A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 Mice
Background/Objectives: In the past, FhSAP-2, an 11.5 kDa recombinant protein belonging to the <i>Fasciola hepatica</i> saposin-like/NK-lysin family, has been shown to induce over 60% partial protection in immunized rabbits and mice when challenged with <i>F. hepatica</i> meta...
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2025-05-01
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| author | Riseilly Ramos-Nieves Albersy Armina-Rodriguez Maria Del Mar Figueroa-Gispert Ghalib Figueroa-Quiñones Carlimar Ocasio-Malavé Ana M. Espino |
| author_facet | Riseilly Ramos-Nieves Albersy Armina-Rodriguez Maria Del Mar Figueroa-Gispert Ghalib Figueroa-Quiñones Carlimar Ocasio-Malavé Ana M. Espino |
| author_sort | Riseilly Ramos-Nieves |
| collection | DOAJ |
| description | Background/Objectives: In the past, FhSAP-2, an 11.5 kDa recombinant protein belonging to the <i>Fasciola hepatica</i> saposin-like/NK-lysin family, has been shown to induce over 60% partial protection in immunized rabbits and mice when challenged with <i>F. hepatica</i> metacercariae. However, despite FhSAP-2 being a promising vaccine candidate, its hydrophobic nature has made its purification a challenging process. The present study aimed to determine whether a modified 9.8 kDa variant of protein (mFhSAP-2), lacking a string of 16 hydrophobic amino acids at the amino terminus and a dominant Th1 epitope, could retain its immunogenic and Th1-inducing properties. Methods: RAW264.7 cells were stimulated with mFhSAP-2, and TNFα levels were determined. C57BL/6 mice were immunized with mFhSAP-2 alone or emulsified with Montanide ISA50. Total anti-mFhSAP-2 IgG subtypes, along with their avidity and titers, were measured using ELISA. The T cell proliferation index and levels of CD4+/CD8+ and IFNγ/IL-4 ratios were determined. Results: In vitro, mFhSAP-2 induced dose-dependent TNFα production in RAW264.7 cells. In vivo, mice immunized with mFhSAP-2 or mFhSAP-2+ISA50 developed high-avidity IgG2a and IgG2c antibodies at levels that were significantly higher than IgG1 antibody levels. However, the mFhSAP-2+ISA50 formulation induced higher and more homogenous antibody titers than mFhSAP-2, suggesting that an adjuvant may be required to enhance mFhSAP-2 immunogenicity. Immunization with mFhSAP-2+ISA50 also induced significantly higher activated CD4+/CD8+ T cell ratios and IFNγ/IL-4 ratios compared to naïve mice. Conclusions: Our results demonstrate that mFhSAP-2 retained its immunogenicity and Th1-polarizing properties, which were enhanced by the Montanide ISA50 adjuvant. The present study highlights the feasibility of inducing Th1-associated immune responses in mice using mFhSAP-2 as an antigen. Further studies are required to assess the potential application of the mFhSAP-2+ISA50 formulation as a vaccine against <i>F. hepatica</i> in natural hosts such as cattle and sheep, which could contribute to improved control and aid in the prevention and eradication of <i>F. hepatica</i> infection. |
| format | Article |
| id | doaj-art-e8d2ed28a632439c8485d7bd7be83828 |
| institution | Kabale University |
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| language | English |
| publishDate | 2025-05-01 |
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| spelling | doaj-art-e8d2ed28a632439c8485d7bd7be838282025-08-20T03:47:57ZengMDPI AGVaccines2076-393X2025-05-0113554510.3390/vaccines13050545A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 MiceRiseilly Ramos-Nieves0Albersy Armina-Rodriguez1Maria Del Mar Figueroa-Gispert2Ghalib Figueroa-Quiñones3Carlimar Ocasio-Malavé4Ana M. Espino5Department of Microbiology and Medical Zoology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USADepartment of Microbiology and Medical Zoology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USADepartment of Microbiology and Medical Zoology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USADepartment of Biology, University of Puerto Rico, Arecibo Campus, Arecibo, PR 00614, USADepartment of Microbiology and Medical Zoology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USADepartment of Microbiology and Medical Zoology, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936, USABackground/Objectives: In the past, FhSAP-2, an 11.5 kDa recombinant protein belonging to the <i>Fasciola hepatica</i> saposin-like/NK-lysin family, has been shown to induce over 60% partial protection in immunized rabbits and mice when challenged with <i>F. hepatica</i> metacercariae. However, despite FhSAP-2 being a promising vaccine candidate, its hydrophobic nature has made its purification a challenging process. The present study aimed to determine whether a modified 9.8 kDa variant of protein (mFhSAP-2), lacking a string of 16 hydrophobic amino acids at the amino terminus and a dominant Th1 epitope, could retain its immunogenic and Th1-inducing properties. Methods: RAW264.7 cells were stimulated with mFhSAP-2, and TNFα levels were determined. C57BL/6 mice were immunized with mFhSAP-2 alone or emulsified with Montanide ISA50. Total anti-mFhSAP-2 IgG subtypes, along with their avidity and titers, were measured using ELISA. The T cell proliferation index and levels of CD4+/CD8+ and IFNγ/IL-4 ratios were determined. Results: In vitro, mFhSAP-2 induced dose-dependent TNFα production in RAW264.7 cells. In vivo, mice immunized with mFhSAP-2 or mFhSAP-2+ISA50 developed high-avidity IgG2a and IgG2c antibodies at levels that were significantly higher than IgG1 antibody levels. However, the mFhSAP-2+ISA50 formulation induced higher and more homogenous antibody titers than mFhSAP-2, suggesting that an adjuvant may be required to enhance mFhSAP-2 immunogenicity. Immunization with mFhSAP-2+ISA50 also induced significantly higher activated CD4+/CD8+ T cell ratios and IFNγ/IL-4 ratios compared to naïve mice. Conclusions: Our results demonstrate that mFhSAP-2 retained its immunogenicity and Th1-polarizing properties, which were enhanced by the Montanide ISA50 adjuvant. The present study highlights the feasibility of inducing Th1-associated immune responses in mice using mFhSAP-2 as an antigen. Further studies are required to assess the potential application of the mFhSAP-2+ISA50 formulation as a vaccine against <i>F. hepatica</i> in natural hosts such as cattle and sheep, which could contribute to improved control and aid in the prevention and eradication of <i>F. hepatica</i> infection.https://www.mdpi.com/2076-393X/13/5/545C57BL6IgG2aIgG2cavidityFhSAP-2IFNγ |
| spellingShingle | Riseilly Ramos-Nieves Albersy Armina-Rodriguez Maria Del Mar Figueroa-Gispert Ghalib Figueroa-Quiñones Carlimar Ocasio-Malavé Ana M. Espino A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 Mice Vaccines C57BL6 IgG2a IgG2c avidity FhSAP-2 IFNγ |
| title | A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 Mice |
| title_full | A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 Mice |
| title_fullStr | A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 Mice |
| title_full_unstemmed | A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 Mice |
| title_short | A Modified Variant of <i>Fasciola hepatica</i> FhSAP-2 (mFhSAP-2) as a Recombinant Vaccine Candidate Induces High-Avidity IgG2c Antibodies and Enhances T Cell Activation in C57BL/6 Mice |
| title_sort | modified variant of i fasciola hepatica i fhsap 2 mfhsap 2 as a recombinant vaccine candidate induces high avidity igg2c antibodies and enhances t cell activation in c57bl 6 mice |
| topic | C57BL6 IgG2a IgG2c avidity FhSAP-2 IFNγ |
| url | https://www.mdpi.com/2076-393X/13/5/545 |
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