role for plant microtubules in the formation of transmission-specific inclusion bodies of Cauliflower mosaic virus

• Published in: The Plant journal : for cell and molecular biology 2009-04, Vol.58 (1), p.135-146
• Main Authors: Martinière, Alexandre, Gargani, Daniel, Uzest, Marilyne, Lautredou, Nicole, Blanc, Stéphane, Drucker, Martin
• Format: Article
• Language: English
• Subjects: Animals; Bioengineering; Biological and medical sciences; Botany; Brassica rapa - metabolism; Brassica rapa - virology; Cauliflower mosaic virus; Caulimovirus - genetics; Caulimovirus - metabolism; Caulimovirus - pathogenicity; cell-microbe interaction; Cellular biology; Economics and Finance; Environmental studies; Escherichia coli - genetics; Escherichia coli - metabolism; fluorescence imaging; Fundamental and applied biological sciences. Psychology; Host-Pathogen Interactions; Humanities and Social Sciences; Imaging; Immune Sera - metabolism; Inclusion Bodies, Viral - metabolism; Insecta; Life Sciences; Microbiology; Microscopy, Fluorescence; microtubules; Microtubules - metabolism; Plant Cells - metabolism; Plant Cells - virology; Plant Diseases - virology; Plant pathology; plant virus; Protein Transport; Proteins; Protoplasts - metabolism; Protoplasts - virology; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains; Transfection; vector transmission; Viral Proteins - genetics; Viral Proteins - metabolism; Virology; Viruses
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2008.03768.x

Interactions between microtubules and viruses play important roles in viral infection. The best-characterized examples involve transport of animal viruses by microtubules to the nucleus or other intracellular destinations. In plant viruses, most work to date has focused on interaction between viral movement proteins and the cytoskeleton, which is thought to be involved in viral cell-to-cell spread. We show here, in Cauliflower mosaic virus (CaMV)-infected plant cells, that viral electron-lucent inclusion bodies (ELIBs), whose only known function is vector transmission, require intact microtubules for their efficient formation. The kinetics of the formation of CaMV-related inclusion bodies in transfected protoplasts showed that ELIBs represent newly emerging structures, appearing at late stages of the intracellular viral life cycle. Viral proteins P2 and P3 are first produced in multiple electron-dense inclusion bodies, and are later specifically exported to transiently co-localize with microtubules, before concentrating in a single, massive ELIB in each infected cell. Treatments with cytoskeleton-affecting drugs suggested that P2 and P3 might be actively transported on microtubules, by as yet unknown motors. In addition to providing information on the intracellular life cycle of CaMV, our results show that specific interactions between host cell and virus may be dedicated to a later role in vector transmission. More generally, they indicate a new unexpected function for plant cell microtubules in the virus life cycle, demonstrating that microtubules act not only on immediate intracellular or intra-host phenomena, but also on processes ultimately controlling inter-host transmission.