Mycoplasma gallisepticum (MG) is an important pathogen of poultry worldwide, causing chronic respiratory disease in chickens and turkeys. MG ts-304 is a GapA positive clone recovered from Vaxsafe MG (strain ts-11) that has been shown to be safe in chickens when delivered by the eye drop route to 3-week-old specific-pathogen-free chickens and to confer protection against challenge at 4 weeks after vaccination, as measured by tracheal mucosal thickness and air sac lesion scores. In this study, specific pathogen-free chickens (SPF) were vaccinated with a single dose of the MG ts-304 vaccine (10^6.0 colour changing units) at 3 weeks of age and experimentally challenged by aerosol with the virulent M. gallisepticum strain Ap3AS at 40, 48 and 57 weeks after vaccination. There were no significant differences in tracheal mucosal thickness 2 weeks after challenge between chickens challenged at the three time points, or between the vaccinated birds after challenge and unvaccinated/unchallenged control birds. Thus there was clear evidence that the immunity conferred by vaccination with the MG ts-304 vaccine resulted in significant protection against tracheitis in chickens that extended to, but was highly likely to exceed, 57 weeks after vaccination and that similar long term protective immunity could be expected to be conferred by a vaccine dose lower than that used in this study.

鸡毒支原体（MG）是全世界家禽的重要病原体，在鸡和火鸡中引起慢性呼吸道疾病。MG ts-304是从Vaxsafe MG（ts-11菌株）中回收的GapA阳性克隆，已显示在通过滴眼剂途径递送至3周龄无特定病原体的鸡中并赋予鸡安全性通过气管粘膜厚度和气囊损伤评分来衡量，在接种疫苗后4周免受攻击。在这项研究中，在3周龄时，给特定的无病原体鸡（SPF）接种了单剂量的MG ts-304疫苗（10 ^6.0变色单位），并通过有毒的鸡毒支原体进行了气溶胶攻击疫苗接种后40、48和57周应接种Ap3AS菌株。在三个时间点被攻击的鸡之间，或在攻击后接种疫苗的鸡与未接种疫苗/未接种疫苗的对照鸡之间，在攻击后两周，气管粘膜厚度没有显着差异。因此，有明确的证据表明，接种MG ts-304疫苗所赋予的免疫力可有效预防鸡的气管炎，这种病可延长至但很可能超过疫苗接种后57周，而且类似的长期保护性免疫力可能是预期疫苗剂量低于本研究中的剂量。