title: Incomplete but infectious vaccinia virions are produced in the absence of oncolysis in feline SCCF1 cells.
abstract: Vaccinia virus is a large, enveloped virus of the poxvirus family. It has broad tropism and typically virus replication culminates in accumulation and lytic release of intracellular mature virus (IMV), the most abundant form of infectious virus, as well as release by budding of extracellular enveloped virus (EEV). Vaccinia viruses have been modified to replicate selectively in cancer cells and clinically tested as oncolytic agents. During preclinical screening of relevant cancer targets for a recombinant Western Reserve strain deleted for both copies of the thymidine kinase and vaccinia growth factor genes, we noticed that confluent monolayers of SCCF1 cat squamous carcinoma cells were not destroyed even after prolonged infection. Interestingly, although SCCF1 cells were not killed, they continuously secreted virus into the cell culture supernatant. To investigate this finding further, we performed detailed studies by electron microscopy. Both intracellular and secreted virions showed morphological abnormalities on ultrastructural inspection, suggesting compromised maturation and morphogenesis of vaccinia virus in SCCF1 cells. Our data suggest that SCCF1 cells produce a morphologically abnormal virus which is nevertheless infective, providing new information on the virus-host cell interactions and intracellular biology of vaccinia virus.
authors: Cancer Gene Therapy Group, Department of Pathology and Transplantation Laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland.
authors: Suvi
authors: S
authors: Parviainen
authors: Cancer Gene Therapy Group, Department of Pathology and Transplantation Laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland; Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
authors: Karoliina
authors: K
authors: Autio
authors: Cancer Gene Therapy Group, Department of Pathology and Transplantation Laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland.
authors: Markus
authors: M
authors: Vähä-Koskela
authors: Cancer Gene Therapy Group, Department of Pathology and Transplantation Laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland.
authors: Kilian
authors: K
authors: Guse
authors: Cancer Gene Therapy Group, Department of Pathology and Transplantation Laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland.
authors: Sari
authors: S
authors: Pesonen
authors: Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, The United States of America.
authors: Thomas J
authors: TJ
authors: Rosol
authors: Advanced Microscopy Unit, Department of Pathology, Haartman Institute, University of Helsinki, Helsinki, Finland.
authors: Fang
authors: F
authors: Zhao
authors: Cancer Gene Therapy Group, Department of Pathology and Transplantation Laboratory, Haartman Institute, University of Helsinki, Helsinki, Finland.
authors: Akseli
authors: A
authors: Hemminki
mesh_terms: D000818:Animals; D002415:Cats; D045744:Cell Line, Tumor; D006801:Humans; D050504:Oncolytic Viruses; D014161:Transduction, Genetic; D014616:Vaccinia virus / Q000235:genetics / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D014771:Virion / Q000235:genetics / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure