KUALA LUMPUR (Nov 25): China-developed monkeypox-specific mRNA vaccines have proved highly effective in protecting mice from a lethal dose of the virus, making them a potential candidate to help prepare the world for monkeypox outbreaks in the future, according to a study released recently by the China National Biotec Group (CNBG) under Chinese state-owned Sinopharm.

In a report on Thursday (Nov 24), Chinese government mouthpiece Global Times (GT) said the study, posted on preprint platform bioRxiv on Tuesday by a research team led by Yang Xiaoming, the chairman of CNBG, is believed to be the world's first released study of monkeypox-specific mRNA vaccines.

It said that in the study, the research team tested three mRNA vaccines, namely VGPox 1-3, which encoded monkeypox proteins M1R and A35R, including A35R-M1R fusions (VGPox1 and VGPox 2) and a combination of encapsulated full-length mRNAs for A35R and M1R (VGPox 3). 

Results showed that the novel mRNA vaccines expressing a fusion protein composed of a truncated form of A35R and a full-length M1R can provide strong immunity and protection against the poxvirus, the study said, noting that all three vaccines induced anti-A35R total IgGs as early as day seven following a single vaccination. 

GT said that specifically, VGPox 1 and VGPox 2 can effectively induce high levels of both A35R and M1R IgGs, and are highly effective in neutralising live virus infection in cell cultures, but not the mixture of the two individual mRNAs (VGPox 3).

VGPox 3 produced M1R specific antibodies much later, and consequently the sera collected at early time points were not able to neutralise the virus, according to the study.

Nevertheless, GT claimed that all three mRNA vaccines (VGPox 1-3) are 100% protective against the virus challenge assay.

It said this is probably because all animals in the current study were challenged with live virus at day 36 when both anti-A35R and anti-M1R neutralising antibodies were present in all three vaccines, read the study.

The vaccines can effectively induce both humoral and cellular immunity against the virus, demonstrating complete protection for the mice with lethal vaccinia virus challenge.

Given the high homology of vaccinia and monkeypox, the results suggest that VGPox can be a potential mRNA vaccine against monkeypox, the study concluded.