Prevalence of Nasal Shedding of Equid Gammaherpesviruses in Healthy Swiss Horses

Multiplex real-time PCR for the detection and differentiation of equid gammaherpesvirus 2 and 5

Equid gammaherpesvirus 2 (EHV-2) and 5 (EHV-5) are widely distributed in the equines. Although their pathogenic potential is not yet fully understood, they appear to play a role in disease patterns like equine multinodular pulmonary fibrosis. In this study, a multiplex real-time PCR (rtPCR) was designed to detect DNA of the glycoprotein H (EHV-2) and E11 gene (EHV-5). Analytical specificity was determined by testing DNA of other herpesviruses by SYBR Green rtPCR and melting curve analysis, as well as Sanger sequencing of positive field samples. Analytical sensitivity was assessed by standard curve generation of serial plasmid dilutions containing the respective target gene. Melting curves and BLAST analysis of the sequences indicated specific detection of the viruses. The lower limit of detection of the singleplex rtPCR was 40 and 29 DNA copies per reaction for EHV-2 and EHV-5, respectively. Comparison of the Ct values of a selection of positive field samples showed only minimal differences between the singleplex and the multiplex assay. The here described multiplex rtPCR protocol allows sensitive and specific detection of EHV-2 and EHV-5. It represents a convenient and rapid tool for future studies to investigate the clinical relevance of EHV-2 and EHV-5 in more detail.

Molecular detection of equid herpesvirus in bronchoalveolar lavage fluid from asymptomatic horses in Southern Brazil

Background and Aim

Molecular approaches to diagnose respiratory viruses have provided an opportunity for early and subclinical pathogen detection, particularly in samples from the upper respiratory tract. This study aimed to investigate the presence of herpesviruses, particularly equid herpesvirus (EHV)-2 and EHV-5, in samples from the lower respiratory tract of healthy racehorses from Southern Brazil.

Materials and Methods

Samples from the lower respiratory tract (i.e., bronchoalveolar lavage fluid [BALF]) were assessed by video endoscopy, cytological evaluation of BALF, and tracheal aspirates (TA), along with quantitative polymerase chain reaction (qPCR), to detect equine herpesvirus infection in the lower respiratory tract samples and compare corresponding cytological and endoscopic findings.

Results

At least one abnormality per horse during endoscopy examination was observed, including, but not limited to, mucous secretion in the airways and pharyngeal lymphoid hyperplasia. The presence of EHV-2 and/or EHV-5 was detected by qPCR in 3/10 animals. One horse was positive for EHV-2 alone, one for EHV-5 alone, and one for both.

Conclusion

To the authors' knowledge, this is the first molecular detection of EHV-2 and EHV-5 in Brazilian thoroughbred horses. These findings may provide new insights into the epidemiology of EHV-2 and EHV-5 in Brazilian horses, evidencing the importance of the molecular investigation, early detection, and prevention of respiratory diseases.