A single dose sub-unit vaccine protects against pneumonic plague

Area of Science:

• Immunology
• Microbiology
• Vaccinology

Background:

• Pneumonic plague, caused by Yersinia pestis, remains a significant public health concern.
• Existing killed whole cell (KWC) vaccines have limitations in protective efficacy.
• Development of effective subunit vaccines is crucial for plague prevention.

Purpose of the Study:

• To compare the protective efficacy of a novel single-dose alhydrogel-adsorbed subunit vaccine against aerosolized Yersinia pestis with an existing licensed KWC vaccine.
• To evaluate the immune response, specifically IgG antibody levels, generated by both vaccine types.

Main Methods:

• An outbred mouse model was used to assess protection against aerosolized virulent Yersinia pestis.
• Mice were vaccinated with either the subunit vaccine or the KWC vaccine.
• Bacterial load in lungs and serum/broncho-alveolar IgG titers against F1 and V antigens were measured post-challenge.

Main Results:

• The subunit vaccine provided full protection against a high dose of aerosolized Yersinia pestis, whereas the KWC vaccine offered only 16% protection.
• Subunit vaccinees cleared bacteria from lungs, while KWC vaccinees showed detectable bacteria.
• Subunit vaccinees exhibited significantly higher F1- and V-specific IgG titers in serum compared to KWC vaccinees.

Conclusions:

• A single dose of the alhydrogel-adsorbed subunit vaccine is highly effective against pneumonic plague in a mouse model.
• The subunit vaccine elicits a superior and more protective immune response than the current KWC vaccine.
• Circulating IgG antibodies to F1 and V antigens are key contributors to the protective efficacy of the subunit vaccine.