Aptamer-assisted phage display: enhancing checkpoint inhibition with a peptide and an aptamer targeting distinct sites on a single PD-L1 protein.

Utilizing a novel approach known as aptamer-assisted phage display (APD), we identified an anti-PD-L1 peptide, NV Pep, capable of simultaneous binding to PD-L1 alongside the DNA aptamer MJ5C. Combined inhibition using NV Pep and MJ5C demonstrated significant enhancement compared to individual ligands against the PD-1/PD-L1 interaction.

Ni aptamer: DNA mimic of His-tag to recognize Ni-NTA.

We introduced Ni Apt as the first aptamer with a characterized dissociation constant for recognizing Ni-NTA. Serving as a nucleic acid analog of the His-tag commonly employed for protein purification using Ni-NTA resin, Ni Apt displays a remarkable binding affinity (Kd = 106 nM) towards Ni-NTA. Furthermore, it can be eluted from the resin using imidazole or EDTA, similar to the removal of His-tag from Ni-NTA resin. The versatile capabilities of Ni Apt make it a valuable molecular tool in nucleic acid purification and recognition applications.

DNA aptamers inhibit SARS-CoV-2 spike-protein binding to hACE2 by an RBD- independent or dependent approach.

Objective: Nobody knows when the COVID-19 pandemic will end or when and where the next coronavirus will outbreak. Therefore, it is still necessary to develop SARS-CoV-2 inhibitors for different variants or even the new coronavirus. Since SARS-CoV-2 uses its surface spike-protein to recognize hACE2, mediating its entry into cells, ligands that can specifically recognize the spike-protein have the potential to prevent infection. Methods: We have recently discovered DNA aptamers against the S2-domain of the WT spike-protein by exploiting the selection process called SELEX. After optimization, among all candidates, the aptamer S2A2C1 has the shortest sequence and the best binding affinity toward the S2-protein. More importantly, the S2A2C1 aptamer does not bind to the RBD of the spike-protein, but it efficiently blocks the spike-protein/hACE2 interaction, suggesting an RBD-independent inhibition approach. To further improve its performance, we conjugated the S2A2C1 aptamer with a reported anti-RBD aptamer, S1B6C3, using various linkers and constructed hetero-bivalent fusion aptamers. Binding affinities of mono and fusion aptamers against the spike-proteins were measured. The inhibition efficacies of mono and fusion aptamers to prevent the hACE2/spike-protein interaction were determined using ELISA. Results: Anti-spike-protein aptamers, including S2A2C1 and S1B6C3-A5-S2A2C1, maintained high binding affinity toward the WT, Delta, and Omicron spike-proteins and high inhibition efficacies to prevent them from binding to hACE2, rendering them well-suited as diagnostic and therapeutic molecular tools to target SARS-CoV-2 and its variants. Conclusions: Overall, we discovered the anti-S2 aptamer, S2A2C1, which inhibits the hACE2/spike-protein interaction via an RBD-independent approach. The anti-S2 and anti-RBD aptamers were conjugated to obtain the fusion aptamer, S1B6C3-A5-S2A2C1, which recognizes the spike-protein by an RBD-dependent approach. Our strategies, which discovered aptamer inhibitors targeting the highly conserved S2-protein, as well as the design of fusion aptamers, can be used to target new coronaviruses as they emerge.

A universal DNA aptamer as an efficient inhibitor against spike-protein/hACE2 interactions.

A universal aptamer against spike-proteins of diverse SARS-CoV-2 variants was discovered via DNA SELEX towards the wild-type (WT) spike-protein. This aptamer, A1C1, binds to the WT spike-protein or other variants of concern such as Delta and Omicron with low nanomolar affinities. A1C1 inhibited the interaction between hACE2 and various spike-proteins by 85-89%. This universal A1C1 aptamer can be used to design diagnostic and therapeutic molecular tools to target SARS-CoV-2 and its variants.

Identification of citrus greening based on visual symptoms: A grower's diagnostic toolkit.

Citrus greening is one of the world's most serious diseases of citrus that affects all cultivars and causes the systematic death of trees worldwide. The disease is caused mostly by the bacteria Candidatus Liberibacter species. The wind, rain, and touch of infected workers cannot transmit this infectious disease. The Asian Citrus Psyllid (ACP), a minuscule insect, is one of the main vectors that transmit the disease by feeding on citrus leaves. Citrus greening management is also quite expensive since no successful treatment for the cure has been found, except to remove all affected vegetables from healthy crops to eliminate the bacterial spread. Citrus greening is also the most challenging task, as signs of other citrus diseases and nutritional deficiencies are identical. The major signs of this disease are asymmetrical, blotchy mottling patterns on leaves. Here, several visible indications of citrus greening were addressed, which will enable farmers at the root level to detect and avoid this condition prior to its having a dramatic influence on citrus plantations. We also talked about the pen test method to determine symptoms as symmetrical or asymmetrical throughout the mid-vine, regardless of whether they are impacted by citrus greening or lack of nutrients.