乳牛衣原体性流产的病原鉴定及免疫原性研究

对采自甘肃、陕西和宁夏奶牛场的发生不明原因流产乳牛病料进行了间接血凝试验(IHA)、PCR、病原分离鉴定和MOMP基因检测,证实病原为鹦鹉热衣原体(Chlamydia psittaci)。对分离株SX5和NX进行毒力稳定性和免疫原性测定,用鸡胚连传20代,SX5和NX株的毒力比较稳定,毒力效价分别为10-11ELD50和10-10ELD50;用这2株菌对小鼠和牛做免疫效力试验,结果显示,免疫鼠5/5和5/5保护,对照鼠0/5保护;免疫牛3/3和3/3保护,对照牛0/3保护。表明,SX5和NX株具有良好的免疫原性,可以作为疫苗研制的候选菌株。

Identification and immunogenicity of pathogen causing chlamydial abortion in dairy cows

The specimens sampled from aborted dairy cattle of unknown cause in Gansu,Shaanxi and Ningxia provinces had been diagnosed through IHA,isolation and identification of pathologic microorga-(nism) and detection of the MOMP gene.It was proved that the pathogen causing dairy abortions was Chlamydia psittaci.Virulence stabilities and immunogenicities of Chlamydia psittaci SX5 and NX isolates were detected,and the virulence titers of SX5 and NX isolates were 10~(-11)and 10~(-10) ELD_(50) through 20 successive passages in hen embryos,respectively.Immunogenicity of both isolates was examined using mouse model and cattle.The results showed that 5/5 and 5/5 mice of the immunized groups were protected from challenges by virulence strains SX5 or NX,but 0/5 mice of the control group.When calves were used,(3/3) and 3/3 calves of the immunized groups were protected but 0/3 calves of the control group.Virulence stability and immunogenicity tests showed that Chlamydia psittaci SX5 and NX isolates may serve as vaccine candidate strains.