Unmasking the ongoing challenge of equid herpesvirus- 1 (EHV-1): A comprehensive review

Equid herpesviruses (EHVs) are a group of highly impactful viral pathogens that affect horses, presenting a substantial risk to the global equine industry. Among these, equid herpesvirus-1 (EHV-1) primarily causes respiratory infections. However, its ability to spread to distant organs can lead to severe consequences such as abortion and neurological diseases. These viruses can enter a dormant phase, with minimal activity, and later reactivate to trigger active infections at any time. Recently, there has been a notable rise in the prevalence of a particularly devastating strains of EHV-1 known as equid herpesviral myeloencephalopathy (EHM). In the light of dynamic nature of EHV-1, this review provides a thorough overview of EHV-1 and explores how advances in viral biology affect the pathophysiology of viral infection. The information presented here is crucial for understanding the dynamics of EHV-1 infections and creating practical plans to stop the virus's global spread among equid populations.

Equine Herpesvirus-I Infection in Horses: Recent Updates on its Pathogenicity, Vaccination, and Preventive Management Strategies

Equine herpesvirus-1 (EHV-1) is one of the most common and ubiquitous viral pathogens infecting equines, particularly horses worldwide. The EHV-1 is known to induce not only humoral but also cellular immune responses in horses. Respiratory distress, abortion in pregnant mares, neurological disorders, and neonatal foal deaths represent EHV-1 infection. Despite the limited success of inactivated, subunit, live, and DNA vaccines, over the past few decades, vaccination remains the prime preventive option to combat EHV-1 infection in horses. However, current vaccines lack the potentiality to protect the neurological form of infections in horses. There is desperate necessity to search effectual EHV-1 vaccines that may stimulate not only mucosal and systemic cellular immunity but also humoral immunity in the horses. This review highlights the state of knowledge regarding EHV-1 biology, EHV-1 pathogenesis, and disparate vaccines studied in the past to prevent EHV-1 infection. The review also underlines the best management strategies which certainly need to be adopted by veterinarians in order to avoid and prevent EHV-1 infection and outbreak in horses in the future.

EHV-1: A Constant Threat to the Horse Industry

Equine herpesvirus-1 (EHV-1) is one of the most important and prevalent viral pathogens of horses and a major threat to the equine industry throughout most of the world. EHV-1 primarily causes respiratory disease but viral spread to distant organs enables the development of more severe sequelae; abortion and neurologic disease. The virus can also undergo latency during which viral genes are minimally expressed, and reactivate to produce lytic infection at any time. Recently, there has been a trend of increasing numbers of outbreaks of a devastating form of EHV-1, equine herpesviral myeloencephalopathy. This review presents detailed information on EHV-1, from the discovery of the virus to latest developments on treatment and control of the diseases it causes. We also provide updates on recent EHV-1 research with particular emphasis on viral biology which enables pathogenesis in the natural host. The information presented herein will be useful in understanding EHV-1 and formulating policies that would help limit the spread of EHV-1 within horse populations.

Failure to detect equid herpesvirus types 1 and 4 DNA in placentae and healthy new-born Thoroughbred foals

Equid herpesvirus type 1 is primarily a respiratory tract virus associated with poor athletic performance that can also cause late gestation abortion, neonatal foal death and encephalomyelopathy. Horizontal transmission is well described, whereas evidence of vertical transmission of equid herpesvirus type 1 associated with the birth of a healthy foal has not been demonstrated. This study sampled a population of Thoroughbred mares (n = 71), and their healthy neonatal foals and foetal membranes, to test for the presence of both equid herpesvirus types 1 and 4 using a quantitative polymerase chain reaction assay. Foetal membrane swabs and tissue samples were taken immediately post-partum, and venous blood samples and nasal swabs were obtained from both mare and foal 8 h after birth. Neither equid herpesvirus type 1 nor equid herpesvirus type 4 nucleic acid was detected in any sample, and it was concluded that there was no active shedding of equid herpesvirus types 1 and 4 at the time of sampling. Consequently, no evidence of vertical transmission of these viruses could be found on this stud farm during the sampling period.