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对分离于我国首例iVDPV病例的Ⅱ型脊髓灰质炎病毒分离株的基因特征进行了研究。随机选择CHN9230-F3-Ⅱ株为研究对象,将其VP1区RT-PCR产物连接到T载体上进行克隆,随机挑选45个阳性克隆进行序列测定后获得45条VP1区核苷酸序列,这45条序列的VP1基因与昆明Ⅱ型疫苗株VP1基因差异13~24个核苷酸,变异率为1.44%~2.66%。45条序列在同源进化树图上分为3组,但都来源于CHN9230-F3-Ⅱ株,组成以优势株为主的相关突变株的病毒群,是典型的居群样存在形式。经RT-PCR后直接进行序列测定,并根据序列图中优势峰判读结果得到的CHN9230-F3-Ⅱ株核苷酸序列位于序列数量最多的第2组中,然而没有任何一条序列与之完全相同,说明它可能并不能代表具体的某一种序列,而只能是代表主序列具有的一般特征。3个组中的核苷酸序列与Ⅱ型疫苗株相比平均变异率分别为97.50%、97.93%和98.31%,根据脊灰病毒的进化率和3个组VP1区核苷酸序列的变异率推测,患者共5次服脊灰减毒活疫苗(OPV)史中的前3次OPV中的Ⅱ型疫苗病毒存活下来,依照疫苗接种顺序,分别形成了第1组、第2组和第3组的病毒居群样存在形式。我国Ⅱ型iVDPV以复杂的居群样形式存在,由于其进化速率较快并且感染了免疫缺陷患者,使其在该患者体内形成了持续性感染,它已经并可能将在更长的时间内在患者体内持续存在,一旦将来我国停止使用OPV后,iVDPV病例长期持续向外环境中排毒将对我国“维持无脊灰”带来严峻的挑战。
The genetic characteristics of poliovirus type Ⅱ isolates isolated from China in the first case of iVDPV were studied. We randomly selected CHN9230-F3-Ⅱ strain as the research object, cloned its VP1 region RT-PCR product to T vector and randomly selected 45 positive clones to obtain 45 VP1 region nucleotide sequences. VP1 gene of the sequence differs from the VP1 gene of Kunming type Ⅱ vaccine by 13-24 nucleotides, with a mutation rate of 1.44% -2.66%. The 45 sequences were divided into three groups on the homologous phylogenetic tree, but all of them originated from the CHN9230-F3-Ⅱ strain, which constituted the virus group of the related mutants mainly dominated by dominant strains, which was a typical population-like existent form. The nucleotide sequence of CHN9230-F3-Ⅱ strain was sequenced directly by RT-PCR and the nucleotide sequence of CHN9230-F3-Ⅱ strain was located in the second group with the largest number of sequences according to the interpretation of the dominant peak in the sequence diagram, however, none of the sequences was exactly the same , Indicating that it may not represent a specific sequence, but only on behalf of the main sequence has the general characteristics. The average mutation rates of the three nucleotide sequences in the three groups were 97.50%, 97.93% and 98.31%, respectively. According to the evolution rate of poliovirus and the mutation rate of the nucleotide sequence of VP1 in three groups Presumably, the patients survived a total of 5 doses of the Type II vaccine virus in the first three OPVs of the live attenuated poliovirus (OPV) episode and, in accordance with the vaccination sequence, formed Groups 1, 2, and 3 Group of virus population exists as a form of existence. Our country type II iVDPV exists as a complex population-like form that, due to its rapid rate of evolution and its ability to infect immunodeficient patients, causes a persistent infection in the patient that has, and may will, be resolved over a longer period of time in patients The persistence of the body, once the future stop using OPV in our country, iVDPV cases long-term continuous detoxification to the outside environment will pose a serious challenge to our country to “maintain polio.”