1. Introduction
Biotechnology patent filings increasingly depend on precise disclosure of nucleotide and amino acid sequences. In Brazil, the National Institute of Industrial Property (INPI Brazil) has aligned its formal requirements with international standards governed by the World Intellectual Property Organization (WIPO).
Since 1 July 2022, Brazil has fully adopted WIPO Standard ST.26, replacing the older ST.25 format. This shift represents not merely a technical formatting update, but a fundamental change in how biological information must be structured, validated, and examined in patent prosecution.
Under current INPI practice, sequence listings are treated as mandatory formal elements of disclosure whenever biological sequences are present in a patent application.
2. Legal and Regulatory Framework
The requirement for sequence listings in Brazil is grounded in:
- Brazilian Industrial Property Law (Law No. 9.279/96) – establishing sufficiency of disclosure and clarity requirements
- INPI Ordinance (Portaria INPI/PR No. 48/2022) – implementing ST.26 adoption rules
- WIPO Standard ST.26 – the international technical framework for sequence representation
- INPI Biotechnology Patent Examination Guidelines
A key regulatory principle is that sequence listing compliance is not optional when biological sequences meet defined thresholds—it is a formal filing requirement impacting admissibility and examination quality.
3. Applicability: When a Sequence Listing Is Mandatory
A sequence listing must be submitted to INPI when the application discloses any of the following:
3.1 Nucleotide sequences
- DNA or RNA sequences
- Natural, synthetic, or engineered sequences
- Hybrid or chimeric constructs
3.2 Amino acid sequences
- Proteins or peptides
- Naturally occurring or recombinant polypeptides
3.3 Threshold rule (ST.26 logic applied in Brazil)
Sequences must be included if they contain:
- 10 or more specifically defined nucleotides, or
- 4 or more specifically defined amino acids
Shorter sequences below these thresholds are generally excluded from the ST.26 listing and must be handled carefully within the description if relevant.
4. Mandatory Format: WIPO ST.26 (XML Standard)
Brazil exclusively requires ST.26-compliant XML sequence listings for applications filed on or after 1 July 2022.
4.1 Structural requirements
An ST.26 sequence listing must be:
- A single XML file
- Encoded in UTF-8
- Fully compliant with the WIPO ST.26 DTD schema
- Machine-readable for patent database integration
4.2 Core components
The ST.26 file is divided into two principal sections:
(A) General Information Section
This includes bibliographic and administrative metadata:
- Applicant name(s)
- Inventor details
- Application title
- Filing data (when available)
- Priority information
- Reference identifiers
(B) Sequence Data Section
This is the technical core of the listing:
Each sequence must include:
- Unique SEQ ID NO
- Molecule type (DNA, RNA, or protein)
- Sequence length
- Organism (if applicable)
- Feature annotations (CDS, promoter, domain, mutation sites, etc.)
- Structured biological qualifiers using controlled vocabulary
5. ST.26 Compliance Requirements in Brazil
Brazilian INPI practice emphasizes strict formal compliance aligned with WIPO rules.
5.1 Unique identification requirement
Each sequence must be assigned a unique identifier:
- No reuse of SEQ ID NOs across unrelated sequences
- Each biologically distinct sequence must be individually listed
- Even subsequences must be separately identified if enumerated
5.2 Feature annotation discipline
ST.26 introduces structured annotation rules requiring:
- Standardized feature keys
- Precise positional mapping of sequence elements
- Mandatory annotation of biologically relevant regions (e.g., coding regions, signal peptides)
5.3 Controlled vocabulary enforcement
INPI expects strict adherence to:
- WIPO-approved feature terminology
- No free-text substitution for biological descriptors
- Standardized organism naming conventions
6. Critical Transition: ST.25 vs ST.26 in Brazil
Brazil’s transition to ST.26 is strictly date-driven, not priority-driven.
| Filing Date | Required Standard |
| Before 1 July 2022 | ST.25 (TXT format) |
| On/After 1 July 2022 | ST.26 (XML format) |
Key legal consequence:
The filing date of the Brazilian application determines compliance—not the priority application.
This means:
- PCT national phase entries entering Brazil after the cutoff must comply with ST.26
- Even if priority application used ST.25, Brazil requires conversion
- No “grandfathering” applies for new filings
7. Common Compliance Risks and Examination Issues
7.1 Missing or incomplete sequence listings
One of the most frequent formal objections arises when:
- Sequences are disclosed in the specification but not included in the XML file
- Applicant assumes disclosure in PDF text is sufficient (it is not)
7.2 Format non-compliance (XML errors)
Common technical failures include:
- Incorrect schema structure
- Invalid UTF-8 encoding
- Missing mandatory ST.26 fields
- Broken sequence tags or invalid identifiers
Such errors may result in formal office actions or requirement for correction before substantive examination.
7.3 “Short sequence” handling issues
ST.26 introduces strict rules regarding short sequences:
- Sequences below threshold are often excluded from listing
- WIPO tools may flag them as “ignored sequences”
- Applicants must ensure these sequences are still properly disclosed elsewhere if technically relevant
7.4 Disclosure inconsistency risk
INPI examiners may raise objections where:
- Sequence listing differs from claims or description
- Mutations are described in text but missing in ST.26 file
- SEQ ID numbering is inconsistent across documents
This can trigger clarity objections or sufficiency-of-disclosure concerns under Brazilian patent law.
8. Use of WIPO Sequence Tool (Best Practice Standard)
INPI strongly recommends the use of:
WIPO Sequence software (official ST.26 authoring tool)
Functional advantages:
- Automatic ST.26 XML generation
- Schema validation before filing
- Error detection (missing features, invalid residues, formatting issues)
- Conversion support from legacy ST.25 files
- Reduced risk of formal rejections
In practice, most professional filings in Brazil rely on this tool or equivalent validated software systems.
9. Strategic Considerations for Patent Drafting
9.1 Early integration into drafting workflow
Best practice is to treat sequence listings as:
- A parallel drafting output, not a post-filing formality
- Integrated with claims and specification drafting from the beginning
9.2 Alignment between claims and sequence data
Critical alignment points include:
- Claim scope must correspond to sequences listed
- Mutational variants must be consistently numbered and defined
- Functional annotations must support claim language
9.3 PCT strategy alignment
For international biotech filings:
- Ensure ST.26 compliance at PCT stage if filing after July 2022
- Maintain consistent sequence IDs across jurisdictions
- Avoid jurisdiction-specific restructuring that introduces inconsistencies
10. Sufficiency of Disclosure and Legal Impact
In Brazil, sequence listings are directly tied to:
Sufficiency requirement (enablement standard)
Under Law 9.279/96, the application must:
- Enable a skilled person to reproduce the invention
- Provide clear and complete technical disclosure
Failure to properly disclose sequences may result in:
- Formal objections
- Substantive rejection for insufficiency
- Narrowing of claim scope during prosecution
11. Conclusion
Brazil’s INPI sequence listing regime under WIPO ST.26 establishes a fully harmonized biotechnology patent framework requiring XML-based sequence listings for all relevant filings, applying a strict 10-nucleotide/4–amino acid threshold, and demanding consistency between claims, description, and sequence data. It relies on WIPO Sequence validation tools to ensure technical accuracy and reduce filing errors. As a result, sequence listing compliance directly affects sufficiency of disclosure and patent enforceability, making it a core strategic requirement in Brazilian biotech patent practice rather than a mere formal step.