CD19 Biologics Sequence Review Report 2026: B-lymphocyte antigen CD19 Similarity and Patent-Risk Signals

This CD19 Biologics Sequence Review Report was produced with PatSnap Biology Modality MCP. The workflow connects patent-scale sequence searching, result retrieval, full-sequence inspection, pairwise alignment and target-linked patent evidence in one reproducible screen. Explore the PatSnap MCP servers used in this report.

Review date: 4 August 2026. The query is the reviewed human B-lymphocyte antigen CD19 reference sequence, UniProt accession P15391, with a length of 556 amino acids. This report is an R&D and IP-triage resource, not a legal opinion, freedom-to-operate conclusion, infringement analysis or validity assessment.

Executive sequence-risk thesis

CD19 is a cell-surface or adhesion protein topic centered on B-lymphocyte antigen CD19. The ALLPATENT protein search returned 20 records within the configured task window. The selected review hit reached 100.00% query identity, 556/556 query coverage and 556/556 subject coverage; its database-level claimed flag was Yes.

The resulting screening position is elevated diligence priority, not “blocked” or “clear.” A high-identity record may reproduce a natural reference protein, an antigen construct, a diagnostic reagent, a control, an expression cassette or a therapeutic component. Conversely, relevant claims may cover variants, fragments, binding regions or percentage-identity genera without reproducing the complete reference sequence. Sequence similarity is therefore a prioritization signal that directs family and claim review.

How the Biology Modality MCP workflow was run

The reference protein was submitted with ls_sequence_search_submit as a PROTEIN-to-PROTEIN query against ALLPATENT, with gaps enabled, E-value at or below 0.001, identity from 30% to 100%, query coverage from 30% to 100% and a 20-record task limit. After status completion, ls_sequence_search_get_results retrieved the ranked evidence. The selected sequence number was resolved with ls_sequence_fetch, and ls_sequence_alignment ran a PSA comparison against the query.

Target context was tested with ls_antibody_antigen_search using both the gene symbol and recommended protein name when needed. When that step returned a target-linked patent number, ls_patent_sequence_fetch retrieved the corresponding patent sequence bundle. The six-tool design separates raw sequence proximity from target annotation and patent-document context, while preserving gaps when a direct target-linked record is unavailable.

Similarity search readout

The selected subject sequence was 98654, with a reported length of 556 amino acids, score 1,126 and E-value 0. The comparison contained 0/556 gaps and mapped query positions 1–556 to subject positions 1–556. The returned organism annotation was synthetic construct, Homo sapiens, unidentified.

Search totals are records, not unique inventions, families or enforceable claims. The same sequence can be repeated across jurisdictions, continuations, examples and reference sections. A useful next step is to consolidate results by earliest priority, simple family, applicant and legal status, then distinguish sequences appearing in claims from those disclosed only in descriptions or sequence listings.

Sequence fetch and pairwise alignment

ls_sequence_fetch resolved the selected record as sequence 98654, annotated “CD19 antigen (human clone MGC:12802 IMAGE:4054919)”, with a stored length of 556 amino acids. Associated gene annotation was CD19, and the record was not marked as an antibody.

The PSA output aligned query positions 1–556 with target positions 1–556. This coordinate-level view is more useful than a percentage alone because it shows whether similarity spans the full reference, a domain, a signal peptide, a transmembrane region or another localized segment.

For diligence, mismatches and gaps should be mapped to functional domains, extracellular versus intracellular regions, cleavage sites, ligand-binding surfaces and construct boundaries. A complete natural-protein match can be highly relevant to antigen and replacement-protein patents, but its meaning differs from a partial intracellular-domain match or a short conserved motif. Domain context should therefore be reviewed before ranking families.

Antibody–antigen and patent-sequence evidence

The target search returned 4,302 antibody–antigen records. The leading evidence references CD19 in Felis catus and patent CN116425859A. Heavy- and light-chain lengths in the retrieved records are preserved as contextual evidence, but antibody naming, species and sequence provenance still require manual review.

The target-linked antibody–antigen record identified CN116425859A, “合成猫CD19多肽氨基酸序列、结合猫CD19的单克隆抗体及应用”. A follow-on ls_patent_sequence_fetch call returned 5 sequence records in the patent bundle. The first retrieved records span 112 aa, 18 aa, 112 aa, 336 aa, 336 aa. These records are evidence for document review, not proof that every sequence is claimed or clinically relevant.

What the claimed flag does—and does not—show

A “Yes” claimed flag raises review priority, but it is not a claim chart. The annotation must be checked against the filed document, the exact SEQ ID, the relevant independent and dependent claims, prosecution history and current legal status. Claims may be abandoned, narrowed, expired, territorially limited or directed to uses and combinations that do not read on a proposed asset.

A “No” or unspecified flag is equally not a clearance result. A family can claim a broader genus, a fragment, a functional binding property, a nucleic acid, a vector, a host cell, a method of treatment or a combination without labeling the exact protein sequence as claimed. The safest interpretation is to use the flag to order document review, never as a substitute for legal analysis.

Patent-risk interpretation

Recommended diligence actions

1. Confirm the exact protein, isoform, mature chain, engineered variant and construct boundaries intended for development.
2. Repeat searches for functional domains, extracellular regions, cleavage products and nucleic-acid sequences where relevant.
3. Cluster high-similarity records by simple family, earliest priority, applicant, inventor and jurisdiction.
4. Retrieve the source documents and verify every important sequence ID against the claims and sequence listing.
5. Review live independent and dependent claims for sequence, identity-threshold, functional, use, combination and manufacturing scope.
6. Record licenses, collaborations, platform rights and prosecution events that can change practical exposure.
7. Rerun the Biology Modality workflow at each transaction or development decision date because database and legal-status coverage changes.

Bottom line

CD19 produced a traceable patent-scale similarity signal: 100.00% closest reviewed query identity, 556/556 query coverage, a Yes claimed annotation, 4,302 antibody–antigen records and 5 directly fetched target-linked patent sequences. Together these support elevated diligence priority. The defensible output is a prioritized, domain-aware patent-family and claim review—not a binary clearance statement.

Explore PatSnap Open Platform MCP Servers to produce sequence similarity and patent-risk reports for antibodies, proteins, peptides and nucleic-acid assets.

Sources and methodology notes

Reference sequence metadata: reviewed human UniProt entry P15391. Patent-scale similarity, sequence-detail, PSA, patent-sequence and antibody–antigen evidence was retrieved through PatSnap Biology Modality MCP on 4 August 2026. Results are bounded by the configured query, thresholds, aliases, task limits and database coverage; rerun at the decision date.