Asia Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary & Agricultural Sciences, The University of Melbourne, Werribee, Victoria, 3030, Australia.
Asia Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary & Agricultural Sciences, The University of Melbourne, Werribee, Victoria, 3030, Australia.
Vet Microbiol. 2019 Apr;231:48-55. doi: 10.1016/j.vetmic.2019.02.029. Epub 2019 Feb 22.
Mycoplasma synoviae (MS) is a major pathogen of poultry globally, causing chronic respiratory disease and arthritis. Vaccination is an effective means for the control of the disease. The MS-H vaccine is an attenuated strain developed through chemical mutagenesis of an Australian field strain, 86079/7NS. Analysis of whole genome of MS-H and its comparison with that of 86079/7NS has revealed a frameshift mutation early in a gene (oppF) that codes for an oligopeptide transporter permease, OppF. Monospecific antibodies raised against peptides upstream and downstream of the mutation in OppF revealed that only N-terminus of the OppF was expressed in MS-H while the full version was expressed in 86079/7NS. Also, examination of the recombinant N- (OppF-N) and C termini (OppF-C) of OppF, upstream and downstream of the mutation site respectively, as well as the full length OppF in Western immunoblotting experiments showed that serum from MS-H vaccinated chicken strongly bound OppF-N while serum from 86079/7NS challenged chicken detected OppF, OppF-N and OppF-C. The potential of the recombinant OppF, OppF-N and OppF-C to discriminate antibody responses to MS-H reisolates with wild or vaccine type OppF was assessed against 88 chicken sera in indirect ELISA and ratios were calculated between optical densities (OD) over those obtained in MS major membrane protein MSPB ELISA. Comparison of the OD ratios revealed that the MSPB/OppF and MSPB/OppF-C OD ratios of the sera against isolates with vaccine type OppF were significantly higher than those against isolates with wild type OppF. These results are in accordance with oppF gene mutation in MS-H and confirms that MS-H does not express OppF beyond the frame shift mutation found in its oppF gene. Also, the indirect ELISA based on OppF-C in combination with the MSPB has the potential to differentiate between MS-H and field strain antibody responses.
滑液支原体（MS）是全球家禽的主要病原体，可引起慢性呼吸道疾病和关节炎。疫苗接种是控制该疾病的有效手段。MS-H 疫苗是通过对澳大利亚田间株 86079/7NS 进行化学诱变而开发的减毒株。对 MS-H 的全基因组分析及其与 86079/7NS 的比较表明，在编码寡肽转运体透酶的基因（oppF）的早期发生了移码突变。针对突变上下游肽的单特异性抗体表明，只有 MS-H 表达 OppF 的 N 端，而 86079/7NS 则表达全长版本。此外，在 Western 免疫印迹实验中检查突变位点上下游的重组 N 端（OppF-N）和 C 端（OppF-C）以及全长 OppF 时，发现 MS-H 疫苗接种鸡的血清强烈结合 OppF-N，而 86079/7NS 攻毒鸡的血清则检测到 OppF、OppF-N 和 OppF-C。在间接 ELISA 中，用 88 份鸡血清评估了重组 OppF、OppF-N 和 OppF-C 区分具有野生型或疫苗型 OppF 的 MS-H 再分离株抗体反应的潜力，并计算了在 MS 主要膜蛋白 MSPB ELISA 中获得的 OD 值与 OD 值的比值。比较 OD 比值表明，针对具有疫苗型 OppF 的分离株的血清的 MSPB/OppF 和 MSPB/OppF-C OD 比值明显高于针对具有野生型 OppF 的分离株的血清。这些结果与 MS-H 中的 oppF 基因突变一致，并证实 MS-H 不会在其 oppF 基因中发现的移码突变之外表达 OppF。此外，基于 OppF-C 的间接 ELISA 与 MSPB 相结合，具有区分 MS-H 和田间株抗体反应的潜力。
