الفهرس 
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Abstract
Twenty five (25) New Zealand white rabbits, each of 2.7-3.0 kg body weight were used in this experiment. They were pregnant at the same time (synchronization) from 16-18 days of pregnancy and kept in cleaned and disinfected cages, fed on prepared ration and clean water was given continuously. Only twenty (20) pregnant female rabbits were inoculated with 1 ml BHV-1/IBR virus containing 105 TCID50 for each rabbit, while the remainder five pregnant female rabbits were kept as control and received 1 ml PBS for each one. All twenty pregnant female rabbits received IBR virus with the same dose and at the same time through intranasal route. The inoculated twenty rabbits were then divided into four groups according to the stage of pathogenesis developed on them due to inoculating IBR virus. The stages of pathogenesis were then divided into: Feverish stage: ranged from 1-3 days post inoculation. Symptomatic stage: ranged from 4-9 days post inoculation. Convalescent or recovery stage: ranged from 10-20 days post inoculation. Latent or recrudescence stage: ranged from 21-30 days post inoculation, by injection of dexamethazone (DXM) for five successive days by I/M route and noticed the results of injection for another five successive days act as immunosuppressive for reactivation of BHV-1/IBR virus on recovered female rabbits during our experiment. All pregnant female rabbits (20) showed clinical manifestations differed from one female to another due to individual resistance. These clinical manifestations include fever, ocular and nasal discharges, rapid respiration, anorexia, depression and slight corneal opacity. Abortion was the important symptom noticed on inoculated female rabbits which proceeded with bleeding during feverish stage. We noticed marked emaciation and exhausted female rabbits (in moribund status) and two female rabbits were died after injection of dexamethazone material for reactivation of BHV-1/IBR virus (latent stage). The mostly affected organs during gross examination of sacrificed female rabbits especially during course of symptomatic stage were trachea, lung, liver, spleen and kidney. These organs showed great pathological alteration due to affection with IBR virus. The histopathological findings during symptomatic stage revealed: (a) interstitial pneumonia, sever congestion and emphysema of lungs, (b) multifocal to diffuse areas of necrosis affected liver with mononuclear infiltration, (c) hyperplastic proliferation of lymphoid follicles of spleen and (d) sever coagulative necrosis with mononuclear cells infiltration of kidneys. The attempts for isolation of IBR virus on MDBK cells were succeeded with most of collected blood samples, swabs and tissue organs from inoculated female rabbits during different stages of pathogenesis. Nasal and ocular swabs were suitable for isolation of IBR virus during different stages of pathogenesis, while vaginal swabs were suitable during abortion only. Also, lung, liver, spleen and kidney were ready for the same purpose. The indirect fluorescent antibody technique as well as immunoperoxidase staining technique were used for identification of IBR virus on MDBK cells during the pathogenesis of the virus within the inoculated female rabbits. Nasal swabs and lung tissues recorded the highest titre of IBR virus (104) TCID50, while pharyngeal swabs, trachea and uterus gave the lowest titre (101) TCID50 from inoculated female rabbits.