Electronic-PCR (e-PCR) is retiring, use Primer-BLAST instead - NCBI Insights (2025)

NCBI is retiring the e-PCR tool effective immediately. The good news is that an existing tool, Primer-BLAST, fills in nicely for the functions of both Forward and Reverse e-PCR, and has the additional benefit of de novo primer design.

• Design primers for your template sequence.

This is similar to using Forward e-PCR to locate STS markers in the provided sequence. It uses the latest version of the primer3 program, and allows adjustment of most of the same primer3 parameters.

• Check the specificity of designed, or supplied, primers.

This is similar to using Reverse e-PCR to search a sequence database with STS markers. For current users of primer3, you do not need to run a separate BLAST search after you’ve designed your primers. Primer-BLAST automatically searches a user-selected database for your organism, or group of organisms, and it provides a nice graphical view of the primer positions.

It is often unnecessary to change the default settings, but here is a selection of the many parameters you can adjust:

• When your template is an NCBI RefSeq mRNA (NM_ or XM_ accession), Primer-BLAST can:
  • include or exclude exon-exon junctions,
  • require that primer pairs are separated by at least one intron, and
  • find primers that amplify splice variants, not just the input template.
• You may also adjust:
  • PCR product size
  • primer melting temperatures
  • whether or not to exclude primer binding sites that contain known SNPs
  • BLAST settings
  • and many more parameters.

You can link to Primer-BLAST from the “Specialized searches” section of the BLAST home page.

For help getting started, see the Primer-BLAST factsheet, and a short, 4 minute demonstration of Primer-BLAST beginning at 50m:13s in this video, “Webinar: A Practical Guide to NCBI BLAST”. Finally, don’t overlook the more than 40 in-page tips that help explain the parameters; use the question mark icons to reveal those tips.

• Quick Tips