TDK conference 2013

Equid herpesvirus 5 (EHV-5) is one of the eleven herpesviruses that have the potential to naturally infect equids. EHV-5 belongs to the Gammaherpesvirinae subfamily as a member of the Percavirus genus. A group of viruses from the Herpesviridae family are well known pathogenes causing very severe diseases both in adult and young horses, they occur frequently and have a worldwide distribution, in contrast the occurrence and the potential pathogenic role of EHV-5 is still undefinde. EHV-5 was first isolated from horses in quarantine in 1970 Australia, with clinical signs of upper respiratory tract disease. Since then EHV-5 has been detected in healthy and clinically affected horses from- all over the world, but more recently in the past twenty years. Based on recent studies there is also increasing evidence that there is a strong association between EHV-5 infection and the development of a newly described disease called equine multinodular pulmonary fibrosis (EMPF). The aim of our study was to estimate the prevalence of EHV-5 in Hungarian horse populations, and to detect the virus in samples from both healthy and clinically affected horses. We have collected 92 bronchoalveolar lavage fluid (BALF) samples (in 5 cases nasal swabs and PBL samples alsow) from horses referred to the University’s Large Animal Clinic, nasal swabs peripheral blood leukocyte (PBL) and BALF samples from a herd of 20 Lippizaners, nasal swabs PBL and BALF samples from 11 mixed breed show jumping horses, nasal swabs and PBL samples from a group of 16 warmblood show jumping horses. We have investigated the presence of EHV-5 nucleic acid in these samples by polymerase chain reaction (PCR) with the use of virus specific primers. Altogether 139 horses were involved in the study, and in 24 (17.3%) horses equid herpesvirus-5 nucleic acid was identified in at least one of the investigated samples. From the positive group 11 (45.8%) horses had chronic respiratory signs, three of them were diagnosed with EMPF based on histologic results of lung biopsy specimens or post-mortem tissue samples. Two other horses suffered of suspected EMPF based on thoracic radiograpy with nodular interstitial pattern, EHV-5 positivity and intranuclear inclusion bodies. The results of the study indicate that EHV-5 is relatively widespread in Hungary. In the background of EMPF, however, further factors besides EHV-5 infection may play significant role.