Mechanism of inactivation of enteric viruses in fresh water

Abstract

Fresh water obtained from nine sources was shown to cause inactivation of poliovirus. Further testing with four of these water samples showed that enteric viruses from different genera were consistently inactivated in these freshwater samples. Studies on the cause of inactivation were conducted with echovirus type 12 as the model virus. The results revealed that the virucidal agents in the waters tested could not be separated from microorganisms. Any treatment that removed or inactivated microorganisms caused loss of virucidal activity. Microbial growth in a sterilized creek water seeded with a small amount of stream water resulted in concomitant production of virucidal activity. When individual bacterial isolates obtained from a stream were grown in this sterilized creek water, most (22 of 27) produced a large amount of virucidal activity, although the amount varied from one isolate to the next. Active and inactive isolates were represented by both gram-positive and gram-negative organisms. Examination of echoviruses inactivated in stream water revealed that loss of infectivity first correlated with a slight decrease in the sedimentation coefficient of virus particles. The cause appeared to be cleavage of viral proteins, most notably, VP-4 and, to a lesser extent, VP-1. Viral RNA associated with particles was also cleaved but the rate was slower than loss of infectivity. These results suggest that proteolytic bacterial enzymes inactivate echovirus particles in fresh water by cleavage of viral proteins, thus exposing the viral RNA to nuclease digestion.

Survivability, Partitioning, and Recovery of Enveloped Viruses in Untreated Municipal Wastewater

“…Discrepancies in inactivation kinetics in sterilized and nonsterilized wastewater have been reported previously for nonenveloped viruses, 46 and may be due to bacterial extracellular enzyme activity and protozoan or metazoan predation. 47,48 Overall, the results suggest that unpasteurized wastewater samples should be employed for survivability tests when feasible.…”

Survival of surrogate coronaviruses in water

“…Water type was also a significant predictor of the rate of viral reduction, with greater reduction in pasteurized settled sewage as compared to reagent-grade water. Factors that have been suggested as contributors to greater virus reduction in more contaminated water include pH extremes, the presence of other microorganisms, and certain chemical constituents, such as proteolytic enzymes (Ward et al, 1986). However, the pasteurization process used to inactivate vegetative bacteria in the pasteurized settled sewage in these experiments may have reduced proteolytic activity in the test water.…”

Ecological Studies on Reovirus Pollution of Rivers in Toyama Prefecture

“…Although the conditions of these experiments may differ from the natural environment, the present experiments indicated that reos and polios are capable of surviving for a very long time in river water. As to the survival time of viruses in water, effects of many factors such as water quality, temperature, light, enzymes derived from microorganisms, and turbidity have to be taken into consideration (2,16,19,22,23). It has been reported that water temperature is the most dominant factor among them.…”