Long term stability and infectivity of herpesviruses in water.

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.

Zebra-borne equine herpesvirus type 1 (EHV-1) infection in non-African captive mammals.

Equine herpesvirus type 1 (EHV-1) was detected in an Indian rhinoceros (Rhinoceros unicornis), which was euthanized because of severe neurological disease. Encephalitis was suspected and EHV-1 DNA was detected in brain, lung, and spleen tissues. The viral IR6 protein was detected in lung tissues by Western blot analysis. Phylogenetic analyses of EHV-1 sequences amplified from various tissues was nearly identical to one recently described that resulted in both non-fatal and fatal encephalitis in polar bears. This represents transmission of EHV-1 to a species that is not naturally sympatric with the natural host of the virus and broadens the host range to Asian non-equid perissodactyls.

West nile virus antibody prevalence in horses of Ukraine.

West Nile virus (WNV) is a mosquito-borne virus of global importance. Over the last two decades, it has been responsible for significant numbers of cases of illness in humans and animals in many parts of the world. In Ukraine, WNV infections in humans and birds were first reported more than 25 years ago, yet the current epidemiological status is quite unclear. In this study, serum samples from over 300 equines were collected and screened in order to detect current WNV activity in Ukraine with the goal to estimate the risk of infection for humans and horses. Sera were tested by enzyme-linked immunosorbent assay (ELISA) and virus neutralization assay (NT) to detect WNV-specific antibodies. The results clearly revealed that WNV circulates in most of the regions from which samples were obtained, shown by a WNV seroprevalence rate of 13.5% of examined horses. This is the first topical report indicating the presence of WNV infections in horses in Ukraine, and the results of this study provide evidence of a widespread WNV circulation in this country.

Development of a peptide ELISA for discrimination between serological responses to equine herpesvirus type 1 and 4.

A peptide-based enzyme-linked immunosorbent assay (ELISA) for discrimination between serological responses to equine herpesvirus type 1 (EHV-1) and 4 (EHV-4) was developed. Three and four peptides for EHV-1 and EHV-4, respectively, were designed and studied initially in the ELISA using sera from foals infected experimentally. The most promising peptide pair, derived from EHV-1 glycoprotein E and EHV-4 glycoprotein G, was evaluated further using acute and convalescent sera from horses infected experimentally and naturally as well as a panel of horse field sera. Ten pre- and post-vaccination serum pairs were similarly tested in the type-specific ELISA. The peptide ELISA was able to identify horses which had been infected with EHV-1 or EHV-4 as derived from the results using acute and convalescent sera collected from natural outbreaks. When applied to a set of field samples, the assay proved robust with respect to determining the EHV-1 and EHV-4 antibody status. Also, the peptide ELISA was able to detect type-specific seroconversion for EHV-1 in vaccinated animals. With further validation, the EHV-1/EHV-4 peptide ELISA described in this study could serve as a reliable and cost-effective alternative to current methods for serological EHV-1 and EHV-4 diagnosis.