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Advisor(s)
Abstract(s)
This report describes the World Health Organization (WHO) project to develop an international
standard (IS) for Chikungunya virus (CHIKV) RNA for use with nucleic acid amplification
technique (NAT)-based assays. An international collaborative study was conducted to determine the
potency of the candidate standard using a range of NAT-based assays for CHIKV, and to evaluate
the suitability of the candidate for the calibration of secondary reference materials and the
standardization of CHIKV viral load measurements.
The candidate standard consisted of a heat inactivated CHIKV strain of the East/South/Central
African genotype (ESCA), also known as the Indian Ocean Lineage, isolated from a patient
returning from India to the United States in 20061
, diluted in human negative plasma. The
lyophilized candidate preparation (Sample 1), the corresponding liquid-frozen bulk material (Sample
2) and three different clinical samples (Sample 3, Sample 4 and Sample 5) were included in the
collaborative study. Twenty-five laboratories representing 14 countries participated in the study to
evaluate the material using their routine CHIKV NAT assays. Twenty-four laboratories returned 31
data sets from 17 commercial assays and 14 in-house methods. Of these 31 methods, 11 were
quantitative and 20 were qualitative.
The results of the study indicate the suitability of the candidate material of the CHIKV strain of
ESCA genotype (Sample 1) as the proposed 1st WHO IS for CHIKV. It is therefore proposed that
the candidate material (PEI code 11785/16) is established as the 1st WHO IS for CHIKV RNA for
NAT-based assays with an assigned potency of 2,500,000 International Units (IU)/mL when
reconstituted in 0.5 mL of nuclease-free water.
On-going studies for real-time and accelerated stability of the proposed IS indicate that the
preparation is stable and suitable for long-term use under the proposed storage conditions.
Description
Collaborative Study Group - Portugal:Maria João Alves, Líbia Zé-Zé (National Institute of Health Dr. Ricardo Jorge, Center for Vectors and Infectious Diseases Research)
Keywords
Chikungunya Virus Evaluate Candidate Standard Nucleic Acid Amplification Techniques Biological Assay Reference Standards Infecções Sistémicas e Zoonoses