ST.25 vs. ST.26 - A Comparison

As we are all aware at this point, there is a large difference between ASCII text format and XML.  While this in and of itself is a dramatic change, the transition is further complicated by the differences in sequence requirements between the two standards. 

A recent WIPO webinar provided a detailed comparison of the differences from which I have summarized some key information. 

Required sequences:

• ST.25: L-amino acid sequences with at least 4 specifically defined residues, DNA with at least 10 specifically defined nucleotides

• ST.26: L- and D-amino acid sequences with at least 4 specifically defined residues, linear portions of branched sequences, DNA with at least 10 specifically defined nucleotides and nucleotide analogs.

Permitted sequences:

• ST.25: DNA and protein sequences shorter than required length.

Prohibited sequences:

• ST.26: DNA and protein sequences shorter than required length.

Organism designations:

• ST.25: “artificial sequence” and “unknown” designations accepted.

• ST.26: “synthetic construct” and “unidentified” designations accepted.

While some of the items above will be addressed by the WIPO sequence tool, it is important to understand these items when creating a ST.26 sequence listing. Furthermore, the differences complicate the process of converting a ST.25 sequence listing to ST.26 and mean that a straight conversion will not always be possible.   We’ll break down some of these complications in a future blog.

WIPO will continue to provide webinars/training on the new standard and the use of their WIPO sequence tool which is available for download and trial here. I encourage everyone to download and test the tool prior to the transition in January 2022.