We have succeeded in developing high affinity and high specificity aptamers for both the spike protein (S1) and the nucleoprotein from SARS-CoV-2 (COVID-19). These aptamers have been characterized and are available for purchase. We are working with several partners globally to apply these aptamers in antigen based test systems using a wide variety of formats.
For our spike protein aptamers we started with recombinant S1 protein produced within HEK293 cells as these proteins are heavily glycosylated and this glycosylation has to be human relevant. We also performed counter selection against the S1 protein from SARS-CoV (SARS) in order to drive specificity for SARS-CoV-2. This was very successful as shown in the surface plasmon resonance imaging analysis below.
Figure 1: SPRi binding curves , with our imbobilized Covid S1 aptamers after injection of S1 protein SARS-CoV( SARS) and S1 protein SARS CoV-2 ( Covid-19)
In applications, we have found that our aptamers for the nucleoprotein outperform those for spike protein by a margin that is larger than would be expected based on the higher abundance of nucleoprotein per virus particle. Coronavirus nucleoproteins function is to pack the RNA genome of the virus, so it is not surprising that they exhibit the capacity to bind to pretty much any single stranded oligonucleotide DNA or RNA. In our selection, we identified aptamers that outperformed all negative controls by orders of magnitude. Given the low levels of sensitivity needed for commercial relevance (1E3 to 1E5 VPs/mL) the higher level of affinity of our oligonucleotides provides us with the necessary level of specificity required for detection.
If you are interested in discussing the use of our aptamers for COVID-19 please let us know by contacting us at firstname.lastname@example.org