Since the World Health Organization declared an outbreak of Mpox in Africa, advancements in vaccinations are vital. One such advancement focuses on Mpox, previously known as monkeypox. This emerging virus has gained global attention due to its potential for human-to-human transmission, particularly through close contact. This new research has found an mRNA-based vaccine called mRNA-1769 that appears to help protect against Mpox and other orthopoxviruses like smallpox and vaccinia. The mRNA-1769 vaccine, developed through collaboration between researchers from the National Institutes of Health (NIH) and Moderna, represents a new approach to viral protection. The COVID-19 pandemic has brought mRNA vaccines to the public’s attention, but their applications go far beyond this pandemic.
Those experts in the research highlight the potential of mRNA vaccines to address viral threats such as Mpox, which is part of the same family of viruses as smallpox. The study, recently published and yet to undergo peer review, investigates how the mRNA-1769 vaccine works to inhibit viral replication and spread. By focusing on crucial proteins found in Mpox, the vaccine trains the immune system to recognize and combat the virus. According to the researchers, the vaccine generates a robust immune response by producing neutralizing antibodies and T cells that target the virus, providing protection in experimental models.
“We found that a single dose of the vaccine significantly reduced the replication of the virus, and even more protection was achieved after a booster,” stated Dr. Catherine A. Cotter, one of the lead researchers from NIH.
What sets this research apart is its comprehensive examination of the vaccine’s effects in different parts of the body where Mpox can spread. The study demonstrated that the mRNA vaccine is effective against the virus in the lungs (after an intranasal infection), in the rectal area (where transmission has been linked to sexual contact), and on the skin (where lesions often form). These findings are critical because they mirror real-world transmission routes of the virus, which, during recent outbreaks, spread mainly through respiratory droplets and close physical contact. The researchers used an innovative technique called live animal imaging to observe how the virus behaves in the body and how the vaccine inhibits its spread. Scientists exposed mice to lethal doses of a related virus, vaccinia, to study the vaccine’s effectiveness under controlled conditions.
“We used bioluminescent imaging to track how the virus spread after infection.” Maxinne Ignacio, a co-author of the study, explained that “we observed a significant reduction in viral replication in vaccinated animals, particularly in the respiratory system and gastrointestinal tract.”
A crucial finding is that a single dose of the vaccine provided significant protection, particularly in real-world settings where outbreaks often require immediate protection. While a second dose further boosted immunity, providing sustained protection for at least four months, the fact that a single shot can make a difference could simplify vaccine distribution efforts in resource-limited settings. This ability to protect quickly makes mRNA vaccines like mRNA-1769 especially valuable during rapid outbreaks. Another important aspect of this research is the role of antibodies in providing protection. The study found that transferring antibodies from vaccinated animals to unvaccinated ones could protect them from a deadly infection.
Passive immunization suggests that vaccines such as mRNA-1769 can provide direct protection to vaccinated individuals and potentially find use in therapeutic settings. Dr. Moss states, “The transfer of immune serum protected both healthy and immunocompromised animals, which means that even people with weakened immune systems might benefit from this approach.”
The vaccine’s performance in immunocompromised models, in which mice without functional immune systems were able to survive infection after receiving immune serum, highlights another potential use of mRNA vaccines. Designed to stimulate the immune system, these vaccines also generate transferable protective antibodies, providing hope for vulnerable populations that may not respond as robustly to vaccinations. Although the study focused on animal models, the findings are encouraging and lay the groundwork for future human clinical trials.
The research team is optimistic that, with further development, the mRNA-1769 vaccine could become a vital tool in preventing future Mpox outbreaks. Given the similarities between Mpox and smallpox, this vaccine could potentially serve as a dual-purpose vaccine, offering protection against both diseases. This research has broader implications than just Mpox. This study contributes to the increasing evidence that we can rapidly adapt mRNA vaccines to counter emerging viral threats.
In the past, traditional vaccine development took years, but with mRNA technology, vaccines can be designed, tested, and deployed within months. This speed could be crucial in responding to future pandemics. Researchers hope that the success of mRNA-1769 will inspire further innovations in vaccine technology. Combining these vaccines with others could provide protection against multiple pathogens in a single shot, thereby streamlining public health efforts. This study represents an exciting step forward in the fight against viral diseases, despite the need for much more research before the vaccine becomes widely available.
Citation: Cotter, C. A., Ignacio, M. A., Americo, J. L., Earl, P. L., Mucker, E. M., Hooper, J. W., Frey, T. R., Carfi, A., Freyn, A. W., & Moss, B. (2024). Mpox mRNA-1769 vaccine inhibits orthopoxvirus replication at intranasal, intrarectal, and cutaneous sites of inoculation. bioRxiv. https://doi.org/10.1101/2024.09.19.613928
