Equine Herpes Virus 4 (EHV4) Investigation in Aborted Egyptian Mares; Molecular Detection, Isolation, and Phylogeny for Viral Glycoprotein B
Omnia Mohamed Khattab, Hala Kamel Abdelmegeed, Mohamed Mahmoud Mashaly, Mervat E. Hamdy, Naglaa M. Hagag, Ayman Hamed, Hanan Aly Fahmy, Essam H. Ibrahim, Momtaz A. Shahein, Elsayyad M. Ahmed
Abstract
An abortion outbreak was reported in horse studs, Egypt, in 2019. Investigating the role of EHV-4 in this abortion outbreak in mares using various molecular detection techniques were done using the tentative diagnosis by rt-PCR. The presence of 16 liver and spleen samples out of 20 (80%) from aborted fetuses were positive for EHV-4, but all were negative for EHV-1. Virus isolation trial for EHV-4 were done, eleven samples out of 20 (55%) on the CAM of ECE were positive. The virus glycoprotein B (gB) fragment (580pb) was amplified in selected isolates using the nested PCR (n-PCR), sanger sequencing of gB from three isolates with phylogenetic analysis reveals the full identity between the Egyptian isolates from the outbreaks and other EHV-4 strains available in databases proving wide distance with other EHV-8 and EHV-1. The study recommends rt-PCR as a screening test for the tentative diagnosis of EHV-4 in epidemiological studies and n-PCR as a sensitive differential test for the virus detection. The virological studies and molecular assays confirm the involvement of EHV-4 in equine abortion, suggests the possibility that latent virus reactivation in mares could result in abortion due to certain factors, including stress more epidemiological investigation. Whole-genome sequencing is required to address any genetic recombination in EHV-4 associated with abortion cases.