台灣地區鴨小病毒與鵝小病毒之抗體力價調查與病毒在病禽體內之分佈研究

Abstract

鴨、鵝小病毒（muscovy duck parvovirus and goose parvovirus）之感染在台灣水禽的疾病中屬於相當重要的疾病，除了導致幼禽的高死亡率之外，還會使成禽的生長情形變差，造成經濟上的損失。由於目前並無快速診斷方式及有效疫苗可供應用，使此項疾病成為本省潛在的水禽疾病危機，因此本實驗主要在於瞭解此病毒於水禽體內之分佈情形及本省水禽血清中之抗體力價，希望能協助對於疫情之控制。本研究首先收集並增殖近年來台灣地區發生之鴨、鵝小病毒株，分別以0.2 ml劑量，以點眼、點鼻方式攻毒，再利用PCR (polymerase chain reaction)方法，檢測採取臟器之病毒存在與否，以瞭解此病毒在不同臟器之分佈情形。結果發現，攻正蕃鴨小病毒之土蕃鴨，於攻毒第二週病毒在臟器中出現，部位在胸腺、鼻竇、食道及肝臟等部位。另一方面，本研究利用大腸桿菌表現系統 (pET32系統)，表現出具抗原性之NS1蛋白，並發現以40 ng之NS1塗鍍於plate上所構築之ELISA (enzyme linked immunosorbent assay)套組檢測效果最佳，之後將收集自全省之水禽血清以此技術檢測，以探討本省水禽鴨、鵝小病毒之感染狀況。結果發現以離島的地區之血清抗體力價最低，推測主要原因為地理隔絕因素影響，使離島地區（含金門、馬祖）罹患此病之機率降低。另一可能因素為農民傳統施打被動免疫方式已因流行時間漸遠而漸被忽略，使得台灣行政區南部（含嘉義、台南、高雄、屏東）出現較高之血清力價。本研究所建立之重組NS1蛋白之ELISA技術應可作為診斷本省鴨、鵝小病毒感染之重要輔助工具。

Infections of Muscovy duck parvovirus (MDPV) and goose parvovirus (GPV) are important diseases of waterfowls in Taiwan. These diseases not only lead to a high mortality in ducklings and goslings, but also cause growth retardation of adult birds and economic losses. Because no effective vaccination and rapid diagnosis method is available, these diseases impose a potential risk on waterfowls in Taiwan. The goal of this study is to understand the distribution of GPV and MDPV in infected birds, and to understand the antibody titers of GPV and MDPV in geese and ducks in Taiwan. We first collected and propagated GPV and MDPV isolated from recent years in Taiwan. We then infected mule ducks by GPV or MDPV by intranasal inoculation of 0.2 ml allantoic fluids containing GPV or MDPV. We examined the presence of virus in the infected birds by PCR. We found that viruses were present in the thymus, sinus nasalis, esophagus, and liver in the second week after infection. We also used E. coli expression system (pET32 system) to express the antigenic NS1 protein of GPV and MDPV. We found that ELISA plates coated with 40 ng of recombinant NS1 per well gave the best result for the detection of antibody against GPV and MDPV. By this ELISA, we examined the antibody titers against GPV and MDPV in sera collected from different areas of Taiwan. We found that the titer is low in birds from isolated islands (Kingman and Machu), probably due to the geographical separation of these islands from Taiwan. In comparison, the titer is relatively high in southern counties of Taiwan (Jaiyi, Tainan, Kaoshun, and Pington), probably because the conduction of traditional vaccination program has been disregarded in recent years. We conclude that the recombinant NS1 ELISA established in this study might save as an important tool for the diagnosis of GPV and MDPV infections in Taiwan.