Broadly neutralizing human antibodies against Omicron subvariants of SARS-CoV-2.

BACKGROUND: The COVID-19 pandemic continues to pose a significant worldwide threat to human health, as emerging SARS-CoV-2 Omicron variants exhibit resistance to therapeutic antibodies and the ability to evade vaccination-induced antibodies. Here, we aimed to identify human antibodies (hAbs) from convalescent patients that are potent and broadly neutralizing toward Omicron sublineages. METHODS: Using a single B-cell cloning approach, we isolated BA.5 specific human antibodies. We further examined the neutralizing activities of the most promising neutralizing hAbs toward different variants of concern (VOCs) with pseudotyped virus. RESULTS: Sixteen hAbs showed strong neutralizing activities against Omicron BA.5 with low IC50 values (IC50 < 20 ng/mL). Among four of the most promising neutralizing hAbs (RBD-hAb-B22, -B23, -B25 and -B34), RBD-hAb-B22 exhibited the most potent and broad neutralization profiles across Omicron subvariant pseudoviruses, with low IC50 values (7.7-41.6 ng/mL) and a low PRNT50 value (3.8 ng/mL) in plaque assays with authentic BA.5. It also showed potent therapeutic effects in BA.5-infected K18-hACE2 mice. CONCLUSIONS: Thus, our efficient screening of BA.5-specific neutralizing hAbs from breakthrough infectious convalescent donors successfully yielded hAbs with potent therapeutic potential against multiple SARS-CoV-2 variants.

EpEX/EpCAM and Oct4 or Klf4 alone are sufficient to generate induced pluripotent stem cells through STAT3 and HIF2α.

Epithelial cell adhesion molecule (EpCAM) was reported to be cleaved into extracellular domain of EpCAM (EpEX) and intracellular domain of EpCAM (EpICD). We previously reported that EpCAM serves as a potent stem cell marker which is highly and selectively expressed by undifferentiated rather than differentiated hESC. However, the functional role of EpCAM remains elusive. Here, we found that EpEX and EpCAM enhance the efficiency of OSKM reprogramming. Interestingly, Oct4 or Klf4 alone, but not Sox2, can successfully reprogram fibroblasts into iPSCs with EpEX and EpCAM. Moreover, EpEX and EpCAM trigger reprogramming via activation of STAT3, which leads to the nuclear-translocation of HIF2α. This study reveals the importance of a novel EpEX/EpCAM-STAT3-HIF2α signal in the reprogramming process, and uncovers a new means of triggering reprogramming by delivery of soluble and transmembrane proteins.