Adaptive Remodeling of the MPXV B21R Receptor-Binding Domain Enhances DC-SIGN Interaction and Identifies Conserved CTL Targets for T-Cell Vaccine Development

Global Mpox transmission is imposing public health concern as the number of cases is progressively increasing since its first major outbreak in 1996. Therefore, understanding its global epidemiological transformation and its underlying mechanism is crucial to decipher the immune evasion strategies exhibited by recent MPXV strains. In the present study, we analyzed the trend of global Mpox epidemiology and identified the current multinational outbreak which has initiated in 2017 from Africa. To explore the molecular basis of this transformation, we considered the B21R protein of MPXV as it may have played a role in viral adaptation and immune escape mechanism as one of the important MPXV structural proteins. Our data shows that Mpox has significantly transformed from 1996 to 2025, where MPXV strains from 2022, 2023, and 2024 are closely clustered whereas 2025 is closely related to 2017 MPXV strain. Structural modeling of B21R using AlphaFold uncovers a modular architecture comprising a putative receptor-binding N-terminal region (p-RBD), a central ectodomain, and a membrane-anchored C-terminal segment. Mapping solvent accessibility across the full-length B21R protein revealed that p-RBD exhibited highest solvent exposure compared to other B21R protein domains. As a potential cellular receptor for entry into the host targeted cell, we evaluated the interaction of p-RBD of B21R protein with CRD region of DC-SIGN, which showed the gradual increase in the binding affinity with acquired mutations. Moreover, we found alteration in the O-linked glycosylation sites at p-RBD regions of B21R protein which is crucial for the MPXV entry into the host cell. Importantly, we observed significant changes in linear B cell epitopes of p-RBD, impacting the humoral immunity, while CTL epitopes remained conserved. Hence, we showed the significance of B21R p-RBD as a T-cell based vaccine candidate for prevention of Mpox. This study provides novel insights into the recent global transmission of the Mpox and explored a plausible mechanism of humoral immune escape strategies through progressive mutations in the B21R protein and potential development of T-cell based vaccine candidate. Significance statementOur study represents the global transmission dynamics of Mpox and immune evasion strategy of recent MPXV strains. Epidemiological transformation analysis revealed that the current multinational outbreak of Mpox originated in Africa in 2017, highlighting the expanding global footprint of MPXV. Our analysis based on the B21R protein shows the evolutionary adaptation of the MPXV associated with progressive mutations responsible for increased affinity towards the DC-SIGN receptor and potential reason for increased infectivity. Importantly, alterations in O-linked glycosylation sites and linear B cell epitopes show potential antigenic drift in the recent Mpox outbreaks showing immune escape strategies. These findings provide insights into Mpox epidemiology and the molecular basis of MPXV adaptation, informing vaccine design, therapeutic strategies, and improved countermeasures against future outbreaks. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=158 SRC="FIGDIR/small/708970v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@7d949forg.highwire.dtl.DTLVardef@a8918corg.highwire.dtl.DTLVardef@eba49forg.highwire.dtl.DTLVardef@84c331_HPS_FORMAT_FIGEXP M_FIG C_FIG