Serum IgG antibody response to the protective antigen (PA) of Bacillus anthracis induced by anthrax vaccine adsorbed (AVA) among U.S. military personnel

Abstract

The seroconversion rates and geometric mean concentrations (GMC) of IgG anti-PA for stored sera from U.S. military personnel immunized 3, 4, and 6 times with the U.S. licensed anthrax vaccine adsorbed were studied. Anti-PA IgG concentrations were measured by ELISA. All 246 vaccinees had low but detectable pre-immunization anti-PA IgG (GMC 1.83μg/mL). Three doses elicited a GMC of 60 μg/mL and a seroconversion rate of 85.3%, four doses elicited a GMC of 157 μg/mL and 67.9% and the sixth of 277 μg/mL and 45.5% respectively. The forth dose elicited 100% seroconversion compared to the pre-immunization level. These results should facilitate comparison between different immunization schedules and new vaccines.

Phase 1 Study of a Recombinant Mutant Protective Antigen of Bacillus anthracis

“…In a previous study of U.S. army recruits' responses to AVA injected according to the then-recommended schedule at 0, 2, and 4 weeks and 6, 12, and 18 months, GM levels of ϳ60 g/ml were measured at 6 weeks from the start, after 3 injections of AVA (23). Similar GM levels were found in our current study after 2 injections of alum-adsorbed rPA, but at 4 months.…”

“…The 1-year-decline slope in antibody levels was steeper during the 1st than during the 2nd year of follow-up, as was the experience with AVA in army recruits (17,23). At the end of the 2nd year, after 4 injections, the GM level of all alum-adsorbed rPA recipients was about 100 g/ml.…”

“…In army recruits, the first postimmunization sera we obtained were drawn after the 3rd injection, at about 6 weeks from the start of AVA vaccination; a GM level of 60 g/ml was found (23). Such GM levels were achieved in this study by 2 injections of alumadsorbed rPA, measured 4 months from the start (sera after the 2nd injection were obtained only at 2 months postinjection, just before the 3rd injection; earlier responses to the 2nd injection were not measured); AVA at the then-recommended schedule induced a GM antibody level of 60 g/ml earlier than the rPA at the schedule used in our study.…”

Vaccine Protection against Bacillus cereus-Mediated Respiratory Anthrax-Like Disease in Mice

“…PA is a major virulence factor of B. anthracis and is also the principal immunogen of AVA (BioThrax) (36). Similar to B. anthracis pXO1, B. cereus G9241 pBCXO1 harbors genes for protective antigen (pagA1), lethal factor (lef1), and edema factor (cya) (Fig.…”

“…We hypothesized that AVA immunization, which raises PA-specific serum IgG protective for anthrax disease (34,36), would protect animals against B. cereus-mediated anthraxlike disease. To test this, cohorts of C57BL/6 mice (n ϭ 10) were immunized by intramuscular injection of 100 l AVA by using a prime-booster regimen with a 14-day interval between injections.…”