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Evolution and phylogenetic analysis of full-length VP3 genes of Eastern Mediterranean bluetongue virus isolates.

Nomikou K, Dovas CI, Maan S, Anthony SJ, Samuel AR, Papanastassopoulou M, Maan NS, Mangana O, Mertens PP - PLoS ONE (2009)

Bottom Line: The BTV genome is composed of ten linear segments of double-stranded RNA (dsRNA), each of which codes for one of ten distinct viral proteins.The full-length nucleotide sequence of genome Seg-3 was determined for thirty BTV isolates recovered in the eastern Mediterranean region, the Balkans and other geographic areas (Spain, India, Malaysia and Africa).These analyses also show that the recent incursions into south-eastern Europe were caused by BTV strains belonging to two different major-lineages: representing an 'eastern' (BTV-9, -16 and -1) and a 'western' (BTV-4) group/topotype.

View Article: PubMed Central - PubMed

Affiliation: Arbovirus Molecular Research Group, Department of vector borne diseases, Institute for Animal Health, Pirbright Laboratory, Woking, Surrey, United Kingdom.

ABSTRACT
Bluetongue virus (BTV) is the 'type' species of the genus Orbivirus within the family Reoviridae. The BTV genome is composed of ten linear segments of double-stranded RNA (dsRNA), each of which codes for one of ten distinct viral proteins. Previous phylogenetic comparisons have evaluated variations in genome segment 3 (Seg-3) nucleotide sequence as way to identify the geographical origin (different topotypes) of BTV isolates. The full-length nucleotide sequence of genome Seg-3 was determined for thirty BTV isolates recovered in the eastern Mediterranean region, the Balkans and other geographic areas (Spain, India, Malaysia and Africa). These data were compared, based on molecular variability, positive-selection-analysis and maximum-likelihood phylogenetic reconstructions (using appropriate substitution models) to 24 previously published sequences, revealing their evolutionary relationships. These analyses indicate that negative selection is a major force in the evolution of BTV, restricting nucleotide variability, reducing the evolutionary rate of Seg-3 and potentially of other regions of the BTV genome. Phylogenetic analysis of the BTV-4 strains isolated over a relatively long time interval (1979-2000), in a single geographic area (Greece), showed a low level of nucleotide diversity, indicating that the virus can circulate almost unchanged for many years. These analyses also show that the recent incursions into south-eastern Europe were caused by BTV strains belonging to two different major-lineages: representing an 'eastern' (BTV-9, -16 and -1) and a 'western' (BTV-4) group/topotype. Epidemiological and phylogenetic analyses indicate that these viruses originated from a geographic area to the east and southeast of Greece (including Cyprus and the Middle East), which appears to represent an important ecological niche for the virus that is likely to represent a continuing source of future BTV incursions into Europe.

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Map of geographical location of the isolates analysed in this study and the sources of BTV incursions in Europe.
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pone-0006437-g001: Map of geographical location of the isolates analysed in this study and the sources of BTV incursions in Europe.

Mentions: Genome segment 3 was sequenced from thirty BTV isolates, including twenty isolates from Greece, Cyprus, Bulgaria, Turkey and Israel, six isolates from Spain, Morocco, Nigeria, Sudan, Malaysia and India and four reference strains (Table 1, Figure 1). The Greek BTV strains were isolated from ruminants during epizootics in 1979 and 1998–2001, using BHK-21 cells (ECACC 85011433) or embryonated chicken eggs, followed by passage in BHK-21 cells [43], [44]. Initial EDTA blood samples were taken from sick or sentinel animals, while spleen samples were taken at post-mortem. Isolates were serotyped by serum neutralization tests (SNTs) as described in the OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals [45], using type specific antisera provided by the OIE Reference Laboratory at the Onderstepoort Veterinary Institute, Onderstepoort, South Africa. Each of these virus isolates is included in the reference collection at IAH Pirbright (see www.reoviridae.org/dsRNA_virus_proteins/ReoID/BTV-isolates.htm) and is identified here by their reference collection number.


Evolution and phylogenetic analysis of full-length VP3 genes of Eastern Mediterranean bluetongue virus isolates.

Nomikou K, Dovas CI, Maan S, Anthony SJ, Samuel AR, Papanastassopoulou M, Maan NS, Mangana O, Mertens PP - PLoS ONE (2009)

Map of geographical location of the isolates analysed in this study and the sources of BTV incursions in Europe.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2713410&req=5

pone-0006437-g001: Map of geographical location of the isolates analysed in this study and the sources of BTV incursions in Europe.
Mentions: Genome segment 3 was sequenced from thirty BTV isolates, including twenty isolates from Greece, Cyprus, Bulgaria, Turkey and Israel, six isolates from Spain, Morocco, Nigeria, Sudan, Malaysia and India and four reference strains (Table 1, Figure 1). The Greek BTV strains were isolated from ruminants during epizootics in 1979 and 1998–2001, using BHK-21 cells (ECACC 85011433) or embryonated chicken eggs, followed by passage in BHK-21 cells [43], [44]. Initial EDTA blood samples were taken from sick or sentinel animals, while spleen samples were taken at post-mortem. Isolates were serotyped by serum neutralization tests (SNTs) as described in the OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals [45], using type specific antisera provided by the OIE Reference Laboratory at the Onderstepoort Veterinary Institute, Onderstepoort, South Africa. Each of these virus isolates is included in the reference collection at IAH Pirbright (see www.reoviridae.org/dsRNA_virus_proteins/ReoID/BTV-isolates.htm) and is identified here by their reference collection number.

Bottom Line: The BTV genome is composed of ten linear segments of double-stranded RNA (dsRNA), each of which codes for one of ten distinct viral proteins.The full-length nucleotide sequence of genome Seg-3 was determined for thirty BTV isolates recovered in the eastern Mediterranean region, the Balkans and other geographic areas (Spain, India, Malaysia and Africa).These analyses also show that the recent incursions into south-eastern Europe were caused by BTV strains belonging to two different major-lineages: representing an 'eastern' (BTV-9, -16 and -1) and a 'western' (BTV-4) group/topotype.

View Article: PubMed Central - PubMed

Affiliation: Arbovirus Molecular Research Group, Department of vector borne diseases, Institute for Animal Health, Pirbright Laboratory, Woking, Surrey, United Kingdom.

ABSTRACT
Bluetongue virus (BTV) is the 'type' species of the genus Orbivirus within the family Reoviridae. The BTV genome is composed of ten linear segments of double-stranded RNA (dsRNA), each of which codes for one of ten distinct viral proteins. Previous phylogenetic comparisons have evaluated variations in genome segment 3 (Seg-3) nucleotide sequence as way to identify the geographical origin (different topotypes) of BTV isolates. The full-length nucleotide sequence of genome Seg-3 was determined for thirty BTV isolates recovered in the eastern Mediterranean region, the Balkans and other geographic areas (Spain, India, Malaysia and Africa). These data were compared, based on molecular variability, positive-selection-analysis and maximum-likelihood phylogenetic reconstructions (using appropriate substitution models) to 24 previously published sequences, revealing their evolutionary relationships. These analyses indicate that negative selection is a major force in the evolution of BTV, restricting nucleotide variability, reducing the evolutionary rate of Seg-3 and potentially of other regions of the BTV genome. Phylogenetic analysis of the BTV-4 strains isolated over a relatively long time interval (1979-2000), in a single geographic area (Greece), showed a low level of nucleotide diversity, indicating that the virus can circulate almost unchanged for many years. These analyses also show that the recent incursions into south-eastern Europe were caused by BTV strains belonging to two different major-lineages: representing an 'eastern' (BTV-9, -16 and -1) and a 'western' (BTV-4) group/topotype. Epidemiological and phylogenetic analyses indicate that these viruses originated from a geographic area to the east and southeast of Greece (including Cyprus and the Middle East), which appears to represent an important ecological niche for the virus that is likely to represent a continuing source of future BTV incursions into Europe.

Show MeSH
Related in: MedlinePlus