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EHV more stable than previously thought Edited press release. Published online 18.05.17

Genetic markers identify EHV-1

EHV-2 in equine kerato-conjunctivitis

Equine herpesvirus myeloencephalopathy

A new study challenges the belief that herpes viruses, like most enveloped viruses, are relatively unstable outside their host.

Herpes viruses, such as EHV-1, have a lipid-containing envelope surrounding the viral DNA.  The envelope is relatively sensitive to desiccation, heat and detergents. This makes these viruses more susceptible to disinfectants than non-enveloped viruses. Typically, they only survive for a limited time outside the host, and tend to spread directly from one animal to another.

A research team lead by scientists from the Leibniz Institute for Zoo and Wildlife Research in collaboration with the Institut für Virologie of the Freie Universität Berlin tested this assumption by spiking water with equine herpes viruses under different conditions over a three-week period and examining whether viral DNA could be retrieved and to what extent the virus remained infectious after having been in the water.

The results demonstrate that the virus does remain stable and infectious for up to three weeks, with pH and temperature being the two most important factors to determine how long the virus ‘survived’.

Surprisingly, the addition of soil to the water appeared to “pull” the virus out of the water and stabilize it in the soil, suggesting that in natural water bodies viruses may persist for an extended time without infecting additional hosts. Therefore, in the case of equine herpes viruses, horses or other mammals susceptible to these viruses could be infected by herpes viruses from water bodies long after the animals that shed the virus had left the area.

These results suggest that viruses such as equine herpes viruses may become a part of the environmental “virome” and remain infectious. Equine herpes viruses have spread among mammals such as polar bears and rhinos without direct contact with horses or their relatives in both the wild and in captivity, often resulting in fatal consequences. Shared water sources may be a source and potential vector for infection.

Not only does this work help explain the spread of equine herpesviruses to other species, when there is no direct contact. It may also prompt a review of the procedures followed for controlling outbreaks of the infection in horses.

The work is part of an ongoing project AquaVir (“Water as an aquatic viral vector for emerging infectious diseases”) funded by the Leibniz Society Intramural Competitive Fund and the Leibniz Research Network Infections 21.

For more details, see:

Long term stability and infectivity of herpesviruses in water.

Dayaram A, Franz M, Schattschneider A, Damiani AM, Bischofberger S, Osterrieder N, Greenwood AD

Scientific Reports. (2017):

The research found that, equine herpesvirus remained stable and infectious over a three-week period, under a variety of conditions. This suggests that untreated water could be a source of infection by some herpesviruses. The results are reported in the scientific journal “Scientific Reports”.

Equine herpesvirus.

Author: Walid A / Leibniz-IZW