title: Mousepox detected in a research facility: case report and failure of mouse antibody production testing to identify Ectromelia virus in contaminated mouse serum.
abstract: An outbreak of mousepox in a research institution was caused by Ectromelia-contaminated mouse serum that had been used for bone marrow cell culture and the cells subsequently injected into the footpads of mice. The disease initially was diagnosed by identification of gross and microscopic lesions typical for Ectromelia infection, including foci of necrosis in the liver and spleen and eosinophilic intracytoplasmic inclusion bodies in the skin. The source of infection was determined by PCR analysis to be serum obtained from a commercial vendor. To determine whether viral growth in tissue culture was required to induce viral infection, 36 mice (BALB/cJ, C57BL/6J) were experimentally exposed intraperitoneally, intradermally (footpad), or intranasally to contaminated serum or bone marrow cell cultures using the contaminated serum in the culture medium. Mice were euthanized when clinical signs developed or after 12 wk. Necropsy, PCR of spleen, and serum ELISA were performed on all mice. Mice injected with cell cultures and their cage contacts developed mousepox, antibodies to Ectromelia, and lesions, whereas mice injected with serum without cells did not. Mouse antibody production, a tool commonly used to screen biologic materials for viral contamination, failed to detect active Ectromelia contamination in mouse serum.
authors.affiliation: Comparative Pathology Laboratory, School of Veterinary Medicine, University of California, Davis, California, USA.
authors.forename: Philippe
authors.initials: P
authors.lastname: Labelle
authors.forename: Nina E
authors.initials: NE
authors.lastname: Hahn
authors.forename: Jenelle K
authors.initials: JK
authors.lastname: Fraser
authors.forename: Lonnie V
authors.initials: LV
authors.lastname: Kendall
authors.forename: Melanie
authors.initials: M
authors.lastname: Ziman
authors.forename: Edward
authors.initials: E
authors.lastname: James
authors.forename: Nilabh
authors.initials: N
authors.lastname: Shastri
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Griffey
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000821:virology; D016026:Bone Marrow Transplantation; D002478:Cells, Cultured / Q000821:virology; D004196:Disease Outbreaks; D004481:Ectromelia virus / Q000378:metabolism*; D004482:Ectromelia, Infectious / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006799:Housing, Animal; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011897:Random Allocation; D012376:Rodent Diseases / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D014611:Vaccination