New Mycobacterium leprae
protein antigens can contribute to improved serologic tests for
leprosy diagnosis/classification and multidrug
therapy (MDT) monitoring. This study describes seroreactivity to M. leprae
proteins among participants from three highly endemic
leprosy areas in Brazil: central-western Goiânia/Goiás (GO) (n = 225), Rondonópolis/Mato Grosso (MT) (n = 764) and northern Prata Village/Pará (PA) (n = 93). ELISA was performed to detect
IgG to
proteins (92f, 46f,
leprosy IDRI diagnostic-1, ML0405, ML1213) and
IgM to phenolic
glycolipid-I (PGL-I). Multibacillary (MB)
leprosy had positive rates for PGL-I that were similar to those for
proteins; however, some anti-PGL-I-negative subjects were positive for
proteins, suggesting that adding
protein antigen to PGL-I can enhance the sensitivity of MB
leprosy detection. In MT, different degrees of seroreactivity were observed and ranked for MB, former patients after MDT, paucibacillary (PB)
leprosy, household contact (HHC) and endemic control (EC) groups. The seroreactivity of PB patients was low in GO and MT. HHCs from different endemic sites had similar
IgG antibody responses to
proteins. 46f and 92f were not recognised by most
tuberculosis patients, ECs or HHCs within GO, an area with high BCG vaccination coverage. Low positivity in EC and HHC was observed in PA and MT. Our results provide evidence for the development of an improved serologic test that could be widely applicable for MB
leprosy testing in Brazil.