發(fā)布時(shí)間：2018-11-06 09:22

【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(xì)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(qiáng)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(lái)困難。課題對(duì)廣西2014-2015年臨床發(fā)生的疑似病例進(jìn)行IBDV的分離鑒定,并利用實(shí)驗(yàn)室準(zhǔn)備的單因子血清在細(xì)胞培養(yǎng)上完成分離株的病毒中和試驗(yàn)。結(jié)果顯示,獲得的14個(gè)分離株全部屬于基因重組毒株即其基因組A、B節(jié)段來(lái)自不同類(lèi)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(duì)分離株中的代表GX151120進(jìn)行了克隆純化并對(duì)其全基因序列進(jìn)行了測(cè)定與分析。結(jié)果顯示,其A節(jié)段長(zhǎng)度為3 260nt,含有兩個(gè)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(zhǎng)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(jìn)化樹(shù)分析顯示,該毒株為重組毒株,即其A節(jié)段來(lái)源于vvIBDV-type,B節(jié)段與HLJ-0504同屬一個(gè)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(duì)結(jié)果顯示,A節(jié)段VP2高變區(qū)的特征性核苷酸位點(diǎn)為222A、256I、294I、299S、279D和284A,符合vvIBDV的特征。其B節(jié)段與中國(guó)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(duì)廣西地方品種雞進(jìn)行免疫試驗(yàn),結(jié)果證明雛雞1日齡孵化房免疫1次,仍然存在危險(xiǎn)期,2周齡的加強(qiáng)免疫有助于延長(zhǎng)抗體水平保護(hù)期,對(duì)于飼養(yǎng)期較長(zhǎng)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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