|摘要: ||雞傳染性支氣管炎(Infectious bronchitis, IB)為雞隻重要呼吸道疾病，高發生率及低致死率，死亡主要由二次性細菌感染所引發，造成家禽產業重大經濟損失。本病多以活毒疫苗防疫，但疫苗在各血清型間之交叉保護效力受限制，而肉雞飼養時間短，以抗生素預防二次性感染，又有公共衛生及停藥期之考量。因此，本試驗擬探討口服人類重組干擾素-α (rhIFN-α)對於雞隻免疫之調控，進而評估對抗雞傳染性支氣管炎(Infectious bronchitis virus, IBV)感染的效益。免疫調控試驗選用三週齡商用肉雞，飼料添加不同劑量rhIFN-α (10及1000 IU rhIFN-α/ kg.bw/日)，於連續投與3天及7天後進行白血球表現型及功能分析。結果顯示rhIFN-α顯著提升淋巴細胞對分裂原刺激之增殖能力，但對於PBMC中淋巴次族群之改變則有程度不等的調降或調升現象，其中CD8+ T 細胞在1000 IU rhIFN-α連續投與3天後具有正向調升作用。但在吞噬功能及自由基產生方面，則呈輕微負調控現象。IBV感染試驗亦選用商用肉雞，評估對於生長性能及病毒感染的影響，小雞於1週齡時依體重平均分配至4組，分別為10 IU rhIFN-α預防組(A組)，於感染前連續一週投予10 IU rhIFN-α/kg.bw/日；10,000 IU rhIFN-α治療組(B組)，於感染IBV隔天單次投予10,000 IU rhIFN-α/kg.bw/日；單純IBV感染之陽性對照組(C組)；及陰性對照組(D組)。A、B及C組雞隻於2週齡點眼接種IBV (4×105 EID50)，並於感染後1週全數犧牲，感染後每日觀察記錄臨床咳嗽指數，以及感染後一週之增重及採食量，評估氣管環纖毛受損情形，以即時定量聚合酶鏈鎖反應檢測肺臟與腎臟的病毒量，本試驗共重複進行3次。結果顯示預防組可改善飼料換肉率，延遲咳嗽發生時間及降低發病嚴重度。而治療組可輕微改善咳嗽症狀，此兩組在於組織病變及臟器之病毒複製量與陽性對照組未有顯著差異。綜合以上結果顯示雞隻口服10 IU rhIFN-α/kg.bw/日可提升淋巴細胞對分裂原刺激之增殖能力及CD8+ T細胞在血液中之相對量，但對吞噬細胞之功能則有負調控現象。口服rhIFN-α對於感染IBV雞隻之生長性能則有輕度提升效益，但對氣管組織傷害及抑制病毒複製則未有顯著影響，這些改變是否與物種間IFN-α交叉調控生物活性不同，投與劑量及投與時間有關，尚待進一步確認。因此，以人類IFN-α在田間作為雞隻之免疫調節劑應用，以對抗家禽病毒感染包括IBV感染之效益，尚待更多評估。|
Infectious bronchitis (IB) is one of the important respiratory diseases in chicken characterized by high morbidity and low mortality. The main cause of the death is triggered by secondary bacterial infection leading to the significant economic losses in poultry industry. In spite of the wide use of vaccines, outbreaks of the disease continue to occur in vaccinated flocks, due to less cross-protection of different serotypes. Additionally, broilers are raised in short time to market with considerations of public health and the withdrawal time of drugs, in which it was not right time to use antibiotics for preventing secondary infection. Therefore, the experiment was to investigate the immunoregulation of oral administration of recombinant human interferon-α (rhIFN-α) in chicken and the protective efficiency of rhIFN-α against IBV infection. The immunomodulant test was conducted on three-week-old commercial broilers that were oromucosally administered with different doses of rhIFN-α (10 and 1,000 IU of rhIFN-α/ kg.bw/ day) for 1 week and the lymphocyte phenotype and functional assays were evaluated at day 4 and 8 post treatment. The results indicated that oral administration of rhIFN-α could significantly enhance the lymphocyte proliferative capacity, but cause mild change in lymphoid populations of PBMC, especially in CD8+ subpopulation. In contrast, the phagocytosis and the generation of free radical of phagocytes were negatively regulated. The IBV infection test was conducted in commercial broilers. One week old chickens were body weight matched and randomly divided into 4 groups, rhIFN-α prevention group (10 IU rhIFN-α/ kg.bw/ day), rhIFN-α treatment group (1000 IU rhIFN-α/ kg.bw/ day), positive control group, and negative control group. Chickens were infected with IBV strain TW1 by ocular inoculation at 2 weeks old and sacrificed one week after infection. The clinical score of cough, feed intake and weight gain, tracheal lesion score, and virus loadings of the lung and kidney were evaluated. The infection tests were repeated in three separate trials. These results showed that the preventive treatment of rhIFN-α could slightly improve the feed conversion ratio and decrease the severity of coughing index. In contrast, one therapy treatment after IBV infection using high dosage of 10,000 IU/ kg.bw/ day of rhIFN-α could slightly alter the symptoms of cough and delay the onset of clinical sign. However, the histopathologic lesions of tracheal epithelium and viral loads in lung and kidney of both rhIFN-α treated groups were not significantly different from the positive control group. Taken together, these results suggested that the cross-immunregulation of rhIFN-α on chicken was not obvious as seen in mammalian. Due to less efficiency of cross regulation between human derived IFN and poultry immune system, the duration, times and dosages of administration on poultry need more assessment for further application.