Table 2.

Summary of Targeting Recommendations for 37°C Systems

Parameter	Recommendation	Comments
CG range	40%‐60%	At lower GC, affinity may be too low to inhibit processes; higher GC favors nonspecific binding of subsequences.
G content	Up to 36% G	Higher G causes loss of water solubility; avoid upper end of acceptable range, if possible.
Self‐complementarity	16 contiguous H‐bonds maximum	For intermolecular (complementary palindrome) and intramolecular (stem loop) binding. Example: AGCGCT has 16 H‐bonds (2+3+3+3+3+2 = 16). Check for non‐Watson‐Crick G‐T pairing, which can participate in self‐complementarities.
Consecutive G	3 consecutive Gs maximum	Runs of ≥4 G can associate through Hoogsteen bonding to form oligo tetramers.
Oligo length	25 bases or shorter by only a few bases	Using shorter oligos can decrease the chance of off‐target interaction for high CG oligos.

This article is being made freely available through PubMed Central as part of the COVID-19 public health emergency response. It can be used for unrestricted research re-use and analysis in any form or by any means with acknowledgement of the original source, for the duration of the public health emergency.