Molecular epidemiological studies on foot-and-mouth disease type O Taiwan viruses from the 1997 epidemic

Sequence diversity was assessed of the complete VP1 gene directly amplified from 49 clinical specimens during an explosive foot-and-mouth disease (FMD) outbreak in Taiwan. Type O Taiwan FMD viruses are genetically highly homogenous, as seen by the minute divergence of 0.2-0.9% revealed in 20 variants. The O/HCP-0314/TW/97 and O/TCP-022/TW/97 viral variants dominated FMD outbreaks and were prevalent in most affected pig-raising areas. Comparison of deduced amino acid sequences around the main neutralizable antigenic sites on the VP1 polypeptide showed no significant antigenic variation. However, the O/CHP-158/TW/97 variant had an alternative critical residue at position 43 in antigenic site 3, which may be due to selective pressure in the field. Two vaccine production strains (O1/Manisa/Turkey/69 and O1/Campos/Brazil/71) probably provide partial heterologous protection of swine against O Taiwan viruses. The type O Taiwan variants clustered in sublineage A1 of four main lineages in the phylogenetic tree. The O/Hong Kong/9/94 and O/1685/Moscow/Russia/95 viruses in sublineage A2 are closely related to the O Taiwan variants. The causative agent for the 1997 epidemic presumably originated from a single common source of type O FMD viruses prevalent in neighboring areas.     

Sequence analysis of the protein-coding regions of foot-and-mouth disease virus O/HK/2001

The nucleotide sequence of the protein-coding region of foot-mouth-disease virus (FMDV) strain O/HK/2001 was determined and compared with the sequences of other FMDVs that were registered in GenBank. The protein-coding region was 6966 nucleotides in length and encoded a protein of 2322 amino acid residues. Comparison of the nucleotide sequence and its deduced amino acid sequence with those of other isolates indicated that O/HK/2001 belonged to the Cathay topotype. A genomic coding region nucleotide sequence phylogenetic tree of several FMDV-O isolates showed that O/HK/2001 was most closely related to FMDV isolates found in Taiwan during 1997, and especially shared significant similarity to HKN/2002, suggesting that the virus causing outbreaks in Hong Kong was genetically most-closely related to that causing an outbreak of type O in Taiwan. Mutations in O/HK/2001 were revealed, including frequent substitutions in the VP1 and L proteins, and deletions involving 10 amino acid residues in the 3A protein. This study was undertaken to assess the regional variation of prevalent FMDV type O viruses and to establish a sequence database for FMDV molecular epidemiological investigation.     

3种口蹄疫O型抗体检测试剂盒对疫苗免疫牛血清抗体检测的比较试验

为了提供检测结果准确且操作便捷的试剂盒,本试验应用两种商品化试剂盒和本实验室研制的一种基于合成肽包被抗原的间接ELISA试剂盒同时对口蹄疫疫苗免疫后14、21和28 d的150份免疫牛血清进行口蹄疫O型抗体水平的检测,并对3种试剂盒测定结果的符合程度、重复性和便捷性进行了比较。试验结果表明3种试剂盒测得的抗体水平检测结果之间高度符合,且3种试剂盒各自的检测结果重复性良好,基于合成肽包被抗原的间接ELISA试剂盒在操作便捷性方面优势明显。     

Molecular epidemiological investigation of foot-and-mouth disease virus in Korea in 2000

The genetic relatedness of 7 Korean type O field strains of foot-and-mouth disease virus (FMDV) in clinical specimens collected from 5 different geographic locations in 2000 was investigated. The sequence of 162 nucleotides (nt 478-639) at the 3' end of the 1D (VP1) genes was determined from amplified cDNA fragments, and subjected to the analysis for the sequence identity/divergence and phylogenetic relationship. The overall nucleotide sequence divergence among the 7 field strains was 0 to 3.8%, suggesting that they are closely related to each other. Phylogenetic analysis with the known Middle East-South Asia (ME-SA) topotype strains showed that the 7 Korean field strains formed two distinct clusters within the same lineage of the ME-SA topotype strains. Cluster 1 consisted of the strains of the primary foci of infection (Paju and Hongseong), and closely related to the strains prevailed in the Far East. Cluster 2 comprised those of subsequently affected regions (Boryeong, Yongin, and Chungju), and was further diverged from the Cluster 1. The result of phylogenetic analysis indicated that the Korean strains may have evolved from a common ancestor of the Pan Asia strains, and that at least 2 phylogenetically clustered variants within the same lineage were prevalent during the epidemic. The potential origin and sources of the virus introduction to Korea were discussed.     

Molecular characterization of foot-and-mouth disease virus isolated from ruminants in Taiwan in 1999-2000

In 1999, 10 sporadic outbreaks of cattle foot-and-mouth disease (FMD) occurred in Taiwan. By the time, infection was limited to the Chinese yellow cattle (a native species of beef cattle in Mainland China), which did not develop vesicular lesions under field conditions. Five viruses isolates obtained from individual farms were confirmed to be the serotype O FMD virus (O/Taiwan/1999). During January-February 2000, however, this virus has spread to dairy cattle and goat herds, causing severe mortality in goat kids and vesicular lesions in dairy cattle. Partial nucleotide sequence of the capsid coding gene 1D (VP1) was determined for the virus isolates obtained in this study. Phylogenetic analysis of the VP1 sequences indicated that the O/Taiwan/1999 viruses shared 95-97% similarities to the virus strains isolated from the Middle East and India. The species susceptibility of the O/Taiwan/1999 virus was experimentally studied in several species of susceptible animals, showing that the virus did cause generalized lesions in dairy cattle and pigs, however, it would not cause vesicular lesions on the Chinese yellow cattle and the adult goats. These studies suggested that the O/Taiwan/1999 virus was a novel FMD virus of Taiwan and it presented various levels of susceptibility in cattle species.     

口蹄疫病毒O/Laos/00株非结构蛋白3A基因特征分析

经反转录聚合酶链式反应(RT-PCR)技术扩增得到口蹄疫病毒O/Laos/00株的非结构蛋白3A基因核苷酸序列,与其他8株代表性参考毒株的3A基因进行比较,分析口蹄疫病毒3A基因的特征.结果表明:O/Laos/00株3A基因含有429核苷酸,编码143氨基酸残基.9株病毒3A氨基酸序列相比较,可分成3种不同的类型:一类是具有全长3A的毒株,一类是具有133～143位氨基酸缺失的毒株,这两类毒株均来源于牛体,核苷酸差异小(＜15 %);另一类是具有93～102位氨基酸缺失的毒株,毒株相互之间核苷酸差异较大(7.25 %～22.2 %).     

Procedures for preventing transmission of foot-and-mouth disease virus (O/TAW/97) by people

The aim of this study was to determine personal hygiene protocols and animal avoidance periods needed to prevent transmission of FMDV (O/TAW/97). Forty-six, 9-week-old barrows free of FMDV were randomly allocated to five treatment groups and a control group. Investigators contacted and sampled FMDV-inoculated pigs for approximately 40 min and then contacted and sampled sentinel pigs after using no biosecurity procedures, washing hands and donning clean outerwear, or showering and donning clean outerwear. Personnel were sampled for nasal carriage of FMDV for 85.43 h. Contaminated personnel did not transmit FMDV to susceptible pigs after handwashing or showering, and donning clean outerwear. FMDV was transmitted when biosecurity procedures were not used. FMDV was not detected in nasal secretions of investigators. Thus, extended animal avoidance periods do not appear to be necessary to prevent transmission of FMDV (O/TAW/97) by people to pigs when organic material is removed through handwashing/showering and donning clean outerwear. This study supports similar findings in a previous publication using FMDV (O/UK/35/2001).     

Phylodynamic reconstruction of O CATHAY topotype foot-and-mouth disease virus epidemics in the Philippines

Reconstructing the evolutionary history, demographic signal and dispersal processes from viral genome sequences contributes to our understanding of the epidemiological dynamics underlying epizootic events. In this study, a Bayesian phylogenetic framework was used to explore the phylodynamics and spatio-temporal dispersion of the O CATHAY topotype of foot-and-mouth disease virus (FMDV) that caused epidemics in the Philippines between 1994 and 2005. Sequences of the FMDV genome encoding the VP1 showed that the O CATHAY FMD epizootic in the Philippines resulted from a single introduction and was characterised by three main transmission hubs in Rizal, Bulacan and Manila Provinces. From a wider regional perspective, phylogenetic reconstruction of all available O CATHAY VP1 nucleotide sequences identified three distinct sub-lineages associated with country-based clusters originating in Hong Kong Special Administrative Region (SAR), the Philippines and Taiwan. The root of this phylogenetic tree was located in Hong Kong SAR, representing the most likely source for the introduction of this lineage into the Philippines and Taiwan. The reconstructed O CATHAY phylodynamics revealed three chronologically distinct evolutionary phases, culminating in a reduction in viral diversity over the final 10 years. The analysis suggests that viruses from the O CATHAY topotype have been continually maintained within swine industries close to Hong Kong SAR, following the extinction of virus lineages from the Philippines and the reduced number of FMD cases in Taiwan.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-014-0090-y) contains supplementary material, which is available to authorized users.     

O型口蹄疫病毒单克隆抗体的制备及生物学特性分析

以纯化的O型口蹄疫泛亚毒株O/YS/CHA/05抗原免疫BALB/c小鼠,在加强免疫3 d后,取脾细胞与SP2/0骨髓瘤细胞进行融合,经间接ELISA法和间接免疫荧光法(IFA)筛选, 获得2株稳定分泌单克隆抗体的杂交瘤细胞株,命名为4A8和1F6,同时确定二者均为O型口蹄疫病毒特异性单克隆抗体.中和试验和Western-blot分析结果表明,4A8和1F6均识别线性表位,无中和活性.亚类鉴定结果显示:4A8和1F6重链类型分别为IgG1和IgG2b;轻链类型均为κ.相加ELISA分析结果表明,两者针对的抗原位点相同或相近.