Affiliation:
1. Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201
Abstract
ABSTRACT
To construct a prototype hybrid vaccine against
Shigella
and enterotoxigenic
Escherichia coli
(ETEC), the genes encoding the production of ETEC CS2 and CS3 fimbriae were isolated and expressed in attenuated
Shigella flexneri
2a
guaBA
strain CVD 1204. The CS2
cotA
to -
D
genes, isolated from ETEC strain C91F, and the CS3
cstA
to -
H
genes, subcloned from plasmid pCS100, were cloned into ∼15-copy-number-stabilized pGA1 behind the osmotically regulated
ompC
promoter, resulting in high expression of both fimbriae. Under nonselective in vitro growth conditions, pGA1-CS2 and pGA1-CS3 were stable in CVD 1204, exhibiting a plasmid loss of only approximately 1% per duplication. Expression of CS2 and CS3 reduced the invasiveness of
Shigella
for HeLa cells and slowed the intracellular growth rate. Guinea pigs immunized intranasally with CVD 1204(pGA1-CS2) or CVD 1204(pGA1-CS3), or with a mixture of these strains, developed secretory immunoglobulin A (IgA) in tears and serum IgG antibodies against
Shigella
lipopolysaccharide, CS2, and CS3 antigens. Moreover, the animals were protected against keratoconjunctivitis following conjunctival challenge with virulent
S. flexneri
2a strain 2457T. Animals immunized with
Shigella
expressing CS2 or CS3 developed serum antibodies that agglutinated
Shigella
as well as an ETEC strain bearing the homologous fimbriae, whereas animals immunized with combined CVD 1204(pGA1-CS2) and CVD 1204(pGA1-CS3) developed antibodies that agglutinated all three test strains. These observations support the feasibility of a multivalent vaccine against shigellosis and ETEC diarrhea consisting of multiple
Shigella
live vectors expressing relevant ETEC antigens.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
45 articles.
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