Potential Outbreak in Brazil by Equine Herpesvirus Type 2 (EHV-2): Detection, Clinical and Genetic Analysis of Equine Gammaherpesvirus 2

Abstract

Equine herpesvirus (EHV) commonly affects horses causing neurologic and respiratory symptoms beside spontaneous abortions, meaning huge economic losses for equine industry worldwide. In foals the virus can facilitate secondary infections by Rhodococcus equi, important in morbidity and mortality in equines. A total of five genotypes of EHV were previously described in Brazil including EHV-1, EHV-2, EHV-3, EHV-4 and EHV-5. EHV-2 genotype had only been previously described in Brazil in asymptomatic animals. We report the dead of 11 foals in Middle-west region of Brazil showing respiratory and neurological symptoms, as well as several abortions in mares from the same farm. Laboratory exams revealed neutrophilia leukocytosis. Necroscopic and histopathologic findings were suppurative bronchopneumonia and ulcerative enteritis. Molecular assays point to the absence of the bacteria Rhodococcus equi and other EHV. The presence of EHV-2 DNA was confirmed by sequencing in serum sample from one foal. This is the first confirmed outbreak of EHV-2 causing disease in Brazilian horses with confirmed presence of the virus. EHV-2 has been neglected and could be highlight the important role of EHV-2 in equine respiratory disease and spontaneous abortions in equid in Brazil. Author SummaryEquid herpesvirus type 2 (EHV-2), a gammaherpesvirus, has been neglected and can cause respiratory infection, abortion and in extreme cases neurologic symptoms and dead.Outbreaks of EHV-2 never was described in Brazil and can be critical to losses in equid industry. Our report provides evidence for a direct link between the EHV-2 strain and the outbreak in foals. We proved the clinical, histopathological and phylogenetic analysis of segment of EHV-2 polymerase.In summary, our study confirm that Gammaherpesvirus 2 is circulating in Brazil and the EHV-2 is a cause of the first outbreak in foals showing the important role of EHV-2 in equid respiratory disease.

Equine coital exanthema caused by equid alphaherpesvirus 3: a report of an outbreak in northeastern Brazil

“…Another types of herpesvirus are known causing distinct diseases and clinical signs in horses: equid alphaherpesvirus 1 (EHV-1), genus Varicellovirus, causing abortions in mares and also keratoconjunctivitis, encephalomyelitis, and neonatal pneumonia (Léon et al 2008, Dubale 2017, Estima-Silva et al 2019, Dunuwille et al 2020; equid gammaherpesvirus 2 (EHV-2), genus Percavirus, that has been found in horses with keratoconjunctivitis, gastroesophageal ulcers, and chronic throat lesions (Agius & Studdert 1994, Kershaw et al 2001, Cicolo et al 2019, Taulescu et al 2021; equid alphaherpesvirus 4 (EHV-4), genus Varicellovirus, an important cause of acute and fatal rhinopneumonithis in fowls and occasionally associated with equine abortions (Crabb & Studdert 1995, Gerst et al 2003; and equid gammaherpesvirus 5 (EHV-5), genus Percavirus, the cause of a severe and progressive syndrome of pulmonary fibrosis in adult horses (Verryken et al 2010, Williams et al 2013, Marenzoni et al 2015, Gulati et al 2019. A sixth virus, equid alphaherpesvirus 9 (EHV-9), genus Varicellovirus can cause subclinical encephalitides in horses, but until to date the disease was described just under experimental conditions (Hussey et al 2021).…”