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Item Studies on the vaccination of sheep against Brucella ovis infection : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University(Massey University, 1986) Bailey, Karen MarieA study was made of the efficacy and adverse effects of an inactivated Brucella ovis saline-in-oil vaccine administered either once or twice by either the subcutaneous or the intraperitoneal route. Seven Brucella ovis isolates from various sources, including the two used in the manufacture of the Brucella ovis vaccine, were subjected to Bacterial Restriction Endonuclease Analysis and no genetic differences were found. It was concluded that there is probably only one strain of the organism. It was found that rams vaccinated by the subcutaneous route in the neck invariably developed a palpable inflammatory lesion at the site of injection. The lesions had a mean diameter of approximately 3cm, about one-third of them discharged, and the majority persisted for at least one year after vaccination. These lesions were chronic granulomatous inflammatory reactions arranged around droplets of the oily Brucella ovis vaccine. The intraperitoneal route of vaccination has been advocated in the past as a way of avoiding visible lesions. Necropsy of vaccinated animals revealed that in over 50% of cases, at least some of the vaccine administered by this technique failed to reach the cavity and was deposited either beneath the parietal peritoneum or between the muscles of the abdominal wall. Regardless of the site of deposition, however, the vaccine always provoked a chronic granulomatous inflammation of the tissues with which it came into contact. Changing from a subcutaneous to an intraperitoneal vaccination technique merely moved the reaction to a site where it was less visible. Serological studies using the Brucella ovis complement fixation test, gel diffusion test and enzyme linked immunosorbent assay demonstrated a consistent difference in the antibody response of rams vaccinated by the subcutaneous technique in comparison with those vaccinated by the intraperitoneal technique. Those vaccinated by the subcutaneous route generally developed antibody titres more rapidly and often had higher peak titres. In the same way, animals vaccinated twice by either route generally had greater and more persistent antibody titres than those vaccinated once by the same method. The differences in the serological response of rams to different vaccination techniques vere reflected by similar differences in resistance to experimental infection. The administration of an inactivated Brucella ovis saline-in-oil vaccine by any of the techniques studied significantly increased resistance to challenge by the intravenous route. However, two spaced doses of vaccine appeared to be more effective than a single dose, and the subcutaneous technique appeared to be more effective than the intraperitoneal method. Using intravenous inoculation, the number of bacteria required to infect 50% of unvaccinated animals was estimated to be 9.5 x 104 organisms. The administration of a single dose of vaccine by the intraperitoneal technique raised that figure to approximately 6.7 x 106, and the administration of two doses of vaccine by the subcutaneous route raised it to approximately 6.8 x 107. A viable count of the number of Brucella ovis bacteria present in the semen of an infected ram showed that at least 3 x 109 organisms could be excreted in a single ejaculate. This was over 31,000 times the number required to infect 50% of unvaccinated rams after intravenous inoculation and 44 times that required to infect 50% of animals vaccinated twice by the subcutaneous route. There is therefore a real possibility that natural challenge through homosexual activity may result in the infection of even vaccinated rams. It vas concluded that if vaccination is to be used as a means of controlling the spread of ovine brucellosis, a programme of two doses of vaccine administered at an interval of at least four weeks should he employed. The second dose of vaccine should be administered at least four weeks before the anticipated period of risk. If this method of control is adopted, a palpable lesion at the site of injection which is likely to persist for over a year should be expected. It should also be understood that rams vaccinated in this way may not be totally resistant to Brucella ovis and may still become infected.Item Studies on Brucella ovis infection in deer : a thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Clinical Science at Massey University, Palmerston North, New Zealand(Massey University, 2002) Ridler, Anne LisaBrucella ovis was first identified in the New Zealand farmed deer population in 1996 but little was known about the disease in deer. These experiments were undertaken to investigate the epidemiology, pathophysiology and diagnosis of B. ovis infection in deer. In addition, B. ovis isolates from commercial rams and stags were strain typed by pulsed-field gel electrophoresis. Transmission of infection was demonstrated from infected rams to stags grazing in the same paddock, suggesting that the initial source of infection for deer in New Zealand was likely to have been from rams. Transmission between stags did not occur after shifting non-infected stags into paddocks immediately vacated by infected stags, or after grazing non-infected stags in a paddock adjacent to infected stags over a five and a half month period. This suggests that the risk of transmission of B. ovis by the environment or indirect deer to deer contact is low. Stags became infected with B. ovis after experimental inoculation of the conjunctival, nasal and rectal mucous membranes. Behavioural observations identified that stags in all-male groups interact by mounting, sniffing the prepuce and perineum and spraying fluid from an extruded penis, which are considered high risk for the transmission of B. ovis. It was established that while stags are initially as susceptible to B. ovis infection as rams the majority of stags stop shedding B. ovis in semen within 11 months of infection, suggesting resolution of infection. In contrast, all rams remained infected with B. ovis and shed the organism in semen for at least 21 months. During the B. ovis shedding phase of infection, the majority of stags produced semen that had poor sperm motility and morphology and contained large numbers of leukocytes and cellular debris. However, following cessation of shedding stags produced semen that had good sperm motility and morphology, although leukocytes were still present. The sensitivity of the commercially available serological tests at detecting infection in deer was 100% during the early stages of the disease but after 60 to 100 days of infection, their sensitivity decreased to 30 to 70%. In contrast, the sensitivity in rams over a 630-day period was 100%. Detection of lesions of epididymitis by scrotal palpation of stags was an insensitive method of diagnosing infection. Stags infected with B. ovis developed lesions in the epididymes, seminal vesicles and ampullae similar to those reported in rams. In the early stages of the infection, lesions in stags were severe but in more chronic infections the lesions were mild. Vaginal inoculation of hinds immediately prior to mating resulted in no measurable adverse effects on reproduction, suggesting the disease is of little significance in hinds. Stags that mated vaginally-infected hinds became infected, demonstrating venereal transmission of the organism. Pulsed-field gel electrophoresis of B. ovis isolates revealed the presence of two strain types of B. ovis in the New Zealand farmed sheep and deer populations. Cervine isolates from two naturally-occurring cases of B. ovis in stags were different strain types. This confirmed that the two cases were unrelated, again highlighting the importance of rams in the epidemiology of this disease in deer