Cross-Resistance of UV- or Chlorine Dioxide-Resistant Echovirus 11 to Other Disinfectants

Abstract

The emergence of waterborne viruses with resistance to disinfection has been demonstrated in the laboratory and in the environment. Yet, the implications of such resistance for virus control remain obscure. In this study we investigate if viruses with resistance to a given disinfection method exhibit cross-resistance to other disinfectants. Chlorine dioxide (ClO2)- or UV-resistant populations of echovirus 11 were exposed to five inactivating treatments (free chlorine, ClO2, UV radiation, sunlight, and heat), and the extent of cross-resistance was determined. The ClO2-resistant population exhibited cross-resistance to free chlorine, but to none of the other inactivating treatments tested. We furthermore demonstrated that ClO2 and free chlorine act by a similar mechanism, in that they mainly inhibit the binding of echovirus 11 to its host cell. As such, viruses with host binding mechanisms that can withstand ClO2 treatment were also better able to withstand oxidation by free chlorine. Conversely, the UV-resistant population was not significantly cross-resistant to any other disinfection treatment. Overall, our results indicate that viruses with resistance to multiple disinfectants exist, but that they can be controlled by inactivating methods that operate by a distinctly different mechanism. We therefore suggest to utilize two disinfection barriers that act by different mechanisms in order to control disinfection-resistant viruses.

Differences in Viral Disinfection Mechanisms as Revealed by Quantitative Transfection of Echovirus 11 Genomes

“…In comparison, qPCR in the literature reports a reduction of genome integrity by UV 254 that is approximately equivalent to the loss of virus infectivity (5,18,27), implying a minimal contribution of protein damage to overall virus inactivation. While this is ideal for studies wishing to use qPCR tools as a rapid alternative to cell culture for estimating loss of infectivity, from a mechanistic standpoint these data diminish the importance of potential protein damage, which, based on the present study, may play a larger role than previously concluded.…”

“…RT-qPCR verification was performed with a previously established qPCR primer set (19) consisting of forward primer 3F (5=-ACT TTGGGTGTCCGTGTTTC-3) and reverse primer 4R (5=-TACTCAGGCCATCGACCATAC-3=). RT-qPCR was performed on an MIC qPCR machine (BioMolecular Systems) utilizing a One-Step TB Green PrimeScript RT-PCR kit (Perfect Real Time) (TaKaRa, Clontech) according to previously established cycling conditions (5). The infection by E11 was considered successful if the E11 genome copy number in a well was greater than the originally transfected E11 RNA concentration.…”

“…Different disinfection methods have various effects on enteric viruses; the virus can be inactivated by disrupting one or a combination of essential structures, including the virus genome (coding for the production of progeny viruses) and the virus protein capsid, which protects the genome and facilitates attachment and entry into host cells. Heat and certain chemical disinfectants (ClO 2 ) tend to disrupt the viral capsid (5,6), whereas disinfection with UV light at 254 nm (UV 254 ) tends to act on the viral genome by causing the formation of pyrimidine dimers (7,8) but can also form oxidants which can be responsible for disinfection (9,10). Chemical disinfectants such as free chlorine (FC) and ozone act on a broad range of targets in viruses, including the viral capsid (6,10,11), specific viral attachment epitopes (5), and viral RNA/DNA (6,10,12).…”

“…Several studies have attempted to discern the mechanism of viral inactivation for these and other disinfectants, focusing on capsid integrity/genome protection (13,14), protein damage (6,(15)(16)(17), genome integrity (6,18), virus attachment to host cells (5,10,13,19), or cell entry (10,19). Many of these studies offer differing mechanisms for a given disinfection method, either contradicting each other or placing differing weights on the importance of different mechanisms and their overall contribution to virus infection loss.…”

Virus control by enhanced physical separation

“…Nevertheless, from a regulatory point of view, a significant barrier exists, as there is no one disinfectant method which is effective against all viruses and can be utilised or applied to all water quality conditions. [51], [116]. An in-depth understanding of the mechanisms which are involved in virus inactivation is still needed if the scientific community wants to be able to predict the susceptibility of nonculturable virus strains to different disinfectants.…”