title: Application of an automated specimen search system installed in a transmission electron microscope for the detection of caliciviruses in clinical specimens.
abstract: To evaluate the performance of an automated specimen search system in the detection of caliciviruses such as Norwalk-like viruses and Sapporo-like viruses, a suitable negative staining method was developed and the viruses were examined using the system installed in a transmission electron microscope (TEM). Clear images of the viruses were obtained by staining with 2% uranyl acetate at pH 4.0 as compared with 2% phosphotungstic acid staining at any pH. When the image parameter of 30+/-6 nm for the diameter of a single virus-like particle of 2% uranyl-acetate-stained Norwalk-like virus was set on the automated specimen search system, 95% of the virus-like particles that were counted by the conventional TEM technique were detected. The system was used to detect Norwalk-like viruses in five semipurified stool samples in which Norwalk-like viruses had already been detected by reverse transcription-polymerase chain reaction assay and conventional electron microscopy. The positive detection rate for Norwalk-like viruses, which had been counted by the conventional technique, ranged from 56.2 to 77.9% using this system. Our findings indicate that the automated specimen search system installed in a TEM is suitable for the detection of caliciviruses in semipurified stool samples. The system is useful for clinical diagnosis without the need for operator intervention.
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan. etu@nih.go.jp
authors.forename: Etsuko T
authors.initials: ET
authors.lastname: Utagawa
authors.forename: Eiko
authors.initials: E
authors.lastname: Nakazawa
authors.forename: Keiko
authors.initials: K
authors.lastname: Matsuo
authors.forename: Isao
authors.initials: I
authors.lastname: Oishi
authors.forename: Naokazu
authors.initials: N
authors.lastname: Takeda
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Miyamura
mesh_terms: D001331:Automation; D017250:Caliciviridae Infections / Q000473:pathology / Q000821:virology*; D005759:Gastroenteritis / Q000473:pathology / Q000821:virology*; D006801:Humans; D008854:Microscopy, Electron / Q000379:methods; D029322:Norovirus / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D009942:Organometallic Compounds; D010772:Phosphotungstic Acid; D029341:Sapovirus / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D013194:Staining and Labeling / Q000379:methods
chemical_list: D009942:Organometallic Compounds; D010772:Phosphotungstic Acid; C005460:uranyl acetate