New WIPO Sequence Listing Standard ST.26
Biotechnology and Life Sciences patent applications may disclose nucleic acid or amino acid sequences. In these cases, there is an international requirement that such sequences are provided in the form of a sequence listing. Sequence listings are then used by patent offices to search for the listed sequences. The new standard ST.26 format will allow patent offices to do this more easily than the current standard ST.25 format.
When is the new ST.26 format applicable?
As of 1 July 2022, all new PCT and national / regional applications filed on or after 1st July 2022, which have nucleic acid or amino acid sequences disclosed in the patent application, will need to be filed in the new updated electronic sequence listing standard, ST.26. which is linked here.
The previous standard, ST.25, for sequence listings will no longer be accepted for new PCT and national / regional applications.
To which applications does the ST.26 format apply?
If a PCT application filed before 1st July 2022 enters the EP regional / GB national phase after that date, the ST.25 format will continue to apply to the EP / GB application.
Any other new filings from 1st July 2022 must comply with the new ST.26 format. This includes new applications claiming priority from an application filed before 1st July 2022, and new European Divisional applications.
In some cases, it will be necessary to convert an existing ST.25 sequence listing into the new ST.26 format for use in a new application. For example, the EPO has confirmed that for European Divisional applications filed from 1st July 2022, which derive from a parent application filed before 1st July 2022, conversion of the parent ST.25 sequence listing into an ST.26 compliant listing will be necessary. Additionally, a declaration that the new sequence listing does not add subject matter beyond that disclosed in the patent application will be necessary.
In contrast, for new GB Divisional applications filed on or after 1st July 2022, the UKIPO requires that the sequence listings accompanying new GB Divisional applications are supplied in the same format as the parent application.
Thus, care must be taken when deciding whether the ST.25 or ST.26 format applies and where conversion from the ST.25 to ST.26 format is necessary.
What are the major changes?
Previously, the ST.25 format used the TXT format for the listings. Now with the ST.26 format, the sequence listings must be in electronic XML format designed to improve data compatibility with public searchable databases (including NCBI GenBank and EMBL-EBI) to make it easier for the patent offices to analyse the sequences for search purposes. As a result, many aspects of a sequence need to be represented differently. For example:
- Amino acids to be represented by their one-letter code instead of their three-letter code
- Uracil and thymine, both to be represented by ‘t’, instead of ‘u’ for uracil and ‘t’ for thymine
- Any annotated features will require strictly defined locations
- Nucleotide analogues (e.g. PNA or GNA), D-amino acids, Linear portions of branched sequences must all now be included
- The molecule type must be further specified beyond DNA/RNA/AA using a defined list (e.g. mRNA, transcribed RNA or viral cRNA)
- Sequences having fewer than ten specifically defined nucleotides (i.e. nucleotides other than ‘n’) must not be included
- Sequences having fewer than four specifically defined amino acids (i.e. amino acids other than ‘X’) must not be included” – NB: condensed section
Are there any risks?
The European Patent Office (EPO) is strict on any amendments that may result in extending the subject matter beyond that originally filed. Great care, therefore, must be taken during conversion from ST.25 format to ST.26 format and editing to not add or delete subject matter in the sequence listings.
There may be a risk that a sequence listing could be filed in the incorrect format. However, it’s anticipated that the EPO will invite the applicant to file a new listing in the correct format. This may incur an official fee.
Where an ST.25 sequence listing is filed as part of application subject to the new ST.26 standard, there is a risk that significant excess pages fees may be incurred, especially at the EPO. It is therefore worth checking on filing that the correct sequence listing format is used.
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