathogen levels and human health risks even though all rivers were highly polluted by wastewater and were located less than 2.5 km from one another. This variability on a localized scale has not, to our knowledge, previously been demonstrated.

Wastewater concentrations of human influenza, metapneumovirus, parainfluenza, respiratory syncytial virus, rhinovirus, and seasonal coronavirus nucleic-acids during the COVID-19 pandemic: a surveillance study

BACKGROUND

Respiratory disease is a major cause of morbidity and mortality; however, surveillance for circulating respiratory viruses is passive and biased. Wastewater-based epidemiology has been used to understand SARS-CoV-2, influenza A, and respiratory syncytial virus (RSV) infection rates at a community level but has not been used to investigate other respiratory viruses. We aimed to use wastewater-based epidemiology to understand community viral respiratory infection occurrence.

METHODS

A retrospective wastewater-based epidemiology surveillance study was carried out at a large wastewater treatment plant located in California, USA. Using droplet digital RT-PCR, we measured RNA concentrations of influenza A and influenza B viruses, RSV A and RSV B, parainfluenza (1-4) viruses, rhinovirus, seasonal coronaviruses, and metapneumovirus in wastewater solids three times per week for 17 months (216 samples) between Feb 1, 2021, and June 21, 2022. Novel probe-based RT-PCR assays for non-influenza viral targets were developed and validated. We compared viral RNA concentrations to positivity rates for viral infections from clinical specimens submitted to California Sentinel Clinical Laboratories (sentinel laboratories) to assess concordance between the two datasets.

FINDINGS

We detected RNA from all tested viruses in wastewater solids. Human rhinovirus (median concentration 4300 [0-9500] copies per gram dry weight) and seasonal human coronaviruses (35 000 [17 000-56 000]) were found at the highest concentrations. Concentrations of viral RNA correlated significantly and positively with positivity rates of associated viral diseases from sentinel laboratories (tau 0·32-0·57, p<0·0009); the only exceptions were influenza B and RSV A, which were rarely detected in wastewater solids. Measurements from wastewater indicated coronavirus OC43 dominated the seasonal human coronavirus infections whereas parainfluenza 3 dominated among parainfluenza infections during the study period. Concentrations of all tested viral RNA decreased noticeably after the omicron BA.1 surge suggesting a connection between changes in human behaviour during the surge and transmission of all respiratory viruses.

INTERPRETATION

Wastewater-based epidemiology can be used to obtain information on circulation of respiratory viruses at a localised, community level without the need to test many individuals because a single sample of wastewater represents the entire contributing community. Results from wastewater can be available within 24 h of sample collection, generating real time information to inform public health responses, clinical decision making, and individual behaviour modifications.

FUNDING

CDC Foundation.

Evaluation of intra- and inter-lab variability in quantifying SARS-CoV-2 in a state-wide wastewater monitoring network

In December 2019, SARS-CoV-2, the virus that causes coronavirus disease 2019, was first reported and subsequently triggered a global pandemic. Wastewater monitoring, a strategy for quantifying viral gene concentrations from wastewater influents within a community, has served as an early warning and management tool for the spread of SARS-CoV-2 in a community. Ohio built a collaborative statewide wastewater monitoring network that is supported by eight labs (university, government, and commercial laboratories) with unique sample processing workflows. Consequently, we sought to characterize the variability in wastewater monitoring results for network labs. Across seven trials between October 2020 and November 2021, eight participating labs successfully quantified two SARS-CoV-2 RNA targets and human fecal indicator virus targets in wastewater sample aliquots with reproducible results, although recovery efficiencies of spiked surrogates ranged from 3 to 75%. When SARS-CoV-2 gene fragment concentrations were adjusted for recovery efficiency and flow, the proportion of variance between laboratories was minimized, serving as the best model to account for between-lab variance. Another adjustment factor (alone and in different combinations with the above factors) considered to account for sample and measurement variability includes fecal marker normalization. Genetic quantification variability can be attributed to many factors, including the methods, individual samples, and water quality parameters. In addition, statistically significant correlations were observed between SARS-CoV-2 RNA and COVID-19 case numbers, supporting the notion that wastewater surveillance continues to serve as an effective monitoring tool. This study serves as a real-time example of multi-laboratory collaboration for public health preparedness for infectious diseases.

Surfactant Treatment for Efficient Gene Detection of Enteric Viruses and Indicators in Surface Water Concentrated by Ultrafiltration

The hollow fiber ultrafiltration (HFUF)-based microbial concentration method is widely applied for monitoring pathogenic viruses and microbial indicators in environmental water samples. However, the HFUF-based method can co-concentrate substances that interfere with downstream molecular processes-nucleic acid extraction, reverse transcription (RT), and PCR. These inhibitory substances are assumed to be hydrophobic and, therefore, expected to be excluded by a simple surfactant treatment before the silica membrane-based RNA extraction process. In this study, the efficacy and limitations of the sodium deoxycholate (SD) treatment were assessed by quantifying a process control and indigenous viruses using 42 surface water samples concentrated with HFUF. With some exceptions, which tended to be seen in samples with high turbidity (> 4.0 NTU), virus recovery by the ultrafiltration method was sufficiently high (> 10%). RNA extraction-RT-quantitative PCR (RT-qPCR) efficiency of the process control was insufficient (10%) for 30 of the 42 HFUF concentrates without any pretreatments, but it was markedly improved for 21 of the 30 inhibitory concentrates by the SD treatment. Detection rates of indigenous viruses were also improved and no substantial loss of viral RNA was observed. The SD treatment was particularly effective in mitigating RT-qPCR inhibition, although it was not effective in improving RNA extraction efficiency. The methodology is simple and easily applied. These findings indicate that SD treatment can be a good alternative to sample dilution, which is widely applied to mitigate the effect of RT-qPCR inhibition, and can be compatible with other countermeasures.

Does normalization of SARS-CoV-2 concentrations by Pepper Mild Mottle Virus improve correlations and lead time between wastewater surveillance and clinical data in Alberta (Canada): comparing twelve SARS-CoV-2 normalization approaches

Wastewater-based surveillance (WBS) data normalization is an analyte measurement correction that addresses variations resulting from dilution of fecal discharge by non-sanitary sewage, stormwater or groundwater infiltration. No consensus exists on what WBS normalization parameters result in the strongest correlations and lead time between SARS-CoV-2 WBS data and COVID-19 cases. This study compared flow, population size and biomarker normalization impacts on the correlations and lead times for ten communities in twelve sewersheds in Alberta (Canada) between September 2020 and October 2021 (n = 1024) to determine if normalization by Pepper Mild Mottle Virus (PMMoV) provides any advantages compared to other normalization parameters (e.g., flow, reported and dynamic population sizes, BOD, TSS, NH3, TP). PMMoV concentrations (GC/mL) corresponded with plant influent flows and were highest in the urban centres. SARS-CoV-2 target genes E, N1 and N2 were all negatively associated with wastewater influent pH, while PMMoV was positively associated with temperature. Pooled data analysis showed that normalization increased ρ-values by almost 0.1 and was highest for ammonia, TKN and TP followed by PMMoV. Normalization by other parameters weakened associations. None of the differences were statistically significant. Site-specific correlations showed that normalization of SARS-CoV-2 data by PMMoV only improved correlations significantly in two of the twelve systems; neither were large sewersheds or combined sewer systems. In five systems, normalization by traditional wastewater strength parameters and dynamic population estimates improved correlations. Lead time ranged between 1 and 4 days in both pooled and site-specific comparisons. We recommend that WBS researchers and health departments: a) Investigate WWTP influent properties (e.g., pH) in the WBS planning phase and use at least two parallel approaches for normalization only if shown to provide value; b) Explore normalization by wastewater strength parameters and dynamic population size estimates further; and c) Evaluate purchasing an influent flow meter in small communities to support long-term WBS efforts and WWTP management.

Bayesian sequential approach to monitor COVID-19 variants through positivity rate from wastewater

Trends in COVID-19 infection have changed throughout the pandemic due to myriad factors, including changes in transmission driven by social behavior, vaccine development and uptake, mutations in the virus genome, and public health policies. Mass testing was an essential control measure for curtailing the burden of COVID-19 and monitoring the magnitude of the pandemic during its multiple phases. However, as the pandemic progressed, new preventive and surveillance mechanisms emerged. Implementing vaccine programs, wastewater (WW) surveillance, and at-home COVID-19 tests reduced the demand for mass severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing. This paper proposes a sequential Bayesian approach to estimate the COVID-19 positivity rate (PR) using SARS-CoV-2 RNA concentrations measured in WW through an adaptive scheme incorporating changes in virus dynamics. PR estimates are used to compute thresholds for WW data using the CDC thresholds for low, substantial, and high transmission. The effective reproductive number estimates are calculated using PR estimates from the WW data. This approach provides insights into the dynamics of the virus evolution and an analytical framework that combines different data sources to continue monitoring the COVID-19 trends. These results can provide public health guidance to reduce the burden of future outbreaks as new variants continue to emerge. The proposed modeling framework was applied to the City of Davis and the campus of the University of California Davis.

Quantitative Assessment of Microbial Pathogens and Indicators of Wastewater Treatment Performance for Safe and Sustainable Water Reuse in India

Currently, there is no data on the molecular quantification of microbial indicators of recycled water quality in India. In this study, multiple microbial pathogens and indicators of water quality were evaluated at three wastewater treatment plants located in two Indian cities (New Delhi and Jaipur) to determine the treatment performance and suitability of recycled water for safe and sustainable reuse applications. Real-time polymerase chain reaction (PCR) was used for the rapid evaluation of six human pathogens and six microbial indicators of fecal contamination. Among the microbial indicators, pepper mild mottle virus (PMMoV), F⁺RNA-GII bacteriophage, Bacteroides thetaiotamicron, and four human pathogens (Norovirus genogroups I & II, Giardia, and Campylobacter coli) were detected in all of the influent samples analyzed. This work suggests that the raw influents contain lower levels of noroviruses and adenoviruses and higher levels of Giardia compared to those reported from other geographic regions. Overall, the efficacy of the removal of microbial targets was over 93% in the final effluent samples, which is consistent with reports from across the world. PMMoV and Giardia were identified as the best microbial targets, from the microbial indicators spanning across bacteria, bacteriophages, DNA/RNA viruses, and protozoan parasites, by which to evaluate treatment performance and recycled water quality in Indian settings, as they were consistently present at high concentrations in untreated wastewater both within and across the sites. Also, they showed a strong correlation with other microbial agents in both the raw influent and in the final effluent. These findings provide valuable insights into the use of culture-independent molecular indicators that can be used to assess the microbial quality of recycled water in Indian settings. IMPORTANCE Wastewater treatment plants (WWTPs) have rapidly increased in India during the last decade. Nonetheless, there are only a few labs in India that can perform culture-based screening for microbial quality. In the last 2 years of the pandemic, India has witnessed a sharp increase in molecular biology labs. Therefore, it is evident that culture-independent real-time PCR will be increasingly used for the assessment of microbial indicators/pathogens in wastewater, especially in resource-limited settings. There is no data available on the molecular quantitation of microbial indicators from India. There is an urgent need to understand and evaluate the performance of widely used microbial indicators via molecular quantitation in Indian WWTPs. Our findings lay the groundwork for the molecular quantitation of microbial indicators in WWTPs in India. We have screened for 12 microbial targets (indicators and human pathogens) and have identified pepper mild mottle virus (PMMoV) and Giardia as the best molecular microbiological indicators in Indian settings.

Temporal dynamics of SARS-CoV-2 genome and detection of variants of concern in wastewater influent from two metropolitan areas in Arkansas

Although SARS-CoV-2 can cause severe illness and death, a percentage of the infected population is asymptomatic. This, along with other factors, such as insufficient diagnostic testing and underreporting due to self-testing, contributes to the silent transmission of SARS-CoV-2 and highlights the importance of implementing additional surveillance tools. The fecal shedding of the virus from infected individuals enables its detection in community wastewater, and this has become a valuable public health tool worldwide as it allows the monitoring of the disease on a populational scale. Here, we monitored the presence of SARS-CoV-2 and its dynamic genomic changes in wastewater sampled from two metropolitan areas in Arkansas during major surges of COVID-19 cases and assessed how the viral titers in these samples related to the clinical case counts between late April 2020 and January 2022. The levels of SARS-CoV-2 RNA were quantified by reverse-transcription quantitative polymerase chain reaction (RT-qPCR) using a set of TaqMan assays targeting three different viral genes (encoding ORF1ab polyprotein, surface glycoprotein, and nucleocapsid phosphoprotein). An allele-specific RT-qPCR approach was used to screen the samples for SARS-CoV-2 mutations. The identity and genetic diversity of the virus were further investigated through amplicon-based RNA sequencing, and SARS-CoV-2 variants of concern were detected in wastewater samples throughout the duration of this study. Our data show how changes in the virus genome can affect the sensitivity of specific RT-qPCR assays used in COVID-19 testing with the surge of new variants. A significant association was observed between viral titers in wastewater and recorded number of COVID-19 cases in the areas studied, except when assays failed to detect targets due to the presence of particular variants. These findings support the use of wastewater surveillance as a reliable complementary tool for monitoring SARS-CoV-2 and its genetic variants at the community level.

Persistence of Endogenous SARS-CoV-2 and Pepper Mild Mottle Virus RNA in Wastewater-Settled Solids

Limited information is available on the decay rate of endogenous SARS-CoV-2 and pepper mild mottle virus (PMMoV) RNA in wastewater and primary settled solids, potentially limiting an understanding of how transit or holding times within wastewater infrastructure might impact RNA measurements and their relationship to community COVID-19 infections. In this study, primary settled solids samples were collected from two wastewater treatment plants in the San Francisco Bay Area. Samples were thoroughly mixed, aliquoted into subsamples, and stored at 4, 22, and 37 °C for 10 days. The concentrations of SARS-CoV-2 (N1 and N2 targets) and PMMoV RNA were measured using an RT-ddPCR. Limited decay (<1 log10 reduction) was observed in the detection of viral RNA targets at all temperature conditions, suggesting that SARS-CoV-2 and PMMoV RNA can be highly persistent in solids. First-order decay rate constants ranged from 0.011 to 0.098 day-1 for SARS-CoV-2 RNA and from 0.010 to 0.091 day-1 for PMMoV RNA depending on the temperature conditions. A slower decay was observed for SARS-CoV-2 RNA in primary settled solids compared to previously reported decay in wastewater influent. Further research is needed to understand if solid content and wastewater characteristics might influence the persistence of viral RNA targets.

Fecal indicators and antibiotic resistance genes exhibit diurnal trends in the Chattahoochee River: Implications for water quality monitoring

Water bodies that serve as sources of drinking or recreational water are routinely monitored for fecal indicator bacteria (FIB) by state and local agencies. Exceedances of monitoring thresholds set by those agencies signal likely elevated human health risk from exposure, but FIB give little information about the potential source of contamination. To improve our understanding of how within-day variation could impact monitoring data interpretation, we conducted a study at two sites along the Chattahoochee River that varied in their recreational usage and adjacent land-use (natural versus urban), collecting samples every 30 min over one 24-h period. We assayed for three types of microbial indicators: FIB (total coliforms and Escherichia coli); human fecal-associated microbial source tracking (MST) markers (crAssphage and HF183/BacR287); and a suite of clinically relevant antibiotic resistance genes (ARGs; blaCTX-M, blaCMY, MCR, KPC, VIM, NDM) and a gene associated with antibiotic resistance (intl1). Mean levels of FIB and clinically relevant ARGs (blaCMY and KPC) were similar across sites, while MST markers and intI1 occurred at higher mean levels at the natural site. The human-associated MST markers positively correlated with antibiotic resistant-associated genes at both sites, but no consistent associations were detected between culturable FIB and any molecular markers. For all microbial indicators, generalized additive mixed models were used to examine diurnal variability and whether this variability was associated with environmental factors (water temperature, turbidity, pH, and sunlight). We found that FIB peaked during morning and early afternoon hours and were not associated with environmental factors. With the exception of HF183/BacR287 at the urban site, molecular MST markers and intI1 exhibited diurnal variability, and water temperature, pH, and turbidity were significantly associated with this variability. For blaCMY and KPC, diurnal variability was present but was not correlated with environmental factors. These results suggest that differences in land use (natural or urban) both adjacent and upstream may impact overall levels of microbial contamination. Monitoring agencies should consider matching sample collection times with peak levels of target microbial indicators, which would be in the morning or early afternoon for the fecal associated indicators. Measuring multiple microbial indicators can lead to clearer interpretations of human health risk associated with exposure to contaminated water.

Testing specificity and sensitivity of wastewater-based epidemiology for detecting SARS-CoV-2 in four communities on Vancouver Island, Canada

We report wastewater surveillance of the spread of SARS-CoV-2 based upon 24-h composite influent samples taken weekly from four wastewater treatment plants (WWTP) on Vancouver Island, BC, Canada between January 3, 2021 and July 10, 2021. Samples were analyzed by reverse transcription quantitative polymerase chain reaction targeting the N1 and N2 gene fragments of SARS-CoV-2 and a region of the replication associate protein of the pepper mottle mosaic virus (PMMoV) serving as endemic control. Only a small proportion of samples had quantifiable levels of N1 or N2. Overall case rates are weakly correlated with the concentration (gene copies/L) and with the flux of viral material influent to the WWTP (gene copies/day); the latter accounts for influent flow variations. Poisson multimodal rank correlation accounts for differences between the four WWTP and shows a significant correlation with a significant positive intercept. Receiver operator characteristics (ROC) analysis confirms a cut-off of cases based on amplified/not-amplified experimental data. At the optimal cut point of 19 (N1) or 17 (N2) cases/week/100,000 the sensitivity and specificity is about 75% for N1 and 67% for N2.

Characterizing the chemical and microbial fingerprint of unsheltered homelessness in an urban watershed

Unsheltered homelessness is rapidly becoming a critical issue in many cities worldwide. The worsening situation not only highlights the socioeconomic plight, but it also raises awareness of ancillary issues such as the potential implications for urban water quality. The objective of this study was to simultaneously leverage diverse source tracking tools to develop a chemical and microbial fingerprint describing the relative contribution of direct human inputs into Las Vegas' tributary washes. By evaluating a wide range of urban water matrices using general water quality parameters, fecal indicator bacteria (FIB), human-associated microbial markers [e.g., HF183, crAssphage, and pepper mild mottle virus (PMMoV)], 16S rRNA gene sequencing data, and concentrations of 52 anthropogenic trace organic compounds (TOrCs), this study was able to differentiate principal sources of these constituents, including contributions from unsheltered homelessness. For example, HF183 (31% vs. 0%), crAssphage (61% vs. 5%), and PMMoV (72% vs. 55%) were more frequently detected in tributary washes with higher homeless census counts vs. 'control' tributary washes. Illicit drugs or their metabolites (e.g., heroin, acetylmorphine, amphetamine, and cocaine) and select TOrCs (e.g., acetaminophen, caffeine, ibuprofen, and naproxen) were also detected more frequently and at higher concentrations in the more anthropogenically-impacted washes. These data can be used to raise awareness of the shared interests between the broader community and those who are experiencing homelessness, notably the importance of protecting environmental health and water quality. Ultimately, this may lead to more rapid adoption of proven strategies for achieving functional zero homelessness, or at least additional resources for unsheltered individuals.

Infectious Pepper Mild Mottle Virus and Human Adenoviruses as Viral Indices in Sewage and Water Samples

The objective of this study was to compare human adenoviruses (HAdVs) genome and infectivity, polyomaviruses (JC and BK) genome (JCPyVs) and (BKPyVs), Pepper Mild Mottle Virus (PMMoV) genome and infectivity, and infectious bacteriophages as viral indices for sewage and water samples. One hundred and forty-four samples were collected from inlets and outlets of water and wastewater treatment plants (WTPs), and WWTPs within Greater Cairo from October 2015 till March 2017. Two methods of viral concentration [Aluminium hydroxide (Al(OH)₃) precipitation method and adsorption-elution technique followed by organic flocculation method] were compared to determine which of them was the best method to concentrate viruses from sewage and water. Although samples with only one litre volume were concentrated using Al(OH)₃ precipitation method and the same samples with larger volumes (5-20 L) were concentrated using the adsorption-elution technique followed by the organic flocculation method, a non-significant difference was observed between the efficiency of the two methods in all types of samples except for the drinking water samples. Based on the qualitative prevalence of studied viruses in water and wastewater samples, the number of genome copies and infectious units in the same samples, resistance to treatment processes in water and wastewater treatment plants, higher frequency of both adenoviruses and PMMoV genomes as candidate viral indices in treated sewage and drinking water was observed. The problem of having a viral genome as indices of viral pollution is that it does not express the recent viral pollution because of the longer survivability of the viral genome than the infectious units in water and wastewater. Both infectious adenovirus and infectious phiX174 bacteriophage virus showed similar efficiencies as indices for viral pollution in drinking water and treated sewage samples. On the other hand, qualitative detection of infectious PMMoV failed to express efficiently the presence/absence of infectious enteric viruses in drinking water samples. Infectious adenoviruses and infectious bacteriophage phiX174 virus may be better candidates than adenoviruses genome, polyomaviruses genome, and PMMoV genome and infectivity as viral indices for water and wastewater.

CrAssphage as an indicator of human-fecal contamination in water environment and virus reduction in wastewater treatment

Viral indicators of human-fecal contamination in wastewaters and environmental waters have been getting much attention in the past decade. Cross-assembly phage (crAssphage) is the most abundant DNA virus in human feces. Recently, the usefulness of crAssphage as a microbial source tracking and water quality monitoring tool for human-fecal contamination has been highlighted. Here, we conducted a comprehensive review on crAssphage in water, focusing on detection methodology, concentration range in various waters and wastewaters, specificity to human-fecal contamination, and reduction in wastewater treatment systems. This review highlights that crAssphage is globally distributed in wastewaters and various fecal-contaminated water bodies at high concentrations without seasonal fluctuations. CrAssphage is highly specific to human-fecal contamination and is rarely found in animal feces. It also has a good potential as a performance indicator to ensure virus reduction in wastewater treatment systems. Accordingly, crAssphage could be an effective tool for monitoring of human-fecal contamination and potential presence of fecal pathogenic microbes in environmental waters. Bridging the research gaps highlighted in this review would make crAssphage a powerful tool to support the control of water-related health risks.

Role of pepper mild mottle virus as a tracking tool for fecal pollution in aquatic environments

The plant pathogen pepper mild mottle virus (PMMoV) has recently been proposed as a water quality indicator, it is a RNA virus belonging to the genus Tobamovirus in the family Virgoviridae that causes harm to the pepper crops. After consuming processed food products containing infected peppers, such as hot sauces, PMMoV is excreted in high concentrations in feces; therefore, this is the most common RNA virus, constantly found in the feces of humans. The fecal-oral pathway is emerging as an environmental problem. The presence of high concentrations of pathogens associated with human excreta in environmental waters or water reuse supplies poses a threat to public health. Due to the difficulty in determining the presence of pathogens effectively in water, attempts to monitor microbial water quality often use surrogates or indicator organisms that can be easily detected; therefore, PMMoV is used as a viral surrogate in aquatic environment. This paper describes the incidence and persistence of PMMoV in aquatic environments and in waste treatment plants and its usefulness for quantifying virus reductions by advanced water treatment technologies. In recent research, SARS-CoV-2 was reported to be found in wastewater and utilized for the purpose of monitoring coronavirus illness outbreaks. Since PMMoV is readily identified in the human feces and can also serve as an indicator of human waste, the determined PMMoV concentrations may be utilized to give the normalized report of the SARS-CoV-2 concentration, so that, the amount of human waste found in the wastewater can be taken into consideration.

Pepper Mild Mottle Virus Coat Protein as a Novel Target to Screen Antiviral Drugs

Pepper mild mottle virus (PMMoV) has caused serious economic losses to crop production in many countries. The coat protein (CP) of PMMoV is a multifunctional protein proved to be a determining factor in the assignment of virulence type. Therefore, we studied the interaction between drugs and PMMoV CP as a method to screen anti-PMMoV agents. In this study, vanisulfane (6f) exhibited good inactivation activity (68.5%) by biological activity screening. Meanwhile, the green fluorescent protein and PMMoV CP expression changes of vanisulfane against PMMoV were verified by western blot and qRT-PCR experiments. The affinity between vanisulfane and PMMoV CP was predicted to be the best by autodocking and molecular dynamics simulation. PMMoV CP was purified for the first time from the soluble fraction, and the strong affinity between vanisulfane and CP was further verified by interaction experiments. Therefore, this study found that vanisulfane is a potential anti-PMMoV drug targeting PMMoV CP.