We report the immunizing capacity of Salmonella enteritidis AL1192, a strain that has been cured of a 36-megadalton plasmid, to protect ddY mice against subsequent challenge with virulent salmonellas. This strain, which was given subcutaneously at a dose of 10(6) organisms, provided significant protection against oral, subcutaneous, or intraperitoneal challenge by virulent wild-type strains of ...

Salmonella enterica serovar Choleraesuis strain C500 is a live vaccine attenuated by chemical methods. Here, we report the complete genome sequence of the strain, which may be helpful for elucidating the attenuation mechanism of the vaccine strain.

Different rough mutants of Salmonella typhimurium were tested to determine their virulence and immunizing capacity when used as live vaccines for mice. All uridine diphosphate-galactose-4-epimeraseless mutants tested were much more potent immunizing agents than any other mutants. This capacity was not correlated with virulence or complexity of cell wall polysaccharide. For good protection, pers...

Attenuated Salmonella has been used as a carrier for DNA vaccine. However, in vitro and in vivo studies on the bacteria following transfection of plasmid DNA were poorly studied. In this paper, eukaryotic expression plasmids encoding avian influenza virus (AIV) subtype H5N1 genes, pcDNA3.1/HA, NA, and NP, were transfected into an attenuated Salmonella enteric typhimurium SV4089. In vitro stabil...

Vaccination with viable cells of an avirulent Salmonella typhimurium galE mutant provides mice with solid specific immunity against subsequent infection with a virulent smooth strain. Such a live vaccine is markedly more potent than one prepared from inactivated cells of the virulent smooth strain. The superiority of the live vaccine is particularly well demonstrated when the oral route of appl...

Understanding immune responses elicited by vaccines, together with immune responses required for protection, is fundamental to designing effective vaccines and immunisation programs. This study examines the effects of the route of administration of a live attenuated vaccine on its interactions with, and stimulation of, the murine immune system as well as its ability to increase survival and pro...

After immunization with either live or heat-killed Salmonella typhimurium, mice responded with an extremely rapid production of bactericidal antibody which was correlated with the appearance of immunity to a heavy challenge dose (100 ld(50)) of the virulent bacteria. Inactivation of sera with mercaptoethanol along with Sephadex fractionation indicated that the observed bactericidal activity was...

Resolution of infection with attenuated Salmonella is an active process that requires CD4(+) T cells. Here, we demonstrate that costimulation via the surface molecule CD28, but not antibody production by B cells, is required for clearance of attenuated aroA Salmonella enterica serovar typhimurium. In contrast, specific antibody is critical for vaccine-induced protection against virulent bacteri...

OBJECTIVE In Australia, Salmonella serovar Typhimurium (S. Typhimurium) is the predominant zoonotic serovar in humans and is frequently isolated from layer hens. Vaccination against this serovar has been previously shown to be effective in broilers and the aim of this current study was to assess and determine the best vaccination strategy (live or inactivated) to minimise caecal colonisation by...

Attenuated strains of invasive enteric bacteria, such as Salmonella, represent promising gene delivery agents for nucleic acid-based vaccines as they can be administrated orally. In this study, we constructed a novel attenuated strain of Salmonella for the delivery and expression of the hemagglutinin (HA) and neuraminidase (NA) of a highly pathogenic H5N1 influenza virus. We showed that the con...