Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2001
Publication Date: 5/1/2002
Citation: Rabenstein, F., Seifers, D., Horken, K.M., Schubert, J., French, R.C., Stenger, D.C. 2002. Phylogenetic relationships, strain diversity, and biogeography of tritimoviruses. Journal Of General Virology 83:895-906.
Interpretive Summary: Relationships among virus isolates of Wheat streak mosaic virus (WSMV) and Oat necrotic mottle virus (ONMV) from North America and Eurasia were examined. Comparison of nucleotide sequences of the coat protein gene indicated that distinct populations of WSMV exist in the U. S., Mexico, and Central Europe. In contrast, WSMV isolates from Turkey were very similar to the U. S. isolates, suggesting that movement of virus between Turkey and the U. S. has occurred in the recent past. Characterization of two ONMV isolates indicated that a European isolate of ONMV recovered from Kentucky blue grass in Germany was nearly identical to the Type isolate of ONMV from Canada. This observation suggests that ONMV also has been recently transported across the Atlantic. Serological relationships and nucleotide sequence comparisons established that WSMV and ONMV are closely related, albeit distinct virus species of the genus Tritimovirus.
Technical Abstract: North American and Eurasian isolates of Wheat streak mosaic virus (WSMV; genus Tritimovirus) and Oat necrotic mottle virus (ONMV; genus Rymovirus) were examined. While all nine WSMV isolates infected wheat, differential abilities to systemically infect oat, barley, inbred maize line SDP2, and sorghum line KS56 were noted. The WSMV isolates grouped into at least three clusters based on phylogenetic analyses of the capsid protein (CP) cistron and flanking regions. WSMV isolates from the U. S. and Turkey were closely related, suggesting recent movement of WSMV between continents. A second cluster of WSMV isolates from central Europe and Russia may represent a distinct Eurasian population. WSMV from Iran (WSMV-I) was nearly equally divergent from the U. S. and other Eurasian isolates, but clustered differently in phylogenetic analyses based on nucleotide versus amino acid alignments. Complete genome sequences of WSMV from the Czech Republic (WSMV-CZ) and Turkey (WSMV-TK1) were determined and comparisons based on complete sequences of five WSMV isolates yielded similar relationships as those based on partial sequences. ONMV-Pp recovered from blue grass (Poa pratensis) in Germany displayed the same narrow host range as ONMV-Type from Canada. Western blots revealed a heterologous relationship among CPs of WSMV and ONMV. Phylogenetic analyses of the CP cistron and flanking genomic regions indicated that WSMV and ONMV are sister species sharing 74.2-76.2% (nucleotide) and 79.2 81.0% (amino acid) identity. Thus, a taxonomic revision is proposed: ONMV should be removed from the genus Rymovirus and designated a definitive member of the genus Tritimovirus.