不同基因型豬瘟病毒抗原性之比較

Abstract

豬瘟為豬隻的高度傳染性疾病，常會造成感染豬隻的死亡。針對台灣從1993到2001年分離到之豬瘟病毒分析其E2核酸序列，可將台灣之豬瘟病毒分為本土型 (subgroup 3.4) 及外來型 (subgroup 2.1)，並發現1996年之後在田間已由外來型病毒完全取代本土型豬瘟病毒。我們懷疑不同型病毒間抗原性的差異可能扮演部分角色而導致病毒間的天然置換現象，因此本實驗針對不同基因型之豬瘟病毒E2醣蛋白進行抗原性之分析。利用昆蟲桿狀病毒 (Baculovirus) 表現系統表現豬瘟病毒不同基因型 ( subgroups 1.1、2.1 及3.4 ) 之E2醣蛋白，共產生十二株重組病毒，利用X-gal染色及間接螢光染色法決定重組病毒力價，顯示力價介於107.3 到108.1 TCID50/ml之間，且病毒間之增殖曲線相似。昆蟲細胞感染重組病毒後所表達的蛋白可由間接螢光染色法及西方墨點法偵測。使用不同之抗E2單株抗體將表達的蛋白作間接螢光染色分析，顯示不同病毒株之E2醣蛋白對單株抗體的反應程度有差異。

Classical swine fever (CSF), also known as hog cholera, is caused by classical swine fever virus (CSFV) and is an economically important and highly contagious disease of pigs. Analysis of the E2 sequences of CSFVs from field outbreaks in Taiwan during 1993 to 2001 showed that the viruses could be divided into historical subgroup (subgroup 3.4) and exotic subgroup (subgroup 2.1). Analysis also showed that, in the field conditions, there has been a switch in CSFV populations from subgroup 3.4 to 2.1 after 1996. To further investigate whether the differences of antigenicity among various CSFVs subgroups were the reasons for this switch, antigenicities of E2 glycoprotein from various subgroups isolated in Taiwan were analyzed. In this study, E2 glycoprotein from subgroups 1.1, 2.1 and 3.4 were expressed by using baculovirus expression system. The twelve recombinant baculoviruses were titrated with indirect fluorescent assay (IFA) and X-gal staining, showing that the titers obtained by both tests were located within a range of 107.3~108.1 TCID50/ml. The one-step replication curves of these recombinant viruses also showed that the replication characteristics of these viruses were similar. Proteins expressed in infected insect cells were detected by IFA and Western blot. The antigenicity of various domains in E2 from three subgroups was analyzed by using five MAbs against different epitopes and strains showing that these expressed proteins could be differentiated by their variable intensities of fluorescence.