The pathogenicity and immune effects of different generations of on chicken embryos.

1. (MS) is the primary causative agent of synovitis in avian species. In order to investigate the pathogenicity and immunological responses associated with MS in specific pathogen-free chicken embryos, a series of generations (F1, F95, F120, F160 and F200) of MS were introduced into 7-day-old SPF chicken embryos and subsequent mortality rates were recorded and analysed2. Reverse transcription-quantitative polymerase chain reaction was performed to detect expression of heat shock proteins HSP27, HSP40, HSP60, HSP70 and HSP90 and inflammatory factors interleukin in the tracheal tissue.3. The results showed that the mortality rate of SPF chicken embryos decreased with an increase in the number of passages, with the highest being 80% (8/10) for F1 generation and the lowest being 10% (1/10) for F200. The expression of and showed a significant downregulation trend with an increase in the generation (except ;  < 0.05). The expression was significantly upregulated with increasing generations ( < 0.05).4. A relationship between pathogenicity and the number of passages was observed and the decrease in pathogenicity appeared to be associated with and genes related to inflammatory factors. The present work offers a scientific foundation for screening potential MS strains that might be employed to develop attenuated vaccines.