The divergence present in pathogen genomes makes it difficult or impossible to design a single probe or primer that is the exact complement of all possible target sequences. In practice this is handled using degenerate or  “universal bases” (e.g. inosine).

Firebird scientists have created two “biversals”^TM.  Each exists in two tautomeric forms that provide alternate hydrogen bonding patterns.  This allows the pyrimidine biversal to pair with either guanine or adenine and the purine biversal to pair with either thymine or cytosine. These bases provide a new alternative to the existing methods of handling divergent sequences for both PCR amplification and SNP detection.

Tautomeric forms of the Pyrimidine biversal:

Tautomeric forms of the Purine biversal:

Yang et al., 2018