Analysis of Antibody Responses to Mycobacterium leprae Phenolic Glycolipid I, Lipoarabinomannan, and Recombinant Proteins To Define Disease Subtype-Specific Antigenic Profiles in Leprosy

Abstract

A simple serodiagnostic test based on the Mycobacterium leprae-specific phenolic glycolipid I(PGL-I), for individuals with leprosy is nearly universally positive in leprosy patients with high bacillary loads but cannot be used as a stand-alone diagnostic test for the entire spectrum of the disease process. For patients with early infection with no detectable acid-fast bacilli in lesions or with low or no antibody titer to PGL-I, as in those at the tuberculoid end of the disease spectrum, this diagnostic approach has limited usefulness. To identify additional M. leprae antigens that might enhance the serological detection of these individuals, we have examined the reactivity patterns of patient sera to PGL-I, lipoarabinomannan (LAM), and six recombinant M. leprae proteins (ML1877, ML0841, ML2028, ML2038, ML0380, and ML0050) by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). Overall, the responses to ML2028 (Ag85B) and ML2038 (bacterioferritin) were consistently high in both multibacillary and paucibacillary groups and weak or absent in endemic controls, while responses to other antigens showed considerable variability, from strongly positive to completely negative. This analysis has given a clearer understanding of some of the differences in the antibody responses between individuals at opposite ends of the disease spectrum, as well as illustrating the heterogeneity of antibody responses toward protein, carbohydrate, and glycolipid antigens within a clinical group. Correlating these response patterns with a particular disease state could allow for a more critical assessment of the form of disease within the leprosy spectrum and could lead to better patient management.Leprosy is a chronic mycobacterial infection caused by Mycobacterium leprae that results in damage to cutaneous tissue and nerves, causing an extraordinary spectrum of skin lesions, peripheral neuropathy, and anesthesia, with the subsequent development of disfigurement, deformity, and disability if not properly treated (27). The efforts of leprosy control programs and multidrug therapy over the last 25 years have dramatically decreased the worldwide prevalence from approximately 5.4 million cases in 1985 to 212,802 registered cases at the start of 2008 (35, 36, 37). Despite reports of leprosy's smaller global health impact, countries such as Brazil, Nepal, and East Timor still face high prevalence rates. Furthermore, local regions of high endemicity still exist in many countries, and the true number of cases may be underreported. For example, a population survey in Bangladesh revealed that the number of active leprosy cases was approximately six times higher than the actual number of registered cases despite effective leprosy control programs (21). Global new case detection declined only 3.5% between 2007 (126 countries reporting) and 2008 (121 countries reporting), but new case detection in children, a sign of continuing transmission, increased by 3.1% during this same period (37). It is generally agreed that the transmission of...

Rapid Quantitative Serological Test for Detection of Infection with Mycobacterium leprae, the Causative Agent of Leprosy

“…To date, leprosy rapid diagnostic tests have comprised only PGL-I mimetics as the antigenic target (ML Flow test and Standard Diagnostics leprosy test [hereinafter called SD Leprosy], containing tri-or disaccharides NTP and NDO, respectively) (14-17). Using laboratory-based assays, our group and others have identified numerous native and recombinant proteins recognized by antibodies in MB leprosy patient serum (18)(19)(20)(21)(22)(23)(24)(25). One example is the chimeric fusion protein leprosy IDRI diagnostic 1 (LID-1), an antigen specifically recognized by sera from leprosy patients from geographically and ethnically diverse populations, with a direct correlation between seroreactivity and BI (18,(26)(27)(28).…”

Enoyl-Coenzyme A Hydratase and Antigen 85B of Mycobacterium habana Are Specifically Recognized by Antibodies in Sera from Leprosy Patients

“…These results suggest that M. bovis Ag85B contains one or several epitopes specifically recognized by sera of LL patients (9). A recent report demonstrated that M. leprae recombinant Ag85B (ML2028) is an ideal candidate for use for leprosy serodiagnosis, as it is recognized by sera from all leprosy patients, regardless of their clinical classification (35).…”

Gene Expression Profile and Immunological Evaluation of Unique Hypothetical Unknown Proteins of Mycobacterium leprae by Using Quantitative Real-Time PCR

“…It was not determined whether the LL patients developed leprosy type 1 or type 2 reactions. Sera from cavitary TB patients were provided by William MacKenzie through a serum bank repository from the Centers for Disease Control, Atlanta, GA (23). All TB patients were smear positive.…”

“…Serum samples were coded to protect donor identities and collected with informed consent and with permission from the institutional review boards of the relevant countries and institutions involved, as described by Spencer et al (23). All leprosy patient sera were obtained from newly diagnosed individuals prior to their receiving the multidrug regimen.…”

“…Blots were blocked with blocking buffer (3% bovine serum albumin [BSA] in phosphate-buffered saline [PBS]-0.05% Tween 80) for 2 h and then probed with both pools of diluted sera (1:5,000 dilution for leprosy sera and 1:1,000 dilution for TB sera). Blots were performed by probing with secondary anti-human IgG-alkaline phosphatase (Sigma, St. Louis, MO) and developed by using 5-bromo-4-chloro-3-indolyl phosphatenitroblue tetrazolium (BCIP/NBT) (Sigma, St. Louis, MO) (23).…”