Background Very little longitudinal information is available regarding the performance of T cell-based tests for Mycobacterium tuberculosis infection. To address this deficiency, we conducted a longitudinal assessment of the enzyme-linked immunosorbent spot test (ELISPOT) test in comparison to the standard tuberculin skin test (TST). Methods and Findings In tuberculosis (TB) contacts we repeated ELISPOT tests 3 mo (n = 341) and 18 mo (n = 210) after recruitment and TSTs at 18 mo (n = 130). We evaluated factors for association with conversion and reversion and investigated suspected cases of TB. Of 207 ELISPOT-negative contacts, 51 (24.6%) had 3-mo ELISPOT conversion, which was associated with a positive recruitment TST (odds ratio [OR] 2.2, 95% confidence interval [CI] 1.0–5.0, p = 0.048) and negatively associated with bacillus Calmette-Guérin (BCG) vaccination (OR 0.5, 95% CI 0.2–1.0, p = 0.06). Of 134 contacts, 54 (40.2%) underwent 3-mo ELISPOT reversion, which was less likely in those with a positive recruitment TST (OR 0.3, 95% CI 0.1–0.8, p = 0.014). Between 3 and 18 mo, 35/132 (26.5%) contacts underwent ELISPOT conversion and 28/78 (35.9%) underwent ELISPOT reversion. Of the 210 contacts with complete results, 73 (34.8%) were ELISPOT negative at all three time points; 36 (17.1%) were positive at all three time points. Between recruitment and 18 mo, 20 (27%) contacts had ELISPOT conversion; 37 (50%) had TST conversion, which was associated with a positive recruitment ELISPOT (OR 7.2, 95% CI 1.4–37.1, p = 0.019); 18 (32.7%) underwent ELISPOT reversion; and five (8.9%) underwent TST reversion. Results in 13 contacts diagnosed as having TB were mixed, but suggested higher TST sensitivity. Conclusions Both ELISPOT conversion and reversion occur after M. tuberculosis exposure. Rapid ELISPOT reversion may reflect M. tuberculosis clearance or transition into dormancy and may contribute to the relatively low reported ELISPOT conversion rate. Therefore, a negative ELISPOT test for M. tuberculosis infection should be interpreted with caution.
References
[1]
Ewer K, Deeks J, Alvarez L, Bryant G, Waller S, et al. (2003) Comparison of T-cell-based assay with tuberculin skin test for diagnosis of infection in a school tuberculosis outbreak. Lancet 361: 1168–1173.
[2]
Hill PC, Brookes RH, Fox A, Fielding K, Jeffries DJ, et al. (2004) Large-scale evaluation of enzyme-linked immunospot assay and skin test for diagnosis of infection against a gradient of exposure in The Gambia. Clin Infect Dis 38: 966973.
[3]
Ferrara G, Losi M, D'Amico R, Roversi P, Piro R, et al. (2006) Use in routine clinical practice of two commercial blood tests for diagnosis of infection with Mycobacterium tuberculosis: A prospective study. Lancet 367: 1328–1334.
[4]
Ewer K, Millington KA, Deeks JJ, Alvarez L, Bryant G, et al. (2006) Dynamic antigen-specific T-cell responses after point-source exposure to . Am J Respir Crit Care Med 174: 831–839.
[5]
Wilkinson KA, Kon OM, Newton SM, Meintjes G, Davidson RN, et al. (2006) Effect of treatment of latent tuberculosis infection on the T cell response to antigens. J Infect Dis 193: 354–359.
[6]
Pathan AA, Wilkinson KA, Klenerman P, McShane H, Davidson RN, et al. (2001) Direct ex vivo analysis of antigen-specific IFN-gamma-secreting CD4 T cells in -infected individuals: associations with clinical disease state and effect of treatment. J Immunol 167: 5217–5225.
[7]
Carrara S, Vincenti D, Petrosillo N, Amicosante M, Girardi E, et al. (2004) Use of a T cell-based assay for monitoring efficacy of antituberculosis therapy. Clin Infect Dis 38: 754–756.
[8]
Nicol MP, Pienaar D, Wood K, Eley B, Wilkinson RJ, et al. (2005) Enzyme-linked immunospot assay responses to early secretory antigenic target 6, culture filtrate protein 10, and purified protein derivative among children with tuberculosis: Implications for diagnosis and monitoring of therapy. Clin Infect Dis 40: 1301–1308.
[9]
Aiken AM, Hill PC, Fox A, McAdam KP, Jackson-Sillah DJ, et al. (2006) Reversion of the ELISPOT test after treatment in Gambian tuberculosis cases. BMC Infect Dis 6: 66.
[10]
Pai M, Joshi R, Dogra S, Mendiratta DK, Narang P, et al. (2006) Serial testing of health care workers for tuberculosis using interferon-gamma assay. Am J Respir Crit Care Med 174: 349–355.
[11]
Menzies R (1999) Interpretation of repeated tuberculin tests. Am J Respir Crit Care Med 159: 15–21.
[12]
Heifets L, Good RB (1994) Current laboratory methods for the diagnosis of tuberculosis. In: Bloom BR, editor. Tuberculosis: Protection, pathogenesis and control. Washington (D. C.): American Society of Microbiology. pp. 85–110.
[13]
Adegbola RA, Hill P, Baldeh I, Otu J, Sarr R, et al. (2003) Surveillance of drug-resistant in The Gambia. Int J Tuberc Lung Dis 7: 390–393.
[14]
Schim van der Loeff MF, Sarge-Njie R, Ceesay S, Awasana AA, Jaye P, et al. (2003) Regional differences in HIV trends in The Gambia: Results from sentinel surveillance among pregnant women. AIDS 17: 1841–1846.
[15]
Lalvani A, Brookes R, Hambleton S, Britton WJ, Hill AV, et al. (1997) Rapid effector function in CD8+ memory T cells. J Exp Med 186: 859–865.
[16]
Jeffries DJ, Hill PC, Fox A, Lugos M, Jackson-Sillah DJ, et al. (2006) Identifying ELISPOT and skin test cut-offs for diagnosis of infection in The Gambia. Int J Tuberc Lung Dis 10: 192–198.
[17]
van Embden JD, Cave MD, Crawford JT, Dale JW, Eisenach KD, et al. (1993) Strain identification of by DNA fingerprinting: Recommendations for a standardized methodology. J Clin Microbiol 31: 406–409.
[18]
Kamerbeek J, Schouls L, Kolk A, van Agterveld M, van Soolingen D, et al. (1997) Simultaneous detection and strain differentiation of for diagnosis and epidemiology. J Clin Microbiol 35: 907–914.
[19]
Fine PE, Bruce J, Ponnighaus JM, Nkhosa P, Harawa A, et al. (1999) Tuberculin sensitivity: Conversions and reversions in a rural African population. Int J Tuberc Lung Dis 3: 962–975.
[20]
Bellete B, Coberly J, Barnes GL, Ko C, Chaisson RE, et al. (2002) Evaluation of a whole-blood interferon-gamma release assay for the detection of infection in 2 study populations. Clin Infect Dis 34: 1449–1456.
[21]
Richards NM, Nelson KE, Batt MD, Hackbarth D, Heidenreich JG (1979) Tuberculin test conversion during repeated skin testing, associated with sensitivity to nontuberculous mycobacteria. Am Rev Respir Dis 120: 59–65.
[22]
Anonymous (1956) BCG and vole bacillus vaccines in the prevention of tuberculosis in adolescents. First (progress) report to the Medical Research Council by their tuberculosis vaccines clinical trials committee. BMJ 1: 413–427.
[23]
Comstock GW, Webster RG (1969) Tuberculosis studies in Muscogee county, Giorgia: VII. A twenty-year evaluation of BCG vaccination in a school population. Am Rev Respir Dis 100: 839–845.
[24]
Wayne LG, Sohaskey CD (2001) Nonreplicating persistence of . Annu Rev Microbiol 55: 139–163.
[25]
Demissie A, Leyten EM, Abebe M, Wassie L, Aseffa A, et al. (2006) Recognition of stage-specific mycobacterial antigens differentiates between acute and latent infections with . Clin Vaccine Immunol 13: 179–186.
[26]
Haile Y, Bjune G, Wiker HG (2002) Expression of the mceA, esat-6 and hspX genes in and their responses to aerobic conditions and to restricted oxygen supply. Microbiology 148: 3881–3886.
[27]
Edwards LB, Palmer CE, Magnus K (1953) WHO Monograph Series No. 12. BCG vaccination: WHO research office. Geneva: World Health Organisation. 307 p.
[28]
Wasz-Hockert O (1947) On the period of incubation in tuberculosis. Ann Med Fenn 96: 764–772.
[29]
Soysal A, Millington KA, Bakir M, Dosanjh D, Aslan Y, et al. (2005) Effect of BCG vaccination on risk of infection in children with household tuberculosis contact: A prospective community-based study. Lancet 366: 1443–1451.
[30]
Pouchot J, Grasland A, Collet C, Coste J, Esdaile JM, et al. (1997) Reliability of tuberculin skin test measurement. Ann Intern Med 126: 210–214.
