Utility of three mammalian cell entry proteins of Mycobacterium tuberculosis in the serodiagnosis of tuberculosis.

SETTING

The mammalian cell entry (mce) proteins Mce3A, Mce3D and Mce3E, encoded by the mce3 operon of Mycobacterium tuberculosis, have recently been shown to be expressed during natural infection in humans.

OBJECTIVE

To determine the potential of Mce3A, Mce3D and Mce3E proteins in the serodiagnosis of tuberculosis (TB).

DESIGN

The quantitative detection of anti-Mce3A, -Mce3D and -Mce3E antibodies in serum samples from active TB patients (n = 58), healthy contacts of TB patients (n = 24) and bacilli Calmette-Guérin (BCG) vaccinated healthy subjects (n = 24) was performed using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Antibodies in serum from 98%, 86% and 90% of active TB patients and from 92%, 75% and 96% of healthy contacts of TB patients reacted with Mce3A, Mce3D and Mce3E proteins, respectively. However, none of the serum from BCG-vaccinated healthy subjects reacted with Mce3A and Mce3E proteins, and only 8% of serum samples reacted with Mce3D protein. Overall, serum from 98% active TB patients, 96% healthy contacts and 0% BCG-vaccinated healthy subjects were positive for anti-Mce3A and/or -Mce3E antibodies.

CONCLUSIONS

Our results suggest that Mce3A and Mce3E proteins may be useful for the serodiagnosis of TB infection.