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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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Related in: MedlinePlus

Sequence alignment of the 5′ terminal NCRs determined, indicating base pairing with the 3′ ends of the RNA transcripts.Only divergent sequences are shown.
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pone-0006437-g004: Sequence alignment of the 5′ terminal NCRs determined, indicating base pairing with the 3′ ends of the RNA transcripts.Only divergent sequences are shown.

Mentions: Comparisons of the near terminal NCRs of Seg-3 from the BTV isolates (Table 1), along with other published sequences (Table 2), showed no differences in their length. The NCRs showed a higher level of conservation overall than the coding region, suggesting an important functional role. The 17 bp upstream-NCR was identical in all of the isolates compared, while the 49 bp downstream-NCR showed only low levels of diversity within each lineage (eastern Pi = 0.049, SD = 0.009; western Pi = 0.044, SD = 0.008). The mean distance between lineages was Dxy = 0.121. In each case the conserved terminal hexanucleotides were in complete agreement with the sequences reported for BTV (+ve 5′-GUUAAA------ACUUAC-3′) [1], [62]. Comparative sequence analysis of the terminal NCRs, also confirmed the existence of short inverted repeat sequences [3], indicating base pairing between the 5′ and 3′ ends of the RNA transcripts (Figure 4).


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)

Sequence alignment of the 5′ terminal NCRs determined, indicating base pairing with the 3′ ends of the RNA transcripts.Only divergent sequences are shown.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0006437-g004: Sequence alignment of the 5′ terminal NCRs determined, indicating base pairing with the 3′ ends of the RNA transcripts.Only divergent sequences are shown.
Mentions: Comparisons of the near terminal NCRs of Seg-3 from the BTV isolates (Table 1), along with other published sequences (Table 2), showed no differences in their length. The NCRs showed a higher level of conservation overall than the coding region, suggesting an important functional role. The 17 bp upstream-NCR was identical in all of the isolates compared, while the 49 bp downstream-NCR showed only low levels of diversity within each lineage (eastern Pi = 0.049, SD = 0.009; western Pi = 0.044, SD = 0.008). The mean distance between lineages was Dxy = 0.121. In each case the conserved terminal hexanucleotides were in complete agreement with the sequences reported for BTV (+ve 5′-GUUAAA------ACUUAC-3′) [1], [62]. Comparative sequence analysis of the terminal NCRs, also confirmed the existence of short inverted repeat sequences [3], indicating base pairing between the 5′ and 3′ ends of the RNA transcripts (Figure 4).

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