柯萨奇B3病毒VP1序列变异与小儿中枢神经系统损害关系的探讨

Relationship between variation of coxsakievirns B3 VP1 sequence from cerebrospinal fluid of children and severity of damage to central nervous system

目的探讨柯萨奇B3（CoxB3）脑炎和脑膜炎患儿脑脊液中病毒VP1段基因和氨基酸序列变异与中枢神经系统损害的关系。方法肠道病毒通用引物扩增阳性的脑脊液标本再用VP1分型引物进行扩增、克隆、测序，VP1基因序列（450bp）结果通过NCBI网站上的BLAST程序进行翻译及比对。结果肠道病毒通用引物扩增阳性的73例患儿中，分型引物检测21例为CoxB3中枢神经系统感染。4例引起重型脑炎的CoxB3VP1段第856氨基酸位点上由谷氨酰胺变异为组氨酸；而引起轻型脑炎的其他3例CoxB3和引起脑膜炎的14例CoxB3的VP1基因序列均未发现规律性的氨基酸变异。4例重症脑炎患儿改良的Glasgow昏迷评分均小于7分，3例意识障碍时间均小于3d，1例脑萎缩明显的患儿，Glasgow昏迷评分4分，昏迷13．5d，留有严重的癫痫发作。结论本地区2005年夏、秋存在着CoxB3中枢神经系统感染的局部小流行，肠道病毒VP1氨基酸序列的变异可能是导致病毒的毒力增加及对中枢神经系统损害加重的主要原因。

Objective To investigate the possible relationship between variation of coxsakievirus B3 （CoxB3） VP1 sequence from cerebrospinal fluid of children with severe and mild central nervous system （CNS） infection and damage to CNS in children from Shandong province. Methods The enteroviruses were detected using VP1 typing and sequencing primer for enteroviruses from 73 enterovirus-infected cases confirmed by detection of cerebrospinal fluid by enteroviruses common primer. VP1 sequences （450 nucleotides） were determined and analyzed for 21 CoxB3 enteroviruses strains isolated in Qingdao and Binzhou, and were compared with that of BLAST search procedures from C, eneBank in NCBI. The variation of VP1 gene and amino acids sequence of CoxB3 enteroviruses was analyzed for severe and mild CNS infection. Results The nucleotide homogeneity of these CoxB3 appeared to be 97% -99%, however, the homogeneity among different genotypes were 83% -76%. Replacement of glutamine by histidine at amino acid locus 856 of VP1 CoxB3 was found in 4 cases with severe encephalitis. There were different variation in VP1 nucleotide sequence of CoxB3 in 3 cases with mild encephalitis and 14 cases with meningitis, but amino acids sequences had no regular variation. The modified Glasgow＇s coma score was below 7 in all the 4 cases with severe encephalitis. Of these 4 cases, 3 had consciousness disturbance for less than 3 days. Lethargy, restlessness and psychiatric symptoms were major manifestations, of whom 3 also had dysphagia, 1 had eneephalatrophy obviously, Glasgow＇s coma score was 3, deep coma lasted for 9 days, and had concomitant fatal epileptic attacks. Of these 4 cases, 2 completely recovered, 1 had high muscle tone, 1 remained under anti-epileptic drug treatment at follow-up 6 months later. Conclusion There were a small epidemic of CoxB3 CNS infection in children in 2005 in this area. The amino acid variation of CoxB3 VP1 possibly caused increased viral virulence and caused damage to CNS.