Abstract
BackgroundPost Kala Azar Dermal Leishmaniasis (PKDL) occurs as dermal consequence of previous Visceral Leishmaniasis (VL) infection and serves as an important reservoir for transmission of VL. Diagnosis of PKDL is often challenging for its symptomatic resemblance to other co-endemic diseases like Leprosy or Vitiligo. Parasitological examination by slit-skin smear and culture are the standard methods but lack high sensitivity. Thus, for efficient control of VL, reliable diagnostic and prognostic assay of PKDL are required.ObjectivePreviously, glycoproteins (9-OAcSA) have been reported as promising biomarkers of Indian VL patients. However, till date, the status of glycans in Indian PKDL patients remains unexplored. Accordingly, in this study, the glyco-profile of PKDL Circulating Immune Complexes (CICs) as compared to other cross diseases like Vitiligo and Leprosyhas been investigated. Further, a novel Glyco CIC assay has been developed for efficient Indian PKDL patient diagnosis.Methods/principal findingIn the present study, 90 PKDL patients were enrolled from 3 VL endemic districts of West Bengal during 2015–16. Glycosylation profile of isolated CICs from sera of PKDL patients were initially analyzed through gradient SDS gel electrophoresis followed by PAS silver double staining, which revealed the presence of several glycan rich PKDL specific proteins of varying molecular weights. To further characterize the glyco-profile of acid dissociated affinity purified immuno-reactive antigens present in the CICs, glycosylation was demonstrated in these purified CIC antigens by DIG glycan differentiation kit with or without glycosidase as well as neuraminidase treatment. Diagnostic evaluation of the newly developed colorimetric Glyco CIC assay through Receiver Operating Characteristic (ROC) curve analysis revealed excellent (0.99) AUC value as compared to other conventional serodiagnostic assays like PEG CIC, Parasite ELISA (IgG and IgM). Additionally, longitudinal monitoring of 18 PKDL patients further revealed its good prognostic utility.ConclusionThese results highlight the glycosylation status of CICs among Indian PKDL patients present in all the studied endemic districts of West Bengal. These PKDL biomarkers were completely absent in cross diseases like Vitiligo and Leprosy. Further, the newly developed Glyco CIC assay had an improved sensitivity of 95.6%, specificity of 99.3%, NPV of 97.1% and PPV of 98.9%.
Highlights
Leishmaniasis is considered as one of the major parasitic disease, affecting individuals, worldwide
The newly developed Glyco Circulating Immune Complexes (CICs) assay had an improved sensitivity of 95.6%, specificity of 99.3%, Negative predictive values (NPV) of 97.1% and Positive predictive values (PPV) of 98.9%
Indian Leishmaniasis are profoundly manifested in two forms- namely (i)Visceral Leishmaniasis (VL); where patients develop characteristics of high fever, hepatosplenomegaly, anemia, loss of appetite and (ii) Post Kala Azar Dermal Leishmaniasis (PKDL); a dermal consequence, which occurs mostly in patients with previous VL history (10–15%), having superficial manifestations as painless dermal lesions of macular, nodular or polymorphic types [3,4,5]
Summary
Leishmaniasis is considered as one of the major parasitic disease, affecting individuals, worldwide. PKDL patients are often reluctant to seek medical care as the disease results in no fatal consequences other than cosmetic complicacies, which is more of a social stigma rather than a grave problem. Considering such neglected scenario, the ongoing VL elimination program in India is targeted to reduce VL incidences to less than 1 per 10,000 population in block and sub block levels, where the upsurge of PKDL cases are posing threat to this holistic approach of elimination. Post Kala Azar Dermal Leishmaniasis (PKDL) occurs as dermal consequence of previous Visceral Leishmaniasis (VL) infection and serves as an important reservoir for transmission of VL. For efficient control of VL, reliable diagnostic and prognostic assay of PKDL are required
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