Invalidity dossier
US 4921794
T7 DNA polymerase
Current assignee: Harvard University
Added 9/23/2026, 8:59:19 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 4921794 A
Title: T7 DNA polymerase
Patent number: US 4,921,794 A
Assignee: Harvard University (original assignee; the source notes listed assignees "may be inaccurate" and that Google has not analyzed or warranted the list).
Inventors: Stanley Tabor and Charles C. Richardson.
Key dates (as stated in the source): Priority date 1987-01-14, claimed from US 07/003,227 (which the source links to patent US4795699A); filing date 1988-12-05 for application US 07/279,990; publication/grant date 1990-05-01; anticipated expiration 2007-05-01. Legal status listed as "Expired - Lifetime" (the source labels legal status an assumption, not a legal conclusion).
Purpose and plain-language scope (from the supplied text): The patent concerns T7 DNA polymerase, a DNA-directed DNA polymerase, and methods relating to DNA synthesis, nucleic acid amplification, and DNA sequencing. The excerpt's prior-art keywords and indexed terms point to core themes: polymerase, DNA, exonuclease activity, DNA polymerase, and primers. Indexed subject matter includes exonuclease, nucleotides, annealing, dideoxynucleotides, single-stranded DNA, polymerase chain reaction, thioredoxin, gene 5 protein, and Enterobacteria phage T7. Mentioned reagents include dATP, dGTP, dCTP, dTTP, dITP, buffers, magnesium chloride, sodium chloride, EDTA, dithiothreitol, and β-mercaptoethanol. The excerpt indicates 10 claims, though their text is not reproduced here.
Source: https://patents.google.com/patent/US4921794/en (fetched 2026-09-23).
What the excerpt does not establish: The excerpt omits the actual claim language and detailed description, so the precise scope of the claims, any exonuclease-deficient modification, and specific sequencing/amplification methods cannot be verified from it. It does not confirm the accuracy of the listed assignee, priority date, or legal status, which the source itself flags as assumptions. It does not establish whether any claim was invalidated, licensed, or transferred. Dates are from the source only. Nothing here should be read as a validity, ownership, or infringement conclusion.
Generated 10/1/2026, 9:41:02 PM
Cases on file (0)
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.