AUTHOR=Marlais Tegwen , Bhattacharyya Tapan , Singh Om Prakash , Mertens Pascal , Gilleman Quentin , Thunissen Caroline , Hinckel Bruno C. Bremer , Pearson Callum , Gardner Bathsheba L. , Airs Stephanie , de la Roche Marianne , Hayes Kiera , Hafezi Hannah , Falconar Andrew K. , Eisa Osama , Saad Alfarazdeg , Khanal Basudha , Bhattarai Narayan Raj , Rijal Suman , Boelaert Marleen , El-Safi Sayda , Sundar Shyam , Miles Michael A. 

TITLE=Visceral Leishmaniasis IgG1 Rapid Monitoring of Cure vs. Relapse, and Potential for Diagnosis of Post Kala-Azar Dermal Leishmaniasis

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=8

YEAR=2018

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2018.00427

DOI=10.3389/fcimb.2018.00427

ISSN=2235-2988

ABSTRACT=<p><bold>Background:</bold> There is a recognized need for an improved diagnostic test to assess post-chemotherapeutic treatment outcome in visceral leishmaniasis (VL) and to diagnose post kala-azar dermal leishmaniasis (PKDL). We previously demonstrated by ELISA and a prototype novel rapid diagnostic test (RDT), that high anti-<italic>Leishmania</italic> IgG1 is associated with post-treatment relapse versus cure in VL.</p><p><bold>Methodology:</bold> Here, we further evaluate this novel, low-cost RDT, named VL Sero K-SeT, and ELISA for monitoring IgG1 levels in VL patients after treatment. IgG1 levels against <italic>L. donovani</italic> lysate were determined. We applied these assays to Indian sera from cured VL at 6 months post treatment as well as to relapse and PKDL patients. Sudanese sera from pre- and post-treatment and relapse were also tested.</p><p><bold>Results:</bold> Of 104 paired Indian sera taken before and after treatment for VL, when deemed clinically cured, 81 (77.9%) were positive by VL Sero K-SeT before treatment; by 6 months, 68 of these 81 (84.0%) had a negative or reduced RDT test line intensity. ELISAs differed in positivity rate between pre- and post-treatment (<italic>p</italic> = 0.0162). Twenty eight of 33 (84.8%) Indian samples taken at diagnosis of relapse were RDT positive. A comparison of Indian VL Sero K-SeT data from patients deemed cured and relapsed confirmed that there was a significant difference (<italic>p</italic> &lt; 0.0001) in positivity rate for the two groups using this RDT. Ten of 17 (58.8%) Sudanese sera went from positive to negative or decreased VL Sero K-SeT at the end of 11–30 days of treatment. Forty nine of 63 (77.8%) PKDL samples from India were positive by VL Sero K-SeT.</p><p><bold>Conclusion:</bold> We have further shown the relevance of IgG1 in determining clinical status in VL patients. A positive VL Sero K-SeT may also be helpful in supporting diagnosis of PKDL. With further refinement, such as the use of specific antigens, the VL Sero K-SeT and/or IgG1 ELISA may be adjuncts to current VL control programmes.</p>