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Induction of long-lasting protective immunity against Toxoplasma gondii in BALB/c mice by recombinant surface antigen 1 protein encapsulated in poly (lactide-co-glycolide) microparticles.

Chuang SC, Ko JC, Chen CP, Du JT, Yang CD - Parasit Vectors (2013)

Bottom Line: We examined the ability of PLG-rSAG1 microparticles to induce and prolong effective anti-Toxoplasma immune responses, in comparison with rSAG1 formulated with a Vet L-10 adjuvant (rSAG1 (Vet L-10)).PLG-rSAG1 microparticles can effectively induce not only significant long-lasting SAG1-specific humoral and cell-mediated immune responses but also high protection against T. gondii tachyzoite infection.Our study provides a valuable basis for developing long-lasting vaccines against T. gondii for future use in humans and animals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, College of Medicine, Kaohsiung Medical University, No 100, Shih-Chuan 1st Road, Kaohsiung 807, Taiwan.

ABSTRACT

Background: Current development efforts of subunit vaccines against Toxoplasma gondii, the etiological agent of toxoplasmosis, have been focused mainly on tachyzoite surface antigen 1 (SAG1). Since microparticles made from poly (lactide-co-glycolide) (PLG) polymers have been developed as safe, potent adjuvants or delivery systems, we aimed to encapsulate recombinant SAG1 (rSAG1) with the PLG polymers to prepare PLG-encapsulated rSAG1 (PLG-rSAG1) microparticles that would sustain rSAG1 release and generate long-lasting protective immunity against T. gondii in BALB/c mice.

Methods: In the present study, rSAG1 was encapsulated into PLG microparticles by the double emulsion method. PLG-rSAG1 microparticles were then intraperitoneally injected twice at a 14-day interval into BALB/c mice. We examined the ability of PLG-rSAG1 microparticles to induce and prolong effective anti-Toxoplasma immune responses, in comparison with rSAG1 formulated with a Vet L-10 adjuvant (rSAG1 (Vet L-10)). Eight weeks after the last immunization, protective activities were also evaluated after a lethal subcutaneous challenge of 1 x 10(4) live T. gondii tachyzoites.

Results: PLG-rSAG1 microparticles, 4.25~6.58 micrometers in diameter, showed 69%~81% entrapment efficiency. The amount of released rSAG1 protein from microparticles increased gradually over a 35-day period and the protein still retained native SAG1 antigenicity. Intraperitoneal vaccination of mice with the microparticles resulted in enhanced SAG1-specific IgG titers as well as lymphocyte proliferation and, more importantly, these enhanced activities were maintained for 10 weeks. In addition, eight weeks after the last immunization, maximum production of gamma interferon was detected in mice immunized with PLG-rSAG1 microparticles. Furthermore, 80% (8/10) of mice immunized with PLG-rSAG1 microparticles survived at least 28 days after a lethal subcutaneous tachyzoite challenge.

Conclusions: Encapsulation of rSAG1 into PLG microparticles preserves the native SAG1 antigenicity and sustains the release of rSAG1 from microparticles. PLG-rSAG1 microparticles can effectively induce not only significant long-lasting SAG1-specific humoral and cell-mediated immune responses but also high protection against T. gondii tachyzoite infection. Our study provides a valuable basis for developing long-lasting vaccines against T. gondii for future use in humans and animals.

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In vitro release of rSAG1 from PLG microparticles over a 35-day period. A total of 5 mg of PLG-rSAG1 microparticles was suspended in 1 ml of PBS (pH 7.4) with 0.02% sodium azide and shaken at 37°C in 1.5 ml microfuge tubes for 35 days. The amount of rSAG1 in the supernatant sampled daily was measured using the BCA protein assay. The release studies were carried out in triplicate, with each point representing the mean ± SD.
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Figure 3: In vitro release of rSAG1 from PLG microparticles over a 35-day period. A total of 5 mg of PLG-rSAG1 microparticles was suspended in 1 ml of PBS (pH 7.4) with 0.02% sodium azide and shaken at 37°C in 1.5 ml microfuge tubes for 35 days. The amount of rSAG1 in the supernatant sampled daily was measured using the BCA protein assay. The release studies were carried out in triplicate, with each point representing the mean ± SD.

Mentions: The in vitro release of rSAG1 from PLG microparticles in PBS at 37°C was analyzed by the BCA protein assay (Figure3). The cumulative rSAG1 release in the supernatant gradually increased over the course of a 35-day period with three distinct phases. Within the first three days, an initial burst released approximately 29.2% of the total protein load. Afterwards, there was a very slow release for 27 days followed by a rapid release during the last 5 days. Altogether, 87.8% of the total protein load was released from the microparticles during the 35-day study.


Induction of long-lasting protective immunity against Toxoplasma gondii in BALB/c mice by recombinant surface antigen 1 protein encapsulated in poly (lactide-co-glycolide) microparticles.

Chuang SC, Ko JC, Chen CP, Du JT, Yang CD - Parasit Vectors (2013)

In vitro release of rSAG1 from PLG microparticles over a 35-day period. A total of 5 mg of PLG-rSAG1 microparticles was suspended in 1 ml of PBS (pH 7.4) with 0.02% sodium azide and shaken at 37°C in 1.5 ml microfuge tubes for 35 days. The amount of rSAG1 in the supernatant sampled daily was measured using the BCA protein assay. The release studies were carried out in triplicate, with each point representing the mean ± SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3584932&req=5

Figure 3: In vitro release of rSAG1 from PLG microparticles over a 35-day period. A total of 5 mg of PLG-rSAG1 microparticles was suspended in 1 ml of PBS (pH 7.4) with 0.02% sodium azide and shaken at 37°C in 1.5 ml microfuge tubes for 35 days. The amount of rSAG1 in the supernatant sampled daily was measured using the BCA protein assay. The release studies were carried out in triplicate, with each point representing the mean ± SD.
Mentions: The in vitro release of rSAG1 from PLG microparticles in PBS at 37°C was analyzed by the BCA protein assay (Figure3). The cumulative rSAG1 release in the supernatant gradually increased over the course of a 35-day period with three distinct phases. Within the first three days, an initial burst released approximately 29.2% of the total protein load. Afterwards, there was a very slow release for 27 days followed by a rapid release during the last 5 days. Altogether, 87.8% of the total protein load was released from the microparticles during the 35-day study.

Bottom Line: We examined the ability of PLG-rSAG1 microparticles to induce and prolong effective anti-Toxoplasma immune responses, in comparison with rSAG1 formulated with a Vet L-10 adjuvant (rSAG1 (Vet L-10)).PLG-rSAG1 microparticles can effectively induce not only significant long-lasting SAG1-specific humoral and cell-mediated immune responses but also high protection against T. gondii tachyzoite infection.Our study provides a valuable basis for developing long-lasting vaccines against T. gondii for future use in humans and animals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, College of Medicine, Kaohsiung Medical University, No 100, Shih-Chuan 1st Road, Kaohsiung 807, Taiwan.

ABSTRACT

Background: Current development efforts of subunit vaccines against Toxoplasma gondii, the etiological agent of toxoplasmosis, have been focused mainly on tachyzoite surface antigen 1 (SAG1). Since microparticles made from poly (lactide-co-glycolide) (PLG) polymers have been developed as safe, potent adjuvants or delivery systems, we aimed to encapsulate recombinant SAG1 (rSAG1) with the PLG polymers to prepare PLG-encapsulated rSAG1 (PLG-rSAG1) microparticles that would sustain rSAG1 release and generate long-lasting protective immunity against T. gondii in BALB/c mice.

Methods: In the present study, rSAG1 was encapsulated into PLG microparticles by the double emulsion method. PLG-rSAG1 microparticles were then intraperitoneally injected twice at a 14-day interval into BALB/c mice. We examined the ability of PLG-rSAG1 microparticles to induce and prolong effective anti-Toxoplasma immune responses, in comparison with rSAG1 formulated with a Vet L-10 adjuvant (rSAG1 (Vet L-10)). Eight weeks after the last immunization, protective activities were also evaluated after a lethal subcutaneous challenge of 1 x 10(4) live T. gondii tachyzoites.

Results: PLG-rSAG1 microparticles, 4.25~6.58 micrometers in diameter, showed 69%~81% entrapment efficiency. The amount of released rSAG1 protein from microparticles increased gradually over a 35-day period and the protein still retained native SAG1 antigenicity. Intraperitoneal vaccination of mice with the microparticles resulted in enhanced SAG1-specific IgG titers as well as lymphocyte proliferation and, more importantly, these enhanced activities were maintained for 10 weeks. In addition, eight weeks after the last immunization, maximum production of gamma interferon was detected in mice immunized with PLG-rSAG1 microparticles. Furthermore, 80% (8/10) of mice immunized with PLG-rSAG1 microparticles survived at least 28 days after a lethal subcutaneous tachyzoite challenge.

Conclusions: Encapsulation of rSAG1 into PLG microparticles preserves the native SAG1 antigenicity and sustains the release of rSAG1 from microparticles. PLG-rSAG1 microparticles can effectively induce not only significant long-lasting SAG1-specific humoral and cell-mediated immune responses but also high protection against T. gondii tachyzoite infection. Our study provides a valuable basis for developing long-lasting vaccines against T. gondii for future use in humans and animals.

Show MeSH
Related in: MedlinePlus