The National WHO Reference Laboratory for Poliovirus

Introduction

The National WHO Poliovirus laboratory at Statens Serum Institut was established to fulfil Denmarks commitment to the global polio eradication initiative run by WHO. There are three types of poliovirus, belonging to the enterovirus family, and the laboratory carries out surveillance of enterovirusinfections in Denmark. Humans can become infected by 280 enterovirus types from seven groups; EV-A, EV-B, EV-C, EV-D, rhinovirus A, rhinovirus B, and rhinovirus C. Enterovirus surveillance in Denmark primarily focuses on 116 virus types from four of these groups, EV-A to EV-D, where poliovirus 1-3 belong to group EV-C.

Enterovirus surveillance is based on epidemiological, clinical, and virological data. 

Analyses

The epidemiological and clinical surveillance is based on information forwarded to SSI by the treating physicians using a questionnaire sent out by the laboratory.

The virological enterovirus surveillance is based on characterization of enterovirus detected in clinical samples sent in by the clinical microbiology laboratories in Denmark.

Confirmatory test for enterovirus RNA: All samples are tested using a real-time RT-PCR to confirm the presence of enterovirus RNA in the sample material. 

Genotypning of enterovirus: PCR and sequencing, followed by bioinformatic investigations to determine the virus type.

Isolation of enterovirus: All stool samples, as well as selected samples of other origin, are tested using cell culture. The purpose of this is to confirm that there is no poliovirus in the samples by utilising poliovirus specific cells, as well as to amplify the virus content in the samples to allow further analysis of the viral RNA.

These analyses determine which of the 116 enterovirus types is present in the sample.

Further to the routine analysis identifying the 116 enterovirus types, the laboratory also characterizes rhinovirus in clinical samples by PCR and sequencing.

Reference functions

Technical expertise

In addition to routine methods, the laboratory uses a range of techniques for more detailed characterization of enterovirus, both traditional cell culture based methods, such as infectivity testing and neutralisation, and advanced molecular biology techniques for sequencing and full-genome analyses.

Support

The laboratory provides active support in connection with clinical investigation of enterovirus infections.

Reporting

Outbreaks and detection of enterovirus types of special interest are reported to relevant clinical departments, and may furthermore be reported in EPI-NYT and relevant international scientific journals.

The laboratory provides weekly reports to WHO on the number of samples investigated. A yearly report of resources, staff, quality assurance and number of tests carried out is also prepared for WHO accreditation. An additional yearly report, to document the poliovirus eradication activities undertaken in Denmark, is prepared in collaboration with the department for Infectious Disease Epidemiology at SSI.

Networks

Denmark

Danish clinical microbiology and infectious disease departments, as well as general practitioners.

International networks

WHO National Reference Laboratory for Poliovirus.

National Microbiology Focal Point for ECDC: Sofie Midgley is the alternate contact for the collaboration with ECDC.

Sofie Midgley is a member of the steering group for ENPEN – European Non-Polio Enterovirus Network.

Quality Assurance

The laboratory is accredited by WHO based on a yearly participation in international accreditation panel tests for the detection and characterization of poliovirus, as well as the yearly reporting of resources, staff, additional quality assurance and number of tests carried out.