Validation study of HLA-B*13:01 as a biomarker of dapsone hypersensitivity syndrome in leprosy patients in Indonesia.

Leprosy is a stigmatizing, chronic infection which degenerates the nervous system and often leads to incapacitation. Multi-drug therapy which consists of dapsone, rifampicin and clofazimine has been effective to combat this disease. In Indonesia, especially in Papua Island, leprosy is still a problem. Furthermore, there had been higher reports of Dapsone Hypersensitivity Syndrome (DHS) which also challenges leprosy elimination in certain aspects. Globally, DHS has a prevalence rate of 1.4% and a fatality rate up to 13%. The aim of this study is to validate HLA-B*13:01, a previously discovered biomarker for DHS in the Chinese population, as a biomarker for DHS in the Papua population.This is a case-control study of 34 leprosy patients who presented themselves with DHS (case subjects) and 52 leprosy patients without DHS (control subjects). Patients were recruited from 2 provinces: Papua and West Papua. DNA was extracted from 3 ml blood specimens. HLA-B alleles were typed using the gold-standard sequence based typing method. Results were then analysed using logistic regression and risk assessment was carried out. The results of HLA-typing showed that HLA-B*13:01 was the most significant allele associated with DHS, with odds ratio = 233.64 and P-value = 7.11×10-9, confirming the strong association of HLA-B*13:01 to DHS in the Papua population. The sensitivity of this biomarker is 91.2% and specificity is 96.2%, with an area under the curve of 0.95. HLA-B*13:01 is validated as a biomarker for DHS in leprosy patients in Papua, Indonesia, and can potentially be a good predictor of DHS to help prevent this condition in the future.

A new Mycobacterium leprae dihydropteroate synthase variant (V39I) from Papua, Indonesia.

Indonesia had the third highest number of new leprosy cases worldwide in 2017. This disease is still prevalent in Papua province, where the number of new cases in 2014 (3.0 cases per 10,000 people) is considered highly endemic and is well above the World Health Organization's (WHO) cutoff of <1 new case per 10,000 people. Since 1995, the WHO has supplied Papua province with a multi-drug therapy (MDT) in which multibacillary (MB) patients are treated with rifampicin, clofazimine, and dapsone and paucibacillary (PB) patients are treated with rifampicin and dapsone. Recent published data on global drug resistance reported cases of dapsone resistance in relapsed and newly diagnosed cases in Indonesia during this period. The detection of specific point mutations in folP1 that encode dihydropteroate synthases (DHPS) is used exclusively to identify dapsone resistant strains of Mycobacterium leprae. The purpose of this study was to test for the presence of folP1 mutations in M. leprae strains isolated from patients residing in Papua Island, Indonesia who responded less effectively to dapsone. This study identified a folP1 point mutation that changed a valine (V) residue at amino acid position 39 (from the N-terminus) to isoleucine (I) (V39I) of DHPS. The V39I variant is located within an α-helix motif that may not much affect its structure. Molecular docking analysis indicated that the binding affinity of the V39I variant was slightly reduced as compared to the wildtype of DHPS. The decreasing of affinity may have a consequence of increasing inhibition constants (Ki) of dapsone on the variant V39I of DHPS. The data suggest that the DHPS V39I variant might cause less sensitive to dapsone. However, in vivo studies (e.g., mouse footpad model) are needed to confirm the effect of this DHPS variant on dapsone therapy.