title: Loss of cytoskeletal transport during egress critically attenuates ectromelia virus infection in vivo.
abstract: Egress of wrapped virus (WV) to the cell periphery following vaccinia virus (VACV) replication is dependent on interactions with the microtubule motor complex kinesin-1 and is mediated by the viral envelope protein A36. Here we report that ectromelia virus (ECTV), a related orthopoxvirus and the causative agent of mousepox, encodes an A36 homologue (ECTV-Mos-142) that is highly conserved despite a large truncation at the C terminus. Deleting the ECTV A36R gene leads to a reduction in the number of extracellular viruses formed and to a reduced plaque size, consistent with a role in microtubule transport. We also observed a complete loss of virus-associated actin comets, another phenotype dependent on A36 expression during VACV infection. ECTV ΔA36R was severely attenuated when used to infect the normally susceptible BALB/c mouse strain. ECTV ΔA36R replication and spread from the draining lymph nodes to the liver and spleen were significantly reduced in BALB/c mice and in Rag-1-deficient mice, which lack T and B lymphocytes. The dramatic reduction in ECTV ΔA36R titers early during the course of infection was not associated with an augmented immune response. Taken together, these findings demonstrate the critical role that subcellular transport pathways play not only in orthopoxvirus infection in an in vitro context but also during orthopoxvirus pathogenesis in a natural host. Furthermore, despite the attenuation of the mutant virus, we found that infection nonetheless induced protective immunity in mice, suggesting that orthopoxvirus vectors with A36 deletions may be considered another safe vaccine alternative.
authors.affiliation: School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia.
authors.forename: Helena
authors.initials: H
authors.lastname: Lynn
authors.forename: Jacquelyn
authors.initials: J
authors.lastname: Horsington
authors.forename: Lee Kuan
authors.initials: LK
authors.lastname: Ter
authors.forename: Shuyi
authors.initials: S
authors.lastname: Han
authors.forename: Yee Lian
authors.initials: YL
authors.lastname: Chew
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Diefenbach
authors.forename: Michael
authors.initials: M
authors.lastname: Way
authors.forename: Geeta
authors.initials: G
authors.lastname: Chaudhri
authors.forename: Gunasegaran
authors.initials: G
authors.lastname: Karupiah
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Newsome
mesh_terms: D000818:Animals; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004481:Ectromelia virus / Q000235:genetics / Q000472:pathogenicity*; D004482:Ectromelia, Infectious / Q000821:virology*; D005260:Female; D017353:Gene Deletion; D054884:Host-Pathogen Interactions; D008099:Liver / Q000821:virology; D008198:Lymph Nodes / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D021381:Protein Transport; D013154:Spleen / Q000821:virology; D019562:Viral Load; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D057074:Virus Release
chemical_list: D003598:Cytoskeletal Proteins; D014764:Viral Proteins