Assessing the Occurrence of Waterborne Viruses in Reuse Systems: Analytical Limits and Needs

Abstract

Detection of waterborne enteric viruses is an essential tool in assessing the risk of waterborne transmission. Cell culture is considered a gold standard for detection of these viruses. However, it is important to recognize the uncertainty and limitations of enteric virus detection in cell culture. Cell culture cannot support replication of all virus types and strains, and numerous factors control the efficacy of specific virus detection assays, including chemical additives, cell culture passage number, and sequential passage of a sample in cell culture. These factors can result in a 2- to 100-fold underestimation of virus infectivity. Molecular methods reduce the time for detection of viruses and are useful for detection of those that do not produce cytopathogenic effects. The usefulness of polymerase chain reaction (PCR) to access virus infectivity has been demonstrated for only a limited number of enteric viruses and is limited by an understanding of the mechanism of virus inactivation. All of these issues are important to consider when assessing waterborne infectious viruses and expected goals on virus reductions needed for recycled water. The use of safety factors to account for this may be useful to ensure that the risks in drinking water and recycled water for potable reuse are minimized.

Capsid integrity quantitative PCR to determine virus infectivity in environmental and food applications – A systematic review

“…Several enteric viruses relevant to human health could pass conventional sewage treatment in high numbers, thus posing a health risk when partially treated reclaimed sewage is utilized to irrigate fruits and vegetables ( Brouwer et al., 2018 ) or released into the aquatic environment of rivers and lakes ( Hellmér et al., 2014 ). Consequently, viral infectivity measurements have been proposed to be included in guidelines of water reuse for potable and non-potable purposes to demonstrate water reuse safety and evaluate water treatment efficiencies through log-reduction value achievements ( Farkas et al., 2020 ; Gerba and Betancourt, 2019 ). Due to their high infectivity and transmission rate as well as usually relatively low infectious dose, virus analysis in water and on fomites is frequently used when investigating likelihood of water-/surface borne transmission.…”

“…While still the gold standard, culture-based methods for propagation of infectious human pathogenic viruses in a laboratory environment require specialized facilities, experienced personnel and appropriate cell lines for virus propagation, and test results may only become available after five to ten days ( Rodriguez et al., 2009 ). Molecular techniques using quantitative polymerase chain reaction (qPCR) are faster and have been successfully used in the past two decades to determine virus loads in the aquatic environment and to comply with food safety regulations ( Bosch et al., 2018 ; Gerba and Betancourt, 2019 ). While robust, cost-efficient and uniquely sensitive and specific, qPCR has the severe limitation of not being able to differentiate between infectious and non-infectious virus particles, thus overestimating the number of viruses present in a sample ( Chhipi-Shrestha et al., 2017 ).…”

Capsid integrity quantitative PCR to determine virus infectivity in environmental and food applications – a systematic review

“…Several enteric viruses relevant to human health could pass conventional sewage treatment in high numbers, thus posing a health risk when partially treated reclaimed sewage is utilized to irrigate fruits and vegetables (Brouwer et al, 2018) or released into the aquatic environment of rivers and lakes (Hellmér et al, 2014). Consequently, viral infectivity measurements are included in guidelines of water reuse for potable and non-potable purposes to demonstrate water reuse safety and evaluate water treatment efficiencies through log-reduction value achievements (Farkas et al, 2020; Gerba and Betancourt, 2019). Due to their high infectivity and transmission rate as well as usually relatively low infectious dose, virus analysis in water and on fomites is frequently used when investigating likelihood of water-/surface borne transmission.…”

“…While still the gold standard, culture-based methods for propagation of infectious human pathogenic viruses in a laboratory environment require specialized facilities and experienced personnel and test results may only become available after five to ten days (Rodriguez et al, 2009). Molecular techniques using quantitative polymerase chain reaction (qPCR) are faster and have been successfully used in the past two decades to determine virus loads in the aquatic environment and to comply with food safety regulations (Bosch et al, 2018; Gerba and Betancourt, 2019). While robust, cost-efficient and uniquely sensitive and specific, qPCR has the severe limitation of not being able to differentiate between infectious and non-infectious virus particles, thus overestimating the number of viruses present in a sample (Chhipi-Shrestha et al, 2017).…”

Viral Communities Distribution and Diversity in a Wastewater Treatment Plants Using High-throughput Sequencing Analysis

“…A number of studies have considered cell culture as a gold standard for the detection of viral species/strain [10,[24][25][26]. However, it has been recognized that cell culture does not allow certain for the replication of all viral species and strains, as a number of mechanisms and conditions control the efficiency of the technique [26,27]. Molecular approaches based on nucleic acid amplification and other techniques have also been considered and demonstrated as a sensitive and better approach for the detection of viral species, but this has its own shortcomings such as the use specific reference sequences for primer design [11,18,19,25,29].…”