title: Diagnosis of latent tuberculosis infection in bacille Calmette-Guérin vaccinated subjects in China by interferon-gamma ELISpot assay.
abstract: OBJECTIVE
  To evaluate the performance of an in-house interferon-gamma (IFN-γ) enzyme-linked immunospot (ELISpot) assay for the detection of latent tuberculosis infection (LTBI) in bacille Calmette-Guérin (BCG) vaccinated individuals with or without human immunodeficiency virus (HIV) infection.
  
  
  METHODS
  A total of 202 participants (93 HIV-infected and 109 non-infected) who received BCG vaccination at birth underwent tuberculin skin testing (TST) and T cell-based ELISpot assays. The performance of an in-house IFN-γ ELISpot assay (ELISpot) was evaluated by parallel comparison with the commercial IFN-γ release assay (IGRA) kit, T-SPOT®.TB, in 127 subjects. The effect of BCG vaccination on the ELISpot assay was prospectively determined by comparing the responses of IGRAs before and 3 months after BCG vaccination in 27 individuals.
  
  
  RESULTS
  High agreement between ELISpot and T-SPOT.TB was observed in both HIV-infected (92.47%, κ = 0.754) and non-HIV-infected subjects (97.06%, κ = 0.653). CD4(+) T-cell count does not affect Mycobacterium tuberculosis IFN-γ response as measured by both ELISpot and T-SPOT.TB. BCG vaccination resulted in 100% conversion of TST, but did not change responses to IGRAs.
  
  
  CONCLUSIONS
  The performance of this in-house ELISpot assay is comparable to commercial T-SPOT.TB in diagnosing LTBI. Both assays are useful for diagnosing LTBI in BCG-vaccinated subjects with or without HIV infection in a setting with a high prevalence of tuberculosis.
authors.affiliation: Shenzhen Clinical Centre for Infectious Diseases, Shenzhen, China.
authors.forename: M
authors.initials: M
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Liao
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Graner
authors.forename: X
authors.initials: X
authors.lastname: Zhu
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: Q
authors.initials: Q
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Lu
authors.forename: B
authors.initials: B
authors.lastname: Zhou
authors.forename: X
authors.initials: X
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D001500:BCG Vaccine / Q000008:administration & dosage*; D002681:China; D058501:Enzyme-Linked Immunospot Assay / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000150:complications; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology*; D055985:Latent Tuberculosis / Q000150:complications / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D001500:BCG Vaccine; D007371:Interferon-gamma