title: Cidofovir inhibits genome encapsidation and affects morphogenesis during the replication of vaccinia virus.
abstract: Cidofovir (CDV) is one of the most effective antiorthopoxvirus drugs, and it is widely accepted that viral DNA replication is the main target of its activity. In the present study, we report a detailed analysis of CDV effects on the replicative cycles of distinct vaccinia virus (VACV) strains: Cantagalo virus, VACV-IOC, and VACV-WR. We show that despite the approximately 90% inhibition of production of virus progeny, virus DNA accumulation was reduced only 30%, and late gene expression and genome resolution were unaltered. The level of proteolytic cleavage of the major core proteins was diminished in CDV-treated cells. Electron microscopic analysis of virus-infected cells in the presence of CDV revealed reductions as great as 3.5-fold in the number of mature forms of virus particles, along with a 3.2-fold increase in the number of spherical immature particles. A detailed analysis of purified virions recovered from CDV-treated cells demonstrated the accumulation of unprocessed p4a and p4b and nearly 67% inhibition of DNA encapsidation. However, these effects of CDV on virus morphogenesis resulted from a primary effect on virus DNA synthesis, which led to later defects in genome encapsidation and virus assembly. Analysis of virus DNA by atomic force microscopy revealed that viral cytoplasmic DNA synthesized in the presence of CDV had an altered structure, forming aggregates with increased strand overlapping not observed in the absence of the drug. These aberrant DNA aggregations were not encapsidated into virus particles.
authors.affiliation: Laboratório de Biologia Molecular de Vírus, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Desyreé Murta
authors.initials: DM
authors.lastname: Jesus
authors.forename: Lilian T
authors.initials: LT
authors.lastname: Costa
authors.forename: Daniela L
authors.initials: DL
authors.lastname: Gonçalves
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Achete
authors.forename: Marcia
authors.initials: M
authors.lastname: Attias
authors.forename: Nissin
authors.initials: N
authors.lastname: Moussatché
authors.forename: Clarissa R
authors.initials: CR
authors.lastname: Damaso
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D000077404:Cidofovir; D003596:Cytosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004279:DNA, Viral / Q000096:biosynthesis; D009024:Morphogenesis / Q000187:drug effects; D063065:Organophosphonates / Q000494:pharmacology*; D014616:Vaccinia virus / Q000187:drug effects* / Q000502:physiology; D014764:Viral Proteins / Q000096:biosynthesis; D014771:Virion / Q000502:physiology; D019065:Virus Assembly / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D063065:Organophosphonates; D014764:Viral Proteins; D003596:Cytosine; D000077404:Cidofovir