Mpox multi-antigen mRNA vaccine candidates by a simplified manufacturing strategy afford efficient protection against lethal orthopoxvirus challenge

Abstract

Current unprecedented mpox outbreaks in non-endemic regions represent a global public health concern. Although two live-attenuated vaccinia virus (VACV)-based vaccines have been urgently approved for people at high risk for mpox, a safer and more effective vaccine that can be available for the general public is desperately needed. By utilizing a simplified manufacturing strategy of mixing DNA plasmids before transcription, we developed two multi-antigen mRNA vaccine candidates, which encode four (M1, A29, B6, A35, termed as Rmix4) or six (M1, H3, A29, E8, B6, A35, termed as Rmix6) mpox virus antigens. We demonstrated that those mpox multi-antigen mRNA vaccine candidates elicited similar potent cross-neutralizing immune responses against VACV, and compared to Rmix4, Rmix6 elicited significantly stronger cellular immune responses. Moreover, immunization with both vaccine candidates protected mice from the lethal VACV challenge. Investigation of B-cell receptor (BCR) repertoire elicited by mpox individual antigen demonstrated that the M1 antigen efficiently induced neutralizing antibody responses, and all neutralizing antibodies among the top 20 frequent antibodies appeared to target the same conformational epitope as 7D11, revealing potential vulnerability to viral immune evasion. Our findings suggest that Rmix4 and Rmix6 from a simplified manufacturing process are promising candidates to combat mpox.

A 10-valent composite mRNA vaccine against both influenza and COVID-19

“…For the development of multivalent or combined mRNA vaccines, encapsulating each mRNA encoding separate antigens is a common approach, despite the efficiency of encapsulating all mRNAs simultaneously (36, 46–48). This method of individual LNP preparation facilitates the convenient verification of each mRNA vaccine component’s qualification, concentration, and immunogenicity (46).…”

Various mpox recombinant subunits induce broadly reactive antibodies against orthopoxvirus in mice

“…5,6 As for the development of specific vaccines against mpox, several mRNA vaccines have been reported recently, which found that the mRNA vaccines composed of different antigens from mpox virus can induce a broad spectrum of humoral and cellular immune responses against orthopoxvirus. 7,8 Previously, Zhang et al designed five mRNA sequences that encoded five mpox antigens: M1R, E8L, A29L, A35R, and B6R. In addition, four types of polyvalent mpox mRNA vaccines in combination were constructed.…”

Breakthrough infection and reinfection in patients with mpox

“…Therefore, it is important to focus on specific and defined targets for the development of Mpox vaccines rather than relying solely on attenuated virus‐based vaccines. Fortunately, several MPXV antigen‐specific mRNA vaccines are being developed, presenting high effectiveness in triggering immune responses and protecting mice from vaccina virus challenge 52–57 . Moreover, based on MPXV specific protective proteins, our team also developed one subunit vaccine and two mRNA vaccine candidates, all of which showed promising results in inducing cellular and humoral immune responses, as well as anti‐vaccinia virus activity in mouse model 58,59 …”