Genetic vaccines for anthrax based on recombinant adeno-associated virus vectors.
Bacillus anthracis represents a formidable bioterrorism and biowarfare threat for which new vaccines are needed with improved safety and efficacy over current options. Toward this end, we created recombinant adeno-associated virus type 1 (rAAV1) vectors containing synthetic genes derived from the protective antigen (PA) or lethal factor (LF) of anthrax lethal toxin (LeTx) and tested them for immunogenicity and induction of toxin-neutralizing antibodies in rabbits. Codon-optimized segments encoding activated PA (PA63), or LF, were synthesized and cloned into optimized rAAV1 vectors containing a human cytomegalovirus (hCMV) promoter and synthetic optimized leader. Serum from rabbits immunized intramuscularly with rAAV1/PA (monovalent), rAAV1/LF (monovalent), rAAV1/PA + rAAV1/LF (bivalent), or rAAV1/enhanced green fluorescent protein (control) exhibited substantial PA- and LF-specific antibody responses at 4 weeks by both western blot (> 1:10,000 dilution) and enzyme-linked immunosorbent assay (ELISA) (mean end-point titer: 32,000-260,000), and contained anthrax LeTx-neutralizing activity in vitro, with peak titers approximating those of a rabbit hyperimmune antisera raised against soluble PA and LF. Compared to the monovalent groups (rAAV1/PA or rAAV1/LF), the bivalent group (rAAV1/PA + rAAV1/LF) exhibited marginally higher ELISA and neutralization activity with dual specificity for both PA and LF. The finding of robust neutralizing antibody responses after a single injection of these rAAV1-based vectors supports their further development as candidate anthrax vaccines.
Liu
Te-Hui
TH
Joseph Stokes Jr. Research Institute, Children's Hospital of Philadelphia, Abramson Research Center, Philadelphia, Pennsylvania, USA.
Oscherwitz
Jon
J
Schnepp
Bruce
B
Jacobs
Jana
J
Yu
Fen
F
Cease
Kemp B
KB
Johnson
Philip R
PR
D000818:Animals; D022122:Anthrax Vaccines / Q000235:genetics* / Q000276:immunology; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology; D015153:Blotting, Western; D003587:Cytomegalovirus / Q000235:genetics; D000229:Dependovirus / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005822:Genetic Vectors / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D011401:Promoter Regions, Genetic / Q000235:genetics; D011817:Rabbits
D022122:Anthrax Vaccines; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; C030325:anthrax toxin; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins