You can freely build on How to Make Many Copies of a Specific DNA Segment

What this patent covers

This patent details a process to amplify, or make many copies of, a specific nucleic acid sequence. First, two short DNA pieces called "oligonucleotide primers" attach to opposite ends of the target DNA (Claim 1a). An enzyme then builds new DNA strands starting from these primers, creating "extension products." Next, these newly made DNA strands are separated from their original templates, often by heating (Claim 1b, 3, 4). Finally, the separated single strands are again treated with the same primers and enzyme to build more new strands (Claim 1c). This cycle of separating and rebuilding is repeated multiple times (Claim 2), creating an exponentially increasing number of copies of the target DNA. For example, if you wanted to copy a specific gene from a human DNA sample, you would design primers that match the beginning and end of that gene, then run these cycles to produce millions of copies.

What is now free to use

All 0 claims of US 4683202 are in the public domain. Specifically:

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover methods that amplify DNA without using two distinct oligonucleotide primers for each strand of the target sequence.

• Does not cover amplification processes that do not involve separating the primer extension products from their templates.

• Does not cover methods where the extension product synthesized from one primer cannot serve as a template for the synthesis of the other primer's extension product.

• Does not cover amplification techniques that do not repeat the separation and extension steps at least once.

• Does not cover direct amplification of RNA without an initial reverse transcription step to convert it to DNA, even though reverse transcriptase is mentioned as an enzyme option for RNA templates (Claim 7).

Who is building on this today

Companies like Thermo Fisher Scientific, Bio-Rad Laboratories, and Qiagen are major players in developing and selling PCR instruments, reagents, and kits. Academic and industrial research labs globally rely on PCR for a vast array of applications, from basic science to drug discovery and development. The original assignee, Cetus Corp, was acquired, but its legacy through this invention continues to underpin much of modern molecular biology.

Products built on expired version of this technology

How to cite this patent in your documentation

Cetus Corp. US Patent 4683202. Process for amplifying nucleic acid sequences. Granted 1987, expired 2005. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.