Anthrax protective antigen delivered by Salmonella enterica serovar Typhi Ty21a protects mice from a lethal anthrax spore challenge.

Bacillus anthracis, the etiological agent of anthrax disease, is a proven weapon of bioterrorism. Currently, the only licensed vaccine against anthrax in the United States is AVA Biothrax, which, although efficacious, suffers from several limitations. This vaccine requires six injectable doses over 18 months to stimulate protective immunity, requires a cold chain for storage, and in many cases has been associated with adverse effects. In this study, we modified the B. anthracis protective antigen (PA) gene for optimal expression and stability, linked it to an inducible promoter for maximal expression in the host, and fused it to the secretion signal of the Escherichia coli alpha-hemolysin protein (HlyA) on a low-copy-number plasmid. This plasmid was introduced into the licensed typhoid vaccine strain, Salmonella enterica serovar Typhi strain Ty21a, and was found to be genetically stable. Immunization of mice with three vaccine doses elicited a strong PA-specific serum immunoglobulin G response with a geometric mean titer of 30,000 (range, 5,800 to 157,000) and lethal-toxin-neutralizing titers greater than 16,000. Vaccinated mice demonstrated 100% protection against a lethal intranasal challenge with aerosolized spores of B. anthracis 7702. The ultimate goal is a temperature-stable, safe, oral human vaccine against anthrax infection that can be self-administered in a few doses over a short period of time.

Considerations in the development of live biotherapeutic products for clinical use.

Food products in the United States (U.S.), including dietary supplements, may contain live microorganisms and can be promoted for general health, nutritional, or structure/function claims. In contrast, such preparations used with the intention of having a preventive or therapeutic effect in humans are regulated by the Food and Drug Administration (FDA) in the U.S. as biological products, specifically as live biotherapeutic products (LBPs). Discussion of considerations in the early development of LBPs may aid in preparation of an Investigational New Drug Application (IND) that is designed to collect clinical data to support marketing approval of a LBP in the U.S. for a specific clinical use. Product information is an important component of an IND to support a proposed clinical study.

Parvovirus B19 DNA in Factor VIII concentrates: effects of manufacturing procedures and B19 screening by nucleic acid testing.

BACKGROUND: Parvovirus B19 (B19) is a common contaminant, especially in coagulation factors. Because of B19 transmission by pooled plasma, solvent/detergent treated in 1999, some fractionators initiated minipool nucleic acid testing (NAT) to limit the B19 load in manufacturing pools. In this study, the extent of B19 DNA contamination in commercial Factor VIII concentrates, that is, antihemophilic factor (human) (AHF), manufactured before and after B19 NAT screening was implemented, was determined. STUDY DESIGN AND METHODS: A total of 284 lots representing six AHF products made during 1993 to 1998 and 2001 to 2004 were assayed for B19 DNA by an in-house NAT procedure. Anti-B19 immunoglobulin G (IgG) was also measured. RESULTS: Most lots made during 1993 to 1998 had detectable B19 DNA. The prevalence ranged from 56 to 100 percent and appeared to differ between manufacturers. The highest level of B19 DNA found was 10(6) genome equivalents (geq or international units [IU]) per mL. Forty percent of the lots tested contained 10(3) geq (IU) per mL. In comparison, both prevalence and levels in source plasma-derived AHF products made in 2001 to 2004 were lower. Both, however, remained unchanged in the recovered plasma-derived product because B19 NAT screening had not been implemented. Only an intermediate-purity AHF product was positive for the presence of anti-B19 IgG. CONCLUSION: The prevalence and levels of B19 DNA in AHF prepared from B19 NAT unscreened plasma were high but varied among products with different manufacturing procedures. B19 NAT screening of plasma effectively lowered the B19 DNA level in the final products and in the majority of cases rendered it undetectable and hence potentially reduced the risk of B19 transmission.