Using Synthetic DNA Fragments to Block HIV Replication

A 1987 patent describing a specific synthetic DNA molecule designed to stop the HIV virus from replicating by blocking a key part of its genetic code.

What it covers

The patent describes an oligodeoxyribonucleoside methylphosphonate, a synthetic molecule that mimics DNA but is chemically modified to be more stable. This molecule is designed to bind specifically to the first splice acceptor site of the HIV tat III gene. By binding to this site, the molecule prevents the virus from producing the proteins it needs to replicate and form syncytial giant cells, which are clusters of infected cells. The patent claims both the specific sequence 3' TCTTAACC 5' and the method of using such sequences to inhibit HIV in laboratory cell cultures.

What it doesn't cover

• —Does not cover naturally occurring DNA or RNA sequences.
• —Does not cover therapeutic methods for treating human patients, as the claims are limited to in vitro applications.
• —Does not cover other chemical modifications to DNA backbones beyond methylphosphonates.
• —Does not cover sequences that do not target the specific tat III splice acceptor site.

The clever bit

The inventors used a methylphosphonate backbone to replace the standard phosphate backbone of DNA, making the molecule resistant to degradation by cellular enzymes that would otherwise destroy it before it could reach its target.

Why it matters

This patent represents an early attempt to use antisense technology to treat viral infections. By targeting the genetic instructions of the virus rather than the proteins it produces, the inventors sought a more precise way to halt the HIV life cycle. It is a foundational example of using synthetic nucleic acids for therapeutic intervention.

Real-world examples

• 1.Antisense oligonucleotide research
• 2.Experimental HIV gene therapy models