title: Disassembly of the cystovirus ϕ6 envelope by montmorillonite clay.
abstract: Prior studies of clay-virus interactions have focused on the stability and infectivity of nonenveloped viruses, yielding contradictory results. We hypothesize that the surface charge distribution of the clay and virus envelope dictates how the components react and affect aggregation, viral stability, and infectivity. The bacteriophage Cystoviridae species φ6 used in this study is a good model for enveloped pathogens. The interaction between φ6 and montmorillonite (MMT) clay (the primary component of bentonite) is explored by transmission electron microscopy. The analyses show that MMT-φ6 mixtures undergo heteroaggregation, forming structures in which virtually all the virions are either sequestered between MMT platelet layers or attached to platelet edges. The virions swell and undergo disassembly resulting in partial or total envelope loss. Edge-attached viral envelopes distort to increase contact area with the positively charged platelet edges indicating that the virion surface is negatively charged. The nucleocapsid (NCs) remaining after envelope removal also exhibit distortion, in contrast to detergent-produced NCs which exhibit no distortion. This visually discernible disassembly is a mechanism for loss of infectivity previously unreported by studies of nonenveloped viruses. The MMT-mediated sequestration and disassembly result in reduced infectivity, suggesting that clays may reduce infectivity of enveloped pathogenic viruses in soils and sediments.
authors.affiliation: Department of Earth and Atmospheric Sciences, City College of New York, 160 Convent Avenue, New York, NY, 10031.
authors.forename: Karin A
authors.initials: KA
authors.lastname: Block
authors.forename: Adrianna
authors.initials: A
authors.lastname: Trusiak
authors.forename: Al
authors.initials: A
authors.lastname: Katz
authors.forename: Paul
authors.initials: P
authors.lastname: Gottlieb
authors.forename: Alexandra
authors.initials: A
authors.lastname: Alimova
authors.forename: Hui
authors.initials: H
authors.lastname: Wei
authors.forename: Jorge
authors.initials: J
authors.lastname: Morales
authors.forename: William J
authors.initials: WJ
authors.lastname: Rice
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Steiner
mesh_terms: D001546:Bentonite / Q000494:pharmacology*; D003102:Colloids; D017910:Cystoviridae / Q000187:drug effects* / Q000472:pathogenicity / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D008854:Microscopy, Electron; D019251:Nucleocapsid / Q000187:drug effects / Q000648:ultrastructure; D012988:Soil Microbiology; D010948:Viral Plaque Assay; D014771:Virion / Q000187:drug effects* / Q000648:ultrastructure
chemical_list: D003102:Colloids; D001546:Bentonite
keywords: Viral envelope disassembly; viral infectivity; virus adsorption; virus-montmorillonite heteroaggregation; ϕ6 nucleocapsid.