# Immunogenicity and Protective Efficacy of Aerosolized Live-Attenuated Yellow Fever 17D Vaccine in Mice

## TL;DR

This study shows that an aerosolized version of the yellow fever vaccine is effective in mice, inducing strong immunity and protection against the virus.

## Contribution

The study demonstrates the feasibility and efficacy of aerosolized delivery of the YF-17D vaccine in mice.

## Key findings

- Aerosolized YF-17D induced robust humoral and cellular immune responses in mice.
- Aerosolized YF-17D triggered specific secretory IgA production in the lungs.
- All mice immunized with aerosolized YF-17D survived a lethal YFV challenge.

## Abstract

Yellow fever (YF), caused by the yellow fever virus (YFV), continually spreads and causes epidemics worldwide, posing a great threat to human health. The live-attenuated YF 17D vaccine (YF-17D) has been licensed for preventing YFV infection and administrated via the intramuscular (i.m.) route. In this study, we sought to determine the immunogenicity and protective efficacy of aerosolized YF-17D via the intratracheal (i.t.) route in mice. YF-17D stocks in liquids were successfully aerosolized into particles of 6 μm. Further in vitro phenotype results showed the aerosolization process did not abolish the infectivity of YF-17D. Meanwhile, a single i.t. immunization with aerosolized YF-17D induced robust humoral and cellular immune responses in A129 mice, which is comparable to that received i.p. immunization. Notably, the aerosolized YF-17D also triggered specific secretory IgA (SIgA) production in bronchoalveolar lavage. Additionally, all immunized animals survived a lethal dose of YFV challenge in mice. In conclusion, our results support further development of aerosolized YF-17D in the future.