In the present study we tried to understand pathogenesis of equine herpes virus 9 (EHV-9) in pregnant animals through experimental infection of early and late pregnant Syrian hamsters which is considered the ideal experimental model for equidae. We described the clinical manifestations and tracked the viral load in different maternal tissues including blood, brain, uterus and placenta by using the absolute quantification technique of real time PCR. The viral load was expressed as the number of EHV-9 ORF30 gene copies and standardized against the house keeping hamster GAPDH gene. The viral load in the blood increased significantly at 6th day post infection regardless stage of infection, while it increased gradually in the brain tissue to reach maximum levels at late stages of pregnancy. In the other hand, the viral load in the uterine and placental tissues increased significantly in late trimester infected group than early trimester infected group. Clinical signs appeared on experimentally infected hamsters were very similar to that appeared in equines due to EHV-1 infection and it synchronically correlated to the viral load in different tissues. On the basis of our results we can conclude that clinical manifestations of EHV-9 are very similar to that of EHV-1 and its appearance is correlated to the increased viral multiplication in blood, brain, uterus and placental tissues of the infected animal.
EHV- 9, PCR, Viral load, EHV-1, Equine.