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Oral Delivery of a Novel Recombinant Streptococcus mitis Vector Elicits Robust Vaccine Antigen-Specific Oral Mucosal and Systemic Antibody Responses and T Cell Tolerance.

Xie E, Kotha A, Biaco T, Sedani N, Zou J, Stashenko P, Duncan MJ, Campos-Neto A, Cayabyab MJ - PLoS ONE (2015)

Bottom Line: Oral vaccination led to the efficient and persistent bacterial colonization of the mouth and the induction of both salivary and systemic antibody responses.Interestingly, persistently colonized animals developed antigen-specific systemic T cell tolerance.Based on these findings we propose the use of rS. mitis vaccine vector for the induction of mucosal antibodies that will prevent the penetration of the mucosa by pathogens such as HIV.

View Article: PubMed Central - PubMed

Affiliation: Global Infectious Disease Research Center and the Department of Immunology and Infectious Diseases, The Forsyth Institute, 245 First Street, Cambridge, Massachusetts, United States of America.

ABSTRACT
The pioneer human oral commensal bacterium Streptococcus mitis has unique biologic features that make it an attractive mucosal vaccine or therapeutic delivery vector. S. mitis is safe as a natural persistent colonizer of the mouth, throat and nasopharynx and the oral commensal bacterium is capable of inducing mucosal antibody responses. A recombinant S. mitis (rS. mitis) that stably expresses HIV envelope protein was generated and tested in the germ-free mouse model to evaluate the potential usefulness of this vector as a mucosal vaccine against HIV. Oral vaccination led to the efficient and persistent bacterial colonization of the mouth and the induction of both salivary and systemic antibody responses. Interestingly, persistently colonized animals developed antigen-specific systemic T cell tolerance. Based on these findings we propose the use of rS. mitis vaccine vector for the induction of mucosal antibodies that will prevent the penetration of the mucosa by pathogens such as HIV. Moreover, the first demonstration of rS. mitis having the ability to elicit T cell tolerance suggest the potential use of rS. mitis as an immunotherapeutic vector to treat inflammatory, allergic and autoimmune diseases.

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Recombinant S. mitis expresses HIV envelope protein.rS. mitis with the integrated HIV HXBc2 Env gp120 was designed to secrete HIV Env by ligating the HIV Env in frame with 250bp 5’ end of the pullulanase gene (pulA/Smt0163) encoding a signal peptide that allows processing and secretion of the HIV antigen. (A) The signal peptide has an amino-terminal region (N), a hydrophobic core (H), a signal peptidase cleavage site (C), and an accessory Sec transport motif (AST). Expression of HIV Env containing a C-terminal His tag was assessed by Western blotting using Penta-His-HRP from a representative recombinant clone in S. mitis lysates (B) and in culture supernatants (C) by TCA-precipitation (TCA), acetone precipitation (Acetone) and Amicon filter-concentration (Sup). HIV Env expression in lysates (B) and supernatants of control S. mitis vector (control) (C) is shown. The arrow denotes expression of the Env Ag band. 100 ng of His-tagged M. tuberculosis protein (MT0401) was used as a positive control (B and C, lane 1). (D) The expression of HIV-1 gp120 in rS. mitis containing the HIV Env gene (lane 2) in Amicon filter-concentrated supernatant was detected using human HIV patient sera. rS. mitis containing the empty plasmid was used as a negative control (lane 1).
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pone.0143422.g002: Recombinant S. mitis expresses HIV envelope protein.rS. mitis with the integrated HIV HXBc2 Env gp120 was designed to secrete HIV Env by ligating the HIV Env in frame with 250bp 5’ end of the pullulanase gene (pulA/Smt0163) encoding a signal peptide that allows processing and secretion of the HIV antigen. (A) The signal peptide has an amino-terminal region (N), a hydrophobic core (H), a signal peptidase cleavage site (C), and an accessory Sec transport motif (AST). Expression of HIV Env containing a C-terminal His tag was assessed by Western blotting using Penta-His-HRP from a representative recombinant clone in S. mitis lysates (B) and in culture supernatants (C) by TCA-precipitation (TCA), acetone precipitation (Acetone) and Amicon filter-concentration (Sup). HIV Env expression in lysates (B) and supernatants of control S. mitis vector (control) (C) is shown. The arrow denotes expression of the Env Ag band. 100 ng of His-tagged M. tuberculosis protein (MT0401) was used as a positive control (B and C, lane 1). (D) The expression of HIV-1 gp120 in rS. mitis containing the HIV Env gene (lane 2) in Amicon filter-concentrated supernatant was detected using human HIV patient sera. rS. mitis containing the empty plasmid was used as a negative control (lane 1).

Mentions: Our strategy was to express foreign vaccine antigens in the secreted form, which enhances the immunogenicity of bacterial antigens [14]. The constructed rS. mitis contains the integrated S. mitis codon-optimized HIV-1 HXBc2 env-His-tag (HIV Env) in-frame with the 250bp 5’ end of the pullulanase gene (pulA/Smt0163) encoding a signal peptide that allows processing and secretion of the HIV antigen (Figs 1A and 2A) [18, 19]. The signal peptide has a predicted amino-terminal region (N), a hydrophobic core (H), a signal peptidase cleavage site (C), and an accessory Sec transport motif (AST).


Oral Delivery of a Novel Recombinant Streptococcus mitis Vector Elicits Robust Vaccine Antigen-Specific Oral Mucosal and Systemic Antibody Responses and T Cell Tolerance.

Xie E, Kotha A, Biaco T, Sedani N, Zou J, Stashenko P, Duncan MJ, Campos-Neto A, Cayabyab MJ - PLoS ONE (2015)

Recombinant S. mitis expresses HIV envelope protein.rS. mitis with the integrated HIV HXBc2 Env gp120 was designed to secrete HIV Env by ligating the HIV Env in frame with 250bp 5’ end of the pullulanase gene (pulA/Smt0163) encoding a signal peptide that allows processing and secretion of the HIV antigen. (A) The signal peptide has an amino-terminal region (N), a hydrophobic core (H), a signal peptidase cleavage site (C), and an accessory Sec transport motif (AST). Expression of HIV Env containing a C-terminal His tag was assessed by Western blotting using Penta-His-HRP from a representative recombinant clone in S. mitis lysates (B) and in culture supernatants (C) by TCA-precipitation (TCA), acetone precipitation (Acetone) and Amicon filter-concentration (Sup). HIV Env expression in lysates (B) and supernatants of control S. mitis vector (control) (C) is shown. The arrow denotes expression of the Env Ag band. 100 ng of His-tagged M. tuberculosis protein (MT0401) was used as a positive control (B and C, lane 1). (D) The expression of HIV-1 gp120 in rS. mitis containing the HIV Env gene (lane 2) in Amicon filter-concentrated supernatant was detected using human HIV patient sera. rS. mitis containing the empty plasmid was used as a negative control (lane 1).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4664415&req=5

pone.0143422.g002: Recombinant S. mitis expresses HIV envelope protein.rS. mitis with the integrated HIV HXBc2 Env gp120 was designed to secrete HIV Env by ligating the HIV Env in frame with 250bp 5’ end of the pullulanase gene (pulA/Smt0163) encoding a signal peptide that allows processing and secretion of the HIV antigen. (A) The signal peptide has an amino-terminal region (N), a hydrophobic core (H), a signal peptidase cleavage site (C), and an accessory Sec transport motif (AST). Expression of HIV Env containing a C-terminal His tag was assessed by Western blotting using Penta-His-HRP from a representative recombinant clone in S. mitis lysates (B) and in culture supernatants (C) by TCA-precipitation (TCA), acetone precipitation (Acetone) and Amicon filter-concentration (Sup). HIV Env expression in lysates (B) and supernatants of control S. mitis vector (control) (C) is shown. The arrow denotes expression of the Env Ag band. 100 ng of His-tagged M. tuberculosis protein (MT0401) was used as a positive control (B and C, lane 1). (D) The expression of HIV-1 gp120 in rS. mitis containing the HIV Env gene (lane 2) in Amicon filter-concentrated supernatant was detected using human HIV patient sera. rS. mitis containing the empty plasmid was used as a negative control (lane 1).
Mentions: Our strategy was to express foreign vaccine antigens in the secreted form, which enhances the immunogenicity of bacterial antigens [14]. The constructed rS. mitis contains the integrated S. mitis codon-optimized HIV-1 HXBc2 env-His-tag (HIV Env) in-frame with the 250bp 5’ end of the pullulanase gene (pulA/Smt0163) encoding a signal peptide that allows processing and secretion of the HIV antigen (Figs 1A and 2A) [18, 19]. The signal peptide has a predicted amino-terminal region (N), a hydrophobic core (H), a signal peptidase cleavage site (C), and an accessory Sec transport motif (AST).

Bottom Line: Oral vaccination led to the efficient and persistent bacterial colonization of the mouth and the induction of both salivary and systemic antibody responses.Interestingly, persistently colonized animals developed antigen-specific systemic T cell tolerance.Based on these findings we propose the use of rS. mitis vaccine vector for the induction of mucosal antibodies that will prevent the penetration of the mucosa by pathogens such as HIV.

View Article: PubMed Central - PubMed

Affiliation: Global Infectious Disease Research Center and the Department of Immunology and Infectious Diseases, The Forsyth Institute, 245 First Street, Cambridge, Massachusetts, United States of America.

ABSTRACT
The pioneer human oral commensal bacterium Streptococcus mitis has unique biologic features that make it an attractive mucosal vaccine or therapeutic delivery vector. S. mitis is safe as a natural persistent colonizer of the mouth, throat and nasopharynx and the oral commensal bacterium is capable of inducing mucosal antibody responses. A recombinant S. mitis (rS. mitis) that stably expresses HIV envelope protein was generated and tested in the germ-free mouse model to evaluate the potential usefulness of this vector as a mucosal vaccine against HIV. Oral vaccination led to the efficient and persistent bacterial colonization of the mouth and the induction of both salivary and systemic antibody responses. Interestingly, persistently colonized animals developed antigen-specific systemic T cell tolerance. Based on these findings we propose the use of rS. mitis vaccine vector for the induction of mucosal antibodies that will prevent the penetration of the mucosa by pathogens such as HIV. Moreover, the first demonstration of rS. mitis having the ability to elicit T cell tolerance suggest the potential use of rS. mitis as an immunotherapeutic vector to treat inflammatory, allergic and autoimmune diseases.

Show MeSH
Related in: MedlinePlus