title: Immunogenicity of the Q fever skin test.
abstract: OBJECTIVE
  The Q fever skin test is used to measure cell-mediated immunity to Coxiella burnetii in pre-vaccination screening to exclude individuals with pre-existing immunity. We investigated whether this in-vivo test influences subsequent measurements of immune response.
  
  
  METHODS
  We assessed the humoral and cellular immune responses before, and 6 and 12 months after skin testing in 63 individuals who were not vaccinated because of either a positive skin test or positive serology in screening. IgG anti-C. burnetii antibodies were measured using immune-fluorescence assay (IFA). The cellular immune response was assessed by measuring in-vitro C. burnetii-specific interferon (IFN)-γ production in blood.
  
  
  RESULTS
  Of the 35 subjects with a positive skin test and negative serology, 15/35 (43%) showed seroconversion at 6 months, and 7/32 (22%) seropositivity at 12 months. The mean ± SE specific IFN-γ production in this group increased from 185 ± 88 pg/mL (at baseline) to 422 ± 141 pg/mL at 6 months (P = 0.009) and 223 ± 91 pg/mL at 12 months (P = 0.17). Of the 28 subjects with positive serology (and unknown skin test results), 21/28 (75%) showed an increase in IgG anti-phase I titres at 6 months, and 11/25 (44%) at 12 months. The mean ± SE specific IFN-γ production was significantly increased at 6 months, but not at 12 months.
  
  
  CONCLUSIONS
  Q fever skin testing causes higher antibody titres and higher in-vitro IFN-γ to C. burnetii, and therefore affects subsequent Q fever diagnostics.
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands. Electronic address: Teske.Schoffelen@Radboudumc.nl.
authors.forename: Teske
authors.initials: T
authors.lastname: Schoffelen
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
authors.forename: Tineke
authors.initials: T
authors.lastname: Herremans
authors.affiliation: Department of Medical Microbiology and Infectious Diseases, Canisius Wilhelmina Hospital, P.O. Box 9015, 6500 GS Nijmegen, The Netherlands; Department of Internal Medicine, Canisius Wilhelmina Hospital, P.O. Box 9015, 6500 GS Nijmegen, The Netherlands.
authors.forename: Tom
authors.initials: T
authors.lastname: Sprong
authors.affiliation: Department of Medical Microbiology and Infectious Diseases, Canisius Wilhelmina Hospital, P.O. Box 9015, 6500 GS Nijmegen, The Netherlands.
authors.forename: Marrigje
authors.initials: M
authors.lastname: Nabuurs-Franssen
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Jos W M
authors.initials: JW
authors.lastname: van der Meer
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Leo A B
authors.initials: LA
authors.lastname: Joosten
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Mihai G
authors.initials: MG
authors.lastname: Netea
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
authors.forename: Henk A
authors.initials: HA
authors.lastname: Bijlmer
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: van Deuren
mesh_terms: D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D016997:Coxiella burnetii / Q000302:isolation & purification; D005260:Female; D006801:Humans; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007074:Immunoglobulin G / Q000097:blood; D007371:Interferon-gamma / Q000097:blood; D008297:Male; D008875:Middle Aged; D011778:Q Fever / Q000175:diagnosis* / Q000276:immunology*; D012882:Skin Tests; D014611:Vaccination
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007371:Interferon-gamma
keywords: Booster effect; Coxiella burnetii; Diagnostic test; Immunogenicity; Interferon-gamma; Q fever; Serology; Skin test