[The immunogenic characteristics of the recombinant 38,000 antigen from Mycobacterium tuberculosis]

To study the ability of recombinant 38,000 protein of Mycobacterium tuberculosis (rMT38) to induce antibodies and its value as a serological diagnostic reagent.

Rabbits were divided into six groups, namely: PPD + physiological saline(group A), rMT38 + physiological saline(group B), rMT38 + adjuvent(group C), 1/2 rMT38 + 1/2 rMT16 + physiological saline(group D), 1/2 rMT38 + 1/2 rMT16 + adjuvent(group E), rMT16 + adjuvent(group F). The sera from the immunized rabbits and the sera immunized by mycobacteria were evaluated by enzyme-linked immunosorbent assay(ELISA) and bilateral agar diffusion assay (BADA). 389 human sera, including 145 patients with pulmonary tuberculosis, 105 healthy controls, 31 non-tuberculosis respiratory patients, 78 BCG-vaccinated healthy controls and 30 patients with M. abscessus infection, were detected by ELISA.

Titers of specific antibodies in sera from C and E groups were 1:16 and 1:4 in BADA, and 1:6,400 and 1:3,200 in ELISA, respectively. Precipitate lines of sera from A, B, D, F groups reacting with rMT38 were not found by BADA. Sera titer of A, B, D, F groups were negative, 1:400, 1:400, and negative by ELISA, respectively. Sera from E group had no reaction with PPD from thirteen mycobacteria, however, sera from E group reacted with PPD from Mycobacterium tuberculosis and BCG. Sera titer of all rabbits decreased with time. After two months, serum titers in B and D groups became negative. However, antibodies were still found in C and E groups after five months. The sensitivity of rMT38 and PPD in detecting pulmonary tuberculosis were 69.0% and 75.2%, respectively. The specificity of rMT38 and PPD in detecting healthy controls, non-tuberculosis respiratory patients, BCG-vaccinated healthy controls and M. abscessus-infected patients were 97.1%, 93.5%, 86.0%, 53.6% and 94.3%, 87.1%, 67.9%, 39.3% respectively.

rMT38 has a strong immunogenicity, which may be used as an immunodiagnostic reagent for tuberculosis.