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

BACKGROUND: Rift 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. METHODS: RVFV-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. RESULTS: rRVFV-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%. CONCLUSIONS: Recombinant 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.

Monoclonal Antibodies for Rift Valley Fever Virus Nucleocapsid: Application in IgG/IgM ELISA for Sero-Diagnosis.

INTRODUCTION: Rift Valley fever virus (RVFV) belonging to the Phenuiviridae family is responsible for a zoonotic disease called Rift Valley fever (RVF). Currently, RVFV has spread from Africa to Asia, and due to its ability to cause high mortality rates, it has significantly impacted human health and economic development in many societies. Highly specific and sensitive systems for sero-diagnosis of RVFV infection are needed for clinical use. METHOD: BALB/c mice were immunized with recombinant RVFV nucleocapsid (rRVFV-N) protein and the spleen cells fused with SP2/0 myeloma cells to create hybridoma cell lines. The secreted monoclonal antibodies (MAbs) were purified and characterized. Enzyme-linked immunosorbent assay (ELISA) systems for the detection of IgG and IgM using the new MAbs were established and evaluated. Serum samples from 96 volunteers and 93 patients of suspected RVF from Kenya were tested compared with the ELISA systems based on inactivated viruses and the rabbit polyclonal antibody. RESULT: Three monoclonal antibodies against rRVFV-N protein were established. The performance of the MAb-based sandwich IgG ELISA and the IgM capture ELISA perfectly matched the ELISA systems using the inactivated virus or the polyclonal antibody. CONCLUSIONS: Recombinant RVFV-N protein-specific MAbs were developed and they offer useful tools for RVFV studies. The MAb-based ELISA systems for detecting IgG and IgM offer safe and useful options for diagnosing RVFV infections in humans.

BSL-3 Laboratory User Training Program at NUITM-KEMRI.

Pathogens handled in a Biosafety Level 3 (BSL-3) containment laboratory pose significant risks to laboratory staff and the environment. It is therefore necessary to develop competency and proficiency among laboratory workers and to promote appropriate behavior and practices that enhance safety through biosafety training. Following the installation of our BSL-3 laboratory at the Center for Microbiology Research-Kenya Medical Research Institute in 2006, a biosafety training program was developed to provide training on BSL-3 safety practices and procedures. The training program was developed based on World Health Organization specifications, with adjustments to fit our research activities and biosafety needs. The program is composed of three phases, namely initial assessment, a training phase including theory and a practicum, and a final assessment. This article reports the content of our training program.

The NUITM-KEMRI P3 Laboratory in Kenya: Establishment, Features, Operation and Maintenance.

A biocontainment facility is a core component in any research setting due to the services it renders towards comprehensive biosafety observance. The NUITM-KEMRI P3 facility was set up in 2007 and has been actively in use since 2010 by researchers from this and other institutions. A number of hazardous agents have been handled in the laboratory among them MDR-TB and yellow fever viruses. The laboratory has the general physical and operational features of a P3 laboratory in addition to a number of unique features, among them the water-air filtration system, the eco-mode operation feature and automation of the pressure system that make the facility more efficient. It is equipped with biosafety and emergency response equipments alongside common laboratory equipments, maintained regularly using daily, monthly and yearly routines. Security and safety is strictly observed within the facility, enhanced by restricted entry, strict documentation and use of safety symbols. Training is also engrained within the operation of the laboratory and is undertaken and evaluated annually. Though the laboratory is in the process of obtaining accreditation, it is fully certified courtesy of the manufactures' and constructed within specified standards.