The capsular antigen F1, the low-calcium-response V antigen (LcrV), and the recombinant fusion protein (rF1-LcrV) of Yersinia pestis, are leading subunit vaccine candidates under intense investigation; however, the inability of recombinant antigens to provide complete protection against pneumonic plague in animal models remains a significant concern.
Inhalation delivery of vaccines has received increasing attention due to its ability to recruit local immune responses of the bronchopulmonary mucosa in addition to the broader systemic immune response.
For more than 70 years, the Y. pestis EV NIIEG strain has been used as a human plague vaccine in the former Soviet Union and confers protection against bubonic and pneumonic plague after administration via inhalation. However, the protection appears to be short-lived and the vaccine is highly reactogenic, limiting licensing of this vaccine for use in many parts of the world. The preparation of live Y. pestis dry powder is rarely reported in the literature, possibly because of bacterial viability being lost during preparation. Subunit vaccine candidates may thus prove a better option for inhalable powder.
In this study, researchers explore the immunogenicity and protective efficacy of three subunit vaccines in different formulations (liquid, powder and reconstituted powder) via intratracheal and subcutaneous administration routes in a mouse model of Y. pestis intratracheal infection.
The results demonstrate preclinical feasibility of using a powder formulation of rF1-V10 and the potential use of an alternative pulmonary delivery method as a promising vaccination strategy.
Complete Protection Against Yersinia pestis in BALB/c Mouse Model Elicited by Immunization With Inhalable Formulations of rF1-V10 Fusion Protein via Aerosolized Intratracheal Inoculation. Frontiers in Immunology, 26 January 2022.