Equine Rotavirus A under the One Health Lens: Potential Impacts on Public Health.

Group A rotaviruses are a well-known cause of viral gastroenteritis in infants and children, as well as in many mammalian species and birds, affecting them at a young age. This group of viruses has a double-stranded, segmented RNA genome with high genetic diversity linked to point mutations, recombination, and, importantly, reassortment. While initial molecular investigations undertaken in the 1900s suggested host range restriction among group A rotaviruses based on the fact that different gene segments were distributed among different animal species, recent molecular surveillance and genome constellation genotyping studies conducted by the Rotavirus Classification Working Group (RCWG) have shown that animal rotaviruses serve as a source of diversification of human rotavirus A, highlighting their zoonotic potential. Rotaviruses occurring in various animal species have been linked with contributing genetic material to human rotaviruses, including horses, with the most recent identification of equine-like G3 rotavirus A infecting children. The goal of this article is to review relevant information related to rotavirus structure/genomic organization, epidemiology (with a focus on human and equine rotavirus A), evolution, inter-species transmission, and the potential zoonotic role of equine and other animal rotaviruses. Diagnostics, surveillance and the current status of human and livestock vaccines against RVA are also reviewed.

Quadruplex Real-Time TaqMan® RT-qPCR Assay for Differentiation of Equine Group A and B Rotaviruses and Identification of Group A G3 and G14 Genotypes.

Equine rotavirus A (ERVA) is the leading cause of diarrhea in foals, with G3P[12] and G14P[12] genotypes being the most prevalent. Recently, equine G3-like RVA was recognized as an emerging infection in children, and a group B equine rotavirus (ERVB) was identified as an emergent cause of foal diarrhea in the US. Thus, there is a need to adapt molecular diagnostic tools for improved detection and surveillance to identify emerging strains, understand their molecular epidemiology, and inform future vaccine development. We developed a quadruplex TaqMan® RT-qPCR assay for differentiation of ERVA and ERVB and simultaneous G-typing of ERVA strains, evaluated its analytical and clinical performance, and compared it to (1) a previously established ERVA triplex RT-qPCR assay and (2) standard RT-PCR assay and Sanger sequencing of PCR products. This quadruplex RT-qPCR assay demonstrated high sensitivity (>90%)/specificity (100%) for every target and high overall agreement (>96%). Comparison between the triplex and quadruplex assays revealed only a slightly higher sensitivity for the ERVA NSP3 target using the triplex format (p-value 0.008) while no significant differences were detected for other targets. This quadruplex RT-qPCR assay will significantly enhance rapid surveillance of both ERVA and ERVB circulating and emerging strains with potential for interspecies transmission.

Equid herpesvirus type 3 infection produces membrane-associated and secreted forms of glycoprotein G that are not required for efficient cell-to-cell spread of the virus in vitro.

The ORF 70 gene of equid alphaherpesvirus type 3 (EHV-3) encodes glycoprotein G (gG), which is conserved in the majority of alphaherpesviruses. This glycoprotein is located in the viral envelope and has the characteristic of being secreted into the culture medium after proteolytic processing. It modulates the antiviral immune response of the host by interacting with chemokines. The aim of this study was to identify and characterize EHV-3 gG. By constructing viruses with HA-tagged gG, it was possible to detect gG in lysates of infected cells, their supernatants, and purified virions. A 100-, 60-, and 17-kDa form of the protein were detected in viral particles, while a 60-kDa form was identified in supernatants of infected cells. The role of EHV-3 gG in the viral infection cycle was assessed by the construction of a gG-minus EHV-3 mutant and its gG-positive revertant. When growth characteristics in an equine dermal fibroblast cell line were compared, the plaque size and the growth kinetics of the gG-minus mutant were similar to those of the revertant virus, suggesting that EHV-3 gG does not play a role in direct cell-to-cell transmission or virus proliferation of EHV-3 in tissue culture. The identification and characterization of EHV-3 gG described here provide a solid background for further studies to assess whether this glycoprotein has a function in modulating the host immune response.

Equine Coital Exanthema: New Insights on the Knowledge and Leading Perspectives for Treatment and Prevention.

Equine coital exanthema (ECE) is a highly contagious, venereally-transmitted mucocutaneous disease, characterized by the formation of papules, vesicles, pustules and ulcers on the external genital organs of mares and stallions, and caused by equid alphaherpesvirus 3 (EHV-3). The infection is endemic worldwide and the virus is transmitted mainly through direct contact during sexual intercourse and by contaminated instruments during reproductive maneuvers in breeding facilities. The disease does not result in systemic illness, infertility or abortion, yet it does have a negative impact on the equine industry as it forces the temporary withdrawal of affected animals with the consequent disruption of mating activities in breeding facilities. The purpose of this review is to provide up-to-date relevant information on the knowledge of EHV-3 infection and to analyze new approaches on diagnostics, treatment and prevention in the interest of minimizing the negative consequences of ECE in light of the current situation of the equine industry.