Poppy Simonson1, Tapan Bhattacharyya2, Sayda El-Safi3, Michael A Miles2. 1. Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. poppy.simonson2@lshtm.ac.uk. 2. Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. 3. Faculty of Medicine, University of Khartoum, Khartoum, Sudan.
Abstract
BACKGROUND: Recombinant antigens rK39 (based on kinesin sequence) and rK28 (comprising kinesin and HASPB sequences) are a mainstay of serological diagnosis for visceral leishmaniasis (VL). However, their key epitopes and the significance of their structural conformation are not clearly defined, particularly in relation to reported cross-reactivity with sera from patients with malaria, schistosomiasis, and tuberculosis. METHODS: To assess the effect of conformation on antigenicity with Sudanese VL sera, antigens rK39 and rK28 were heat-denatured at 95 °C for 10 min and then assayed by enzyme-linked immunosorbent assay (ELISA). Amino acid sequences of rK39 and rK28 were submitted to NCBI BLASTp to assess homology with Plasmodium, Schistosoma, and Mycobacterium. RESULTS: Heat denaturation significantly diminished the antigenicity of rK39 compared to non-denatured antigen (P = 0.001), but not for rK28 (P = 0.275). In BLASTp searches, HASPB sequences from rK28 had similarities with sequences from Plasmodium, encompassing software-predicted B-cell epitopes. CONCLUSIONS: The antigenicity of rK39 appears to be dependent on structural conformation, whereas that of rK28 depends on linear sequence. HASPB sequence homology with Plasmodium may be responsible for the reported cross-reactivity of rK28 with malaria sera. Further work is warranted to refine the specificity of these antigens.
BACKGROUND: Recombinant antigens rK39 (based on kinesin sequence) and rK28 (comprising kinesin and HASPB sequences) are a mainstay of serological diagnosis for visceral leishmaniasis (VL). However, their key epitopes and the significance of their structural conformation are not clearly defined, particularly in relation to reported cross-reactivity with sera from patients with malaria, schistosomiasis, and tuberculosis. METHODS: To assess the effect of conformation on antigenicity with Sudanese VL sera, antigens rK39 and rK28 were heat-denatured at 95 °C for 10 min and then assayed by enzyme-linked immunosorbent assay (ELISA). Amino acid sequences of rK39 and rK28 were submitted to NCBI BLASTp to assess homology with Plasmodium, Schistosoma, and Mycobacterium. RESULTS: Heat denaturation significantly diminished the antigenicity of rK39 compared to non-denatured antigen (P = 0.001), but not for rK28 (P = 0.275). In BLASTp searches, HASPB sequences from rK28 had similarities with sequences from Plasmodium, encompassing software-predicted B-cell epitopes. CONCLUSIONS: The antigenicity of rK39 appears to be dependent on structural conformation, whereas that of rK28 depends on linear sequence. HASPB sequence homology with Plasmodium may be responsible for the reported cross-reactivity of rK28 with malaria sera. Further work is warranted to refine the specificity of these antigens.
Authors: M Boelaert; S El-Safi; A Hailu; M Mukhtar; S Rijal; S Sundar; M Wasunna; A Aseffa; J Mbui; J Menten; P Desjeux; R W Peeling Journal: Trans R Soc Trop Med Hyg Date: 2007-10-22 Impact factor: 2.184
Authors: Ehab Kotb Elmahallawy; Antonio Sampedro Martinez; Javier Rodriguez-Granger; Yannick Hoyos-Mallecot; Ahamd Agil; Jose Mari Navarro Mari; Jose Gutierrez Fernandez Journal: J Infect Dev Ctries Date: 2014-08-13 Impact factor: 0.968
Authors: Kyoko Fujisawa; Charlotte Silcott-Niles; Poppy Simonson; Daniela Lamattina; Cristian A Humeres; Tapan Bhattacharyya; Pascal Mertens; Caroline Thunissen; Victoria O'Rourke; Magdalena Pańczuk; James A Whitworth; Oscar Daniel Salomón; Michael A Miles Journal: PLoS Negl Trop Dis Date: 2021-07-19