Abstract
Simple SummaryEquine herpesvirus 9 (EHV-9) is a virus belonging to the family of equine herpesviruses. EHV-9 has been isolated from natural infections of different wild and zoo animals. In addition, it has been associated with encephalitis and abortion in several animal species. However, the host range and pathogenesis of this virus are still unknown. Herein, we investigated the underlying pathogenesis of EHV-9-induced abortion in relation to the gestation period in either early or late trimester infection. We noticed that the late trimester infection of EHV-9 was associated with more severe death and both placental and fetal tissue localization of the virus. Also, early stage infection was accompanied by band necrotic changes within the placenta, which usually led to abortion.This study aimed to follow the time-course pathogenesis of EHV-9 abortion in early and late trimesters. Twenty-seven pregnant hamster dams were divided into three groups: (G1) control, (G2) EHV-9-inoculated on the 5th day (early trimester), and (G3) EHV-9-inoculated on the 10th day of gestation (late trimester). Dams were sacrificed at different time points during gestation and examined for viremia and viral DNA in different fetal and maternal tissues and pathological changes in fetal tissue, placenta, and cytokines. Animals in G3 showed a marked increase in the number of dead fetuses than those in G2. Histopathological findings of G2 showed early band coagulative necrosis of maternal spaces and stromal decidual cells. Necrotic changes were observed within the decidua basalis, spongiotrophoblast layer, and labyrinth. First, the virus was localized within mononuclear leukocytes in the decidua capsularis and basalis, and within the necrotic chorionic villi and cervical epithelium. G3 demonstrated degenerative changes within the chorionic villi and trophospongium. The virus antigen was observed within the chorionic villi, trophoblasts, mononuclear cells, and fetal tissues. In conclusion, EHV-9 induced abortion mostly occurs through necrosis of the chorionic villi and cannot cross through the capsular placenta in the early trimester but can through the developed decidual placentation.
Highlights
Equine herpesvirus 9 (EHV-9) is the newest member of the family of equine herpesviruses belonging to the subfamily Alphaherpesvirinae genus Varicellovirus
Dams inoculated with EHV-9 in the early trimester rapidly progressed to neurological signs consisting of tremor and convulsions with paddling as well as nasal discharge and ruffled fur at the third dpi (Figure 1a)
This study investigated the time-course of EHV-9 infection in EHV-9 during gestation may potentially impact the breeding of many effects domestic animals, as it is pregnant hamsters in has the early and laterange trimesters to follow the pathogenesis of abortioneffects induced known that the virus a wide host
Summary
Equine herpesvirus 9 (EHV-9) is the newest member of the family of equine herpesviruses belonging to the subfamily Alphaherpesvirinae genus Varicellovirus. The virus was isolated from Thomson’s gazelles (Gazella Thomsoni) that died in a Japanese zoo from fulminated encephalitis. It was called gazelle herpesvirus 1 (GHV-1) but later was renamed EHV-9 due to its close genetic homology to other members of the equine herpesvirus family [1,2]. To equine herpesvirus 4 (EHV-4), based on analysis of the glycoprotein G and the conserved region of glycoprotein B gene sequences [1]. Intranasal inoculation was the most common method of virus administration in the experimental studies; a strong affinity of EHV-9 for the olfactory system as the site of viral replication has been observed in all animals experimentally expressing encephalitis [11,13]
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