Molecular Detection and Genetic Characteristics of Equine Herpesviruses 1 and 4 in Egypt

The present study investigated the molecular detection and genetic characteristics of equine herpesvirus 1 (EHV‐1) and EHV‐4 circulating within Egyptian horse populations during 2019–2022. A total of 79 animals were sampled (54 nasal swabs and 25 aborted fetal tissues). PCR assays revealed that 24 (30.3%) and 7 (8.8%) samples were positive for EHV‐1 and EHV‐4, respectively. Additionally, 5 (6.3%) samples were concurrently infected with both viruses. Four EHV‐1 and three EHV‐4 isolates were genetically characterized based on partial sequencing of gB gene. The four EHV‐1 strains displayed 100% nucleotide identity to one another and to EHV‐1 reference strains reported in Egypt and other countries. The three EHV‐4 strains were phylogenetically classified into two distinct clusters based on their nucleotide sequences (76%–100% identity). Meanwhile, their deduced amino acid sequences differed by only one amino acid substitution. Our results underscore the critical importance of EHV‐1 and EHV‐4 as primary contributors of abortion and respiratory illness in horses and highlight the need for further large‐scale surveillance and in‐depth characterization studies to improve our understanding of these viruses’ epidemiology in Egypt and to develop a robust control strategy.