Researchers from the U.S. Army Medical Research Institute of Infectious Diseases and Moderna recently published a research paper titled "Comparison of protection against mpox following mRNA or modified vaccinia Ankara vaccination in nonhuman primates" in the journal Cell. The study compared the effectiveness of modified vaccinia Ankara (MVA) and mRNA-1769 vaccines in non-human primates. The results showed that, similar to MVA, mRNA-1769 produced a protective effect against monkeypox virus attack and further reduced symptoms and course of the disease. Compared with MVA, mRNA-1769 enhanced viral control and disease reduction, highlighting the potential of mRNA vaccines in reducing the threat of future pandemics.
This study is the first to directly compare an investigational mRNA monkeypox vaccine to a current standard vaccine in a non-human primate model. When given directly to primates, the researchers saw positive effects from the mRNA vaccine, including improved survival, fewer lesions and shorter duration of disease.
| Cat.No. | Product Name | Size | Test Method | Sample Type | Price |
|---|---|---|---|---|---|
| PDPS-AR064 | Monkeypox Virus Real Time PCR Kit (RUO) | 25 reactions | Real-Time PCR | Serum/Lesion exudate | Inquiry |
| PDPS-AR064-05 | Monkeypox Virus (G2R+CL3) Real Time PCR Kit (RUO) | 24 reactions | Real-Time PCR | Serum/Lesion exudate | Inquiry |
| PDPS-AR064-02 | Monkeypox Virus (G2R+CL3) Real Time PCR Kit (Lyophilized Powder Version) (RUO) | 50 reactions | Real-Time PCR | Serum/Lesion exudate | Inquiry |
| PDPS-AR064-06 | Monkeypox Virus Single Target Antigen Rapid Test Kit (RUO) | 96 reactions | Colloidal Gold | Rash fluid/Throat swabs | Inquiry |
| PDPS-AR064-07 | Monkeypox Virus Single Target Antibody Rapid Test Kit (RUO) | 96 reactions | Colloidal Gold | Serum/Whole blood/Plasma | Inquiry |
Originally developed to combat smallpox, the MVA vaccine contains a whole virus that has been weakened so it cannot cause disease in humans. However, this weakening also means that the MVA vaccine offers limited protection compared to other vaccines, such as the potent but potentially infectious ACAM2000. In contrast, using mRNA technology allows the vaccine to include only the parts of the virus most likely to elicit a lasting, protective immune response without exposing people to the entire infectious virus. In this case, the monkeypox mRNA vaccine in the study consists of four viral antigens that are essential for the virus to attach to and enter host cells.
"With mRNA vaccines, we can pick out the pieces of the virus that produce the most effective immune response," said Galit Alter, corresponding author of the paper. "That way, you can target a precise circle of protection from the virus, rather than being distracted by all the viruses."
Although studies have shown that mRNA vaccines can prevent infection in non-human primates, their ability to limit disease severity has not been tested before. To directly compare the mRNA and MVA vaccines, the researchers vaccinated macaques and then exposed them to a deadly strain of monkeypox virus eight weeks after the initial vaccination. They also exposed six unvaccinated animals to the virus as a control group. After infection, the researchers monitored the animals' health for four weeks and collected blood samples to check their immune responses.
Regardless of which vaccine was used, all 12 vaccinated animals survived, while five of the six unvaccinated animals died from the disease. While both vaccines reduced disease severity compared with the control group, animals vaccinated with the mRNA vaccine lost less weight and had fewer lesions than those vaccinated with the MVA vaccine. On average, animals in the control group had a maximum of 1,448 lesions, animals vaccinated with the MVA vaccine had a maximum of 607 lesions, and animals vaccinated with the mRNA vaccine had a maximum of 54 lesions. The mRNA vaccine also shortened the duration of the disease (the number of days it took the animals to develop lesions) by more than 10 days compared to the MVA vaccine and led to lower viral loads in blood and throat swabs. This suggests that the mRNA vaccine may also be more effective in reducing transmission.
Figure 1. mRNA-1769 enhanced viral control and disease attenuation compared with MVA. (Mucker E M, et al., 2024)
"With mRNA technology, we were able to produce a vaccine that produced a fairly effective response with a very good safety profile," said Jay Hooper, a virologist at the U.S. Army Medical Research Institute of Infectious Diseases. "We have been working to develop a vaccine that can protect against viral transmission like the ACAM2000 vaccine, but without the safety issues. Our study shows that mRNA technology may fill this gap."
When the researchers compared the immune responses elicited by the mRNA vaccine and the MVA vaccine, they found that the mRNA vaccine produced a higher number of antibodies with more diverse immune functions. The study also identified different classes of antibodies that were associated with enhanced viral control and fewer lesions. The mRNA vaccine also showed the potential to induce cross-immunity to other poxviruses, while the MVA vaccine produced a smaller immune response and had a weaker neutralizing effect on more distantly related poxviruses. It neutralized not only monkeypox, but also viruses such as cowpox, rabbitpox, camelpox and sheeppox. This vaccine may protect against other poxvirus threats that may emerge in the future.
It is reported that Moderna's mRNA-1769 vaccine is currently being evaluated in a Phase 1/2 clinical trial (NCT05995275) to determine the safety, tolerability and immune response of a series of doses of mRNA-1769 vaccine in humans.
Reference
Mucker E M, et al. Comparison of protection against mpox following mRNA or modified vaccinia Ankara vaccination in nonhuman primates. Cell, 2024.