Microneedle-Delivered Multivalent MPXV DNA Vaccines Induce Promising Immunity Profiles and Cross-Protection in Mice

Traditional DNA vaccines, typically administered via intramuscular injection with electroporation (IM-E), often cause discomfort and require trained personnel. Addressing these challenges, we developed multivalent DNA vaccines targeting both intracellular mature virion (IMV) and extracellular enveloped virion (EEV) proteins of the monkeypox virus (MPXV), designated as M2 (A29L, B6R), M3 (A29L, B6R, M1R) and M4 (A29L, B6R, M1R, A35R). These vaccine constructs were formulated into dissolvable microneedle array patches (D-MAPs) for intradermal delivery. Comparative studies in mice demonstrated that D-MAPs achieved approximately 70% delivery efficiency and elicited robust humoral immune responses in mice, including antigen-specific IgG and cross-neutralising antibodies against MPXV, VACV and ECTV-comparable to those induced by IM-E. Furthermore, D-MAP immunisation induced stronger T cell responses, particularly in the draining lymph nodes. Importantly, the multivalent DNA vaccines-especially M3 and M4-conferred substantial protection against lethal VACV-WR challenge, achieving levels of protection comparable to the traditional replication-competent smallpox vaccine TianTan (VTT), with significant viral suppression and mitigation of pathological damage. Collectively, this study provided valuable insights for the development of innovative MPXV DNA vaccines, highlighting a minimally invasive and suitable for field application with D-MAP with broad potential for combating mpox outbreaks and future orthopoxvirus pandemics.