You can freely build on How to Make Billions of Copies of a DNA Segment
This patent expired in 2006. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Cetus Corp
Patent granted
1987
Expired
2006
Forward citations
6,231
What this patent covers
This patent details a process for amplifying and detecting specific nucleic acid sequences. First, a sample containing DNA or RNA is treated with two short DNA pieces called oligonucleotide primers, one for each strand of the target sequence (Claim 1a). These primers attach to the target, and an enzyme then extends them, building new complementary strands. Next, the sample is heated to separate the newly made strands from their original templates (denaturing, Claim 1b). The process of adding primers and extending them is then repeated, using the newly separated strands as templates (Claim 1c). Repeating these steps many times creates a massive number of copies of the target sequence (Claim 2). Finally, a labeled probe is added to detect if the amplified sequence is present (Claim 1d, 1e). For example, this process can detect a specific genetic mutation like the one causing sickle cell anemia (Claim 11, 12).
What is now free to use
All 0 claims of US 4683195 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 amplification methods that do not use two oligonucleotide primers for each strand of the target sequence.
Does not cover detection methods that do not involve adding a labeled oligonucleotide probe after amplification.
Does not cover processes where the primer extension products are not separated from their templates before further amplification steps.
Does not cover amplification using enzymes that are inactivated by the high temperatures required for strand separation, unless a heat-stable enzyme is explicitly used (Claim 15).
Does not cover methods that amplify nucleic acids without repeating the primer extension and denaturation steps at least once.
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. These companies continuously innovate on PCR technology, creating faster, more sensitive, and more specialized versions. Diagnostic companies worldwide rely on PCR for their testing services.
Products built on expired version of this technology
COVID-19 diagnostic tests (RT-PCR)
Forensic DNA analysis (e.g., crime scene investigation)
Paternity testing
Genetic disease screening (e.g., cystic fibrosis, sickle cell anemia)
Gene cloning and sequencing in research labs
Detection of pathogenic organisms in clinical samples
How to cite this patent in your documentation
Cetus Corp. US Patent 4683195. Process for amplifying, detecting, and/or-cloning nucleic acid sequences. Granted 1987, expired 2006. 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.