A novel antibody nasal spray has demonstrated potential for guarding against influenza, according to initial human trials. This development follows successful validation in studies involving mice and monkeys. The spray’s broad efficacy against various influenza virus types, including those that can transfer from animals to humans, suggests it could be a valuable tool in combating future flu pandemics.
Currently, the primary strategy for influenza containment relies on annual vaccines. These vaccines work by stimulating the immune system to produce antibodies against prevalent influenza virus strains. However, the constantly evolving nature of these strains limits the vaccines’ overall effectiveness, often resulting in moderate protection only.
Addressing this limitation, pharmaceutical company Johnson & Johnson developed a specialized antibody, CR9114. This antibody is designed to neutralize a wide spectrum of influenza strains. Its mechanism of action involves identifying and binding to a conserved region of the virus, a part that remains unchanged irrespective of alterations in other viral components.
Early attempts to administer CR9114 involved injecting it directly into the bloodstream of animals. This method proved insufficient for robust protection against flu. The issue stemmed from a low proportion of the antibody reaching the nasal passages, which represent the primary entry point for influenza viruses into the body.
In 2022, Leyden Labs acquired the license for CR9114. The company subsequently formulated the antibody into a nasal spray, enabling direct application to the nasal cavity. This approach aimed to enhance the antibody’s concentration at the site of viral entry.
Following this innovation, Leyden Labs conducted studies demonstrating the spray’s effectiveness. When administered to mice and macaques, the CR9114 nasal spray successfully prevented illness upon exposure to diverse influenza A and B strains. Notably, this included a strain isolated from a scientist during a severe flu season in 1933, highlighting the spray’s historical strain coverage.
Preliminary Human Testing and Findings
Preliminary research was also carried out on 143 human participants, aged between 18 and 55. The study revealed that administering the nasal spray twice daily successfully maintained consistent levels of the antibody within the participants’ nasal passages. Importantly, no significant adverse side effects were reported. Analysis of nasal mucus samples collected post-administration showed that the antibodies present could neutralize a range of influenza strains. This included a bird flu strain that had previously transmitted to humans in China in 2013.
The next crucial phase of research will involve directly exposing individuals who have used the spray to various influenza viruses. This will serve to definitively confirm the spray’s ability to prevent infection in humans.
Potential and Limitations
While the nasal spray offers promising broad-spectrum protection, it may not provide complete immunity. Linda Wakim from the University of Melbourne in Australia noted that the influenza virus can enter the body through routes other than the nose, such as the mouth. Nevertheless, Wakim stated that blocking nasal entry alone would still intercept the virus at a significant point of infection.
Wakim also pointed out that the spray’s twice-daily administration schedule could be less convenient compared to the single-dose flu vaccine. However, she suggested that this nasal spray could represent a significant advancement for specific high-risk populations. These include individuals with compromised immune systems and frontline healthcare workers. Furthermore, during pandemic situations, it could provide rapid, short-term protection while vaccines are developed or distributed.
Journal Reference: Science Translational Medicine DOI: 10.1126/scitranslmed.adz1580