Development of a Bacillus subtilis-based rotavirus vaccine.

Bacillus subtilis vaccine strains engineered to express either group A bovine or murine rotavirus VP6 were tested in adult mice for their ability to induce immune responses and provide protection against rotavirus challenge. Mice were inoculated intranasally with spores or vegetative cells of the recombinant strains of B. subtilis. To enhance mucosal immunity, whole cholera toxin (CT) or a mutant form (R192G) of Escherichia coli heat-labile toxin (mLT) were included as adjuvants. To evaluate vaccine efficacy, the immunized mice were challenged orally with EDIM EW murine rotavirus and monitored daily for 7 days for virus shedding in feces. Mice immunized with either VP6 spore or VP6 vegetative cell vaccines raised serum anti-VP6 IgG enzyme-linked immunosorbent assay (ELISA) titers, whereas only the VP6 spore vaccines generated fecal anti-VP6 IgA ELISA titers. Mice in groups that were immunized with VP6 spore vaccines plus CT or mLT showed significant reductions in virus shedding, whereas the groups of mice immunized with VP6 vegetative cell vaccines showed no difference in virus shedding compared with mice immunized with control spores or cells. These results demonstrate that intranasal inoculation with B. subtilis spore-based rotavirus vaccines is effective in generating protective immunity against rotavirus challenge in mice.

Efficacy, heat stability and safety of intranasally administered Bacillus subtilis spore or vegetative cell vaccines expressing tetanus toxin fragment C.

Bacillus subtilis strains expressing tetanus toxin fragment C (TTFC) were tested as vaccine candidates against tetanus in adult mice. Mice received three intranasal (IN) exposures to 10(9) spores or 10(8) vegetative cells of B. subtilis expressing recombinant TTFC. Immunized mice generated protective systemic and mucosal antibodies and survived challenge with 2× LD(100) of tetanus toxin. Isotype analysis of serum antibody indicated a balanced Th1/Th2 response. Lyophilized vaccines stored at 45° C for ≥ 12 months, remained effective. Immunized conventional and SCID mice remained well, and no histological changes in brain or respiratory tract were detected. Lyophilized/reconstituted B. subtilis tetanus vaccines administered IN to mice appear safe, heat-stable, and protective against lethal tetanus challenge.

A DNA oligonucleotide microarray for detecting human astrovirus serotypes.

Human astroviruses have been shown in numerous studies to be an important cause of gastroenteritis in young children worldwide. The present communication addresses their characterization by use of oligonucleotide microarray hybridization. The system developed consists of an RT-PCR using primers of low degeneracy capable of detecting all eight serotypes of human astroviruses. RT-PCR products are then hybridized against a microarray consisting of short oligonucleotide probes 17-18 nucleotides in length. Cy3-labeled ssDNA targets are generated using a Cy3-labeled primer in the RT-PCR. The non-labeled strand is enzymatically digested, and the labeled target is rescued by column purification. This method of generating labeled target uses equimolar concentrations of the amplifying primers and does not compromise assay sensitivity for initial detection of the virus. Hybridization can be performed without the need for additional amplification. Although the amplicon spans a relatively conserved region of the astrovirus genome, the use of short probes enables type distinction despite such limited diversity. Probes differing by as little as a single nucleotide can be used to distinguish isolates. The microarray developed was capable of distinguishing representatives of the eight known serotypes of human astroviruses.