Adenovirus-Mediated Delivery of an Anti-V Antigen Monoclonal Antibody Protects Mice against a Lethal Yersinia pestis Challenge

Abstract

Pneumonic plague, caused by inhalation of Yersinia pestis, represents a major bioterrorism threat for which no vaccine is available. Based on the knowledge that genetic delivery of monoclonal antibodies (MAbs) with adenovirus (Ad) gene transfer vectors results in rapid, high-level antibody expression, we evaluated the hypothesis that Ad-mediated delivery of a neutralizing antibody directed against the Y. pestis V antigen would protect mice against a Y. pestis challenge. MAbs specific for the Y. pestis V antigen were generated, and the most effective in protecting mice against a lethal intranasal Y. pestis challenge was chosen for further study. The coding sequences for the heavy and light chains were isolated from the corresponding hybridoma and inserted into a replication-defective serotype 5 human Ad gene transfer vector (Ad␣V). Western analysis of Ad␣V-infected cell supernatants demonstrated completely assembled antibodies reactive with V antigen. Following Ad␣V administration to mice, high levels of anti-V antigen antibody titers were detectable as early as 1 day postadministration, peaked by day 3, and remained detectable through a 12-week time course. When animals that received Ad␣V were challenged with Y. pestis at day 4 post-Ad␣V administration, 80% of the animals were protected, while 0% of control animals survived (P < 0.01). Ad-mediated delivery of a V antigen-neutralizing antibody is an effective therapy against plague in experimental animals and could be developed as a rapidly acting antiplague therapeutic.

Adenovirus Vector Expressing Stx1/Stx2-Neutralizing Agent Protects Piglets Infected with Escherichia coli O157:H7 against Fatal Systemic Intoxication

“…A wide variety of genetic delivery vehicles have already been developed, including direct administration of DNA and RNA, recombinant adenovirus (Ad) (28)(29)(30), and adeno-associated virus (AAV) (31,32). Furthermore, gene delivery vehicles can effec-tively promote in vivo expression of a range of antibody species for passive immunotherapy (28,29,33,34). We have shown that gene therapy with an Ad expressing a VNA that neutralizes botulinum neurotoxin serotype A (VNA-BoNT/A) resulted in sustained high levels of VNA-BoNTA in serum that protected mice from BoNT/A challenge for several months (27).…”

Dual-Function Antibodies to Yersinia pestis LcrV Required for Pulmonary Clearance of Plague

“…However, it remains controversial whether the direct inhibition of the TTSS by ␣-LcrV leads to phagocytosis or if the direct promotion of phagocytosis leads to the inhibition of the TTSS because it cannot function intracellularly (59,60). Three monoclonal antibodies (MAbs) have been independently cloned that can protect mice from bubonic and pneumonic plague (2,27,48). Although it is unclear whether each of these targets the same epitope, deletion studies of LcrV antigen suggest multiple protective epitopes exist (13,39,44,51).…”

“…Current subunit vaccine candidates are formulated from two protective antigens, Fraction 1 (F1) and LcrV, which are undergoing extensive testing to satisfy the Animal Rule requirements (2,5,13,26,55,(57)(58)(59). Both antigens elicit a neutralizing antibody response that can be translated to passive antibody or even gene therapies (2,4,13,28,37,48). These protective antibodies act directly on the bacteria and alter its interactions with innate immune cells such that the host clears the infection.…”

Recent Advancement in the Development of Vaccines Against Y. pestis - A Potential Agent of Bioterrorism

“…Recently, modified, non-replicating adenovirus vectors were evaluated for the development of antibodies against both the heavy and light chains of a previously identified anti-LcrV protective antibody. Surprisingly, immunized C57BL/6J male mice showed significant levels of IgG that persisted for up to 12 weeks and exhibited 80% protection in mice after intranasal challenge with a 2×10 4 -cfu of fully virulent Y. pestis CO92 (Sofer-Podesta et al, 2009). …”