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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 colonizes germ-free mice efficiently and persistently.Germ-free Balb/c mice and conventional SPF mice were inoculated orally with 109 cfu rS. mitis expressing HIV Env gp120 (Smitis HIV Env), rS. mitis containing an integrated Ermr gene without Env (Smitis) or PBS (Non-Immunized). Following inoculation the upper right buccal cheek was swabbed and two pellets of feces were collected from each mouse at various time points. rS.mitis colonization was assessed by growth on THB plates containing 50 μg/ml erythromycin. The mean colony-forming-units, cfu (±SEM) from 3 mice/group at various timepoints, present in the mouth (A) and feces (B) of germ-free mice and in the mouth (C) and feces (D) of conventional mice inoculated with rS. mitis are shown.
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pone.0143422.g004: Recombinant S. mitis colonizes germ-free mice efficiently and persistently.Germ-free Balb/c mice and conventional SPF mice were inoculated orally with 109 cfu rS. mitis expressing HIV Env gp120 (Smitis HIV Env), rS. mitis containing an integrated Ermr gene without Env (Smitis) or PBS (Non-Immunized). Following inoculation the upper right buccal cheek was swabbed and two pellets of feces were collected from each mouse at various time points. rS.mitis colonization was assessed by growth on THB plates containing 50 μg/ml erythromycin. The mean colony-forming-units, cfu (±SEM) from 3 mice/group at various timepoints, present in the mouth (A) and feces (B) of germ-free mice and in the mouth (C) and feces (D) of conventional mice inoculated with rS. mitis are shown.

Mentions: Oral pioneer commensal bacteria such as S. mitis, S. salivarius and S. oralis are excellent colonizers of the mouth. Therefore, a suitable animal model to test the preclinical efficacy of recombinant S. mitis must be able to be effectively colonized. A prior study showed that gnotobiotic or germ-free mice were colonized by human oral bacteria, including S. mitis [21]. To assess whether germ-free mice are a suitable animal model, germ-free mice as well as conventional mice were inoculated orally with 109 cfu rS. mitis expressing HIV Env gp120 (Smitis HIVEnv) and control S. mitis (Smitis). Following oral vaccination, colonization of the mouth was observed at day 7 and the number of bacteria continued to increase over time, peaking on day 30 and remained persistently high thereafter (Fig 4A). Both rS. mitis HIV Env and control S. mitis colony-forming-units were significantly higher in immunized compared to non-immunized mice on day 7, 14, 28, 42, 56 and 70 (p < 0.05 at each timepoint). On those same days, rS. mitis was also found abundantly in the feces of the immunized mice but not in non-immunized mice (Fig 4B). Conventional SPF mice were not colonized by rS. mitis (Fig 4C and 4D). These results demonstrate that germ-free mice are efficiently and persistently colonized by S. mitis and therefore are a viable animal model for the preclinical testing of rS. mitis vaccine vectors.


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 colonizes germ-free mice efficiently and persistently.Germ-free Balb/c mice and conventional SPF mice were inoculated orally with 109 cfu rS. mitis expressing HIV Env gp120 (Smitis HIV Env), rS. mitis containing an integrated Ermr gene without Env (Smitis) or PBS (Non-Immunized). Following inoculation the upper right buccal cheek was swabbed and two pellets of feces were collected from each mouse at various time points. rS.mitis colonization was assessed by growth on THB plates containing 50 μg/ml erythromycin. The mean colony-forming-units, cfu (±SEM) from 3 mice/group at various timepoints, present in the mouth (A) and feces (B) of germ-free mice and in the mouth (C) and feces (D) of conventional mice inoculated with rS. mitis are shown.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4664415&req=5

pone.0143422.g004: Recombinant S. mitis colonizes germ-free mice efficiently and persistently.Germ-free Balb/c mice and conventional SPF mice were inoculated orally with 109 cfu rS. mitis expressing HIV Env gp120 (Smitis HIV Env), rS. mitis containing an integrated Ermr gene without Env (Smitis) or PBS (Non-Immunized). Following inoculation the upper right buccal cheek was swabbed and two pellets of feces were collected from each mouse at various time points. rS.mitis colonization was assessed by growth on THB plates containing 50 μg/ml erythromycin. The mean colony-forming-units, cfu (±SEM) from 3 mice/group at various timepoints, present in the mouth (A) and feces (B) of germ-free mice and in the mouth (C) and feces (D) of conventional mice inoculated with rS. mitis are shown.
Mentions: Oral pioneer commensal bacteria such as S. mitis, S. salivarius and S. oralis are excellent colonizers of the mouth. Therefore, a suitable animal model to test the preclinical efficacy of recombinant S. mitis must be able to be effectively colonized. A prior study showed that gnotobiotic or germ-free mice were colonized by human oral bacteria, including S. mitis [21]. To assess whether germ-free mice are a suitable animal model, germ-free mice as well as conventional mice were inoculated orally with 109 cfu rS. mitis expressing HIV Env gp120 (Smitis HIVEnv) and control S. mitis (Smitis). Following oral vaccination, colonization of the mouth was observed at day 7 and the number of bacteria continued to increase over time, peaking on day 30 and remained persistently high thereafter (Fig 4A). Both rS. mitis HIV Env and control S. mitis colony-forming-units were significantly higher in immunized compared to non-immunized mice on day 7, 14, 28, 42, 56 and 70 (p < 0.05 at each timepoint). On those same days, rS. mitis was also found abundantly in the feces of the immunized mice but not in non-immunized mice (Fig 4B). Conventional SPF mice were not colonized by rS. mitis (Fig 4C and 4D). These results demonstrate that germ-free mice are efficiently and persistently colonized by S. mitis and therefore are a viable animal model for the preclinical testing of rS. mitis vaccine vectors.

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