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Hepatitis C VLPs delivered to dendritic cells by a TLR2 targeting lipopeptide results in enhanced antibody and cell-mediated responses.

Chua BY, Johnson D, Tan A, Earnest-Silveira L, Sekiya T, Chin R, Torresi J, Jackson DC - PLoS ONE (2012)

Bottom Line: Although many studies provide strong evidence supporting the development of HCV virus-like particle (VLP)-based vaccines, the fact that heterologous viral vectors and/or multiple dosing regimes are required to induce protective immunity indicates that it is necessary to improve their immunogenicity.While co-formulation of this lipopeptide with VLPs only resulted in marginal improvements in dendritic cell (DC) uptake, its ability to concomitantly induce DC maturation at very small doses is a feature not observed using VLPs alone or in the presence of an aluminium hydroxide-based adjuvant (Alum).These results suggest overall that the immunogenicity of HCV VLPs can be significantly improved by the addition of this novel adjuvant by targeting their delivery to DCs and could therefore constitute a viable vaccine strategy for the treatment of HCV.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia.

ABSTRACT
Although many studies provide strong evidence supporting the development of HCV virus-like particle (VLP)-based vaccines, the fact that heterologous viral vectors and/or multiple dosing regimes are required to induce protective immunity indicates that it is necessary to improve their immunogenicity. In this study, we have evaluated the use of an anionic self-adjuvanting lipopeptide containing the TLR2 agonist Pam(2)Cys (E(8)Pam(2)Cys) to enhance the immunogenicity of VLPs containing the HCV structural proteins (core, E1 and E2) of genotype 1a. While co-formulation of this lipopeptide with VLPs only resulted in marginal improvements in dendritic cell (DC) uptake, its ability to concomitantly induce DC maturation at very small doses is a feature not observed using VLPs alone or in the presence of an aluminium hydroxide-based adjuvant (Alum). Dramatically improved VLP and E2-specific antibody responses were observed in VLP+E(8)Pam(2)Cys vaccinated mice where up to 3 doses of non-adjuvanted or traditionally alum-adjuvanted VLPs was required to match the antibody titres obtained with a single dose of VLPs formulated with this lipopeptide. This result also correlated with significantly higher numbers of specific antibody secreting cells that was detected in the spleens of VLP+E(8)Pam(2)Cys vaccinated mice and greater ability of sera from these mice to neutralise the binding and uptake of VLPs by Huh7 cells. Moreover, vaccination of HLA-A2 transgenic mice with this formulation also induced better VLP-specific IFN-γ-mediated responses compared to non-adjuvanted VLPs but comparable levels to that achieved when coadministered with complete freund's adjuvant. These results suggest overall that the immunogenicity of HCV VLPs can be significantly improved by the addition of this novel adjuvant by targeting their delivery to DCs and could therefore constitute a viable vaccine strategy for the treatment of HCV.

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Antibody responses elicited by vaccination.Groups of BALB/c mice (n = 5 per group) were inoculated (100 µl) sub-cutaneously at the base of the tail with 20 µg of VLPs alone, pre-incubated with an equal volume of aluminium hydroxide (13 mg/ml) or 60 µg of E8Pam2Cys in saline on days 0 and 21. (A) VLP-specific antibody levels in sera prepared from blood taken on days 21 (white circles) and 35 (black circles) were then determined by ELISA. Individual animal antibody titres are presented with the mean value represented by the horizontal bar. An additional dose of each formulation was also administered to 3 mice from each group on day 56 and antibody titres determined on day 63 (grey circles). (B) E2-specific antibody titres in these animals were also determined at this same time point.
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pone-0047492-g003: Antibody responses elicited by vaccination.Groups of BALB/c mice (n = 5 per group) were inoculated (100 µl) sub-cutaneously at the base of the tail with 20 µg of VLPs alone, pre-incubated with an equal volume of aluminium hydroxide (13 mg/ml) or 60 µg of E8Pam2Cys in saline on days 0 and 21. (A) VLP-specific antibody levels in sera prepared from blood taken on days 21 (white circles) and 35 (black circles) were then determined by ELISA. Individual animal antibody titres are presented with the mean value represented by the horizontal bar. An additional dose of each formulation was also administered to 3 mice from each group on day 56 and antibody titres determined on day 63 (grey circles). (B) E2-specific antibody titres in these animals were also determined at this same time point.

Mentions: Administration of VLPs alone in saline was able to elicit detectable titres of specific antibody that were marginally increased after each dose of antigen (Figure 3A). In animals that received HCV VLPs mixed with E8Pam2Cys, however, antibody levels were significantly higher, in some cases by up to ten-fold more than those from animals that received the same dose of HCV VLPs alone. In fact the titre of specific antibody induced following administration of 3 doses of HCV VLPs alone was achieved using a single dose only of HCV VLP mixed with E8Pam2Cys. When compared to animals that were inoculated with HCV VLPs formulated with Alhydrogel, an adjuvant widely used to induce antibody responses to both human and veterinary vaccines [29], lower antibody titres were observed in these animals than in those that received the VLP-lipopeptide formulation. In examining levels of E2 specific antibodies elicited by vaccination, higher titres were once again demonstrated in animals that received 3 doses of VLPs mixed with E8Pam2Cys compared to those that were inoculated with VLPs alone or with Alhydrogel (Figure 3B).


Hepatitis C VLPs delivered to dendritic cells by a TLR2 targeting lipopeptide results in enhanced antibody and cell-mediated responses.

Chua BY, Johnson D, Tan A, Earnest-Silveira L, Sekiya T, Chin R, Torresi J, Jackson DC - PLoS ONE (2012)

Antibody responses elicited by vaccination.Groups of BALB/c mice (n = 5 per group) were inoculated (100 µl) sub-cutaneously at the base of the tail with 20 µg of VLPs alone, pre-incubated with an equal volume of aluminium hydroxide (13 mg/ml) or 60 µg of E8Pam2Cys in saline on days 0 and 21. (A) VLP-specific antibody levels in sera prepared from blood taken on days 21 (white circles) and 35 (black circles) were then determined by ELISA. Individual animal antibody titres are presented with the mean value represented by the horizontal bar. An additional dose of each formulation was also administered to 3 mice from each group on day 56 and antibody titres determined on day 63 (grey circles). (B) E2-specific antibody titres in these animals were also determined at this same time point.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3472981&req=5

pone-0047492-g003: Antibody responses elicited by vaccination.Groups of BALB/c mice (n = 5 per group) were inoculated (100 µl) sub-cutaneously at the base of the tail with 20 µg of VLPs alone, pre-incubated with an equal volume of aluminium hydroxide (13 mg/ml) or 60 µg of E8Pam2Cys in saline on days 0 and 21. (A) VLP-specific antibody levels in sera prepared from blood taken on days 21 (white circles) and 35 (black circles) were then determined by ELISA. Individual animal antibody titres are presented with the mean value represented by the horizontal bar. An additional dose of each formulation was also administered to 3 mice from each group on day 56 and antibody titres determined on day 63 (grey circles). (B) E2-specific antibody titres in these animals were also determined at this same time point.
Mentions: Administration of VLPs alone in saline was able to elicit detectable titres of specific antibody that were marginally increased after each dose of antigen (Figure 3A). In animals that received HCV VLPs mixed with E8Pam2Cys, however, antibody levels were significantly higher, in some cases by up to ten-fold more than those from animals that received the same dose of HCV VLPs alone. In fact the titre of specific antibody induced following administration of 3 doses of HCV VLPs alone was achieved using a single dose only of HCV VLP mixed with E8Pam2Cys. When compared to animals that were inoculated with HCV VLPs formulated with Alhydrogel, an adjuvant widely used to induce antibody responses to both human and veterinary vaccines [29], lower antibody titres were observed in these animals than in those that received the VLP-lipopeptide formulation. In examining levels of E2 specific antibodies elicited by vaccination, higher titres were once again demonstrated in animals that received 3 doses of VLPs mixed with E8Pam2Cys compared to those that were inoculated with VLPs alone or with Alhydrogel (Figure 3B).

Bottom Line: Although many studies provide strong evidence supporting the development of HCV virus-like particle (VLP)-based vaccines, the fact that heterologous viral vectors and/or multiple dosing regimes are required to induce protective immunity indicates that it is necessary to improve their immunogenicity.While co-formulation of this lipopeptide with VLPs only resulted in marginal improvements in dendritic cell (DC) uptake, its ability to concomitantly induce DC maturation at very small doses is a feature not observed using VLPs alone or in the presence of an aluminium hydroxide-based adjuvant (Alum).These results suggest overall that the immunogenicity of HCV VLPs can be significantly improved by the addition of this novel adjuvant by targeting their delivery to DCs and could therefore constitute a viable vaccine strategy for the treatment of HCV.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia.

ABSTRACT
Although many studies provide strong evidence supporting the development of HCV virus-like particle (VLP)-based vaccines, the fact that heterologous viral vectors and/or multiple dosing regimes are required to induce protective immunity indicates that it is necessary to improve their immunogenicity. In this study, we have evaluated the use of an anionic self-adjuvanting lipopeptide containing the TLR2 agonist Pam(2)Cys (E(8)Pam(2)Cys) to enhance the immunogenicity of VLPs containing the HCV structural proteins (core, E1 and E2) of genotype 1a. While co-formulation of this lipopeptide with VLPs only resulted in marginal improvements in dendritic cell (DC) uptake, its ability to concomitantly induce DC maturation at very small doses is a feature not observed using VLPs alone or in the presence of an aluminium hydroxide-based adjuvant (Alum). Dramatically improved VLP and E2-specific antibody responses were observed in VLP+E(8)Pam(2)Cys vaccinated mice where up to 3 doses of non-adjuvanted or traditionally alum-adjuvanted VLPs was required to match the antibody titres obtained with a single dose of VLPs formulated with this lipopeptide. This result also correlated with significantly higher numbers of specific antibody secreting cells that was detected in the spleens of VLP+E(8)Pam(2)Cys vaccinated mice and greater ability of sera from these mice to neutralise the binding and uptake of VLPs by Huh7 cells. Moreover, vaccination of HLA-A2 transgenic mice with this formulation also induced better VLP-specific IFN-γ-mediated responses compared to non-adjuvanted VLPs but comparable levels to that achieved when coadministered with complete freund's adjuvant. These results suggest overall that the immunogenicity of HCV VLPs can be significantly improved by the addition of this novel adjuvant by targeting their delivery to DCs and could therefore constitute a viable vaccine strategy for the treatment of HCV.

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