背景:我们研究了生物标志物,在多雨和炎热的热带条件下,用溶血分枝杆菌血清型A2实验攻击的接种和未接种的山羊的免疫应答和细胞变化。总共24名临床健康的人,没有怀孕,随机分为2组的雌性山羊,每组12只.每个季节的12只山羊被细分为三组(n=4),作为对照(G-NEG),未接种疫苗(G-POS),并接种疫苗(G-VACC)。在第1周,G-VACC接受2mL明矾沉淀的巴氏杆菌病疫苗,而G-POS和G-NEG接受2ml无菌PBS。在第2周,G-POS和G-VACC接受含有105CFU的溶血分枝杆菌血清型A2的1mL鼻内喷雾。接种后进行每日监测和每周出血八周,以使用商业ELISA测试试剂盒收集生物标志物和免疫反应的数据和血清。在实验结束时,对山羊进行人道安乐死,以收集肺和颌下淋巴结组织样品用于大体和组织病理学检查。
结果:无论季节如何,我们观察到急性时相蛋白(触珠蛋白,血清淀粉样蛋白A),促炎细胞因子(白介素-1β,白细胞介素-6),抗体(免疫球蛋白M,免疫球蛋白G),与G-VACC和G-NEG相比,G-POS山羊中的压力标记(皮质醇和热休克蛋白70)。关于季节,血清白细胞介素(IL)-1β的血清浓度显着(p<0.05)升高1.5、2和1倍,皮质醇,与炎热季节相比,雨季G-POS中的热休克蛋白(HSP)-70。G-POS山羊的肺组织病理学显示炎性细胞浸润,变性,出血/充血,和肺泡腔的肺水肿;间质增厚,细支气管上皮脱皮。淋巴结中的细胞变化的特征是G-POS山羊中明显的细胞过多。
结论:宿主对肺炎曼氏病的反应基于血清生物标志物水平的升高(皮质醇,与接种疫苗的山羊和对照组相比,在G-POS山羊的肺和淋巴结中看到的HSP70,IL-1β和IL-6)和严重的细胞变化受到雨季记录的高环境湿度的影响。雨季相对湿度的增加是热带地区山羊肺炎性曼氏病易感性和严重性较高的重要压力因素。建议在雨季开始之前使用明矾沉淀的多杀性巴氏杆菌疫苗对山羊进行疫苗接种,以最大程度地减少由于雨季期间肺炎的潜在爆发而导致的死亡率。
BACKGROUND: We investigated the biomarkers, immune responses and cellular changes in vaccinated and non-vaccinated goats experimentally challenged with M. haemolytica serotype A2 under
rainy and hot tropical conditions. A total of twenty-four clinically healthy, non-pregnant, female goats randomly allocated to 2 groups of 12 goats each were used for the study. The 12 goats in each season were subdivided into three groups (n = 4), which served as the control (G-NEG), non-vaccinated (G-POS), and vaccinated (G-VACC). In week-1, the G-VACC received 2 mL of alum-precipitated pasteurellosis vaccine while G-POS and G-NEG received 2 ml of sterile PBS. In week 2, the G-POS and G-VACC received 1 mL intranasal spray containing 105 CFU of M. haemolytica serotype A2. Inoculation was followed by daily monitoring and weekly bleeding for eight weeks to collect data and serum for biomarkers and immune responses using commercial ELISA test kits. The goats were humanely euthanised at the end of the experiments to collect lungs and the submandibular lymph nodes tissue samples for gross and histopathological examinations.
RESULTS: Regardless of the season, we have observed a significant (p < 0.05) increase in serum concentrations of acute-phase proteins (haptoglobin, serum amyloid A), proinflammatory cytokines (interleukine-1β, interleukin-6), antibodies (immunoglobulin M, immunoglobulin G), and stress markers (cortisol and heat shock protein 70) in the G-POS goats compared to G-VACC and G-NEG. With regards to seasons, there was a significantly (p < 0.05) higher serum concentration with 1.5, 2 and 1-folds increase in the serum interleukin (IL)-1β, cortisol, and heat shock protein (HSP)-70 in the G-POS during rainy compared to the hot season. Histopathology of the lungs in G-POS goats revealed inflammatory cell infiltration, degeneration, haemorrhage/congestion, and pulmonary oedema in the alveoli spaces; thickening of the interstitium, and desquamation of bronchiolar epithelium. Cellular changes in the lymph node were characterized by a marked hypercellularity in G-POS goats.
CONCLUSIONS: Host responses to pneumonic mannheimiosis based on increased serum levels of biomarkers (cortisol, HSP70, IL-1β and IL-6) and severe cellular changes seen in the lungs and lymph nodes of G-POS goats compared to vaccinated goats and control group are influenced by the high environmental humidity recorded in the
rainy season. Increased relative humidity in the
rainy season is a significant stress factor for the higher susceptibility and severity of pneumonic mannheimiosis of goats in the tropics. Vaccination of goats using the alum precipitated Pasteurella multocida vaccine before the onset of the
rainy season is recommended to minimise mortality due to potential outbreaks of pneumonia during the
rainy season.