Critical Patent Landscape and Claim Analysis for US Patent 4,956,281

US 4,956,281 claims DNA sequences and expression constructs for producing LFA-3-derived polypeptides that bind CD2 on T-lymphocytes and inhibit T-cell adhesion to target cells. The claims cover (i) the specific coding DNA for “LFA-3 polypeptide carried in phage λ.HT16,” (ii) broader hybridization-defined DNA variants, and (iii) recombinant DNA, host cells, and production methods. This is a typical early-1990s antibody/adhesion biology patent structure, with a heavy emphasis on nucleic acid definitions and expression-ready vectors rather than on specific therapeutic uses.

What is claimed, in enforceable scope terms?

Claim set overview

Claim	Subject matter	What the claim actually covers	Scope strength
1	DNA sequence	(a) exact coding DNA for LFA-3 from λ.HT16; (b) hybridization variants defined by temperature and salt; (c) any DNA encoding a CD2-binding polypeptide encoded by the above	Broad by construction (hybridization + any expression product)
2	DNA sequence	Polypeptide binds CD2 and inhibits adhesion between T-cells and target cells	Narrows functional endpoint (inhibition)
3	DNA sequence	Polypeptide is soluble	Adds solubility limitation
4-5	DNA sequences	Specific constructs by residue-number “N.sub.*” formulas and ATG-start variants, including coding versions	Medium: narrows to enumerated sequences/regions
6	Recombinant DNA molecule	DNA from claims 1-5 operably linked to expression control sequence	Expansive across vector/backbone designs
7	Recombinant DNA control	Lists promoter systems (SV40, adenovirus, lac, trp, TAC/TRC, λ, fd, glycolytic promoters, acid phosphatase, yeast α-mating factor)	Moderate: limits control elements to specified promoter categories
8	Host	Any unicellular host transformed with recombinant DNA of claim 6	Broad host class
9	Host types	E. coli, Pseudomonas, Bacillus, Streptomyces, fungi, animal/plant/human cells in culture	Very broad
10	Method of producing LFA-3 polypeptide	Culturing transformed host to produce LFA-3	Typical downstream method claim

Functional claims versus sequence claims

The strongest claim breadth is claim 1, because it mixes:

A literal “DNA sequence which codes for the LFA-3 polypeptide carried in phage λ.HT16” (anchoring the invention to a known clone/source), and
Hybridization-defined DNA variants that code for CD2-binding polypeptides (not limited to the exact clone),
Follow-on coverage for “any” DNA encoding a CD2-binding polypeptide encoded by the above.

Claims 2 and 3 then try to limit the intended expression product by function (inhibits adhesion) and property (soluble). Claims 4 and 5 further narrow the DNA candidates to specific residue-region constructs enumerated in FIG. 3 using “N.sub.*” notations and ATG-start versions.

What is the critical legal vulnerability: are the claims overbroad or under-definite?

1) Hybridization-defined nucleic acids can expand scope beyond the exact disclosure

Claim 1(b) defines hybridization “under conditions equivalent to about 20°C to 27°C below Tm and 1 M sodium chloride” relative to the LFA-3 DNA of (a). This is a broad selector because:

“Equivalent conditions” can be met by multiple laboratory protocols,
Hybridization windows can capture nucleic acids with significant divergence depending on length, probe design, and target-processing conditions,
The claim is not limited to a specific identity percentage (no explicit % identity or codon-level constraints are stated in the claim text you provided).

Business impact: competitors working on CD2-binding LFA-3 derivatives, even if intended to be “engineered,” may still fall within claim 1 if their nucleic acids hybridize under those conditions to the claimed LFA-3 λ.HT16 coding sequence and encode a CD2-binding polypeptide.

2) The “CD2-binding polypeptide” endpoint shifts the claim from sequence to biology

Claim 1(c) reaches “any of the foregoing DNA sequences” that code on expression for a polypeptide that binds to CD2. Claim 2 further adds inhibition of adhesion between T-cells and target cells.

This creates two key risks for an accused infringer:

Product-by-function capture: if a design yields CD2 binding, the nucleic acid claim can attach even when sequence similarity is partial but hybridization still occurs under the defined conditions.
Assay-dependent limitation: “inhibits adhesion” can be disputed experimentally, but the claim text makes the endpoint part of the asserted metes-and-bounds for claim 2. If the accused product shows measurable inhibition, claim 2 aligns closely.

3) Solubility limitation (claim 3) is narrower but still enforceable

“Soluble” polypeptides exclude membrane-tethered or strongly insoluble forms. In practice, many LFA-3 fragments and ectodomains can be soluble if engineered with truncations and secretion signals. If the claim is asserted against a soluble CD2-binding construct, claim 3 becomes a straightforward technical match rather than a barrier.

4) “N.sub.*” residue formulas are narrow but can be reinterpreted

Claims 4-5 hinge on “DNA sequence of the formula N.sub.1-1047 of FIG. 3,” and other windows such as “N.sub.17-766” or “N.sub.101-766,” plus combined windows like “N.sub.101-611 -N.sub.716-766.” These are fragment/combinatorial notations rather than explicit full sequences in the claim text you provided.

That can cut both ways:

For enforcement: the enumerated fragment windows can be relatively clear if FIG. 3 defines the boundaries and those boundaries map to exact residue numbering.
For validity/attack: if “N.sub.*” notation is not self-contained in the claim and depends on reading FIG. 3, then scope can be argued as dependent on specification interpretation. That said, patents routinely use figure-based residue numbering for nucleic acid/peptide fragments, and courts generally follow the specification’s definitions.

How do the claims map to the likely invention: what are competitors actually building?

The claim language signals a standard engineering pattern:

Start from LFA-3 coding DNA (from a λ.HT16 carried LFA-3 polypeptide).
Express CD2-binding LFA-3 variants in unicellular hosts (bacterial, yeast/fungal, or mammalian cells).
Prefer soluble ectodomains or fragments.
Use conventional promoters (SV40/adenovirus/lac/trp/TAC/TRC, λ major operator/promoter, fd coat protein control region, glycolytic promoters, acid phosphatase, yeast α-mating factor).
Deliver nucleic acid and recombinant construct coverage rather than only formulation or therapeutic use.

If a competitor produces a secreted LFA-3 ectodomain or engineered soluble CD2 ligand using a coding sequence that would hybridize under the claim’s conditions, the direct risk is claim 1 and claim 2. If they produce it in a transformed unicellular host using one of the listed promoter systems and operatively linked constructs, claims 6-10 become direct risk pathways.

What does the promoter list imply about design-around?

Claim 7 restricts expression control sequences to a defined set of promoters/control regions. This is not a complete escape for design-arounds, but it matters:

If a competitor uses a promoter not in that list (e.g., CMV immediate early promoter, EF1α, CAG, SV40 early variants not listed by name, PGK variants depending on how “selected from” is interpreted), they may argue non-coverage for claim 7.
However, claim 6 already requires an expression control sequence, and claim 7 narrows only if claim 7 is asserted. If enforcement focuses on claim 6 alone (with “operatively linked to an expression control sequence” broadly), then the promoter list in claim 7 may matter less.
The host claims (8-9) do not restrict promoter systems directly; they rest on the recombinant DNA molecule of claim 6.

Practical takeaway: a design-around focused only on promoter choice may not fully avoid claim 6 if the claim’s “expression control sequence” is treated as broad and the asserted claim set includes claim 6 rather than claim 7.

What does the claim coverage mean for an LFA-3/CD2 program?

Direct infringement pathways

Activity	Likely implicated claims	Why
Synthesizing/isolating a nucleic acid encoding LFA-3 (λ.HT16 coding or hybridizing variants)	1	Claim 1 defines DNA sequences directly
Engineering an LFA-3-based soluble CD2-binding inhibitor	1-3	Function and solubility add requirements but align to common constructs
Building expression constructs with conventional control sequences	6-7	Recombinant DNA and promoter categories are covered
Expressing in bacterial or mammalian culture	8-9	Host transformation and broad host types
Producing the polypeptide by culturing a transformed host	10	Method claim tracks routine production

Likely proof set the patentee can marshal

Sequencing data demonstrating the accused nucleic acid hybridizes under the defined conditions to the λ.HT16 LFA-3 coding DNA (claim 1(b)),
Expression assays showing CD2 binding (claims 1 and 2),
Cell adhesion inhibition assays showing inhibition between T-lymphocytes and target cells (claim 2),
Solubility characterization (claim 3),
Construct maps for promoter elements and operable linkage (claims 6-7),
Transformation and culture records (claims 8-10).

How strong is the patent as a “landscape asset” versus likely prior art?

Because you provided only the claim text (not the specification, filing date, priority, prosecution history, or the exact patent bibliographic record), a complete prior-art and invalidity assessment cannot be made to a level consistent with high-stakes infringement or freedom-to-operate conclusions. Under the operating constraints, this analysis therefore focuses on the intrinsic claim architecture and landscape implications that can be derived from the claim language you supplied.

What the claim architecture indicates about novelty strategy

The claims are built around nucleic acid encoding of LFA-3 and CD2-binding soluble variants.
The hybridization definition suggests the patentee anticipated that exact sequences could be copied or close variants produced and wanted coverage beyond literal sequence copying.
The promoter list shows the patentee expected broad recombinant expression and wanted to capture common expression system usage in the early biotech toolkit.
FIG.-anchored fragment definitions (N.sub.* windows) indicate multiple engineered truncations were part of the disclosed invention.

Where patents like this tend to face vulnerability

Hybridization-defined claims can be attacked for lack of clear boundary if the hybridization conditions can be met by materially different sequences.
Functional endpoints like “inhibits adhesion” can be attacked if assay definitions and reproducibility are not anchored in the intrinsic record.
If earlier publications already disclosed LFA-3 soluble CD2-binding fragments or recombinant nucleic acids with similar expression contexts, the breadth of claim 1(b) can amplify invalidity exposure.

Key claim-to-landscape issue: are there multiple ways to achieve the same biology?

Yes. A CD2-binding, adhesion-inhibiting soluble polypeptide can be made via:

Different LFA-3 fragment boundaries,
Different signal peptides and secretion tags,
Different coding variants (codon optimization, alternative splice forms if relevant),
Alternative expression systems and promoters,
Alternative proteins (e.g., antibodies or fusion proteins) that still bind CD2 but do not rely on LFA-3 coding sequences.

US 4,956,281 primarily targets nucleic acids encoding LFA-3-derived CD2-binding polypeptides and the recombinant DNA/host production chain. It does not, from the claim language alone, read on anti-CD2 monoclonal antibodies or entirely different CD2-binding scaffolds that are not encoded by these LFA-3 sequences or hybridizing variants.

What does the claim set imply for enforcement strategy?

A patent owner typically asserts the claim tier that gives the cleanest technical match.

Best-case for a patentee: assert claim 1(a) if an accused nucleic acid is literally the λ.HT16 coding sequence or an unmodified copy. This collapses hybridization debates.
Fallback: assert claim 1(b) plus claim 2 if the accused construct is functionally a CD2-binding adhesion inhibitor and their nucleic acid hybridizes under the specified conditions.
Tighten with claim 3: if the accused product is soluble, this becomes an additional alignment lever.
Expand with claim 6-10: pair nucleic acid coverage with production and host claims to reach activity-based evidence (constructs, plasmids, transformed lines, fermentation records).

Key Takeaways

US 4,956,281 is a nucleic-acid-forward patent: it covers LFA-3 coding DNA from λ.HT16 and hybridization-defined variants that encode CD2-binding polypeptides.
Claims 2 and 3 narrow the biological endpoint to adhesion inhibition and solubility, but they align with common LFA-3 ectodomain inhibitor engineering.
Claims 6-10 broadly capture recombinant DNA construction, host transformation, and production methods, with claim 7 narrowing promoter choices only if that claim is asserted.
The hybridization definition in claim 1(b) is the main breadth driver and the main boundary vulnerability for design-around and validity challenges.
The patent is better aligned to LFA-3-derived CD2 ligands than to unrelated CD2-binding modalities that do not rely on these LFA-3 coding sequences.

FAQs

1) What is the core invention covered by US 4,956,281?

It is DNA sequences and recombinant expression systems that produce LFA-3-derived soluble polypeptides binding CD2 and inhibiting adhesion between T-lymphocytes and target cells.

2) Which claim is likely the broadest?

Claim 1, because it includes literal LFA-3 λ.HT16 coding DNA and hybridization-defined DNA variants encoding CD2-binding polypeptides.

3) Does claim 7 limit infringement to specific promoters?

Claim 7 restricts “expression control sequence” options to listed promoter systems. But claim 6 only requires an operatively linked expression control sequence, so promoter restrictions matter most when claim 7 is asserted.

4) How does claim 2 narrow the DNA scope?

Claim 2 ties the expressed product to a functional endpoint: it must inhibit adhesion between T-lymphocytes and target cells.

5) Is the patent focused on antibodies against CD2?

No. The claims are directed to LFA-3 coding DNA and constructs expressing CD2-binding LFA-3 polypeptides, not antibody scaffolds.

References

[1] US Patent 4,956,281. “DNA sequences and recombinant DNA molecules encoding LFA-3 polypeptides binding to CD2.” (Claim text as provided in the prompt.)

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Astellas Pharma Us, Inc.	AMEVIVE	alefacept	For Injection	125036	January 30, 2003	⤷ Start Trial	2007-06-03
>Applicant	>Tradename	>Biologic Ingredient	>Dosage Form	>BLA	>Approval Date	>Patent No.	>Expiredate

Country	Patent Number	Estimated Expiration
Austria	176502	⤷ Start Trial
Australia	1955288	⤷ Start Trial
Australia	634464	⤷ Start Trial
Canada	1340232	⤷ Start Trial
Germany	3856301	⤷ Start Trial
European Patent Office	0315683	⤷ Start Trial
Hong Kong	1009291	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration

Patent: 4,956,281

Summary for Patent: 4,956,281