If a patent application discloses any nucleotide or amino acid sequences, the description of the invention must contain a 'sequence listing'. A sequence listing is a list of biological sequences using defined terms for certain features. This includes descriptive information about each sequence, which is known as annotations.

The Indian Patent Office (IPO) requires applicants to file sequence listings in a standardised format when no sequence listing has been furnished for the sequences referred to in the description, claims, or figures in a patent application. This makes it simpler to collect information when an application is being published. These patent sequences become easily searchable not only within the IPO, but also in the public databases once the application is published.

As per Rule 9(3) of the Patents Rules, 2003, if the application for a patent discloses sequence listing of nucleotides or amino acid sequences, the sequence listing of nucleotides or amino acid sequences must be filed in computer readable text format along with the application, and no print form of the sequence listing of nucleotides or amino acid sequences is required to be submitted.

Sequence listing format

Sequence listing in electronic document format must preferably be created by dedicated software such as PatentIn (WIPO STANDARD ST.25). The existing prescribed format for a sequence listing is as follows:

a. A nucleotide sequence to be listed with a maximum of 60 bases per line, with a space between each group of 10 bases.

b. The bases of a nucleotide sequence (including introns) to be listed in groups of 10 bases, except in the coding parts of the sequence.

c. Leftover bases, fewer than 10 in number at the end of non-coding parts of a sequence, to be grouped together and separated from adjacent groups by a space. The bases of the coding parts of a nucleotide sequence to be listed as triplets (codons).

However, there are some issues associated with this prescribed format for sequence listings. The ST.25 format is not in compliance with the International Nucleotide Sequence Database Collaboration (INSDC) requirements which leads to data being lost when it enters the public databases. Further, the rules are not very clear and therefore patent offices around the world interpret and enforce the rules differently.

Thus, a new standard for patent applications that involve sequence listings has been proposed by the World Intellectual Property Organization (WIPO), which will take effect from 1 July 2022, at the IPO. This new standard is WIPO ST.26 which addresses the issues with the existing format that do not meet the requirements of the INSDC. A key change in the new standard is the inclusion of certain sequence types that are common today such as nucleotide analogs, D-amino acids, and branched sequences. These were not covered by the ST.25 format.

If a sequence listing is included in a patent application and is not in accordance with this new standard, the applicant will have 15 months from the date of filing to furnish a compliant sequence listing.

Additionally, for international applications, if a sequence listing cannot be incorporated by reference, it can be submitted to the receiving office within 2 months of the international filing date to complete the international application. In such instance, the date of submission of the sequence listing shall become the international filing date.

Official fees

The IPO currently enforces a page fee per page of the application over 30 pages, including pages of sequence listings. This fee is imposed even in cases which consist of hundreds to thousands of Sequence Listing pages, regardless of whether the listings are electronically submitted.

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