Abstract: The risk of respiratory disease in the transported horse can increase as a consequence of immunosuppression and stress associated primarily with opportunistic bacterial proliferation and viral reactivation. This study examines the ecology of equid herpesviruses (EHV) in these horses, exploring reactivation and changes in infection and shedding associated with transport, and any potential contributions to transport-related respiratory disease. Twelve horses were subjected to an 8-h road-transport event. Antibodies to EHV-1 and EHV-4 were detected by ELISA in serum collected prior to, immediately after and 2 weeks post transport. Respiratory tract endoscopy and tracheal washes were collected prior to and 5 days after transportation. Nasal swabs collected prior to, immediately after, 1 and 5 days following transport were screened for EHV-1,-2,-4,-5 using qPCR. Six horses had persistent neutrophilic airway infiltrates post transportation, indicative of subclinical respiratory disease. No horses were qPCR positive for either of the alphaherpesviruses (i.e., EHV-1/-4) nor did any seroconvert to either virus. Four out of nine horses positive for either EHV-2 or EHV-5 on qPCR prior to transport developed neutrophilic airway inflammation. Five horses showed increasingly positive readings on qPCR (i.e., reduced Cq) for EHV-2 after transportation and seven out of eleven horses positive for EHV-2 after transport shared strains of high sequence similarity with other horses in the study. One EHV-2 virus detected in one horse after transport was genetically different which may be due to reactivation. The clinical significance of EHV-2 and EHV-5 remains in question. However these results indicate that transportation may lead to increased shedding, transmission and reactivation of EHV-2 and EHV-5 but not EHV-1/-4. Unlike previous work focusing on the role of alphaherpesviruses, this research suggests that investigation of the gammaherpesviruses (i.e., EHV-2/-5) in transport-related disease should not be dismissed, particularly given that these viruses can encode suppressive immunomodulators that may affect host health.
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The study investigates the impact of transportation on horses’ health, particularly concerning the reactivation and progression of equid herpesviruses (EHV), which are potentially contributing to transport-related respiratory illnesses.
Objective of the Research
This study aims to examine the effect of transportation on the behaviour of equid herpesviruses (EHV) in horses. It seeks to understand EHV’s reactivation and how changes in its infection and shedding could contribute to transport-associated respiratory diseases.
Methodology
Twelve horses were subjected to an 8-hour road-transport event, and samples were then collected at various stages, including before, immediately after, and two weeks post-transport.
Serum samples were screened for antibodies against EHV-1 and EHV-4 using enzyme-linked immunosorbent assay (ELISA).
Respiratory tract endoscopy and tracheal washes were analysed before and 5 days after transport.
Nasal swabs, collected at key stages of the study, were tested for EHV-1, -2, -4, -5 using quantitative PCR.
Key Findings
Six out of twelve horses exhibited persistent neutrophilic airway infiltrates after transport, indicative of subclinical respiratory disease.
None of the horses tested positive for alphaherpesviruses (EHV-1/-4), nor was there any seroconversion observed.
Four out of nine horses testing positive for either EHV-2 or EHV-5 prior to transport developed neutrophilic airway inflammation.
Transportation increased the shedding and reactivation of EHV-2 and EHV-5 but not EHV-1/-4.
The detected EHV-2 and EHV-5 strains shared high sequence similarity amongst transported horses, suggesting transmission via transport.
One horse developed a genetically different strain of EHV-2 post-transport, possibly the result of reactivation.
Conclusion
The importance of EHV-2 and EHV-5 in transport-related diseases cannot be overlooked, given that these viruses can produce suppressive immunomodulators potentially affecting host health.
The study does not fully clarify the clinical significance of EHV-2 and EHV-5 but highlights the transportation-related increase in virus shedding, transmission, and reactivation.
Unlike previous studies that chiefly focused on alphaherpesviruses, this research emphasizes the need to investigate gammaherpesviruses’ role (EHV-2 and EHV-5) in transport-related illnesses.
Cite This Article
APA
Muscat KE, Padalino B, Hartley CA, Ficorilli N, Celi P, Knight P, Raidal S, Gilkerson JR, Muscatello G.
(2018).
Equine Transport and Changes in Equid Herpesvirus’ Status.
Front Vet Sci, 5, 224.
https://doi.org/10.3389/fvets.2018.00224
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