In order to isolate and identify Mycoplasma synoviae(MS),35 aseptic samples of joint cavity mucus and joint tissue from chickens suspected of MS infection were collected across various farms in Nanyang City.Through pathogen isolation,culture,colony observation,PCR identification,and sequencing,we successfully isolated MS strains.The results showed that the isolates were characterized by a distinct"fried egg"-like colony morphology on solid medium,and PCR analysis consistently amplified the 16S rRNA gene.Sequence alignment with the ATCC 25204 standard strain in the NCBI database revealed a high homology of over 99%,confirming the identity of MS.A total of 5 MS strains were isolated.ZP-1 strain was selected for an in-depth examination of its biological characteristics.Its growth titer was determined by Colour change unit(CCU)experiment,the level of hydrogen peroxide produced by metabolism was determined by kit,and its pathogenicity and immunogenicity were evaluated by animal experiments.The strain demonstrated a remarkable growth titer of up to 1012CCU/mL within 24-36 hours,highlighting its rapid growth and high yield.The ZP-1 strain also exhibited a significantly higher relative level of hydrogen peroxide production in the presence of glycerol compared to an attenuated vaccine strain,which may be indicative of its virulence.Further animal experiments confirmed the pathogenicity of the ZP-1 strain,as it induced typical MS symptoms in SPF chickens following foot pad and intravenous inoculation.Notably,an inactivated vaccine derived from the ZP-1 strain achieved an 80%protection rate upon subcutaneous administration and subsequent challenge,a rate that rivals that of commercial vaccines.In conclusion,ZP-1 strain not only exhibits a high growth titer(1012CCU/mL),but also marks the first instance where a correlation between hydrogen peroxide production and virulence has been established.The strain's demonstrated immunoprotective efficacy as an inactivated vaccine lays a robust groundwork for advancing future vaccine research and development.
Mycoplasma synoviaeisolation and identificationpathogenicityimmunogenicity
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