Usefulness of MycoDot test for the detection of anti-mycobacterial antibodies as an aid in the diagnosis of experimental Mycobacterium tuberculosis and Mycobacterium avium complex infections in mice

Abstract

The MycoDot is a new diagnostic kit for tuberculosis which was devised by DynaGen Inc., USA. The MycoDot test is based on the detection of anti-mycobacterial antibodies in the serum samples of patients by employing plastic combs coated with lipoarabinomannan (LAM) antigen which is a highly immunogenic lipopolysaccharide presenting in the cell wall of all species of mycobacteria. It has been reported that healthy infected and BCG-vaccinated individuals do not react to the MycoDot test, while a positive reaction occurs in patients with active tuberculosis or atypical mycobacteriosis with good sensitivity and specificity. In this study, we evaluated the efficacy of MycoDot test for the detection of anti-LAM antibodies in sera of mice infected with Mycobacterium tuberculosis or M. avium complex (MAC). By using the MycoDot test, anti-LAM antibodies were positive in 2 out of 4 mice infected with M. tuberculosis 2 weeks before, while all of M. intracellulare-infected mice were negative at the same phase of infection. On the other hand, anti-mycobacterial (MB) antibodies were detected in the serum samples of mice infected with M. intracellulare as well as M. tuberculosis by home-made ELISA testing using whole cells of test mycobacteria as antigen. In the next experiment, mice were infected with M. avium. All the serum samples of mice obtained at 13 weeks after infection were negative for anti-LAM antibodies in MycoDot test, whereas they reacted positively to anti-MB antibodies in ELISA test. These results indicate that the MycoDot test is capable of detecting M. tuberculosis infection but not MAC infection induced in mice.