Despite the reduction in the number of
leprosy cases registered worldwide as a result of the widespread use of multidrug
therapy, the number of new cases detected each year remains stable in many countries. This indicates that Mycobacterium leprae, the causative agent of
leprosy, is still being transmitted and that, without an earlier diagnosis, transmission will continue and
infection will remain a health problem. The current means of diagnosis of
leprosy is based on the appearance of clinical symptoms, which in many cases occur after significant and irreversible nerve damage has occurred. Our recent work identified several recombinant
antigens that are specifically recognized by
leprosy patients. The goal of the present study was to produce and validate the reactivity of a chimeric fusion
protein that possesses the antibody binding properties of several of these
proteins. The availability of such a chimeric fusion
protein will simplify future test development and reduce production costs. We first identified the antibody binding regions within our top five
antigen candidates by performing
enzyme-linked
immunosorbent assays with overlapping
peptides representing the amino acid sequences of each
protein. Having identified these regions, we generated a fusion construct of these components (
protein advances diagnostic of
leprosy [PADL]) and demonstrated that the PADL
protein retains the antibody reactivity of the component
antigens. PADL was able to
complement a
protein that we previously produced (the
leprosy IDRI [
Infectious Disease Research Institute] diagnostic 1 [LID-1]
protein) to permit the improved diagnosis of
multibacillary leprosy and that had a good ability to discriminate patients with
multibacillary leprosy from control individuals. A serological diagnostic test consisting of these
antigens could be applied within
leprosy control programs to reduce transmission and to limit the appearance of
leprosy-associated disabilities and stigmatizing
deformities by directing treatment.