Assessment of IgA anti-PT and IgG anti-ACT reflex testing to improve Bordetella pertussis serodiagnosis in recently vaccinated subjects. (May 2020)

• Record Type: Journal Article
• Authors: Subissi, L.; Rodeghiero, C.; Martini, H.; Litzroth, A.; Huygen, K.; Leroux-Roels, G.; Piérard, D.; Desombere, I.
• Is Part Of: Clinical microbiology and infection. Volume 26:Number 5(2020)
• Page Start: 645.e1
• Page End: 645.e8
• Publication Date: 2020-05
• Subjects: ACT -- Antibody -- Bordetella pertussis -- IgA -- Pertussis toxin -- Serodiagnosis -- Serology -- Vaccination; Medical microbiology -- Periodicals; Diagnostic microbiology -- Periodicals; Communicable diseases -- Periodicals; Infection -- Periodicals; 616.01
• DOI: 10.1016/j.cmi.2019.10.001
• Languages: English
• ISSNs: 1198-743X

Abstract

Abstract: Objectives: Quantifying IgG antibodies to pertussis toxin (PT) is the most specific and sensitive method for the serodiagnosis of a Bordetella pertussis infection. Since PT is a component of acellular pertussis vaccines, anti-PT IgG is also induced by vaccination, precluding pertussis serodiagnosis based exclusively on anti-PT IgG in recently vaccinated subjects. Here, we aim to identify additional B. pertussis- specific serological markers that can discriminate between infection and recent vaccination. Methods: The clinical usefulness of measuring IgA directed to the vaccine antigen PT and IgG directed to non-vaccine antigens (Fim2/3, LPS, ACT, CatACT) was evaluated in nine well characterized subject groups, aged 10–89 years ( n = 390). Serum anti-PT IgG levels (>125 IU/mL) served as an indicator for a recent B. pertussis infection. Comparing symptomatic pertussis-infected subjects ( n = 140) with recently vaccinated, non-infected subjects ( n = 100) revealed the optimal cut-off, accuracy, sensitivity and specificity for each single parameter. Results: For pertussis diagnosis in recently vaccinated subjects, the measurement of anti-PT IgA (cut-off 15 IU/mL) and anti-ACT IgG (cut-off 15 U/mL) resulted in accuracies of 95% (91.5–97.1) and 87.5% (82.7–91.1), sensitivities of 92.9% (87.4–96.0) and 83.6% (76.5–88.8) and specificities of 98% (93.0–99.4) and 93% (86.3–96.6), respectively. Comparing anti-PT IgA levels between the youngest (10–19 years, n = 38) and oldest (70–89 years, n = 17) age groups revealed an age-dependent increase in antibody levels in pertussis-infected subjects (p < 0.0001). Conclusions: Reflex testing of anti-PT IgA and anti-ACT IgG improves pertussis serodiagnosis in recently vaccinated symptomatic subjects with elevated anti-PT IgG levels. Furthermore, both markers can discriminate between vaccination and recent infection in pertussis serosurveillance studies.