Complete Genome Sequence Analysis of a Reference Strain of Bluetongue Virus Serotype 16

Abstract

The entire genome of the reference strain of bluetongue virus (BTV) serotype 16 (strain RSArrrr/16) was sequenced (a total of 23,518 base pairs). The virus was obtained from the Orbivirus Reference Collection (ORC) at IAH, Pirbright, United Kingdom. The virus strain, which was previously provided by the Onderstepoort Veterinary Research Institute in South Africa, was originally isolated from the Indian subcontinent (Hazara, West Pakistan) in 1960. Previous phylogenetic comparisons show that BTV RNA sequences cluster according to the geographic origins of the virus isolate/lineage, identifying distinct BTV topotypes. Sequence comparisons of segments Seg-1 to Seg-10 show that RSArrrr/16 belongs to the major eastern topotype of BTV (BTV-16e) and can be regarded as a reference strain of BTV-16e for phylogenetic and molecular epidemiology studies. All 10 genome segments of RSArrrr/16 group closely with the vaccine strain of BTV-16 (RSAvvvv/16) that was derived from it, as well as those recently published for a Chinese isolate of BTV-16 (>99% nucleotide identity), suggesting a very recent common ancestry for all three viruses. B luetongue (BT) is an economically important arthropodborne disease, caused by the bluetongue virus (BTV), which can infect most ruminants (including sheep, goats, cattle, and deer). Bluetongue virus is the type species of the genus Orbivirus (family Reoviridae). The BTV genome, which codes for 7 structural and 4 nonstructural proteins, is composed of 10 linear segments of double-stranded RNA (dsRNA) that are packaged within an icosahedral, ϳ90-nm-diameter, triple-layered protein capsid (1,2,4,11,12,14,15).Multiple BTV strains have recently emerged in Europe, emphasizing the importance of accurate strain identification (through molecular typing and epidemiology studies) to support the development and deployment of appropriate vaccines.BTV-16 was first isolated in 1960 in Pakistan (5, 13). We report the complete genome sequence of the BTV-16 reference strain (RSArrrr/16) (which was supplied to the Orbivirus Reference Collection [ORC] at IAH, Pirbright, by the Onderstepoort Veterinary Institute [OVI], South Africa). The genome of RSArrrr/16 was converted to cDNA by full-length amplification of cDNAs (FLAC) (10). Corresponding cDNAs for each segment were purified and sequenced on a 3730 capillary sequencer (Applied Biosystems), using "phased primers" to generate near-terminal sequences (10) and "walking-segment-specific primers" to determine the full nucleotide sequence. The sizes (in base pairs) of Seg-1 to Seg-10 from RSArrrr/16 are 3,944, 2,935, 2,772, 1,981, 1,763, 1,637, 1,156, 1,127, 1,054, and 822, respectively, encoding structural proteins VP1 to VP7 (with open reading frame [ORFs] sizes of 1,302 aa for VP1, 959 for VP2, 901 for VP3, 644 for VP4, 526 for VP5, 330 for VP6, and 349 for VP7) and four nonstructural proteins, NS1 to NS4 (length of 552 aa for NS1, 354 for NS2, 229/216 for NS3/ NS3a, and 77 for NS4).Previously, two BTV-16 field strains from China and Australia have been fully seq...

Molecular Characterization of Segment 6 of Bluetongue Serotype 16 of Sheep Origin from India

“…The sequence analyses revealed that Indian BT16/07 isolate share >99.0% nucleotide and amino acid identity with Indian isolates of BTV16 (GenBank accession number JQ924825 and JN572918). It showed 97.6% nucleotide and 98.8% amino acid identity with reference eastern BTV16 isolates from Pakistan (Maan et al, 2012b). The BT16/07 isolate showed 97.8 -91.1% nucleotide and 99.2 -97.6% amino acid identity with other eastern BTV16 isolates from Australia, Japan, Indonesia, China, Italy, Turkey, Greece isolates.…”

Complete Genome Sequence Analysis of a Reassortant Strain of Bluetongue Virus Serotype 16 from Italy

“…The quality-filtered sequence reads were aligned against the reference sequences by use of the CLC Genomics Workbench. The 10 segments of BTV serotype 16 (BTV-16) strain ITL2002 were amplified successfully for their entire length (14). Sizes in base pairs for Seg-1 to Seg-10 of BTV-16 ITL2002 were 3,944, 2,935, 2,272, 1,981, 1,776, 1,637, 1,156, 1,125, 1,052, and 822, respectively.…”

“…BTV-16 was isolated for the first time in 1960 in Pakistan, supplied to the Onderstepoort Veterinary Research Institute, and named RSArrrr/16 (South Africa). It was recently fully sequenced at Pirbright, United Kingdom (14). All segments except Seg-5 showed >99% sequence identity with RSArrrr/16 and the corresponding vaccine strain RSAvvvv/16.…”

Bluetongue: Virus proteins and recent diagnostic approaches

“…Bluetongue virus with closely related species African Horse Sickness virus (AHSV) and Epizootic Hemorrhagic Disease virus (EHDV) belongs to the genus Orbivirus (comprising at least 20 species overall) in the family Reoviridae (Eschbaumer et al, 2009;Maan et al, 2012a). The virions have a diameter of 90 nm.…”

“…It is characterized by high fever, catarrhal inflammation of the buccal and nasal mucous membranes, and inflammation of the tongue, intestine and sensitive laminae of the foot. Bluetongue has been known in South Africa for over a 100 years and endemic in wild ruminants since antiquity (Maclachlan et al, 2009, Maclachlan, 2011Sperlova and Zendulkova, 2011;Maan et al, 2012a;Bitew et al, 2013).…”