Fig. 4.

MTP are produced during human TB infection. (A) IF showing that MTP incubated with TB patient sera produced fluorescent MTP fibers. (B) No reaction was observed when MTP was incubated with sera from healthy donors. (Original magnification: ×1,000.) (C) Sera from TB patients (n = 36) and from healthy donors (n = 5) were tested for anti-MTP IgG antibodies by ELISA. Most of the patients' sera (60%) showed a significant IgG titer against immobilized MTP fibers. Results obtained at sera diluted 1:3,200 are shown. The horizontal line represents the cut-off value of two times the average ELISA reading of healthy control sera. All of the sera positive by ELISA produced a positive IF reaction as shown in A.