ABSTRACT
Foot-and-mouth disease virus (FMDV) is a highly contagious and genetically variable virus. Sporadic introductions of this virus into FMD-free countries may cause outbreaks with devastating consequences. In 2010 and 2011, incursions of the FMDV O/SEA/Mya-98 strain, normally restricted to countries in mainland Southeast Asia, caused extensive outbreaks across East Asia. In this study, 12 full genome FMDV sequences for representative samples collected from the People's Republic of China (PR China) including the Hong Kong Special Administrative Region (SAR), the Republic of Korea, the Democratic People's Republic of Korea, Japan, Mongolia and The Russian Federation were generated and compared with additional contemporary sequences from viruses within this lineage. These complete genomes were 8119 to 8193 nucleotides in length and differed at 1181 sites, sharing a nucleotide identity ≥ 91.0% and an amino acid identity ≥ 96.6%. An unexpected deletion of 70 nucleotides within the 5'-untranslated region which resulted in a shorter predicted RNA stem-loop for the S-fragment was revealed in two sequences from PR China and Hong Kong SAR and five additional related samples from the region. Statistical parsimony and Bayesian phylogenetic analysis provide evidence that these outbreaks in East Asia were generated by two independent introductions of the O/SEA/Mya-98 lineage sometime between August 2008 and March 2010. The rapid emergence of these viruses from Southeast Asia highlights the importance of adopting approaches to closely monitor the spread of this lineage that now poses a threat to livestock industries in other regions.
Subject(s)
Base Sequence , Foot-and-Mouth Disease Virus/genetics , Foot-and-Mouth Disease/epidemiology , Genome, Viral , Pandemics/veterinary , Sequence Deletion , Animals , Asia, Eastern/epidemiology , Foot-and-Mouth Disease/virology , Foot-and-Mouth Disease Virus/chemistry , Foot-and-Mouth Disease Virus/classification , Foot-and-Mouth Disease Virus/isolation & purification , Molecular Sequence Data , Phylogeny , Protein Structure, Secondary , Serotyping/veterinary , Siberia/epidemiologyABSTRACT
Foot-and-mouth disease (FMD) is endemic in mainland Southeast Asia where up to seven genetically distinct viral lineages co-circulate (O/SEA/Mya-98, O/SEA/Cam-94, O/ME-SA/PanAsia, O/ME-SA/PanAsia-2, O/CATHAY, A/ASIA/Sea-97, and serotype Asia 1). The aim of this study was to analyse the sequence variability between representative complete genomes for these seven lineages. The genome sequences varied from 8130 to 8192 nucleotides in length and shared nucleotide identities ranging from 91.8 to 78.9%. Broad-scale differences such as block and codon deletions observed in these genomes paralleled features that have been reported previously for other FMDV sequences from Southeast Asia. Comparison between these sequences revealed the presence of 2501 variant sites which were more evident in regions encoding surface capsid proteins (VP2, VP3 and VP1) compared to regions encoding non-structural proteins. Specific comparisons between closely related O/ME-SA sequences showed that the distribution of variant sites was focussed particularly at the 5' end of the genome indicating that recombination may have occurred during the evolution of the O/ME-SA/PanAsia-2 lineage. These sequences provide insights into the evolutionary mechanisms by which new lineages generate genetic and antigenic novelty in the region and will form the basis of studies to define the spatio-temporal epidemiology of FMDV.
Subject(s)
Foot-and-Mouth Disease Virus/genetics , Foot-and-Mouth Disease/virology , Genetic Variation , Genome, Viral , RNA, Viral/genetics , Animals , Asia, Southeastern , Evolution, Molecular , Foot-and-Mouth Disease Virus/isolation & purification , Molecular Sequence Data , Recombination, Genetic , Sequence Analysis, DNA , Sequence DeletionABSTRACT
Foot-and-mouth disease (FMD) is endemic in the countries of mainland Southeast Asia where it represents a major obstacle to the development of productive animal industries. The aim of this study was to use genetic data to determine the distribution of FMD virus (FMDV) lineages in the Southeast Asia region, and in particular identify possible sources of FMDV causing outbreaks in Malaysia. Complete VP1 sequences, obtained from 214 samples collected between 2000 and 2009, from FMD outbreaks in six Southeast Asian countries, were compared with sequences previously reported. Phylogenetic analysis of these sequences showed that there were two patterns of FMDV distribution in Malaysia. Firstly, for some lineages (O/SEA/Mya98 and serotype A), outbreaks occurred every year in the country and did not appear to persist, suggesting that these incursions were quickly eradicated. Furthermore, for these lineages FMD viruses in Malaysia were closely related to those from neighbouring countries, demonstrating the close epidemiological links between countries in the region. In contrast, for O/ME-SA/PanAsia lineage, viruses were introduced and remained to cause outbreaks in subsequent years. In particular, the recent incursion and maintenance of the PanAsia-2 sublineage into Malaysia appears to be unique and independent from other outbreaks in the region. This study is the first characterisation of FMDV in Malaysia and provides evidence for different epidemiological sources of virus introduction into the country.
