Colombian biotechnology company VaxThera S.A.S. and US-based Codagenix Inc, a clinical-stage biotechnology company focused on synthetic biology-based vaccines, announced on Tuesday an agreement on terms for VaxThera to exclusively license Codagenix's yellow fever vaccine candidate, Syn17D-YF (CDX-470).

Under the agreement, VaxThera plans to advance Syn17D-YF through manufacturing, preclinical and clinical development, regulatory registration, and commercialisation in selected global markets.

Developed through Codagenix's proprietary synthetic biology technology, Syn17D-YF is a fully synthetic DNA virus based on the genome sequence of yellow fever virus vaccine strain 17D-204. Syn17D-YF corresponds in genome sequence to the FDA authorised vaccine strain YF-VAX (Sanofi Pasteur; Genbank accession # X503529) as well as the Robert Koch Institute 17D vaccine strain (Stock et al., 20121; GenBank accession # JN628279.1) and the WHO 17D Reference Lot 168-73.

The companies say that Syn17D-YF has been tested to be genetically stable and can be produced to high yields in modern cell culture without risk of mutation to pathogenicity. Production in cell culture also supports facile vaccine virus recovery and purification, leading to fewer excipient host proteins and DNA. Until now, attempts to modernise manufacture of derivative strains of 17D-204 have been frustrated by the accumulation of pathogenic mutations during cell culture passages (Holbrook et al., 20002).

All current licensed yellow fever vaccines, originating from the wild-type strain Asibi or 17D-204 in the 1930s, are manufactured in embryonated chicken eggs, leading to regular vaccine shortages worldwide and a poor reactogenicity profile contributed likely from egg- and process-related impurities (Zurbia-Flores et al., 20213).