Search

We investigated the molecular epidemiology of foot-and-mouth disease virus (FMDV) serotype Asia 1, which caused outbreaks of disease in Asia during 2003-2007. Since 2004, the region affected by outbreaks of this serotype has increased from disease-endemic countries in southern Asia (Afghanistan, India, Iran, Nepal, Pakistan) northward to encompass Kyrgyzstan, Tajikistan, Uzbekistan, several regions of the People's Republic of China, Mongolia, Eastern Russia, and North Korea. Phylogenetic analysis of complete virus capsid protein 1 (VP1) gene sequences demonstrated that the FMDV isolates responsible for these outbreaks belonged to 6 groups within the Asia 1 serotype. Some contemporary strains were genetically closely related to isolates collected historically from the region as far back as 25 years ago. Our analyses also indicated that some viruses have spread large distances between countries in Asia within a short time. [ABSTRACT FROM AUTHOR]

Foot-and-mouth disease virus (FMDV) serotype Asia1 was first reported in India in 1951, where three major genetic lineages (B, C and D) of this serotype have been described until now. In this study, the capsid protein coding region of serotype Asia1 viruses (n = 99) from India were analyzed, giving importance to the viruses circulating since 2007. All of the isolates (n = 50) recovered during 2007-2013 were found to group within the re-emerging cluster of lineage C (designated as sublineage C(R)). The evolutionary rate of sublineage C(R) was estimated to be slightly higher than that of the serotype as a whole, and the time of the most recent common ancestor for this cluster was estimated to be approximately 2001. In comparison to the older isolates of lineage C (1993-2001), the re-emerging viruses showed variation at eight amino acid positions, including substitutions at the antigenically critical residues VP279 and VP2131. However, no direct correlation was found between sequence variations and antigenic relationships. The number of codons under positive selection and the nature of the selection pressure varied widely among the structural proteins, implying a heterogeneous pattern of evolution in serotype Asia1. While episodic diversifying selection appears to play a major role in shaping the evolution of VP1 and VP3, selection pressure acting on codons of VP2 is largely pervasive. Further, episodic positive selection appears to be responsible for the early diversification of lineage C. Recombination events identified in the structural protein coding region indicates its probable role in adaptive evolution of serotype Asia1 viruses.

A full-length cDNA clone of an Indian foot-and-mouth disease virus strain, Asia 1 IND 491/1997 was assembled downstream of the T7 promoter in the pBluescript II SK (+) vector by sequential ligation of four PCR-generated subgenomic fragments. RNA transcribed from that construct were transfected into BHK-21 and LFBK cells to rescue infectious virus. The in vitro growth kinetics, plaque morphology, infectivity titer, antigenic profile and virulence characteristics in unweaned mice infected with the recombinant virus were comparable to those infected with the parental virus. However, repeated attempts to recover viable virus from the RNA transcripts with a G320-T point mutation introduced in the short fragment of the 5' untranslated region failed. The possible destabilizing effect of such a mutation on the predicted long stem-loop structure at the 5'-end of the genome and its implications for viral genome replication are discussed., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Foot-and-mouth-disease virus (FMDV) serotype Asia1 causes significant number of disease outbreaks in India. Indian Asia1 virus isolates were shown to be genetically heterogeneous and of the two lineages (lineage B and lineage C) described in India, lineage C caused majority of the outbreaks. Emergence of a novel divergent lineage (lineage D) within lineage C has been described in 2001. In the present report, the complete VP1 genomic region of 41 FMDV Asia1 field isolates collected between 2003 and 2008 was sequenced. Phylogenetic analysis revealed reemergence of lineage C since 2005 following exclusive dominance of lineage D in the period between 2002 and 2004. At many positions lineage specific signature residues were identified. The antigenic relationship of the field isolates with the currently used vaccine strain IND63/72 was also determined, which reflects antigenic stability of serotype Asia1 in-spite of genetic heterogeneity., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)