Leifels, M. | bioRxiv Science

bioRxiv2025

Enteric Viruses and Free-Living Amoebae: Protozoa as Potential Reservoirs and Transport Vessels for human Norovirus and Adenovirus

Human norovirus (HNoV) and human adenovirus (HAdV) are major causes of acute viral gastroenteritis globally and environmentally transmitted via the faecal-oral route through contaminated food and water. Recent evidence of these enteric viruses residing within environmental free-living amoebae (FLA)--specifically Vermamoeba vermiformis, Acanthamoeba polyphaga, and Willaertia magna--has significant implications for environmental virology and public health. The incorporation of HNoV into the cytoplasm and vacuoles of V. vermiformis and A. polyphaga, as well as the nuclear localization of HAdV within W. magna, was demonstrated using quantitative PCR and fluorescence microscopy. Intact HNoV and HAdV virions persisted inside FLA trophozoites, cysts, and extracellular vesicles for up to 12 days. Moreover, HAdV retained infectivity in buffalo green monkey kidney cells following intracellular persistence, suggesting these viruses can evade amoebal digestion and structural degradation. In the case of HAdV, nuclear incorporation, preservation of capsid integrity, and detection of mRNA associated with adenoviral fiber protein synthesis further suggest the possible initiation of virus-related transcriptional activity within the amoeba host. These findings challenge current assumptions about virus removal rates in sewage treatment, food safety protocols, and drinking water production. The enhanced persistence and protection conferred by FLA may also impact microbial risk assessments for recreational water use, particularly in sewage-impacted rivers and lakes. Recognition of FLA as reservoirs and transport vessels for enteric viruses necessitates a re-evaluation of existing water and sanitation guidelines to better mitigate environmental transmission pathways. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=115 SRC="FIGDIR/small/647535v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@5bff70org.highwire.dtl.DTLVardef@1df3d54org.highwire.dtl.DTLVardef@1338905org.highwire.dtl.DTLVardef@68d2f6_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2021

Factors Shaping Young and Mature Bacterial Biofilm Communities in Two Drinking Water Distribution Networks

The presence of biofilms in drinking water distribution systems (DWDS) can affect both water quality and system integrity; yet these systems remain poorly studied due to lack of accessibility. We established two independent full-scale DWDS Testbeds (A and B) on two different campuses situated in a tropical urban environment and equipped them with online sensors. Testbed B experienced higher levels of monochloramine and lower water age than Testbed A within the campus. Based on long amplicon-sequencing of bacterial 16S rRNA genes extracted from the mature biofilms (MPB) growing on pipes and young biofilms (YSB) growing on the sensors, a core community was identified in the two testbeds. The relative abundances of operational taxonomic units at the family level, including Mycobacteriaceae, Methylobacteriaceae, Rhodospirillaceae, Nitrosomonadaceae, and Moraxellaceae, were consistent for MPB and YSB on each campus. The MPB community was found to be influenced by conductivity, sample age, and pipe diameter as determined by both canonical correlation analysis and fuzzy set ordination. MPB displayed higher -diversity based on Hill numbers than YSB; in general, second order Hill numbers correlated positively with conductivity and sample age, but negatively with ORP and nitrite. Pseudomonas spp. together with Bacillus spp. likely initiated biofilm formation of YSB on Testbed A under conditions of reduced monochloramine and high water age. Significant levels of orthophosphate were detected in YSB samples at two stations and associated with higher levels of stagnation based on long-term differential turbidity measurement (DTM). Orthophosphate and DTM may act as indicators of the biofilm growth potential within DWDS. Highlights- Established two testbeds to study biofilms in full-scale distribution system - Biofilms on pipes and sensors had core community - Temporal effect and higher -diversity for biofilms on pipes - Water chemistry was related to biofilm community differences O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/434709v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@c392aforg.highwire.dtl.DTLVardef@1d355eborg.highwire.dtl.DTLVardef@1addf37org.highwire.dtl.DTLVardef@19cc22_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG

ecology↗