Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2005
Publication Date: 10/1/2005
Citation: Stenger, D.C., French, R.C., Gildow, F.E. 2005. Complete deletion of wheat streak mosaic virus hc-pro: a nulll mutant is viable for systemic infection. Journal of Virology. v. 79. p. 12077-12080. Interpretive Summary: The genome of Wheat streak mosaic virus (WSMV) was modified by removal of the HC-Pro gene. Infectivity assays on wheat, corn, and oats indicated that HC-Pro was not required for systemic infection and symptom production. Functional assays for proteinase activity indicated that deletion of HC-Pro did not affect post-translational processing of the WSMV polyprotein. Electron microscopy revealed that the WSMV HC-Pro deletion mutant was competent to form virus particles, although estimations of virus titer by ELISA indicated that concentration of the deletion mutant in systemically infected wheat was reduced 4.5-fold relative to wild type WSMV. Collectively, these results indicate that WSMV HC-Pro is dispensable for replication and movement, two essential processes that are disrupted by point and small insertion mutations introduced into potyvirus HC-Pro.
Technical Abstract: A Wheat streak mosaic virus (WSMV) genome lacking HC-Pro was constructed and confirmed by RT-PCR to systemically infect wheat, oat, and corn. Coupled in vitro transcription/translation reactions indicated that WSMV P1 proteinase cleaved the polyprotein at the P1/P3 junction of the HC-Pro null mutant. The WSMV HC-Pro null mutant was competent for virion assembly but virus titer was reduced 4.5-fold relative to wild type. Collectively, these results indicate that WSMV HC-Pro is dispensable for replication and movement, two essential processes that are disrupted by point and small insertion mutations introduced into potyvirus HC-Pro.