【摘要】：傳染性法氏囊病(infectious bursal disease,IBD)是由雙RNA病毒科禽雙RNA病毒屬傳染性法氏囊病毒(infectious bursal disease virus,IBDV).引起的一種急性、溶淋巴細胞性疾病。IBDV有四種致病型(pathotypes),即經(jīng)典毒力株(classicalIBDV,cIBDV)及其致弱疫苗毒株(attenuated IBDV,attIBDV)、超強毒株(very virulent IBDV,vvIBDV)以及抗原變異株(variant IBDV,vIBDV)。它們的致病性和抗原性均存在許多差異,這給疾病的防控帶來困難。課題對廣西2014-2015年臨床發(fā)生的疑似病例進行IBDV的分離鑒定,并利用實驗室準備的單因子血清在細胞培養(yǎng)上完成分離株的病毒中和試驗。結(jié)果顯示,獲得的14個分離株全部屬于基因重組毒株即其基因組A、B節(jié)段來自不同類型毒株,其中11株的A節(jié)段屬于vvIBDV-type分支、B節(jié)段屬于HLJ-0504-type分支,1株(141203)A節(jié)段屬于vvIBDV-type分支、B節(jié)段為新的分支,1株(14007)A節(jié)段屬于attIBDV-type分支、B節(jié)段屬于HLJ-0504-type分支,1株(140021)A節(jié)段屬于中等毒力分支、B節(jié)段為新的分支;血清學(xué)鑒定則表明,它們均屬于血清Ⅰ型亞型1。課題對分離株中的代表GX151120進行了克隆純化并對其全基因序列進行了測定與分析。結(jié)果顯示,其A節(jié)段長度為3 260nt,含有兩個完整的閱讀框架 ORF A1 和 ORFA2,ORF A1 范圍 131nt-3 169nt,ORF A2 范圍97nt-534nt,分別編碼VP2-VP4-VP3和VP5蛋白;B節(jié)段長度為2 827nt,閱讀框范圍112nt-2751nt,編碼VP1蛋白,兩節(jié)段均未發(fā)生堿基的缺失和插入;遺傳進化樹分析顯示,該毒株為重組毒株,即其A節(jié)段來源于vvIBDV-type,B節(jié)段與HLJ-0504同屬一個分支。A節(jié)段核苷酸相似性分析顯示,它與vvIBDV的重組株HLJ-0504的相似性最高(98%),B節(jié)段核苷酸相似性也是與HLJ-0504的最高(98.4%)。核苷酸序列比對結(jié)果顯示,A節(jié)段VP2高變區(qū)的特征性核苷酸位點為222A、256I、294I、299S、279D和284A,符合vvIBDV的特征。其B節(jié)段與中國分離株HLJ-0504、GX、Harbin-1等屬于基因Ⅱ亞群,該分離毒株的220R具有特異性,不同于其他參考毒株的220K。課題還選用不同市售的IBD疫苗對廣西地方品種雞進行免疫試驗,結(jié)果證明雛雞1日齡孵化房免疫1次,仍然存在危險期,2周齡的加強免疫有助于延長抗體水平保護期,對于飼養(yǎng)期較長的地方品種而言免疫兩次更合適。
[Abstract]:Infectious bursal disease (infectious bursal disease,IBD) is a kind of infectious bursal virus (infectious bursal disease virus,IBDV) belonging to double RNA virus, avian double RNA virus. IBDV has four pathogenic types of (pathotypes),: classical virulent strain (classicalIBDV,cIBDV) and attenuated vaccine strain (attenuated IBDV,attIBDV), supervirulent strain (very virulent IBDV,vvIBDV, and antigenic variant strain (variant IBDV,. VIBDV). There are many differences in pathogenicity and antigenicity, which makes it difficult to prevent and control diseases. IBDV was isolated from suspected cases in Guangxi in 2014-2015, and the virus neutralization test of the isolated strain was carried out in cell culture using single-factor serum prepared by laboratory. The results showed that all of the 14 isolates belonged to the recombinant gene strain, that is, the B segment of the genome was from different types of virus strains. The A segment of 11 strains belonged to the vvIBDV-type branch, and the B segment belonged to the HLJ-0504-type branch. One strain (141203) A belongs to vvIBDV-type branch, B segment is new branch, one strain (14007) A segment belongs to attIBDV-type branch, B segment belongs to HLJ-0504-type branch, 1 strain (140021) A segment belongs to medium virulence branch. Segment B is a new branch; Serological identification showed that they all belong to serotype 鈪，

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