|Ma,, H. - NAQI - CHINA|
|Venter,, E. - UNIV OF PRETORIA,S AFRICA|
|Van Kjik, A. - ONDERSTEPOORT, S AFRICA|
Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 2000
Publication Date: August 15, 2000
Citation: Wilson, W.C., Ma,, H.C., Venter,, E.H., Van Kjik, A.A., Seal, B.S., Mecham, J.O., Phylogenetic relationships of bluetongue viruses based on gene S7. Virus Research, 67:141-151, 2000. Interpretive Summary: Several proteins are important to blueongue virus being able to infect insect cells. Insects are an important transport vehicle for this economically important virus that causes disease in cattle. Therefore, genetic relationships among these virus types may correlate with differences in a structural protein important to bluetongue viruses ability yto infect insects. The genetics of the bluetongue inner core protein was compared among viruses from different regions of the world. This protein was found to be very similar among all the virus isolates examined. Those differences in the protein were not necessarily dependent on the geographic origin of the virus or to the type of insect the virus may transported by.
Technical Abstract: The inner core protein, VP7, of BTV has been identified as a viral attachment protein for insect cell infection. The inner core proteins are involved with infectivity of insect cells. We compared the gene segment S7, which encodes VP7, from 39 strains of BTV isolated from Central America, the Caribbean Basin, the United States, South Africa and Australia. For comparison, the S7 sequences from strains of the related orbiviruses, epizootic hemorrhagic disease virus (EHDV) and African horse sickness virus (AHSV) were included. The S7 gene was highly conserved among BTV strains and fairly conserved among the other orbiviruses examined. VP7 sequence alignment suggests that the BTV receptor-binding site in the insect is also conserved. Phylogenetic analyses revealed that the BTV S7 nucleotide sequences do not unequivocally display geographic distribution. The BTV strains can be separated into five clades based on the deduced VP7 amino acid sequence alignment and phylogeny but evidence for preferential selection by available gnat species for a particular VP7 clade is inconclusive. Differences between clades indicate allowable variation of the VP7 binding protein.