Affiliation:
1. Department of Biology, Washington University, St. Louis, Missouri 63130
Abstract
ABSTRACT
Attenuated
Salmonella enterica
serovar Typhimurium expressing recombinant antigens from other pathogens elicits primarily a Th1-type dominant immune response to both recombinant and
Salmonella
antigens. The immunogenicity and appropriate subcellular location of the recombinant antigen in the
Salmonella
vaccine strain may contribute to augmenting immune responses by facilitating adequate exposure of recombinant antigen to antigen-presenting cells for processing. To allow for secretion from gram-negative bacteria and overexpression of antigen, a DNA fragment encoding a highly antigenic α-helical region of PspA (pneumococcal surface protein A) was subcloned downstream from the β-lactamase signal sequence in the multicopy Asd
+
pYA3493 vector to create pYA3494. pYA3493 was derived from a class of Asd
+
vectors with reduced expression of Asd to minimize selective disadvantage and enhance immunization of expressed recombinant antigens. The
S. enterica
serovar Typhimurium vaccine strain was constructed by the introduction of deletion mutations Δ
crp-28
and Δ
asdA16
. Approximately 50% of the recombinant PspA (rPspA) expressed in a
Salmonella
strain harboring pYA3494 was detected in the combined supernatant and periplasmic fractions of broth-grown recombinant
Salmonella
. After a single oral immunization in BALB/c mice with 10
9
CFU of the recombinant
Salmonella
vaccine strain carrying pYA3494, immunoglobulin G (IgG) antibody responses were stimulated to both the heterologous antigen rPspA and
Salmonella
lipopolysaccharide (LPS) and outer membrane proteins (OMPs). About half, and even more at later times after immunization, of the antibodies induced to rPspA were IgG1 (indicating a Th2-type response), whereas 60 to 70% of the antibodies to LPS and 80 to 90% of those to OMPs were IgG2a (indicating a Th1-type response). A sublethal infection with
Streptococcus pneumoniae
WU2 boosted PspA antibody levels and maintained IgG2a/IgG1 ratios similar to those seen before the challenge. Oral immunization with
Salmonella-
PspA vaccine protected 60% of immunized mice from death after intraperitoneal challenge with 50 times the 50% lethal dose of virulent
S. pneumoniae
WU2.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Reference59 articles.
1. Bertani, G. 1952. Studies on lysogenesis. I. The mode of phage liberation by lysogenic Escherichia coli. J. Bacteriol.62:293-300.
2. Structures of Gram-Negative Cell Walls and Their Derived Membrane Vesicles
3. Bolivar, F., R. L. Rodriguez, P. J. Greene, M. C. Betlach, H. L. Heyneker, and H. W. Boyer. 1977. Construction and characterization of new cloning vehicles. II. A multipurpose cloning system. Gene2:95-113.
4. Cyclic AMP in prokaryotes
5. Breiman, R., J. C. Butler, F. C. Tenover, J. Elliot, and R. R. Facklam. 1994. Emergence of drug-resistant pneumococcal infections in the United States. JAMA271:1831-1835.
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