A broadly neutralizing monoclonal antibody overcomes the mutational landscape of emerging SARS-CoV-2 variants of concern.

The emergence of new variants of SARS-CoV-2 necessitates unremitting efforts to discover novel therapeutic monoclonal antibodies (mAbs). Here, we report an extremely potent mAb named P4A2 that can neutralize all the circulating variants of concern (VOCs) with high efficiency, including the highly transmissible Omicron. The crystal structure of the P4A2 Fab:RBD complex revealed that the residues of the RBD that interact with P4A2 are a part of the ACE2-receptor-binding motif and are not mutated in any of the VOCs. The pan coronavirus pseudotyped neutralization assay confirmed that the P4A2 mAb is specific for SARS-CoV-2 and its VOCs. Passive administration of P4A2 to K18-hACE2 transgenic mice conferred protection, both prophylactically and therapeutically, against challenge with VOCs. Overall, our data shows that, the P4A2 mAb has immense therapeutic potential to neutralize the current circulating VOCs. Due to the overlap between the P4A2 epitope and ACE2 binding site on spike-RBD, P4A2 may also be highly effective against a number of future variants.

Generation of a Large Repertoire of Monoclonal Antibodies against Dengue Virus NS1 Antigen and the Development of a Novel NS1 Detection Enzyme-Linked Immunosorbent Assay.

Commercial dengue virus (DENV) nonstructural-1 (NS1) Ag detection immunoassays often perform poorly, particularly in secondary DENV infection. To develop a highly sensitive NS1 ELISA, we generated a large repertoire of anti-DENV NS1 mouse mAbs (n = 95) that falls into 36 mAb classes based on binding specificities. The identified mAb pair, capable of efficiently detecting NS1 from four DENV serotypes in an immunoassay, was selected based on multiparametric analysis. The selected mAbs have subnanomolar affinities for NS1 with recognition sites outside the immunodominant wing domain. The assay was converted to an ELISA kit, which showed higher analytical sensitivity (3-fold to 83-fold) for NS1 from four DENV serotypes than commercial Platelia NS1 ELISA (Bio-Rad Laboratories). Compared to RT-PCR, the developed NS1 ELISA showed 78.57% (66 of 84) sensitivity, whereas Platelia NS1 ELISA showed a sensitivity of 60.71% (51 of 84). In a subgroup of RT-PCR-positive secondary dengue samples, our ELISA showed a sensitivity of 70.18% (40 of 57), whereas Platelia ELISA detected only 47.37% (27 of 57) samples. Furthermore, unlike Platelia ELISA, our test equally detected NS1 from four serotypes; Platelia ELISA performed poorly for the DENV-2 serotype, in which only 8 of 21 (38.10%) samples were detected compared with 17 of 21 (80.95%) in our ELISA. Moreover, our ELISA showed 100% specificity in 342 challenging dengue-negative samples. The large and diverse mAb repertoire generated against DENV NS1 and the appropriate selection of mAbs allowed us to establish an ELISA that can efficiently detect NS1 Ag even in secondary dengue and without serotype level bias.