Enhancing polio detection with advanced sequencing technology

This year alone, 290 poliovirus detections have been reported in 23 African countries

The African region declared free of Indigenous wild poliovirus in August 2020, faces an urgent threat: the intense transmission of type 2 variant poliovirus (cVDPV2). This year alone, 290 poliovirus detections have been reported in 23 African countries.

As countries ramp up vaccination efforts to protect children against the virus, one of the most critical components of the response is early and accurate detection. To enhance the effort, the World Health Organization Regional Office for Africa (WHO AFRO), together with the United States Centers for Disease Control and Prevention (US CDC) and the Gates Foundation, is focusing on equipping and training laboratories across Africa with an innovative advanced Sanger sequencing technology, a crucial method in investigating new regions in the poliovirus genome.

The poliovirus has a genome that is 7.5 kilobases long (a kilobase, or kb, is a unit of measurement used to describe the length of DNA). This genome has one main part that is used to create four proteins, named VP1 to VP4. The VP1 protein is important for how the virus attaches to cells and has been used to identify and track the spread of poliovirus.

In 2024, WHO AFRO initiated targeted training on Advanced Sanger Sequencing training aimed at diversifying the diagnostic windows for polioviruses which will eventually reduce the turn-around time of poliovirus detection. These trainings are essential to equip lab personnel with the skills to operate advanced sequencing technologies and provide timely results for public health decision-makers.

Sequencing allows laboratories to pinpoint genetic changes in poliovirus strains, providing critical data for tracking transmission pathways and understanding viral evolution. The technology offers a level of precision that helps identify mutations in real time, making it possible to detect emerging threats swiftly. This technique has hitherto been limited to the VP1 region of the gene but after this training laboratories will be able to use the entire five prime untranslated regions and the remaining VP4/2 of the poliovirus gene.

Irene Turyahabwe from Uganda highlights the accuracy of polio eradication by expanding the sequencing window to other poliovirus regions, alongside the VP1 region.

Advanced sequencing will improve diagnostics, provide evidence for vaccination campaigns, and inform decision-making for polio eradication. Dr. Jude Kfutwah, coordinator of the Regional Polio Laboratory Network at the WHO Regional Office for Africa, believes this technology will help deploy the right public health interventions in time to prevent further virus spread.

WHO is supporting 16 polio laboratories in the African region that are providing environmental surveillance support, and testing for poliovirus in stool and wastewater samples to track geographic patterns of spread.

With laboratories across Africa enhancing their capacity to process samples quickly, there is an added layer of regional cooperation that strengthens the entire surveillance network. This collaborative spirit is vital in eradicating polio once and for all.