Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
Vet Res. 2021 May 8;52(1):67. doi: 10.1186/s13567-021-00941-x.
Mycoplasma hyopneumoniae (M. hyopneumoniae) is one of the primary agents involved in the porcine respiratory disease complex, economically one of the most important diseases in pigs worldwide. The pathogen adheres to the ciliated epithelium of the trachea, bronchi, and bronchioles, causes damage to the mucosal clearance system, modulates the immune system and renders the animal more susceptible to other respiratory infections. The pathogenesis is very complex and not yet fully understood. Cell-mediated and likely also mucosal humoral responses are considered important for protection, although infected animals are not able to rapidly clear the pathogen from the respiratory tract. Vaccination is frequently practiced worldwide to control M. hyopneumoniae infections and the associated performance losses, animal welfare issues, and treatment costs. Commercial vaccines are mostly bacterins that are administered intramuscularly. However, the commercial vaccines provide only partial protection, they do not prevent infection and have a limited effect on transmission. Therefore, there is a need for novel vaccines that confer a better protection. The present paper gives a short overview of the pathogenesis and immune responses following M. hyopneumoniae infection, outlines the major limitations of the commercial vaccines and reviews the different experimental M. hyopneumoniae vaccines that have been developed and tested in mice and pigs. Most experimental subunit, DNA and vector vaccines are based on the P97 adhesin or other factors that are important for pathogen survival and pathogenesis. Other studies focused on bacterins combined with novel adjuvants. Very few efforts have been directed towards the development of attenuated vaccines, although such vaccines may have great potential. As cell-mediated and likely also humoral mucosal responses are important for protection, new vaccines should aim to target these arms of the immune response. The selection of proper antigens, administration route and type of adjuvant and carrier molecule is essential for success. Also practical aspects, such as cost of the vaccine, ease of production, transport and administration, and possible combination with vaccines against other porcine pathogens, are important. Possible avenues for further research to develop better vaccines and to achieve a more sustainable control of M. hyopneumoniae infections are discussed.
猪肺炎支原体（M. hyopneumoniae）是猪呼吸道疾病综合征的主要病原体之一，是全球范围内对猪最重要的疾病之一。该病原体附着在气管、支气管和细支气管的纤毛上皮上，导致黏膜清除系统受损，调节免疫系统，使动物更容易感染其他呼吸道感染。发病机制非常复杂，尚未完全了解。细胞介导的和可能的黏膜体液免疫反应被认为对保护很重要，尽管感染动物不能迅速从呼吸道清除病原体。全世界经常接种疫苗来控制 M. hyopneumoniae 感染及其相关的生产性能损失、动物福利问题和治疗成本。商业疫苗大多是肌肉内注射的菌苗。然而，商业疫苗提供的保护作用有限，不能预防感染，对传播的影响也有限。因此，需要开发新型疫苗以提供更好的保护。本文简要概述了 M. hyopneumoniae 感染后的发病机制和免疫反应，概述了商业疫苗的主要局限性，并回顾了已在小鼠和猪中开发和测试的不同实验性 M. hyopneumoniae 疫苗。大多数实验性亚单位、DNA 和载体疫苗都是基于 P97 黏附素或其他对病原体生存和发病机制很重要的因素。其他研究集中在菌苗与新型佐剂结合。尽管减毒疫苗可能具有很大的潜力，但很少有研究致力于开发减毒疫苗。由于细胞介导的和可能的黏膜体液免疫反应对保护很重要，新疫苗应该针对这些免疫反应。选择适当的抗原、给药途径和佐剂类型以及载体分子对于成功至关重要。此外，疫苗的成本、生产、运输和管理的便利性以及与其他猪病原体疫苗的可能结合等实际问题也很重要。讨论了进一步研究开发更好疫苗和实现更可持续控制 M. hyopneumoniae 感染的可能途径。
