Long term stability and infectivity of herpesviruses in water

Anisha Dayaram,Alexander Schattschneider,Sebastian Bischofberger,Armando M Damiani,Nikolaus Osterrieder,Mathias Franz,Alex D Greenwood

doi:10.1038/srep46559

Anisha Dayaram, Alexander Schattschneider + Show 5 more

Open Access

https://doi.org/10.1038/srep46559

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Abstract

For viruses to utilize environmental vectors (hard surfaces, soil, water) for transmission, physical and chemical stability is a prerequisite. There are many factors including pH, salinity, temperature, and turbidity that are known to contribute to the ability of viruses to persist in water. Equine herpesvirus type-1 (EHV-1) is a pathogenic alphaherpesvirus associated with domestic horses and wild equids. EHV-1 and recombinants of EHV-1 and EHV-9 are able to cause infections in non-equid animal species, particularly in captive settings. Many of the captive non-equid mammals are not naturally sympatric with equids and do not share enclosures, however, in many cases water sources may overlap. Similarly, in the wild, equids encounter many species at waterholes in times of seasonal drought. Therefore, we hypothesized that EHV-1 is stable in water and that water may act as a vector for EHV-1. In order to establish the conditions promoting or hindering EHV-1 longevity, infectivity and genomic stability in water; we exposed EHV-1 to varied water environments (pH, salinity, temperature, and turbidity) in controlled experiments over 21 days. The presence and infectivity of the virus was confirmed by both qPCR and cell culture experiments. Our results show that EHV-1 remains stable and infectious under many conditions in water for up to three weeks.

Highlights

For viruses to utilize environmental vectors for transmission, physical and chemical stability is a prerequisite
Equine herpesvirus type-1 (EHV-1) was stable in distilled water for up to 14 days, as cytopathic effect (CPE) were still detectable at this time point (Table 1)
Our results suggest that high pH increases the time that EHV-1 remains infectious, while salinity does not demonstrate a significant effect on the persistence or infectivity of EHV-1

Summary

Introduction

For viruses to utilize environmental vectors (hard surfaces, soil, water) for transmission, physical and chemical stability is a prerequisite. Horses are natural hosts for equine herpesviruses, several viruses have recently been discovered that are closely related to EHV-1 and were isolated from both captive and wild animals, including Thompson’s gazelles (Eudorcas thomsoni)[4], Ilamas (Lama glama)[5], alpacas (Vicugna pacos)[6], black bears (Ursus americanus), polar bears (Ursus maritimus)[7] and rhinos (Rhinoceros unicornis)[8,9]. It is evident that cross species transmission of EHV-1-like viruses occurs in both captive and wild animals; the mechanism by which virus is transmitted is yet to be determined. It is possible that water may act as an environmental vector mediating the transmission of EHV-1 in both captive and wild animal populations. Studies of viral stability have demonstrated that environmental factors such as temperature, humidity, salinity, pH, and ultraviolet light affect the time that enteric viruses remain infectious. We contend that water is a likely transmission vehicle used by many viruses to maintain themselves within populations

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