WIPO ST.26 Breakdown - Part I

As we settle into 2022, the year of ST.26 implementation, I’ll breakdown the standard and guidance document and point out important changes to Sequence Listing preparation. I’ll begin with the first section by highlighting various definitions that impact the preparation of a compliant Sequence Listing. 

If you are familiar with Sequence Listings than you are familiar with DNA and protein sequences and their components; however, it is important to under stand how the Standard defines the components to include them accurately in a Sequence Listing.  Below is a breakdown of some key definitions and the impact they have on Sequence Listing preparation.

The Definitions:

"Amino acids" – Any of the amino acids “A”, “R”, “N”, “D”, “C”, “Q”, “E”, “G”, “H”, “I”, “L”, “K”, “M”, “F”, “P”, “O”, “S”, “U”, “T”, “W”, “Y”, or “V,” regardless of whether they are L- or D- oriented and/or have modified or synthetic side chains.  A peptide nucleic acid (PNA) is not considered an amino acid but is considered a nucleic acid.

What this means – The new ST.26 definition for amino acids broadens the sequences that are required to be included in a Sequence Listing when the standard takes effect.  First, the amino acids listed include "O" and "U" which were classified as "X" under ST.25.  The definition also includes D-amino acids which under ST.25 were not required, and a sequence containing a single D-amino acid would not be required in and ST.25 Sequence Listing.  All D-amino acid sequences will now be required with features/qualifiers for the D-amino acid positions.   

"enumeration of its residues" – the disclosure of a sequence in a patent application by listing the residues in order.  This includes by name, abbreviation, symbol or structure.  

What this means – Again, the definition broadens the scope of the sequences that need to be included in an ST.26 Sequence Listing, especially regarding structures.  Previously, under ST.25, sequences disclosed as structures were not required to be included except under rare instances that the structure was claimed and the examiner specifically requested their inclusion. Depending on the disclosure, this change could have a large impact on preparation as structures take time to manually review and determine the residues (especially if they are modified residues) prior to being imported into WIPO sequence.

"nucleotide" – Any nucleotide of a, c, g, t, m, r, w, s, y, k, v, h, d, b, or n or any nucleotide analog with a backbone of a 2’ deoxyribose 5’ monophosphate or ribose 5’ monophosphate or "an analogue of a 2’ deoxyribose 5’ monophosphate or ribose 5’ monophosphate, which when forming the backbone of a nucleic acid analogue, results in an arrangement of nucleobases that mimics the arrangement of nucleobases in nucleic acids containing a 2’ deoxyribose 5’ monophosphate or ribose 5’ monophosphate backbone, wherein the nucleic acid analogue is capable of base pairing with a complementary nucleic acid."  This definition includes peptide nucleic acids, glycol nucleic acids, threose nucleic acids, morpholinos and cyclohexenyl nucleic acids.

What this means – As with the definition of amino acids, the nucleic acid definition is significantly broader than the definition in ST.25 with PNA, threose nucleic acids, morpholinos and glycol nucleic acids all now required.  These molecule types will also require features/qualifiers with the appropriate definitions which will add complexity to the ST.26 Sequence Listing.

"may" – any optional and permissible approach but not a requirement.

"must" – a requirement of the standard. Failure to include will result in a noncompliant listing.

"must not" – prohibition of the standard. Inclusion will result in a noncompliant listing.

 "should" – strongly encouraged approach but not required.

"should not" – strongly discouraged approach but not prohibited.

What these mean – ST.26 more clearly outlines items that are required versus prohibited.  The most obvious "must not" is the prohibition of sequences with fewer than 10 specifically defined nucleotides or 4 specifically defined amino acids.  These sequences were previously accepted in ST.25 (although not required), therefore, caution must be used if converting a ST.25 listing to ST.26. Many features/qualifiers fall under the "should"/"should not" categories, therefore, careful review of the guidance document is required to fully understand the instances various features/qualifiers should be included. It is also yet to be seen how different patent offices will interpret the “should”/”should not” definitions and if the “gray area” will lead to issues with the acceptance of Sequence Listings.

To review the standard yourself, the most recently adopted version of the standard is available here.

I will continue to breakdown the standard and guidance documents in future blogs.  If you have any questions or comments regarding ST.26, please do not hesitate to reach out to me.