Scientist III USAMRIID Fort Detrick, Maryland, United States
Introduction/Rationale: Yersinia pestis (Yp) is a gram-negative bacillus that causes plague in humans and animals and is endemic in Africa, Asia, and the Americas. When aerosolized, bacterium can cause an acute, often fatal disease that requires antibiotic intervention within 24hr of exposure. Antibodies have been previously raised against two protective antigens, F1 and LcrV, unfortunately Yp is able to circumvent these countermeasures.
Methods: To expand the breadth of protective targets we generated cow anti-sera against four novel antigens with potential induction of bovine exclusive ultralong CDR H3 antibodies. Cows were administered six doses of Pla, LptED, Ail and BamA, 3-4 weeks apart and antibody titers were evaluated throughout the duration of the study.
Results: Functional activity of anti-sera was evaluated utilizing gentamicin protection assay, by enumeration of internalized Yp by RAW cells in the presence or absence of complement. A prominent anti-LptED antibody response developed early during the course of vaccination, followed by anti-Pla, -Ail and -BamA. The number of RAW cells that internalized viable Yp was considerably lower in the presence of fresh or C8 repleted serum relative to heat inactivated or C8 depleted sera.
Conclusion: The inhibitory properties of cow anti-sera against four Yp antigens will enable identification of novel protective targets that will be used to produce additional countermeasures, especially if they stem from the ultralong CDR H3 repertoire.
