Nasal vaccine additive improves flu survival in mice even 100 days after treatment

A nasal vaccine additive, K3-SPG, has shown promising results in enhancing flu survival in mice even 100 days after treatment, according to research published in Science Advances. This additive, which combines a synthetic DNA component and a β-glucan, activates the immune sensor toll-like receptor 9 (TLR9). The study, led by professor Ken Ishii from the University of Tokyo, found that nasal administration of K3-SPG provided stronger protection than other routes.

The treatment led to reduced weight loss, higher survival rates, and less lung damage in mice infected with influenza A virus and SARS-CoV-2. However, it did not significantly decrease the amount of virus in the lungs, suggesting it mainly helped the host tolerate the infection and minimize tissue damage. The protective effect involved both early macrophage and later innate lymphoid cell responses, with some innate lymphoid cells showing chromatin changes indicating longer-lasting function changes.

While these findings are encouraging, they were demonstrated in mice and do not guarantee protection for humans. Further research is needed to assess the safety, effectiveness, and suitability of K3-SPG for human use, taking into account differences in TLR9 biology and respiratory delivery. The researchers believe adjuvant-based preventive approaches could provide an additional layer of protection during the development of pathogen-specific vaccines, potentially complementing pandemic preparedness efforts.