从鼠类中检出博卡样病毒及其系统发育分析

目的对我国啮齿类动物博卡病毒的感染情况展开调查。方法 2011—2015年,分别从辽宁大连、丹东、东港,内蒙古满洲里,西藏樟木和新疆哈密境内采集鼠类样本,采用巢氏PCR方法扩增博卡病毒NS1片段和鼠类样本的Cytb片段。结果分别从黑家鼠、褐家鼠、黑线姬鼠、黑线仓鼠、小家鼠、黄胸鼠以及大沙鼠体内检测出博卡病毒65份。系统进化分析表明,鼠博卡病毒同已发现的其他博卡病毒属于不同的进化分支。通过对65个NS1蛋白序列分析,发现其中2个进化支氨基酸一致性小于85%。结论可能存在2个不同的病毒种类,揭示在啮齿动物中博卡病毒有较高的多样性。     

我国部分新型布尼亚病毒分离株全基因组序列分析

目的分析我国新型布尼亚病毒分离株全基因组序列,了解遗传进化特点。方法利用DNA STAR和MEGA6.0软件,对GenBank数据库收录的我国75株分离株全基因组序列进行分析,构建系统进化树,并对毒株核苷酸和氨基酸突变位点进行统计。结果 75株新型布尼亚病毒分离株流行优势株为基因型C;分离株核苷酸碱基突变总数合计5 938bp,主要为碱基转换(占79.86%);氨基酸间突变总数合计3 304aa。结论我国新型布尼亚病毒全基因组序列系统进化树具有相似的拓补结构。     

新疆库蚊分离的0507JS11病毒为Brevidensovirus新成员

目的 揭示新疆库蚊分离的0507JS11病毒的基本特征,明确其分类地位.方法 对0507JS11病毒进行细胞感染特点观察、负染电子显微镜(简称电镜)观察、基因组核酸电泳检测、全基因序列测定和系统进化分析.结果 0507JS11病毒可以引起Aedes albopictus C6/36细胞病变;完整病毒颗粒呈20面立体对称,直径20 nm,无包膜;病毒基因组为长3977 nt的单股正链DNA,基因组核酸电泳检测呈大小约4 kbp的DNA条带;病毒基因组编码区包括3个开放读码框(open readingframe,ORF),ORF1和ORF2编码非结构蛋白(non-structural protein,NS),ORF3编码衣壳蛋白(capsidprotein,VP);全基因序列系统进化分析显示病毒位于Brevidensovirus内一个独立进化分支.结论 新疆库蚊分离的0507JS11病毒为Brevidensovirus新成员.     

首次从阿拉山口口岸地区沙鼠中检测到博卡病毒

目的掌握中国-哈萨克斯坦边境阿拉山口口岸地区鼠类携带博卡病毒情况,为中哈边境口岸鼠传疾病的防控提供技术支持。方法 2016年3-11月,采用夹夜法、弓形夹法在中哈边境铁路沿线区域开展鼠类监测,利用巢式PCR法对95份鼠类样本进行博卡病毒检测。结果共捕获鼠类300只,隶属8属12种,其中大沙鼠为优势鼠种。首次从1只大沙鼠和1只红尾沙鼠的肺脏样本中检测到博卡病毒核酸,阳性率为2.11%;2个博卡病毒NS1基因序列同源性为99.5%,在遗传进化树中单独聚为一支。结论中哈边境阿拉山口铁路沿线区域鼠类存在博卡病毒感染,应加强该区域鼠类监测,保障口岸公共卫生安全。     

朝阳病毒:黄病毒新种-辽宁首次发现

目的 对辽宁省朝阳市蚊虫中分离的一种新病毒进行分子生物学鉴定.方法 在辽宁省朝阳市采集蚊虫,用细胞培养方法分离病毒,对引起126/06细胞病变(CPE)的病毒进行逆转录-聚合酶链式反应(RT-PCR)检测,并对阳性PCR产物进行测序分析;对病毒编码区全基因进行测序并与GenBank中36株黄病毒参考毒株序列进行比较;用Mega 3.1软件、以邻位相连法构建黄病毒属编码区全基因遗传进化树.结果 从蚊虫中分离到2株病毒,黄病毒属通用引物RT-PCR检测均为阳性,扩增片段大小986 bp,其中有600～750 bp核苷酸碱基序列与登革病毒2型、伊桂普病毒、塞皮克病毒和班奇病毒有66%～68%的一致性,2株病毒间碱基序列100%一致,为同一种黄病毒;病毒编码区基因序列全长10 308 bp,与其他黄病毒比较结果表明,分离株E基因、NS3基因及NS5基因碱基序列与其他黄病毒碱基序列一致性最高分别为59.6%,61.7%和67.0%;编码区全基因遗传进化树分析结果显示,分离株与登革病毒群、日本脑炎病毒群等蚊传黄病毒拥有共同进化祖先,但在系统发生树上处在单独进化分支.结论 辽宁省朝阳市分离到的黄病毒毒株不属于现有黄病毒属任何一种群,为黄病毒属的一个新种群,经GenBank分析确认为世界首次发现,并命名为朝阳病毒,收录号为FJ883471.     

2010年与2011年流感病毒广州分离株全基因组序列分析

目的 研究2010与2011年广州地区流感病毒全基因组序列的特性与变异特点,为预防控制流感暴发提供参考.方法 参照GenBank流感病毒全基因组序列设计分段扩增引物,进行RT-PCR一次扩出全基因组序列后,再分段扩增病毒各基因片段,PCR产物直接进行序列测定,用ClustalW/X、DNASTAR、MEGA5.0等软件分析基因组序列.结果 克隆了4株广州株流感病毒全基因组序列,将4株广州株流感病毒与墨西哥株和中国四川株全基因组核苷酸序列进行ClustalW比较,发现除PB2片段为98％外,其他各片段均为99％,将基因组序列与北美地区和欧亚地区的猪流感进行CLUSTALW比较,广州株GZ49号基因组的第1、2、3、4、5和第8片段与北美和亚洲地区HIN2型猪流感具有94％～95％相似性,广州株GZ49号基因组的第6和7片段与欧亚大陆的H1N1型猪流感病毒同源性分别为90％～93％和94％～95％;对4株病毒PB2、PB1、PA片段进行了点突变分析,其中4株病毒在PB2基因均出现的位点突变为D195N,R293K,V344M,I354L,V731I.结论 4株广州株新甲流病毒(H1N1)与墨西哥株和中国四川株全基因组具有很高同源性,这4株流感病毒很可能是起源于同一株病毒;PB2基因变异相对较大,这些氨基酸点突变均是新出现的突变.     

云南省文山中越边境地区虫媒病毒调查

目的 对云南省文山县、河口县等中越边境地区开展虫媒病毒调查,以期了解当地蚊虫携带虫媒病毒情况.方法 2007年9月在当地5个采集点共采集蚊虫8326只,包括库蚊6091只,中华按蚊1334只,刺扰伊蚊848只,阿蚊53只,并保存于液氮.经消毒、研磨、离心等处理后进行组织培养细胞接种,分离病毒和对病毒分离物进行血清学和分子生物学鉴定,以软件进行病毒的核苷酸序列比对和系统发生分析.结果 从库蚊分离到4株对C6/36细胞致病变的病毒分离物,其他蚊种没有分离到病毒分离物.鉴定结果表明,标本WS0704-2与版纳病毒抗体反应,PCR鉴定为版纳病毒,该病毒基因组第12片段的进化关系同中国其他版纳病毒有明显差异,位于一条独立的进化枝中,在进化上相对独立.标本WS0704-1、WS0708-1、WS0708-2为浓核病毒.结论 云南省文山中越边境地区存在多种蚊虫媒介并携带版纳病毒等虫媒病毒.     

A型流感病毒非结构蛋白NS1的研究进展

<正>A型流感病毒引起的疾病主要包括猪流感、禽流感、人类流感等,主要通过飞沫传播,可引起全身肌肉酸痛、疲倦无力、厌食,并可能引发病毒性肺炎[1]。高致病性禽流感感染还可能引发严重的并发症,包括广泛的肺水肿、急性呼吸窘迫综合症、以肾和心脏功能失调为代表的多器官功能衰竭[2],病死率极高。NS1蛋白(non-structural protein 1)是A型流感病毒的非结构蛋白,由病毒基因组中最小的基因编     

北京地区婴幼儿急性腹泻病例5种腹泻相关病毒感染状况

目的了解北京地区婴幼儿急性腹泻病例5种腹泻相关病毒的感染状况。方法采集北京地区哨点医院2016年1~12月<60月龄急性腹泻患儿便标本,用实时荧光PCR对A组轮状病毒、诺如病毒、肠道腺病毒、星状病毒进行检测;同时用巢式PCR检测人博卡病毒。结果共采集354份粪便标本,A组轮状病毒检出率13.84%,诺如病毒检出率10.45%,肠道腺病毒检出率4.52%,星状病毒检出率3.95%,人博卡病毒检出率7.34%。混合感染18例,占5.08%。轮状病毒发病高峰为冬季,诺如病毒的发病高峰为春季,其他病毒感染无明显季节特征。2岁以内患儿5种病毒的检出率分别为81.63%、78.38%、81.25%、71.43%、84.62%。结论北京地区急性腹泻患儿5种腹泻相关病毒检出率从高到低依次为:A组轮状病毒、诺如病毒、人博卡病毒、肠道腺病毒、星状病毒;2岁以内患儿是病毒性腹泻的高发人群。     

云南边境地区禽流感H5N1亚型病毒NS基因进化分析

目的 阐明云南边境地区禽流感H5N1亚型病毒NSl、NS2基因变异特征及遗传进化关系。方法 在云南边境地区采集境外家禽和野生鸟类棉拭子样品,经H5N1亚型特异性多重RT-PCR检测,阳性样品对病毒NS基因进行扩增,克隆Z至pMDl8一T载体测序,获得NSl、NS2基因序列,并与已知参考毒株序列进行序列比对及系统发育分析。结果 自1240份样品中检出H5N]亚型阳性样品71份,阳性率为5．72％;30份代表性阳性样品病毒NS基因测序获得17种序列,存在3个不同进化(亚)分支(I一1、I一2、Ⅱ);NSl／NS2基因与病毒血凝素(HA)基因呈现不同进化关系;NSl蛋白涉及核定位信号区、RNA结合区、效应区及其他致病性相关的关键性氨基酸位点存在替代或突变。结论 云南边境地区H5N1亚型病毒NSl／NS2基因具有遗传差异,2010年以来NS基因进化分支I一2、Ⅱ已成为当地流行的优势毒株。     

Complete genome sequence analysis of novel human bocavirus reveals genetic recombination between human bocavirus 2 and human bocavirus 4

Epidemiological surveillance of human bocavirus (HBoV) was conducted on fecal specimens collected from hospitalized children with diarrhea in Chiang Mai, Thailand in 2011. By partial sequence analysis of VP1 gene, an unusual strain of HBoV (CMH-S011-11), was initially identified as HBoV4. The complete genome sequence of CMH-S011-11 was performed and analyzed further to clarify whether it was a recombinant strain or a new HBoV variant. Analysis of complete genome sequence revealed that the coding sequence starting from NS1, NP1 to VP1/VP2 was 4795 nucleotides long. Interestingly, the nucleotide sequence of NS1 gene of CMH-S011-11 was most closely related to the HBoV2 reference strains detected in Pakistan, which contradicted to the initial genotyping result of the partial VP1 region in the previous study. In addition, comparison of NP1 nucleotide sequence of CMH-S011-11 with those of other HBoV1–4 reference strains also revealed a high level of sequence identity with HBoV2. On the other hand, nucleotide sequence of VP1/VP2 gene of CMH-S011–11 was most closely related to those of HBoV4 reference strains detected in Nigeria. The overall full-length sequence analysis revealed that this CMH-S011-11 was grouped within HBoV4 species, but located in a separate branch from other HBoV4 prototype strains. Recombination analysis revealed that CMH-S011-11 was the result of recombination between HBoV2 and HBoV4 strains with the break point located near the start codon of VP2.     

The whole structure of the human nonfunctional L-gulono-gamma-lactone oxidase gene--the gene responsible for scurvy--and the evolution of repetitive sequences thereon

L-Gulono-gamma-lactone oxidase (GULO), which catalyzes the last step of ascorbic acid biosynthesis, is missing in humans. The whole structure of the human gene homologue for this enzyme was disclosed by a computer-assisted search. Only five exons, as compared to 12 exons constituting the functional rat GULO gene, remain in the human genome. A comparison of these exons with those of their functional counterparts in rat showed that there are two single nucleotide deletions, one triple nucleotide deletion, and one single nucleotide insertion in the human sequence. When compared in terms of codons, the human sequence has a deletion of a single amino acid, two stop codons, and two aberrant codons missing one nucleotide besides many amino acid substitutions. A comparison of the remaining human exon sequences with the corresponding sequences of the guinea pig nonfunctional GULO gene revealed that the same substitutions from rats to both species occurred at a large number of nucleotide positions. From analyses of the molecular evolution of Alu sequences in the human GULO gene homologue, it is thought that two Alu sequences were inserted in the vicinity of a presumed position of lost exon 11 during the same period as GULO lost its function. It is predicted that six LINE-1 sequences located in and near the gene homologue were inserted not during that period.     

小儿急性呼吸道感染与人博卡病毒相关性的研究

目的:了解小儿急性呼吸道感染与人博卡病毒(Human Bocavirus,HBoV)的相关性。方法:对2008年1～5月在长春市儿童医院住院的1007例急性呼吸道感染患儿鼻咽深部分泌物样本用PCR扩增的方法进行HboV NS1基因检测。随机选取8例HBoV阳性产物进行测序,并将测到的序列与GenBank中的基因序列和HBoV阳性病例的临床资料进行分析。结果:1007例标本共检测出44例HBoV阳性,阳性率为4.37%,其中急性上呼吸道感染、急性支气管炎、毛细支气管炎和支气管肺炎患儿人博卡病毒阳性检出率分别为1.29%(2/155)、5.71%(2/35)、8.70%(2/23)和4.79%(38/794)。HboV急性呼吸道感染的年龄分布为1岁以下39例,占88.64%;1岁以上5例,占11.36%;男女性别比值是1.75∶1;临床表现咳嗽伴喘憋占97.56%,咳嗽伴腹泻占34.14%,入院时体温升高占54.55%,肺部听诊闻及干和/或湿性罗音者占95.12%,X线胸片片状影占87.80%,病程平均为13.79天。结论:人博卡病毒是引起小儿急性呼吸道感染的病原之一;HboV所致呼吸道感染部位多在下呼吸道;感染患儿以1岁以内婴儿为主。     

Evolutionary time-scale of primate bocaviruses

Human bocavirus (HBoV) is associated with acute gastroenteritis in humans, occurring mostly in young children and elderly people. Four bocavirus genotypes (HBoV1–HBoV4) have been found so far. Since there were no data on the contribution of HBoV to gastroenteritis in Russia, 1781 fecal samples collected from infants hospitalized with acute gastroenteritis in Novosibirsk, Russia during one year were tested for the presence of nucleic acids from HBoV and three major gastrointestinal viruses (rotavirus A, norovirus II, and astrovirus). HBoV was detected only in 1.9% of the samples: HBoV1 was detected in 0.6% and HBoV2, in 1.3%. Complete genome sequencing of three Novosibirsk isolates was performed. An evolutionary analysis of these sequences and the available sequences of human and great apes bocaviruses demonstrated that the current HBoV genotypes diverged comparatively recently, about 60–300 years ago. The independent evolution of bocaviruses from chimpanzees and gorillas commenced at the same time period. This suggests that these isolates of great apes bocaviruses belong to separate genotypes within the species of human bocavirus, which is actually the primate bocavirus. The rate of mutation accumulation in the genome of primate bocaviruses has been estimated as approximately 9 × 10^–4 substitutions/site/year. It has been demonstrated that HBoV1 diverged from the ancestor common with chimpanzee bocavirus approximately 60–80 years ago, while HBoV4 separated from great apes bocaviruses about 200–300 years ago. The hypothesis postulating independent evolution of HBoV1 and HBoV4 genotypes from primate bocaviruses has been proposed.     

Genome characteristics and molecular evolution of the human sapovirus variant GII.8

Human sapovirus is regarded as an important viral agent for acute diarrhea worldwide. GII.8, a recently reported genotype, has been detected in a few countries and regions. In this study, we obtained the first genome sequence of a sapovirus GII.8 strain isolated in mainland China, and comprehensively analyzed the genetic diversity and evolutionary process of this genotype. The viral genome of the new GII.8 Guangzhou strain GZ2014-L231 comprised 7433 nucleotides, including two ORFs. Pairwise alignments of the new genome with representative sequences of different genotypes showed inconsistent homology between different protein-encoding regions, of which NS1 and VP2 were found as the variable proteins, and NS3, NS5, and NS6/7 were found as the conserved ones. Compared with other reported GII.8 genomes, the Guangzhou strain introduced 34 new nucleotide changes and one new amino acid change. Phylogenetic analysis based on full-length VP1 sequences demonstrated that 11 GII.8 strains could be divided into 4 clusters A-D, with 88 SNP and 10 SAP spots occurred during their evolutionary process. The Guangzhou strain has higher homology with seven GII.8 strain detected after 2014, especially the US and Peruvian strains of 2015/2016, which have the identical VP1 amino acid sequences. Using a Bayesian coalescent method based on VP1 sequences, GII.8 was predicted to emerge in 2001 with the evolution rate of 1.45 × 10⁻³ nucleotide substitutions/site/year (strict clock). In summary, the data in this study not only provided reference data from mainland China for sapovirus researches in future, but also firstly described the evolutionary process of the GII.8 genotype.     

一株人感染H9N2禽流感病毒高通量测序及序列分析

目的 对一株人感染H9N2禽流感病毒进行高通量测序（next-generation sequencing,NGS）分析,探讨其在人群流行的可能性。方法 应用高通量测序技术进行全基因组序列测定（whole genome sequencing,WGS）。对8个基因进行相似性检索,构建系统进化树并分析其关键位点的分子特征。结果 8个基因与GenBank基因库相似度最高序列的来源不完全一致,系统进化树显示HA基因属于欧亚系I群,M基因位于G1-like分支,PB2位于G9-like分支,NA位于一独立分支,PBl,PA,NP,NS均位于SH/F/98-like分支。HA基因裂解位点为PSRSSR/GLF,226位受体结合位点为L。除M2基因S31N突变之外,NA基因茎63~65位缺失,PA和PB2基因未发生L336M和Q591R,E627K等可以增强病毒对哺乳动物适应性的突变,但发现可以增强病毒毒力的突变如M1基因N30D和T215A,PB2基因L89V,NSl基因P42S。除M2基因S31N突变外,NA基因和M2基因的药物结合位点未发生E119G,R152K,H274Y,R292K和L26F,V27A,A30T,G34E等耐药性突变。HA和NA糖基化位点预测结果都有8个糖基化位点,其中分别有7个和5个可靠程度较高。结论 该H9N2禽流感病毒的大部分关键性位点较保守,只有少部分位点发生一定程度进化与变异,在人群引起流行的可能性不大,但需加强分子方面动态监测。     

Sequence conservation in the Ancylostoma secreted protein-2 of Necator americanus (Na-ASP-2) from hookworm infected individuals in Thailand

The Ancylostoma secreted protein-2 of Necator americanus (Na-ASP-2) was one of the promising vaccine candidates against the most prevalent human hookworm species as adverse vaccine reaction has compromised further human vaccine trials. To elucidate the gene structure and the extent of sequence diversity, we determined the complete nucleotide sequence of the Na-asp-2 gene of individual larvae from 32 infected subjects living in 3 different endemic areas of Thailand. Sequence analysis revealed that the gene encoding Na-ASP-2 comprised 8 exons. Of 3 nucleotide substitutions in these exons, only one causes an amino acid change from leucine to methionine. A consensus conserved GT and AG at the 5′ and the 3′ boundaries of each intron was observed akin to those found in other eukaryotic genes. Introns of Na-asp-2 contained 23 nucleotide substitutions and 0–18 indels. The mean number of nucleotide substitutions per site (d) in introns was not significantly different from the mean number of synonymous substitutions per synonymous site (d_S) in exons whereas d in introns was significantly exceeded d_N (the mean number of nonsynonymous substitutions per nonsynonymous site) in exons (p < 0.05), suggesting that introns and synonymous sites in exons may evolve at a similar rate whereas functional constraints at the amino acid could limit amino acid substitutions in Na-ASP-2. A recombination site was identified in an intron near the 3′ portion of the gene. The positions of introns and the intron phases in the Na-asp-2 gene comparing with those in other pathogenesis-related-1 proteins of Loa loa, Onchocerca volvulus, Heterodera glycines, Caenorhabditis elegans and human were relatively conserved, suggesting evolutionary conservation of these genes. Sequence conservation in Na-ASP-2 may not compromise further vaccine design if adverse vaccine effects could be resolved whereas microheterogeneity in introns of this locus may be useful for population genetics analysis of N. americanus.     

Population structure of the dengue viruses, Aragua, Venezuela, 2006-2007. Insights into dengue evolution under hyperendemic transmission

During the past three decades there has been a notable increase in dengue disease severity in Venezuela. Nevertheless, the population structure of the viruses being transmitted in this country is not well understood. Here, we present a molecular epidemiological study on dengue viruses (DENV) circulating in Aragua State, Venezuela during 2006-2007. Twenty-one DENV full-length genomes representing all of the four serotypes were amplified and sequenced directly from the serum samples. Notably, only DENV-2 was associated with severe disease. Phylogenetic trees constructed using Bayesian methods indicated that only one genotype was circulating for each serotype. However, extensive viral genetic diversity was found in DENV isolated from the same area during the same period, indicating significant in situ evolution since the introduction of these genotypes. Collectively, the results suggest that the non-structural (NS) proteins may play an important role in DENV evolution, particularly NS1, NS2A and NS4B proteins. The phylogenetic data provide evidence to suggest that multiple introductions of DENV have occurred from the Latin American region into Venezuela and vice versa. The implications of the significant viral genetic diversity generated during hyperendemic transmission, particularly in NS protein are discussed and considered in the context of future development and use of human monoclonal antibodies as antivirals and tetravalent vaccines.     

SARS-CoV毒株E、M、N和S基因分子变异研究

目的通过对SARS-CoV毒株基因序列的变异分析,揭示SARS-CoV毒株出现和流行与基因进化的关系.方法对广东地区SARS-CoV毒株进行序列分析,其余毒株序列从GenBank检索,采用DNAstar 5.0软件,对检索的SARS-CoV的E、M、N、S基因核苷酸序列进行比对和分析;并结合临床资料对变异毒株进行流行病学分析.结果以果子狸冠状病毒(SZ-3)为基准,102株人类毒株中,6株毒株E基因的4个氨基酸发生置换,两株毒株发生缺失变异;果子狸毒株M基因的第5位丝氨酸置换为人类毒株甘氨酸并减少1个糖蛋白位点,此外M基因有38株毒株发生8个氨基酸置换变异;6株毒株N基因发生氨基酸置换,3株毒株发生缺失变异;人类毒株S基因中9个氨基酸全部发生变异并增加1个糖蛋白位点,与果子狸毒株不同比例占0.72%(9/1255);部分毒株中S基因的27个氨基酸在发生置换变异,7株毒株发生缺失变异.结论冠状病毒S基因中9个氨基酸置换和1个糖蛋白位点影响,可能导致人类SARS-CoV毒株出现和SARS流行;SARS流行持续和传播扩大与S基因进化变异相一致.所以认为,SARS-CoV毒株S基因变异可能在SARS出现和流行中发挥极其重要的作用.     

Serotype-specific differences in antigenic regions of foot-and-mouth disease virus (FMDV): A comprehensive statistical analysis

Although vaccines are available for prophylaxis of foot-and-mouth disease virus (FMDV), few cases of escape mutants have been reported. To develop serotype-specific FMDV vaccination strategies it is imperative to understand how host selection has influenced evolution of FMDV. This study identified several possible targets for serotype-specific FMDV vaccines using a novel statistical approach. Pairs of closely related FMDV genomes identified in a phylogenetic analysis representing all seven serotypes were examined in order to understand the long term effects of host selection on well-characterized and predicted antigenic regions of importance (B, T_H, and T_C). Estimates of synonymous and non-synonymous substitution rates for antigenic and non-antigenic regions were calculated for individual pairs of FMDV genomes. We found that on average, both antigenic and non-antigenic regions were subject to purifying selection acting at non-synonymous sites and that several antigenic sites showed a pattern of nucleotide substitution suggesting repeated positive selection across the population. In addition, we found that antigenic regions from the individual FMDV serotypes differed with respect to the extent of amino acid conservation. For a capsid T_H epitope currently used in one synthetic vaccine, we found that serotypes SAT1-3 had significantly greater non-synonymous nucleotide substitutions than the other serotypes. In contrast, in a second well-studied B-cell epitope, there were no serotype-dependent differences in synonymous or non-synonymous nucleotide substitutions. These results support the hypothesis that host selection acting on individual serotypes has been an important factor in the long-term evolution FMDV and needs to be considered for vaccine design.