Contagious bovine pleuropneumonia (CBPP) caused by vaccine strain T1/44 of Mycoplasma mycoides subsp. mycoides SC

A study was carried out on four adult cattle to assess the pathogenicity of Mycoplasma mycoides subsp. mycoides SC strain T1/44, currently used as a vaccine for the control of contagious bovine pleuropneumonia (CBPP) in Namibia. Post mortem examination 9 weeks after endobronchial inoculation of the vaccine strain to three of the four animals revealed unilateral pleuropneumonic lesions, pleuritis and well-developed sequesters in two of the three inoculated animals and several small sequesters surrounded by pleuropneumonic lesions in the diaphragmatic and apical lobes in one animal. The fourth animal, which was not directly inoculated but was in close contact with the inoculated animals, revealed only an adhesion area of the lung to the ribcage. Serological examination carried out using the complement fixation test (CFT) detected positive titres in all three intubated animals and the indirect CBPP-LppQ-ELISA was positive for two of the three inoculated animals. The contact animal showed no seroconversion. M. mycoides subsp. mycoides SC was isolated from the sequesters of two of the inoculated animals. Isolation of mycoplasmas was not possible from the third inoculated animal due to heavy contamination of the samples by other bacteria, but the presence of M. mycoides subsp. mycoides SC could be evidenced by PCR from clinical samples. The identity of the T1/44 vaccine strain isolated from the sequesters of two animals was confirmed by T1/44-specific PCR analysis and by IS1296 typing using Southern blot. These results clearly show that inoculation of T1/44 vaccine via the endobronchial route can lead to CBPP.     

追忆国际卓越小麦育种家拉贾拉姆

拉贾拉姆博士从事小麦育种研究50多年,在布劳格博士创立的国际小麦育种的基础上,实现了CIMMYT小麦育种全球化,主要贡献包括四个方面:(1)大规模开展冬春杂交,在产量、抗性和适应性等方面取得了重大进展;(2)将慢锈性理念系统融入小麦育种项目,成功培育并在全世界推广高产慢病性品种;(3)耐酸性土壤和耐旱育种方面取得了显著...