title: Comparison of 10 indirect fluorescent antibodies to detect and type influenza A specimens.
abstract: BACKGROUND
  Management of influenza infections relies on rapid, accurate, and sensitive diagnostic techniques. Influenza A (IA) strain typing has become more important since the emergence of highly pathogenic avian and novel influenza strains and the high frequency of oseltamivir resistance in circulating H1N1 isolates.
  
  
  OBJECTIVE
  To analyze the performance of indirect fluorescent antibody testing for subtyping a broad range of IA strains.
  
  
  METHODS
  Ten indirect fluorescent antibody reagents were used to detect and type 100 archived IA respiratory specimens from 1986 through 1995 and 2006 through 2007 and a reassortant, nonpathogenic H5N1 sample. Both direct specimen and cultured isolates were tested. Reverse transcription-polymerase chain reaction was used to confirm indirect fluorescent antibody results. Three H1N1-, 2 H3N2-, and 1 H1-H2-H3-H5-specific antibodies (Chemicon Diagnostics), an IA pool reagent (Trinity Biotech), and H1, H3, and H1-H3-specific antibodies (Centers for Disease Control and Prevention) were used.
  
  
  RESULTS
  Reverse transcription-polymerase chain reaction confirmed all 100 isolates as IA and identified 71 as H1, 22 as H3, and 7 as non-H1-H3. Sensitivity of direct specimen testing ranged was 18.3% to 57.7% for the H1 reagents, 36.4% to 50.0% for the H3 reagents, and 40.0% to 53.8% for the pool reagents. Subtyping was more sensitive on cultured isolates than direct specimens. Specificity for all antibodies was 89.7% to 100%. The H5N1 sample was positive by direct testing and culture (reverse transcription-polymerase chain reaction, Centers for Disease Control and Prevention H5N1 pool, Chemicon H1-H2-H3-H5). No cross-reactivity was observed when the 10 antibodies were tested against other common respiratory viruses.
  
  
  CONCLUSIONS
  When positive, IA subtyping antibodies can serve as a useful diagnostic tool when multiple influenza virus subtypes are cocirculating with different susceptibility patterns.
authors.affiliation: Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA. rosemary.she-bender@hsc.utah.edu
authors.forename: Rosemary C
authors.initials: RC
authors.lastname: She
authors.forename: Edward W
authors.initials: EW
authors.lastname: Taggart
authors.forename: Cathy A
authors.initials: CA
authors.lastname: Petti
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D003429:Cross Reactions; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000254:growth & development / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000097:blood / Q000175:diagnosis* / Q000821:virology; D011237:Predictive Value of Tests; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
chemical_list: D000914:Antibodies, Viral