2009-2020年我国轮状病毒腹泻流行特征和基因型变化趋势

目的 了解2009-2020年我国全人群腹泻患者中轮状病毒感染者的流行特征和基因型变化趋势,为进一步开展腹泻监测和防控提供科学依据。方法 资料来源于国家科技重大专项传染病监测技术平台信息管理系统的我国28个省份252家哨点医院腹泻症候群监测数据,采用描述性流行病学方法分析2009-2020年轮状病毒腹泻病例在不同气候带地区、人群以及时间的分布特点及A组轮状病毒腹泻病例的基因分型特征和变化趋势。结果 2009-2020年共对114 606例腹泻病例进行轮状病毒检测,轮状病毒阳性率为19.1%（21 872/114 606）,阳性病例以A组轮状病毒为主（98.2%,21 471/21 872）。轮状病毒阳性率较高的年份分别为2009年（36.9%,2 436/6 604）和2010年（30.6%,5 130/16 790）,2011-2017年在14.0%~18.0%之间变化,2018年小幅上升（20.3%,2 211/10 900）,之后两年连续下降（15.5%,2 262/14 611和9.5%,470/4 963）。男性（20.2%,13 660/67 471）的轮状病毒阳性率明显高于女性（17.4%,8 212/47 135）;＜5岁婴幼儿的轮状病毒阳性率最高（28.4%,18 261/64 300）,是成年人的4倍以上。中温带、暖温带及亚热带地区的轮状病毒阳性率于12月至次年2月达高峰,而高原寒带存在2个高峰,分别出现在11月至次年1月及5-6月。2009-2020年A组轮状病毒优势基因型由G3P［8］、G1P［8］逐步发展为G9P［8］。结论 2009-2020年我国轮状病毒感染总体呈现下降趋势,呈明显的季节性流行,各年龄组人群阳性率差异较大,儿童腹泻仍是重点关注的问题,需进一步加强轮状病毒疫苗的接种,持续开展流行特征和基因型变化的监测。     

Characterization and Phylogenetic Analysis of Brazilian Chicken Anaemia Virus

Chicken anaemia virus (CAV) was detected by a Nested-PCR assay in field samples from different regions of Brazil. The 539 bp amplified fragments of vp1 gene from 44 field samples were sequenced and 10 new nucleotide sequences of CAV were observed. These sequences were phylogenetically analysed by Mega2 using neighbour joining distance methods with 1000 bootstrap replications. Phylogenetic analysis did not show correlation between CAV pathology pattern and genetic groups. The 10 nucleotide sequences of the Brazilian samples were also analysed together with 30 sequences of CAV strains previously described from other countries. The genetic variability observed was not related to the geographical distribution. Amino acid substitutions were detected at 9 positions of the Brazilian sequences and two of them had not been observed before, ⁶⁵R replacing the Q residue and ⁹⁸F replacing Y residue. The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers AY855079 to AY855088.     

Optimum two-stage designs in case–control association studies using false discovery rate

Genetic association studies using case–control designs are often done to identify loci associated with disease susceptibility. These studies are often expensive to perform, due to a large number of genetic markers. Several types of two-stage designs are proposed and used from the point of cost effectiveness. We proposed to control the false discovery rate for multiple-testing correction in two-stage designs, using optimal sample sizes and criteria for selecting markers associated with a disease in each stage to minimize the cost of genotyping. The expected power and cost of two-stage designs were compared with those of one-stage designs, under the assumptions that the genetic markers are independent and total sample size is fixed. The results showed that the proposed two-stage procedure usually reduced the cost of genotyping by 40–60%, with a power similar to that of the one-stage designs. In addition, the sample size and selection criteria, which are optimized parameters, are defined as a function of a prior probability that marker–disease association is true. So, the effects of mis-specification of a prior probability on efficiency were also considered.Aya Kuchiba and Noriko Y. Tanaka have contributed equally to this study.     

Relationships among porcine and human P[6] rotaviruses: evidence that the different human P[6] lineages have originated from multiple interspecies transmission events

Porcine rotavirus strains (PoRVs) bearing human-like VP4 P[6] gene alleles were identified. Genetic characterization with either PCR genotyping or sequence analysis allowed to determine the VP7 specificity of the PoRVs as G3, G4, G5 and G9, and the VP6 as genogroup I, that is predictive of a subgroup I specificity. Sequence analysis of the VP8* trypsin-cleavage product of VP4 allowed PoRVs to be characterized further into genetic lineages within the P[6] genotype. Unexpectedly, the strains displayed significantly higher similarity (up to 94.6% and 92.5% at aa and nt level, respectively) to human M37-like P[6] strains (lineage I), serologically classifiable as P2A, or to the atypical Hungarian P[6] human strains (HRVs), designated as lineage V (up to 97.0% aa and 96.1% nt), than to the porcine P[6] strain Gottfried, lineage II (<85.1% aa and 82.2 nt), which is serologically classified as P2B. Interestingly, no P[6] PoRV resembling the original prototype porcine strain, Gottfried, was detected, while Japanase P[6] PoRV clustered with the atypical Japanase G1 human strain AU19. By analysis of the 10th and 11th genome segments, all the strains revealed a NSP4B genogroup (Wa-like) and a NSP5/6 gene of porcine origin. These findings strongly suggest interspecies transmission of rotavirus strains and/or genes, and may indicate the occurrence of at least 3 separate rotavirus transmission events between pigs and humans, providing convincing evidence that evolution of human rotaviruses is tightly intermingled with the evolution of animal rotaviruses.     

天津地区结核分枝杆菌可变串联重复序列多态性研究

目的:分析天津地区流行结核分枝杆菌(MTB)基因组中分布的可变串联重复序列(VNTR)拷贝数目多态性,探讨不同MTB菌株分辨能力强的VNTR基因分型方法.方法:根据VNTR位点PCR扩增产物片段长度分析临床分离的102株MTB菌基因组中22个VNTR位点中重复序列拷贝数目,使用Hunter-Gaston分辨指数(H)评估各个VNTB位点的多态性和VNTR基因分型方法对菌株的综合辨别能力.结果:13个VNTR位点对不同MTB菌株具有较强的分辨能力,其分辨指数达0.9963.其中QUB11b、11a、18、26,MIRU-26、31和Mtub21的多态性较好(H值为0.442～0.699);MIRU-10、27、39、40,QUB1895和ETR-A位点的多态性尚可(H值为0.203～0.316);而MIRU-2、4、16、20、23、24,QUB1451,ETR-B和C的多态性差(H值为0.000～0.150),其中MIRU-2、20、24和QUB1451在北京家族菌株中没有多态性(H=0).结论:选择多态性好的位点组合可以有效地区分不同的MTB北京家族菌株,建立起菌株分辨能力强的VNTR分型方法.     

弓形虫基因分型研究进展

弓形虫感染可引起严重的弓形虫病, 而不同宿主感染的弓形虫株基因型差异较大, 不同基因型弓形虫株的致病力及药物敏感性亦存在较大差异。目前, 对弓形虫基因型的分析多选用限制性片段长度多态性PCR（PCR?RFLP）、 高度重复序列PCR、 多重PCR和巢氏PCR等技术, 扩增位点多选择B1、 SAG2、 HSP70、 GRA6等遗传标记。传统的弓形虫基因型主要有3个, 随着研究的不断深入, 越来越多的基因型被发现。本文就弓形虫基因分型研究进展进行综述。     

女性宫颈细胞中人乳头瘤病毒感染基因型的研究

目的探讨北京地区女性宫颈细胞中23种人乳头瘤病毒（HPV）感染的基因型分布情况,为宫颈癌的防治及疫苗的研发提供流行病学资料。方法采用HPV基因分型技术对北京地区2050例女性宫颈上皮细胞标本进行23种HPV基因型别检测,并对各种亚型的感染情况进行分析。结果2050例宫颈上皮细胞标本中检出HPV感染总体阳性率为25．85％（530／2050）,其中高危型阳性率为17．37％（356／2050）;低危型阳性率为5．02％（103/050）;在23种亚型中,最常见的类型依次为16、6、58、52、43型,未检测出44、39及MM4型。HPV单一感染共检测出20种型别,其阳性检出率为19．12％（392／2050）,最主要的为16亚型,占21．43％（84／392）。多重型别HPV感染阳性率为6．73（138／2050）;以二重感染最常见,占78．79％（109／138）,其中（HPV11＋43）、（HPV16＋6）型各6例,是混合型感染的主要型别。结论本地区女性宫颈细胞HPV感染高危型以16、52、58型为主,低危型以6、43型为主。对宫颈HPV感染基因型的调查,可以有效降低HPV感染导致宫颈癌的概率,并为宫颈癌疫苗的研发提供流行病学资料。