Changes to PCT sequence listing format delayed until July 2022


Further to our previous article on the new sequence listing standard ST.26 at WIPO, the implementation date of ST.26 has now been delayed until 1 July 2022.

This means that any PCT applications with a filing date as of 1 July 2022 (and not the priority date).  This includes any divisional applications filed after 1 July 2022 (even though the parent application was filed before 1 July 2022).

WIPO ST.26 is an XML document (eXtensible Markup Language) with elements and attributes, which is very different from the text document with numeric identifiers currently required in WIPO ST.25.  The change to WIPO ST.26 aims to provide a uniform format of sequence listing data across member states that is both human and machine-readable for automated validation and data exchange and can be searched in publically available databases.

One of the main changes of ST.26 is that the sequence listing must not include any sequences having fewer than ten specifically defined nucleotides, or fewer than four specifically defined amino acids.

A “specifically defined” nucleotide or amino acid is any nucleotide other than those represented by “n” or “x”.  Only specifically defined residues count towards the new minimum length requirement in ST.26.

A summary of the main changes between ST.25 and ST.26 is set out in the table below:

WIPO has released a desktop tool to support the generation of ST.26 compliant sequence listing.  Our team have spent considerable time familiarising themselves with the new standard.  Therefore, your usual Forresters attorney will be ready to provide compliant sequence listings for our clients, when this comes into force in 2022.

If you have any questions about the changes to sequence listing format in PCT applications, please contact your usual Forresters attorney.

Kate Selwyn