The Egyptian Arabian horse is one of the oldest and most popular horse breeds in the world. No previous efforts have been done to investigate the existence and prevalence of EHV infections in these precious horses. In this report, ninety three clinical samples were collected from a cohort of Arabian horses located in Cairo, Egypt. Screening of the clinical samples for the presence of EHV antigens by cell-ELISA utilizing a polyclonal antibody pool against EHV-1, 2, and 4 identified 34 (36.56%) positive samples. Virus-specific semi-nested PCR assays were used for typing the positive samples. Three samples were found positive for EHV-1, seventeen for EHV-2, seven for EHV-4, one was a mixed infection of EHV-1 and EHV-4, and six did not produce any amplification signal with all assays. Sequence analysis of the amplified semi-nested PCR products of representative EHV strains further confirmed the virus identity. This study is the first that outlines the involvement of EHV infections in Arabian horse diseases worldwide. Besides, it presents new data about the prevalence of EHVs in the Egyptian horse population.

Coronaviruses (CoVs) produce a wide spectrum of disease syndromes in different mammalian
and avian host species. These viruses are well-recognized for their ability to change tissue
tropism, to hurdle the interspecies barriers and to adapt ecological variations. It is predicted
that the inherent genetic diversity of CoVs caused by accumulation of point mutations and
high frequency of homologous recombination is the principal determinant of these competences. Several CoVs (e.g. Severe acute respiratory syndrome-CoV, Middle East respiratory
syndrome-CoV) have been recorded to cross the interspecies barrier, inducing different disease conditions in variable animal hosts. Bovine CoV (BCoV) is a primary cause of gastroenteritis and respiratory disease in cattle calves, winter dysentery in lactating cows and
shipping fever pneumonia in feedlot cattle. Although it has long been known as a restrictive
cattle pathogen, CoVs that are closely related to BCoV have been recognized in dogs, humans
and in other ruminant species. Biologic, antigenic and genetic analyses of the so-called
‘bovine-like CoVs’ proposed classification of these viruses as host-range variants rather
than distinct virus species. In this review, the different bovine-like CoVs that have been identified in domesticated ruminants (water buffalo, sheep, goat, dromedary camel, llama and
alpaca) and wild ruminants (deer, wild cattle, antelopes, giraffes and wild goats) are discussed
in terms of epidemiology, transmission and virus characteristics. The presented data denote
the importance of these viruses in the persistence of BCoV in nature, spread to new geographical zones, and continuous emergence of disease epidemics in cattle farms.