US Patent 5,276,019: What Is Claimed, Where It Maps in HIV Antisense/Complementary Oligonucleotides, and How the Landscape Likely Cuts

US 5,276,019 claims a class of sequence-complementary nucleic-acid–binding compounds built around a repeating oligomeric backbone containing heteroatoms X = S or O (with at least one S), with base B selected from A/C/G/T such that the compound has a complementary base sequence to a portion of a foreign nucleic acid. The claims then narrow into longer oligomers (n = 14 to 30) and high sulfur substitution (>95% X = S), and finally tie specific HIV genomic regions (gag, tat-III, art/trs) and a particular HIV nucleic acid context. The patent scope therefore tracks classic antisense/complementary oligonucleotide paradigms but is drafted tightly around a sulfur-containing modified backbone and complementary sequence targeting.

Because the supplied record includes only claim text (not the patent bibliographic header, assignee, priority dates, specification details, or prosecution history), the analysis below focuses strictly on claim scope, claim construction vectors, and the typical infringement/validity pressure points that such claim language creates.

What Do the Independent Claims Actually Cover? (Compound, Composition, Method)

Claim 1: The compound scope

Claim 1 covers “a compound capable of inhibiting the replication or cytopathic effect of a foreign nucleic acid” that is defined by three technical elements:

Backbone/heteroatom variable (X):
- X is selected from S and O
- At least one X is S
- This implies the oligomer backbone has positions that can be S or O, and the patent requires sulfur in the structure.
Base identity variable (B):
- B is selected from adenine, cytosine, guanine, thymine
- The compound is defined by sequence such that it has a complementary base sequence to a portion of the foreign nucleic acid.
Length (n):
- n ranges from 2 to 30, inclusive

Functional language matters: “capable of inhibiting the replication or cytopathic effect” is a broad capability limitation. In practice, this is often construed as requiring the compound to have antisense/complementary inhibitory activity, but the patent does not quantify potency in Claim 1.

Claim 23: The composition scope

Claim 23 covers a pharmaceutically acceptable carrier + effective amount of the compound of the Claim 1 formula. The composition scope is therefore coextensive with the compound scope, subject to formulation typicalities.

Claim 35: The method scope

Claim 35 covers a method of inhibiting replication/cytopathic effect by administering an effective amount of a compound of the formula. This is typical antisense method claim drafting.

How Far Does the Claim Territory Expand or Narrow? (Key Dependent Claim Filters)

The dependent claims function like “gating variables” that progressively narrow structural and sequence space.

Length gating

Claim 2 narrows to n = 14 to 30
Claims 24, 36, 28, 40 mirror the same n-range for composition and methods

Impact: requiring 14 to 30 shifts the scope away from very short oligos and toward hybridization-capable lengths often used in antisense.

Sulfur content gating

Claim 3: >95% of X are S
Claim 4: X is S (as written, this appears to read as full sulfur replacement)
Claim 16 / 17 / 19: parallel HIV-specific sulfur claims
Similar gating appears throughout composition and method claims

Impact: these claims carve out a distinct structural family: near fully sulfur-substituted backbones. That often matters for novelty and design-around decisions because many adjacent antisense backbones use O (phosphate or phosphodiester) rather than sulfur-rich analogs.

Distribution/order gating

Claim 5: two X are S and remaining X are O
Claim 6: those two S are at opposite terminal ends
Claim 7: number of S equals number of O
Claim 8: X grouped in alternating units where one unit is all S and the next unit is all O, with unit sizes equal
Claim 9: each unit size is one

Impact: These “pattern” claims are narrower than the generic “at least one S” of Claim 1. They can support distinct infringement theories if accused products match the exact substitution pattern, but they also narrow protection.

Target nucleic acid gating

Claim 10: foreign nucleic acid is viral
Claim 12: viral nucleic acid is HIV nucleic acid
Then specific HIV gene targets:
- Claim 13: gag gene
- Claim 14: tat-III gene
- Claim 15: art/trs gene
Parallel claims exist for composition and method:
- Claims 18-22 and 20-22 mirror gag/tat-III/art/trs
- Composition: Claims 30-32, 33-34
- Method: Claims 41-43

Impact: the broadest independent claims cover any “foreign nucleic acid,” but the later narrowing claims lock to HIV and specific genomic regions. This has two direct consequences:

For enforcement, the narrower dependent claims provide a cleaner match to a competitor’s HIV targeting sequence.
For validity, HIV gene-targeting limitations may reduce prior-art overlap compared to generic antisense claims.

What Is the Practical Meaning of “Complementary Base Sequence”?

The claims define activity through base complementarity: the compound has a complementary base sequence with a portion of the foreign nucleic acid.

Claim consequences

The scope depends on sequence definition, not just chemistry. Even if the backbone meets the sulfur/length constraints, infringement requires that the B pattern be complementary to the targeted viral region.
The claims do not specify exact nucleotide positions, only that it is “a portion.” With the stated lengths (2-30, or 14-30 in narrowed claims), the “portion” will likely be interpreted as a contiguous segment compatible with the oligomer length.

Sequence risk for competitors

A competitor can potentially avoid infringement by:

using a backbone where X is all O or otherwise lacking required sulfur presence, or
shifting length outside the constrained ranges, or
using a backbone pattern not matching the S/O arrangement where those dependent claims are pursued, or
targeting a different viral region (for the HIV gene-dependent claims).

HIV Coverage: Which Viral Regions Are Explicitly Claimed?

The claims explicitly name HIV genomic targets:

HIV target limitation	Claim numbers (compound / composition / method)	Additional structural filters nearby
gag gene	Claim 13; Claim 30; Claim 20 and 41	often paired with n = 14-30 and/or >95% X = S in dependent sets
tat-III gene	Claim 14; Claim 31; Claim 21	often paired with n = 14-30 and/or >95% X = S
art/trs gene	Claim 15; Claim 32; Claim 22	often paired with n = 14-30 and/or >95% X = S

The HIV-specific dependent claims also include sulfur content limitations (e.g., >95% X = S; X = S). As drafted, those dependent claims create a ladder: broad HIV viral applicability in Claim 12, then specialized to gag/tat-III/art/trs in Claims 13-15 and further specialized by backbone sulfur content.

Scope Mechanics: How Broad vs. Narrow the Claim Set Actually Is

Broadest structural breadth

n = 2 to 30 (Claim 1)
X includes S and O with at least one S
any foreign nucleic acid (Claim 1)
any base pattern complementary to a portion (Claim 1)

Most enforceable narrowing steps

n = 14 to 30 (Claims 2, 24, 36, 28, 40)
>95% X are S (Claims 3, 25, 37, 33, 42)
X is S (Claims 4, 26, 38, 34, 43)
exact S/O patterning (Claims 5-9 and corresponding structures in dependent claim pathways)
HIV target gene limitations (Claims 12-15 and mirrors)

From a landscape perspective, the broadest claim language is most vulnerable to prior art in the generic antisense space; the narrower sulfur-rich and HIV-region limitations are more likely to represent a distinguishable claim position.

Where the Patent Likely Sits in the Broader Antisense/Oligonucleotide Landscape

Even without specification details, the claim architecture places US 5,276,019 in the overlap zone between:

antisense/complementary oligonucleotides (sequence complementarity + inhibitory function), and
modified backbone chemistry with sulfur in place of oxygen (S/O pattern gating and high sulfur substitution thresholds).

That combination is important because prior art often splits into two camps:

sequence-only antisense (often with standard phosphate backbones or other oxygen-rich chemistries), and
chemistry-only modified oligos (often without the same sequence/complementarity targeting limitations, or without HIV gene region specificity).

US 5,276,019 explicitly ties both: chemistry requirements (X = S and/or O with sulfur presence and thresholds) and sequence complementarity (B complementary to a portion of the viral nucleic acid), with HIV gene targeting in dependent claims.

Potential Claim Construction Pressure Points (Infringement and Validity Vectors)

1) “X is selected from S and O such that at least one X is S”

This allows many sulfur-substituted partial-backbone configurations.
But dependent claims narrow strongly to >95% S and full S, creating multiple “capture rings.”

2) “complementary base sequence with a portion of the foreign nucleic acid”

Competitors can argue that the designed molecule does not have the claimed complementary sequence with the targeted portion (sequence non-infringement).
If sequences are provided in marketing or regulatory filings, enforcement becomes tractable.

3) Functional clause “capable of inhibiting replication or cytopathic effect”

This can support arguments that a claim is not purely structural if performance is central.
In practice, functional clauses can also be used to argue non-utility or non-enablement depending on how the specification supports performance. Claim text alone does not resolve that.

4) HIV gene specificity in dependent claims

If a competitor targets a different HIV region, the HIV-gag/tat-III/art/trs dependent claims likely do not read onto the competitor’s products.
The base Claim 1 does cover “foreign nucleic acid” broadly; so design-around against the gene-specific dependent claims does not eliminate potential risk under the broader foreign-nucleic-acid claim.

5) Patterning limitations (Claims 5-9)

These are structurally precise and can be used both for enforcement and for narrowing invalidity/obviousness arguments.

Actionable Landscape Read-Through: How a Competitor Could Design Around

Based on the claim language alone, design-around strategies cluster into four buckets:

Remove sulfur from the backbone
- If X is all O, likely avoids the “at least one X is S” requirement in Claim 1 and the higher thresholds in dependent claims.
Use sulfur but not in the required proportion
- If sulfur content stays below “>95% X are S” where that dependent claim is asserted.
Use sulfur but different S/O distribution
- If accused molecule does not match the dependent pattern claims (terminal opposite ends; equal counts; alternating all-S/all-O units).
Target a non-HIV region or different HIV gene segment
- This mainly impacts the HIV gag/tat-III/art/trs dependent claims.
- It does not necessarily avoid the broad “foreign nucleic acid” coverage in Claim 1, if the sulfur-containing chemistry and complementarity requirements are met.

Key Takeaways

US 5,276,019 claims sulfur-containing oligo-like compounds (X = S/O with at least one S) that bind by complementary base sequence to a portion of a foreign nucleic acid, inhibiting viral replication or cytopathic effect.
The enforceability ladder in the claim set moves from broad foreign-nucleic-acid coverage (Claim 1) to strong structural narrowing on n = 14 to 30 and high sulfur substitution (>95% X = S), then to HIV gene targets: gag, tat-III, and art/trs (dependent claims).
The most landscape-relevant claim features for freedom-to-operate are the S/O backbone constraints, the length window, and the sequence complementarity requirement tied to specific HIV regions in narrower dependent claims.
Competitor design-around primarily targets either backbone sulfur presence/content/distribution or targeted nucleic acid region/sequence.

FAQs

1) Does US 5,276,019 require that the foreign nucleic acid be HIV?
No. Claim 1 covers “foreign nucleic acid” generally; HIV appears in dependent claims via Claim 12 and subsequent gag/tat-III/art/trs limitations.

2) What length range is most important to the narrower claim set?
Claims 2, 24, 36, 28, and 40 narrow length to n = 14 to 30.

3) How strict is the sulfur requirement?
Claim 1 requires at least one X is S. Dependent claims impose >95% X are S and in some branches X is S.

4) Can a product avoid the gag/tat-III/art/trs dependent claims by targeting another HIV gene?
Yes, it would avoid those specific dependent limitations, but it does not automatically eliminate risk under the broader “foreign nucleic acid” claim if the core structural and complementarity requirements match.

5) What is the central infringement test implied by the claim language?
Whether the accused compound matches the S/O backbone definition, the length, and whether its base sequence is complementary to a targeted portion of the foreign (often HIV) nucleic acid described in the dependent claims.

References

[1] US Patent 5,276,019 claim set as provided in the prompt.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	116857	⤷ Start Trial
Australia	1571788	⤷ Start Trial
Australia	619180	⤷ Start Trial
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Details for Patent: 5,276,019

Summary for Patent: 5,276,019