Limsatanun Arithat, Sasipreeyajan Jiroj, Pakpinyo Somsak
Avian Health Research Unit, Department of Veterinary Medicine, Faculty of Veterinary Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
Avian Dis. 2016 Dec;60(4):799-804. doi: 10.1637/11437-051716-Reg.
Mycoplasma gallisepticum (MG) is one of the major pathogens that cause respiratory signs in the poultry industry. To control MG infection, vaccination is the useful procedure. In this study, MG vaccine was developed by using the local Thai MG isolate (AHRL 20/52). Chitosan, a polysaccharide adjuvant derived from crustaceans, has been successfully used in various vaccines. The objectives of this study were to prepare MG bacterins by using chitosan, serving as an adjuvant, to determine protection against the field Thai MG isolate and to evaluate tissue reaction at the injection site. Six groups of 6-wk-old layers (20 birds/group) were intramuscularly vaccinated with bacterin containing various concentrations of chitosan (0.25, 0.5, and 1%), a commercially available MG bacterin, respectively. Sham-negative and sham-positive controls were included in the experiment. Six weeks postvaccination, all groups excluding the negative control were intratracheally challenged with 100 μl of 10 colony-forming units of Thai MG isolate (AHRL 58/46). At 1, 2, 3, and 4 wk postchallenge, five birds from each group were euthanatized and necropsied to determine the gross and histopathologic lesions. For a tissue reaction study, three groups of 24 birds each including sham negative control, 0.5% chitosan bacterin and commercial vaccine were given as previously described. At 1, 2, and 3 wk postvaccination, 8 birds from each group were randomly selected to euthanatize, necropsy, and determine the gross lesions, and 3 out of 8 birds were randomly selected to determine the histopathologic lesions. The results demonstrated that prepared bacterins induced lower numbers of positive antibody birds compared to the commercial vaccine, but groups receiving bacterin containing 0.5 and 1% chitosan exhibited significantly lower tracheal lesions than the positive control and commercial vaccine groups (P < 0.05). Chitosan formulation caused less tissue reaction than the commercial vaccine. These results demonstrated that the prepared MG bacterins could effectively reduce MG-induced pathologic lesions and that chitosan could be used as adjuvant in MG bacterins.
鸡毒支原体（MG）是家禽业中引起呼吸道症状的主要病原体之一。为控制MG感染，疫苗接种是一种有效的方法。在本研究中，利用泰国当地的MG分离株（AHRL 20/52）研制了MG疫苗。壳聚糖是一种源自甲壳类动物的多糖佐剂，已成功应用于多种疫苗。本研究的目的是使用壳聚糖作为佐剂制备MG菌苗，确定其对泰国野外MG分离株的保护作用，并评估注射部位的组织反应。将6组6周龄蛋鸡（每组20只）分别肌肉注射含有不同浓度壳聚糖（0.25%、0.5%和1%）的菌苗、一种市售MG菌苗。实验中包括假阴性和假阳性对照。疫苗接种6周后，除阴性对照外的所有组均经气管内接种100 μl含10个菌落形成单位的泰国MG分离株（AHRL 58/46）。攻毒后1、2、3和4周，每组处死5只鸡并进行剖检，以确定大体和组织病理学病变。为进行组织反应研究，按照之前描述的方法，每组24只鸡分为3组，分别为假阴性对照、0.5%壳聚糖菌苗组和市售疫苗组。疫苗接种后1、2和3周，每组随机选取8只鸡处死、剖检并确定大体病变，从这8只鸡中随机选取3只确定组织病理学病变。结果表明，与市售疫苗相比，制备的菌苗诱导产生阳性抗体的鸡数量较少，但接受含0.5%和1%壳聚糖菌苗的组气管病变明显低于阳性对照和市售疫苗组（P < 0.05）。壳聚糖制剂引起的组织反应比市售疫苗少。这些结果表明，制备的MG菌苗可有效减少MG引起的病理病变，壳聚糖可作为MG菌苗的佐剂。
