ABSTRACT
Sequence analysis of segment 2 (seg-2) of three Indian bluetongue virus (BTV) isolates, Dehradun, Rahuri and Bangalore revealed 99% nucleotide identity amongst them and 96% with the reference BTV 23. Phylogenetic analysis grouped the isolates in 'nucleotype D'. The deduced amino acid (aa) sequence of the Bangalore isolate showed a high variability in a few places compared to other isolates. B-cell epitope analyses predicted an epitope that is present exclusively in the Bangalore isolate. Two-way cross serum neutralization confirmed that Bangalore isolate is antigenically different from the other two isolates. The results of this study suggest that these three isolates are VP2 variants of BTV 23. This signifies that non-cross-neutralizing variants of the same BTV serotype should be included in vaccine preparation.
Subject(s)
Bluetongue virus/classification , Bluetongue virus/isolation & purification , Bluetongue/virology , Capsid Proteins/genetics , Animals , Bluetongue/immunology , Bluetongue virus/genetics , Bluetongue virus/immunology , Capsid Proteins/immunology , Molecular Sequence Data , Neutralization Tests , Phylogeny , RNA, Viral/genetics , SheepABSTRACT
This study deals with a comparative analysis of complete genome sequences of twenty-one serotype Asia 1 foot-and-mouth disease (FMD) field viruses isolated over a period of two decades from India, two vaccine strains and seven exotic sequences. The Indian viruses could be grouped in to three distinct lineages at the entire coding region, evolving independently probably under differential selection pressure as evident from the lineage-specific signatures identified. This comparison revealed 80% of amino acids at the polyprotein region to be invariant. Twenty-one residues in L, 3A and P1 region were identified to be under positive selection of which some are antigenically critical. Analysis at functionally crucial motifs, receptor contact residues, polyprotein cleavage sites and at putative T-cell epitopes expands the knowledge beyond other serotypes. Antigenic site II in betaB-betaC loop of VP2 was highly unstable suggesting its exposure to extreme immune pressure. A single cross-over at the L proteinase region in an isolate from buffalo, also featuring an extensive deletion at the 5' untranslated region (UTR), reflects the role of intraserotypic genetic recombination in natural evolution. The likely biological relevance of deletions/insertions observed at UTRs, VP1 and 3A could not be deduced. Altogether, a substantial amount of data raised on full length genomes of type Asia 1 virus adds value to the FMD virus genomics.
Subject(s)
Foot-and-Mouth Disease Virus/classification , Foot-and-Mouth Disease Virus/genetics , Foot-and-Mouth Disease/epidemiology , Foot-and-Mouth Disease/virology , Genome, Viral , Amino Acid Sequence , Amino Acid Substitution/genetics , Animals , Antigens, Viral/genetics , Antigens, Viral/immunology , Base Sequence , Cluster Analysis , Conserved Sequence , Evolution, Molecular , Foot-and-Mouth Disease Virus/immunology , Foot-and-Mouth Disease Virus/isolation & purification , Genotype , India/epidemiology , Models, Molecular , Molecular Sequence Data , Mutation, Missense , Nucleic Acid Conformation , Phylogeny , RNA, Viral/genetics , Recombination, Genetic , Selection, Genetic , Sequence Analysis, DNA , Sequence Deletion , Sequence Homology , Serotyping , Viral Proteins/genetics , Viral Proteins/immunologyABSTRACT
A multiplex PCR (mPCR) for the differentiation of Indian FMDV serotypes, O, A, Asia 1 and C was developed and evaluated on 142 clinical and 39 cell culture samples. On the latter samples both the tests worked well with 100% efficiency, whereas on clinical samples mPCR had better efficiency than ELISA. The test was found to be specific for FMDV. The detection limit of the assay was varied among the serotypes; it was most sensitive on types A and Asia 1 and least sensitive on type C. The mPCR clearly identified the serotype and in some cases detected dual infections. The test is sensitive and reliable and can be used for serotyping of ELISA negative samples.
