Back to Search
Start Over
Involvement of methylated HBHA expressed from Mycobacterium smegmatis in an IFN-γ release assay to aid discrimination between latent infection and active tuberculosis in BCG-vaccinated populations.
- Source :
- European Journal of Clinical Microbiology & Infectious Diseases; Aug2017, Vol. 36 Issue 8, p1415-1423, 9p
- Publication Year :
- 2017
-
Abstract
- IFN-γ release assays (IGRAs) based on region of difference 1 (RD1) antigens have improved diagnosis of Mycobacterium tuberculosis ( M. tb) infection. However, IGRAs with these antigens cannot discriminate between active tuberculosis (ATB) and latent tuberculosis infection (LTBI). M. tb heparin-binding-hemagglutinin (HBHA) induces relatively high IFN-γ responses in LTBI individuals and low responses in ATB patients, but purification of the native methylated HBHA from cultures of M. tb for immunological tests is complex and time-consuming. To overcome these cumbersome procedures, we constructed a recombinant Mycobacterium smegmatis strain that over-expressed HBHA under control of a strong furA promoter. The methylated activity of purified protein was verified by hybridization with anti-methylated Lys antibody, and the methylated HBHA (mHBHA) was further evaluated for antigen-specific IFN-γ responses in BCG-vaccinated Chinese population. A total of 138 individuals including 86 active TB (ATB) patients, 15 latent TB infection (LTBI) cases, and 37 healthy controls (HC) were tested by using an IFN-γ enzyme-linked immunospot (ELISPOT) assay. The results showed that T-cell responses against mHBHA were always lower in ATB patients than in LTBI individuals, regardless of the site of infection or the results of bacteriological tests. This allowed for a good discrimination between these two groups of M. tb-infected individuals, even in the BCG-vaccinated and high TB-incidence setting that is China. Additionally, combination of mHBHA and RD1 antigens in an IFN-γ release assay enhanced diagnostic efficacy for active TB cases. Taken together, inclusion of the immune response to mHBHA can discriminate healthy LTBI cases from ATB patients. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09349723
- Volume :
- 36
- Issue :
- 8
- Database :
- Complementary Index
- Journal :
- European Journal of Clinical Microbiology & Infectious Diseases
- Publication Type :
- Academic Journal
- Accession number :
- 124276672
- Full Text :
- https://doi.org/10.1007/s10096-017-2948-1