Attenuated enterohemorrhagic E. coli-based vaccine vector and methods relating thereto
Inventors
Boedeker, Edgar C. • Byrd, Isaac Wyatt
Assignees
US Department of Veterans Affairs • UNM Rainforest Innovations
Publication Number
US-9327019-B2
Publication Date
2016-05-03
Expiration Date
2030-06-30
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Abstract
An attenuated enterohemorrhagic E. coli-based vaccine vector is disclosed. Enterotoxigenic E. coli colonization factor antigen 1 and the B subunit of E. coli heat labile toxin have been expressed in the attenuated enterohemorrhagic E. coli vector strain. Immunized animals are further protected against lethal and non lethal challenges with the enterotoxigenic E. coli strain. Immunization of mice with the vaccine construct induces mucosal antibody against both antigens, establishing the attenuated E. coli vector strain as a generally useful vector for presenting one or more antigens to a subject in a vaccine.
Core Innovation
The present invention relates to methods involving the administration of a composition comprising an attenuated enterohemorrhagic E. coli (EHEC) to induce an immune response against one or more immunogens expressed by the attenuated EHEC. The immunogen can be naturally expressed by EHEC or can be heterologous, expressed from a heterologous polynucleotide inserted into and expressed by the attenuated EHEC. The vector strain is an attenuated EHEC with truncation of the intimin adhesin (eae gene mutation) and may further express heterologous immunogens such as colonization factor antigen I (CFA/I) and a mutant heat-labile toxin (mLT) from enterotoxigenic E. coli (ETEC).
Enterotoxigenic E. coli are significant pathogens causing morbidity and mortality, especially in infants and children under five in developing countries, as well as travelers to high-risk areas. Despite understanding ETEC virulence factors and several vaccine candidates tested, no safe and effective vaccine is available. The invention addresses this problem by providing a safe, live attenuated EHEC vector modified to express ETEC antigens, which induces protective mucosal and serum immune responses in subjects against lethal and non-lethal ETEC challenges.
Claims Coverage
The patent contains one independent claim presenting inventive features related to a method using an attenuated EHEC vaccine vector. This claim covers modifications of the vector, expressed immunogens, and method of administration.
Vector attenuation by intimin adhesin truncation
The attenuated EHEC strain is modified by a mutation truncating the intimin adhesin via a mutation of the eae gene at the locus of enterocyte effacement (LEE).
Expression of mutant heat-labile toxin in periplasmic space
The EHEC vector carries a plasmid expressing a mutant heat-labile toxin (LT) of enterotoxigenic E. coli, where the mutant LT is expressed specifically in the periplasmic space.
Expression of a heterologous microbial antigen via plasmid
The vector further comprises a plasmid expressing a heterologous microbial antigen distinct from the mutant LT, such as colonization factor antigen I (CFA/I) of enterotoxigenic E. coli.
Administration method to induce antibody response
The method involves administering an effective amount of the attenuated EHEC composition to a subject, with intranasal administration explicitly identified as an embodiment, to induce both serum and mucosal antibody responses against wild-type ETEC and EHEC.
In summary, the claim covers a method of inducing antibody responses by administering an attenuated EHEC vaccine vector with intimin adhesin truncation, expressing both a mutant heat-labile toxin in its periplasmic space and a heterologous microbial antigen, optionally via intranasal delivery, providing immune protection against wild-type ETEC and EHEC challenges.
Stated Advantages
The vaccine vector is safe and well tolerated in mice at immunogenic doses with minimal distress.
The vector induces both mucosal and systemic immune responses against both native EHEC antigens and heterologous ETEC antigens such as CFA/I and mutant LT.
It provides protective immunity against lethal and non-lethal challenges with wild-type enterotoxigenic E. coli.
The vector expresses stable plasmid-encoded antigens maintaining antigen expression in vitro and in vivo.
Intranasal administration effectively stimulates mucosal immunity at distant sites such as the intestine and induces systemic immunity.
Documented Applications
Use as a live, attenuated vaccine vector for vaccination against infections by enterotoxigenic E. coli (ETEC) and enterohemorrhagic E. coli (EHEC).
Intranasal immunization of mammals, including mice and potentially humans, with this vector to generate protective mucosal and systemic immune responses against ETEC and EHEC infections.
Delivery of heterologous microbial immunogens from diverse microbial origins (Gram-negative, Gram-positive, fungi, viruses) via the EHEC-based vaccine vector.
Use of the vector in a small animal (mouse) model to study immunogenicity and efficacy of vaccines against ETEC using intranasal challenge and active or passive immunization protocols.
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