Capsid Integrity Detection of Enteric Viruses in Reclaimed Waters

© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Climate change, unpredictable weather patterns, and droughts are depleting water resources in some parts of the globe, where recycling and reusing wastewater is a strategy for different purposes. To counteract this, the EU regulation for water reuse sets minimum requirements for the use of reclaimed water for agricultural irrigation, including a reduction in human enteric viruses. In the present study, the occurrence of several human enteric viruses, including the human norovirus genogroup I (HuNoV GI), HuNoV GII, and rotavirus (RV), along with viral fecal contamination indicator crAssphage was monitored by using (RT)-qPCR methods on influent wastewater and reclaimed water samples. Moreover, the level of somatic coliphages was also determined as a culturable viral indicator. To assess the potential viral infectivity, an optimization of a capsid integrity PMAxx-RT-qPCR method was performed on sewage samples. Somatic coliphages were present in 60% of the reclaimed water samples, indicating inefficient virus inactivation. Following PMAxx-RT-qPCR optimization, 66% of the samples tested positive for at least one of the analyzed enteric viruses, with concentrations ranging from 2.79 to 7.30 Log10 genome copies (gc)/L. Overall, most of the analyzed reclaimed water samples did not comply with current EU legislation and contained potential infectious viral particles.

This research was funded by project INNCAD/2021/95-96-101, MCEC WATER (PID 2020 116789 RB C 42 AEI/FEDER, UE), PTI Salud Global CSIC, and the Lagoon project (PROMETEO/2021/044). The Accreditation as Center of Excellence Severo Ochoa CEX2021-001189-S funded by MICIU/AEI/10.13039/501100011033 is also fully acknowledged. PPC is supported by a CEX2021-001189-S-20-9 grant. IG-G is recipient of a predoctoral contract from the Generalitat Valenciana (ACIF/2021/181), EC-F is recipient of a postdoctoral contract from the MICINN Call 2018 (PRE2018-083753). AP-C is recipient of the grant IJC2020-045382-I, financed by MCIN/AEI/10.13039/501100011033, and by the European Union “NextGenerationEU/PRTR”.

With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2021-001189-S).

Peer reviewed