Comparison of enzyme-linked immunosorbent assay systems using rift valley fever virus nucleocapsid protein and inactivated virus as antigens

Fuxun Yu,Yan Zha,Shingo Inoue,Matilu Mwau,Salame Ashur,Ferdinard Adungo,Leo Uchida,Corazon C Buerano,Samson Limbaso Konongoi,Kouichi Morita,Rosemary Sang,Yingjie Nie,Allan Ole Kwallah

doi:10.1186/s12985-018-1071-y

Abstract

BackgroundRift Valley Fever (RVF) is a mosquito-borne viral zoonosis. To detect RVF virus (RVFV) infection, indirect immunoglobulin G (IgG) and immunoglobulin M (IgM) enzyme linked immunosorbent assays (ELISAs) which utilize recombinant RVFV nucleocapsid (RVFV-N) protein as assay antigen, have reportedly been used, however, there is still a need to develop more sensitive and specific methods of detection.MethodsRVFV-N protein was expressed in Escherichia coli (E. coli) and purified by histidine-tag based affinity chromatography. This recombinant RVFV-N (rRVFV-N) protein was then used as antigen to develop an IgG sandwich ELISA and IgM capture ELISAs for human sera. Ninety six serum samples collected from healthy volunteers during the RVF surveillance programme in Kenya in 2013, and 93 serum samples collected from RVF-suspected patients during the 2006–2007 RVF outbreak in Kenya were used respectively, to evaluate the newly established rRVFV-N protein-based IgG sandwich ELISA and IgM capture ELISA systems in comparison with the inactivated virus-based ELISA systems.ResultsrRVFV-N protein-based-IgG sandwich ELISA and IgM capture ELISA for human sera were established. Both the new ELISA systems were in 100% concordance with the inactivated virus-based ELISA systems, with a sensitivity and specificity of 100%.ConclusionsRecombinant RVFV-N is a safe and affordable antigen for RVF diagnosis. Our rRVFV-N-based ELISA systems are safe and reliable tools for diagnosis of RVFV infection in humans and especially useful in large-scale epidemiological investigation and for application in developing countries.

Highlights

Rift Valley Fever (RVF) is a mosquito-borne viral zoonosis
Enzyme linked immunosorbent assay (ELISA) procedures To evaluate the possibility of applying the recombinant RVF virus (RVFV) nucleocapsid (RVFV-N) (rRVFV-N) protein for diagnosis of RVFV infection, we developed an immunoglobulin G (IgG) sandwich and an immunoglobulin M (IgM) capture ELISA system for human sera by using rRVFV-N protein as antigen
IgM capture ELISA using inactivated RVFV The IgM capture ELISA system using inactivated RVFV was routinely used for diagnosis in the WHO RVF diagnosis reference laboratory in the Kenya Medical Research Institute

Summary

Introduction

Rift Valley Fever (RVF) is a mosquito-borne viral zoonosis. Rift Valley Fever (RVF) is a mosquito-borne viral zoonosis, which periodically causes disease outbreaks in humans and livestock. Infection by RVF virus (RVFV) causes abortion or resorption of the fetus in pregnant domestic ruminants, with newborn mortality approaching 100%. The recent outbreak of RVF in Kenya in November 2006 through March 2007, where several hundred human cases were confirmed in 6 of 8 provinces had a devastatingly high case-fatality rate for hospitalized patients while there were up to 180,000. Sero-surveys suggested an attack rate up to 13% of residents in heavily affected areas; livestock deaths and abortions were noted during the outbreak [9, 11]

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