Complete sequence characterization of the genome of the St Croix River virus, a new orbivirus isolated from cells of Ixodes scapularis

Abstract

An orbivirus identified as St Croix River virus (SCRV) was isolated from cells of Ixodes scapularisticks. Electron microscopy showed particles with typical orbivirus morphology. The SCRV genome was sequenced completely and compared to previously characterized orbivirus genomes. Significant identity scores (21-38 %) were detected between proteins encoded by segments S1, S2, S4, S5, S6, S8, S9 and S10 of SCRV and those encoded by segments S1, S3, S4, S5, S6, S7, S9 and S10, respectively, of Bluetongue virus (BTV), the prototype orbivirus species. The protein encoded by SCRV genome segment 3 (VP3) is thought to be the equivalent of VP2 of BTV. Segment 7 encodes a protein homologous to non-structural protein NS2(ViP) of BTV. Analysis of VP1(Pol) (segment 1) shows that SCRV is an orbivirus, distantly related to the other sequenced species. Blot hybridizations and sequence comparisons of the conserved protein encoded by genome segment 2 (the T2 subcore shell protein) with previously identified orbiviruses confirm that SCRV is a distinct orbivirus species, unrelated to another tick-borne species, Great Island virus. The presence of SCRV in cells prepared from tick eggs suggests that transovarial transmission of SCRV may occur in ticks.

Tick cell lines: tools for tick and tick-borne disease research

“…Infection and development of A. marginale in tick cells ( Figure I) eggs) because IDE2 was embryo-derived [39]. This virus is also present in IDE8, but is absent from ISE6 (U.G.…”

Rickettsia peacockii, an endosymbiont of Dermacentor andersoni, does not elicit or inhibit humoral immune responses from immunocompetent D. andersoni or Ixodes scapularis cell lines

“…Cultures were maintained at 34°C and fed fresh medium weekly. IDE cell lines have been shown to be chronically infected with the St. Croix River virus (Reoviridae: Orbivirus) (22). However, this does not appear to impair their phagocytic ability, since the ISE6 line from the same tick species, but which does not carry that virus (H. Attoui, pers.…”

Mobuck virus genome sequence and phylogenetic analysis: identification of a novel Orbivirus isolated from a white-tailed deer in Missouri, USA

“…VP1 amino acid sequence identities of at least 20 % are classified to a single genus within the family Reoviridae (Attoui et al, 2000). Polymerase proteins of different Orbivirus species share 36-73 % amino acid identity (Attoui et al, 2001). Mobuck virus VP1 amino acid sequence identity ranges from 35.9 to 71.2 % to other orbiviruses.…”

“…Phylogenetic analysis shows that the mobuck virus has a close relationship and similar coding pattern to other mosquito-borne orbiviruses, suggesting a mosquito vector. As proposed by Attoui et al (2001), a T2 amino acid identity cut-off of 91 % is used for species determination. Thus, with only 69.1 % homology to PHSV, mobuck virus represents a novel and distinct Orbivirus species.…”