The Sterne live spore vaccine (SLSV, Bacillus anthracis strain 34F2) is the veterinary vaccine
of choice against anthrax though contra-indicated for use with antimicrobials. However, the use
of non-living anthrax vaccine (NLAV) candidates can overcome the SLSV limitation. In this study,
cattle were vaccinated with either of the NLAV (purified recombinant PA (PrPA) or crude rPA (CrPA)
and formaldehyde-inactivated spores (FIS of B. anthracis strain 34F2) and emulsigen-D®/alhydrogel®
adjuvants) or SLSV. The immunogenicity of the NLAV and SLSV was assessed and the protective
efficacies evaluated using a passive immunization mouse model. Polyclonal IgG (including the
IgG1 subset) and IgM responses increased significantly across all vaccination groups after the first
vaccination. Individual IgG subsets titres peaked significantly with all vaccines used after the
second vaccination at week 5 and remained significant at week 12 when compared to week 0.
The toxin neutralization (TNA) titres of the NLAV vaccinated cattle groups showed similar trends
to those observed with the ELISA titres, except that the former were lower, but still significant,
when compared to week 0. The opsonophagocytic assay indicated good antibody opsonizing
responses with 75% (PrPA+FIS), 66% (CrPA+FIS) and 80% (SLSV) phagocytosis following spores
opsonization. In the passive protection test, A/J mice transfused with purified IgG from cattle
vaccinated with PrPA+FIS+Emulsigen-D®/Alhydrogel® and SLSV had 73% and 75% protection
from challenge with B. anthracis strain 34F2 spores, respectively, whereas IgG from cattle vaccinated
with CrPA+FIS+Emulsigen-D®/Alhydrogel® offered insignificant protection of 20%. There was no
difference in protective immune response in cattle vaccinated twice with either the PrPA+FIS or SLSV.
Moreover, PrPA+FIS did not show any residual side effects in vaccinated cattle. These results suggest
that the immunogenicity and protective efficacy induced by the NLAV (PrPA+FIS) in the cattle and passive mouse protection test, respectively, are comparable to that induced by the standard SLSV.
Supplementary material 1: Purified and crude rPA calculation for vaccine formulation.
Allsopp, Basil A.(International Office of Epizootics, 2015)
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Sterne live spore vaccine (SLSV) is the current veterinary anthrax vaccine of choice. Unlike
the non-living anthrax vaccine (NLAV) prototype, SLSV is incompatible with concurrent antibiotics use
in an anthrax outbreak ...
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