【摘要】 布氏菌猪二号菌种是一株在人工培养基上长期移植传代而自然变弱的菌种,用豚鼠测毒时,它所产生的脾脏含菌量与牛型19号菌种所产生的相近似,而比强毒猪型菌种产生的约低100～500倍。给怀孕猪皮下注射本菌种的500亿活菌,不引起流产,而注射强毒猪型菌种的5～15万个菌,即可引起流产或正产排菌;给性成熟公猪皮下注射500亿活菌,在体内活存不到45天,而注射强毒猪型菌种的10万个菌,经过45天剖检,仍有35～67％器信出菌。可见猪二号菌种对其天然宿主的毒力比性毒猪型菌种低30～100万倍以上。猪二号菌种的弱毒性在易感动物体内是稳定的。连续通过豚鼠5代,怀孕猪4代、怀孕绵羊5代和怀孕山羊4代,毒力都不增强。猪二号菌种对豚鼠和非怀孕羊具有较好的免疫原性。更多还原

【Abstract】 Brucella suis strain 2 is an old laboratory strain which was attenuated naturally after serial transfer on media for years.It shares all of the characteristics of Br.suis biotype I and is of smooth type.The virulence of the strain is a little higher than that of strain 19,but much lower than that of the pathogenic strain of Br.suis.When injected in large doses of about 10~9 live cells into guinea pigs,strain 2 gave a spleen count of about 2×10~4-6×10~4 organisms at 14-15 days after injection, strain 19 gave about 1×10~4-5×10~4,Ray.I gave about 12×10~4-14× 10~4 and Br.suis pathogenic strain 1330,strain 12 and strain 14 gave about 280×10~4-4200×10~4 Inoculation of pregnant sows with 50×10~9 live cells of strain 2 did not cause abortion or infected parturition,whereas inoculation with 5×10~4-15×10~4 cells of a virulent strain of Br.suis always did so.In boars inoculated with 18.6×10~9 live cells of strain 2 and killed 45 days after injection,no brucella was recovered from their lymph nodes and internal organs examined,whereas in those inoculated with about 10~5 organisms of a pathogenic strain of Br.suis,39-60% of their lymph nodes and organs yielded brucella. The avirulent property of Br.suis strain 2 was found to be stable when inoculated into susceptible animals.After passaging 5 times in guinea pigs,5 times in pregnant sheep,4 times in pregnant goats,4 times in pregnant sows or 5 times in boars,the virulence of the strain remained unchanged as evidenced by the fact that the spleen count it gave in guinea pigs remained at the same level as the stock culture gave. Br.suis strain 2 is able to provoke a good immunity in guinea pigs and goats.In 4 experiments,39 guinea pigs were vaccinated with strain 2,26 were vaccinated with strain 19,22 were controls.Forty-five days after vaccination,they were challenged with a virulent strain of Br. melitensis and 30 days later they were killed.Bacterial cultures were made of lymph nodes an internal organs and the infection indexes (No.of organs infected/No.of organs cultured×100)of the vaccinated and the control groups were calculated.It was found that the infection indexofthe strain 2 vaccinated group was 6.5 only,of the strain 19 group 28.2,and of the control group 88.9.Good results were obtained from goats also.In two experiments,12 goats were vaccinated with Strain 2,3 were vacci- nated with strain 19,8 were controls.Three months after vaccination they were challanged with Br.melitensis and 45 days later they were killed for bacteriological examination.The strain 2 vaccinated group showed an infection index of 4.9%,the strain 19 group showed 13.3%,the control group showed 38.9%.strain 2 gave the better protection against Br. melitensis infection.更多还原