title: Superinfection exclusion by Citrus tristeza virus does not correlate with the production of viral small RNAs.
abstract: Superinfection exclusion (SIE), a phenomenon in which a preexisting viral infection prevents a secondary infection with the same or closely related virus, has been described for different viruses, including important pathogens of humans, animals, and plants. Several mechanisms acting at various stages of the viral life cycle have been proposed to explain SIE. Most cases of SIE in plant virus systems were attributed to induction of RNA silencing, a host defense mechanism that is mediated by small RNAs. Here we show that SIE by Citrus tristeza virus (CTV) does not correlate with the production of viral small interfering RNAs (siRNAs). CTV variants, which differed in the SIE ability, had similar siRNAs profiles. Along with our previous observations that the exclusion phenomenon requires a specific viral protein, p33, the new data suggest that SIE by CTV is highly complex and appears to use different mechanisms than those proposed for other viruses.
authors.affiliation: University of Florida, Department of Plant Pathology, 2550 Hull Road, Gainesville, FL 32611, USA. Electronic address: svetlana@ufl.edu.
authors.forename: Svetlana Y
authors.initials: SY
authors.lastname: Folimonova
authors.affiliation: University of Florida, Citrus Research and Education Center, Lake Alfred, FL 33850, USA.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Harper
authors.affiliation: University of Florida, Department of Microbiology and Cell Science, Gainesville, FL 32611, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Leonard
authors.affiliation: University of Florida, Department of Microbiology and Cell Science, Gainesville, FL 32611, USA.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Triplett
authors.affiliation: University of Florida, Citrus Research and Education Center, Lake Alfred, FL 33850, USA.
authors.forename: Turksen
authors.initials: T
authors.lastname: Shilts
mesh_terms: D002957:Citrus / Q000821:virology*; D060085:Coinfection; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D010935:Plant Diseases / Q000821:virology*; D010942:Plant Viruses / Q000235:genetics / Q000502:physiology*; D012367:RNA, Viral / Q000145:classification* / Q000235:genetics / Q000378:metabolism*
chemical_list: D012367:RNA, Viral
keywords: Citrus tristeza virus; Homologous interference; Plant virus; Superinfection exclusion