Development of a novel recombinant ELISA for the detection of Crimean-Congo hemorrhagic fever virus IgG antibodies

Sultan Gülce-İz,Aysu Değirmenci Döşkaya,Adnan Yüksel Gürüz,Esra Atalay Şahar,Philip Louis Felgner,Aytül Gül,Hüseyin Can,Gizem Örs Kumoğlu,Huw Davies,Aykut Özdarendeli,Mert Döşkaya,Nazif Elaldı,Muhammet Karakavuk

doi:10.1038/s41598-021-85323-1

Abstract

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral infection caused by Crimean-Congo hemorrhagic fever virus (CCHFV). Serological screening of CCHF is important and current ELISA use antigens prepared from virus which is expensive due to requirement of high bio-containment facilities. In this study, we aimed to develop a new recombinant ELISA. For this purpose, CCHFV genome were expressed as 13 proteins in E. coli and among them abundantly purified recombinant Nucleocapsid protein (rNP) and Mucin-like variable domain (rMLD) were used as antigen in ELISA (Rec-ELISA). Rec-ELISA using rNP, rMLD and a combination of both (rNP/rMLD) were probed with acute (n = 64; collected between days 1 and 7 after onset of symptoms), convalescent (n = 35; collected 8 days after onset of symptoms), consecutive sera (n = 25) of confirmed CCHF cases and control sera (n = 43). The sensitivity and specificity of Rec-ELISA using rNP/rMLD were 73% and 98% in acute cases and 97% and 98% in convalescent cases. The median interquartile absorbance value to discriminate the acute and convalescent phases of CCHF was significantly higher with ELISA using rNP/rMLD (P < 0.0001) compared to rNP (P > 0.05) and rMLD (P = 0.001). These results indicate that the Rec-ELISA using rNP/rMLD may be very useful to diagnose convalescent CCHF cases especially in field studies.

Highlights

Crimean-Congo hemorrhagic fever (CCHF) is an acute, highly-contagious and life-threatening viral infection with a case fatality rate of up to 30%1
O D450 values decreased in two patients in Rec-ELISA using recombinant protein of full length S-segment (rNP) and rMLD or rNP/rML and slightly decreased in one patient assayed with rMLD or rNP/rMLD, and four with rNP ELISA
According to the Pearson correlation analyses, highest comparable results obtained by Rec-ELISAs using rMLD and rNP as well as rNP/rMLD and rNP were achieved in convalescent sera

Summary

Introduction

Crimean-Congo hemorrhagic fever (CCHF) is an acute, highly-contagious and life-threatening viral infection with a case fatality rate of up to 30%1. CCHF is a neglected disease and re-emerging due to the climate change effecting tick distribution w orldwide[5]. ELISAs frequently use antigen derived from the virus propagated in cell culture or brain tissue of suckling mice[21] This is an important problem since CCHFV is a high level biosafety pathogen and the preparation of the antigen requires high bio-containment facilities[27]. World Health Organization’s “WHO R&D Blueprint: Priority Diagnostics for CCHF” documentation prioritized the need for development and validation of new serological tests including ELISA in 2 01928 To address this necessity, ELISAs using recombinant NP protein of CCHFV are being d eveloped[16,17,19,21,27,29]

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