title: The ϕ6 cystovirus protein P7 becomes accessible to antibodies in the transcribing nucleocapsid: a probe for viral structural elements.
abstract: Protein P7 is a component of the cystovirus viral polymerase complex. In the unpackaged procapsid, the protein is situated in close proximity to the viral directed RNA polymerase, P2. Cryo-electron microscopy difference maps from the species ϕ6 procapsid have demonstrated that P7 and P2 likely interact prior to viral RNA packaging. The location of P7 in the post-packaged nucleocapsid (NC) remains unknown. P7 may translocate closer to the five-fold axis of a filled procapsid but this has not been directly visualized. We propose that monoclonal antibodies (Mabs) can be selected that serve as probe- reagents for viral assembly and structure. A set of Mabs have been isolated that recognize and bind to the ϕ6 P7. The antibody set contains five unique Mabs, four of which recognize a linear epitope and one which recognizes a conformational epitope. The four unique Mabs that recognize a linear epitope display restricted utilization of Vκ and VH genes. The restricted genetic range among 4 of the 5 antibodies implies that the antibody repertoire is limited. The limitation could be the consequence of a paucity of exposed antigenic sites on the ϕ6 P7 surface. It is further demonstrated that within ϕ6 nucleocapsids that are primed for early-phase transcription, P7 is partially accessible to the Mabs, indicating that the nucleocapsid shell (protein P8) has undergone partial disassembly exposing the protein's antigenic sites.
authors: Sophie Davis School of Biomedical Education, City College of New York, New York, NY 10031, United States of America.
authors: Alexandra
authors: A
authors: Alimova
authors: Sophie Davis School of Biomedical Education, City College of New York, New York, NY 10031, United States of America.
authors: Hui
authors: H
authors: Wei
authors: Department of Physics, City College of New York, New York, NY 10031, United States of America.
authors: Al
authors: A
authors: Katz
authors: Sophie Davis School of Biomedical Education, City College of New York, New York, NY 10031, United States of America.
authors: Linda
authors: L
authors: Spatz
authors: Sophie Davis School of Biomedical Education, City College of New York, New York, NY 10031, United States of America.
authors: Paul
authors: P
authors: Gottlieb
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D000914:Antibodies, Viral / Q000276:immunology* / Q000378:metabolism; D000915:Antibody Affinity / Q000276:immunology; D017910:Cystoviridae / Q000145:classification / Q000235:genetics* / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D051379:Mice; D019251:Nucleocapsid / Q000235:genetics* / Q000276:immunology* / Q000648:ultrastructure; D011485:Protein Binding / Q000276:immunology; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D014764:Viral Proteins