Limits...
Immunogenicity when utilizing adenovirus serotype 4 and 5 vaccines expressing circumsporozoite protein in naïve and adenovirus (Ad5) immune mice.

Schuldt NJ, Aldhamen YA, Godbehere-Roosa S, Seregin SS, Kousa YA, Amalfitano A - Malar. J. (2012)

Bottom Line: Priming with Ad4-CSP followed by a homologous boost resulted in significantly less CSP specific humoral responses than any other vaccination regimen tested in Ad naïve animals.In Ad5 immune animals use of Ad4-CSP improved CSP specific immune responses as compared to repeated use of Ad5-CSP, but could not achieve the levels of immunogenicity observed when the same vaccine regimens were used in Ad naïve animals.Based on these results, it is suggested that future studies should undertake similarly stringent analyses of alternative Ad serotypes to establish their effectiveness as replacements for Ad5.

View Article: PubMed Central - HTML - PubMed

Affiliation: Genetics Program, Michigan State University, 2240 E Biomedical and Physical Sciences Building, East Lansing, MI 48824, USA.

ABSTRACT

Background: Induction of potent long lasting effector T cell responses against liver stage malaria antigens strongly correlates with protection from malaria. While Adenovirus serotype 5 (Ad5) based malaria vaccine platforms have the ability to induce potent effector T cell responses against transgenes, high rates of pre-existing Ad5 immunity in malaria endemic regions has prompted study of alternative Ad serotype based malaria vaccines as replacements for Ad5 based malaria vaccines. The research described in this article examines the utility of alternative serotype adenovirus serotype 4 (Ad4) expressing a sporozoite surface protein (circumsporozoite protein (CSP)) (Ad4-CSP) to induce immune responses against CSP. The immunogenicity of Ad4-CSP was also tested in homologous and heterologous prime boost vaccinations in both Ad5 naïve and Ad5 immune backgrounds as compared to use of Ad5-CSP.

Results: In Ad5 naïve animals, use of Ad4-CSP priming vaccinations followed by boosting with Ad5-CSP (Ad4-CSP/Ad5-CSP) maximally increased the numbers of CSP specific cytokine secreting cytotoxic T cells relative to repeated use of Ad5-CSP. The Ad4-CSP/Ad5-CSP regimen also induced equivalent levels of CSP specific cell killing as did homologous prime-boost vaccinations with Ad5-CSP, despite stimulating lower numbers of CSP specific cytotoxic T cells. Priming with Ad4-CSP followed by a homologous boost resulted in significantly less CSP specific humoral responses than any other vaccination regimen tested in Ad naïve animals. In Ad5 immune animals, addition of Ad4-CSP in homologous or heterologous prime boost resulted in inductions of higher CSP specific responses than animals repeatedly vaccinated with Ad5-CSP alone. However, the observed responses were well below those observed in similarly treated Ad naïve mice.

Conclusions: While the Ad4-CSP/Ad5-CSP and Ad5-CSP/Ad5-CSP vaccination regimens resulted in equivalent CSP specific killing in Ad naïve animals, Ad4-CSP/Ad5-CSP achieved this result with a lower percentage of CSP specific CD8+ T cells and a higher number of IFNγ secreting cells, suggesting that the Ad4-CSP/Ad5-CSP vaccination regimen elicits more efficient cytotoxic T cells. In Ad5 immune animals use of Ad4-CSP improved CSP specific immune responses as compared to repeated use of Ad5-CSP, but could not achieve the levels of immunogenicity observed when the same vaccine regimens were used in Ad naïve animals. These data indicate the existence of some level of immunological cross-reactivity between these two adenovirus subgroups. Based on these results, it is suggested that future studies should undertake similarly stringent analyses of alternative Ad serotypes to establish their effectiveness as replacements for Ad5.

Show MeSH

Related in: MedlinePlus

IFNγ secretion of cells from Ad5 immune mice vaccinated with heterologous and homologous prime boost regimens utilizing Ad4-CSP and Ad5-CSP. All vaccinations were capable of stimulating significantly more IFNγ secreting cells than unvaccinated and Ad5-CSP/Ad5-CSP vaccinated Ad5 immune animals. Splenocytes were collected 14 days after final vaccination. Splenocytes were then stimulated with CSP dominant antigen NYDNAGTNL and IFNγ secretion was measure by ELISpot. Bars represent ± standard error. Statistical analysis was completed using One Way ANOVA with Student-Newman-Keuls post-hoc test, *, ** denotes significance over naïve, P < 0.05, P < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3472263&req=5

Figure 6: IFNγ secretion of cells from Ad5 immune mice vaccinated with heterologous and homologous prime boost regimens utilizing Ad4-CSP and Ad5-CSP. All vaccinations were capable of stimulating significantly more IFNγ secreting cells than unvaccinated and Ad5-CSP/Ad5-CSP vaccinated Ad5 immune animals. Splenocytes were collected 14 days after final vaccination. Splenocytes were then stimulated with CSP dominant antigen NYDNAGTNL and IFNγ secretion was measure by ELISpot. Bars represent ± standard error. Statistical analysis was completed using One Way ANOVA with Student-Newman-Keuls post-hoc test, *, ** denotes significance over naïve, P < 0.05, P < 0.01.

Mentions: Given the high seroprevalence of wild type Ad5 in adults living in malaria endemic regions, the ability of these homologous and heterologous prime boost vaccine regimens to elicit potent CSP specific adaptive responses was also analysed in animals that were made Ad5 immune prior to receipt of the various vaccine regimens. BALB/cJ mice received two injections 14 days apart of 1x1010 vp/mouse of an Ad5 vector that does not express a transgene (Ad5-Null). It has been previously demonstrated that two immunizations with 1x1010 vps of rAd5-Null vector induced Ad5 neutralizing antibodies titers that were >1/200, a level that closely parallels levels of pre-existing Ad5 immunity noted in human populations[39]. 14 days after the last injection of Ad5-Null, Ad5-immune animals received 1×1010 vp/mouse prime injection of either Ad4-CSP or Ad5-CSP followed by either a heterologous or homologous boost 14 days after the initial priming vaccination. 28 days after the prime vaccination plasma, PBMCs, and splenocytes were collected. Splenocytes were stimulated as before with NYDNAGTNL and were analyzed for CSP specific IFNγ secreting cells by ELISpot. Ad5-CSP/Ad4-CSP, Ad4-CSP/Ad4-CSP, and Ad4-CSP/A5-CSP vaccinated Ad5 immune animals all had significantly higher numbers of NYDNAGTNL responsive IFNγ secreting cells present when compared to the Ad5-CSP/Ad5-CSP cohort or the non-vaccinated animals (Figure 6). However, as compared to Ad5 naive animals, overall induction of NYDNAGTNL responsive, IFNγ secreting splenocytes was notably diminished in Ad5 immune animals despite use of Ad4-CSP in some of the regimens (Table 1). The reductions prevented detection of significant differences between the treatments when ICS of the splenocytes for IFNγ, TNF, and Granzyme B was undertaken ( Additional file4A-C).


Immunogenicity when utilizing adenovirus serotype 4 and 5 vaccines expressing circumsporozoite protein in naïve and adenovirus (Ad5) immune mice.

Schuldt NJ, Aldhamen YA, Godbehere-Roosa S, Seregin SS, Kousa YA, Amalfitano A - Malar. J. (2012)

IFNγ secretion of cells from Ad5 immune mice vaccinated with heterologous and homologous prime boost regimens utilizing Ad4-CSP and Ad5-CSP. All vaccinations were capable of stimulating significantly more IFNγ secreting cells than unvaccinated and Ad5-CSP/Ad5-CSP vaccinated Ad5 immune animals. Splenocytes were collected 14 days after final vaccination. Splenocytes were then stimulated with CSP dominant antigen NYDNAGTNL and IFNγ secretion was measure by ELISpot. Bars represent ± standard error. Statistical analysis was completed using One Way ANOVA with Student-Newman-Keuls post-hoc test, *, ** denotes significance over naïve, P < 0.05, P < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472263&req=5

Figure 6: IFNγ secretion of cells from Ad5 immune mice vaccinated with heterologous and homologous prime boost regimens utilizing Ad4-CSP and Ad5-CSP. All vaccinations were capable of stimulating significantly more IFNγ secreting cells than unvaccinated and Ad5-CSP/Ad5-CSP vaccinated Ad5 immune animals. Splenocytes were collected 14 days after final vaccination. Splenocytes were then stimulated with CSP dominant antigen NYDNAGTNL and IFNγ secretion was measure by ELISpot. Bars represent ± standard error. Statistical analysis was completed using One Way ANOVA with Student-Newman-Keuls post-hoc test, *, ** denotes significance over naïve, P < 0.05, P < 0.01.
Mentions: Given the high seroprevalence of wild type Ad5 in adults living in malaria endemic regions, the ability of these homologous and heterologous prime boost vaccine regimens to elicit potent CSP specific adaptive responses was also analysed in animals that were made Ad5 immune prior to receipt of the various vaccine regimens. BALB/cJ mice received two injections 14 days apart of 1x1010 vp/mouse of an Ad5 vector that does not express a transgene (Ad5-Null). It has been previously demonstrated that two immunizations with 1x1010 vps of rAd5-Null vector induced Ad5 neutralizing antibodies titers that were >1/200, a level that closely parallels levels of pre-existing Ad5 immunity noted in human populations[39]. 14 days after the last injection of Ad5-Null, Ad5-immune animals received 1×1010 vp/mouse prime injection of either Ad4-CSP or Ad5-CSP followed by either a heterologous or homologous boost 14 days after the initial priming vaccination. 28 days after the prime vaccination plasma, PBMCs, and splenocytes were collected. Splenocytes were stimulated as before with NYDNAGTNL and were analyzed for CSP specific IFNγ secreting cells by ELISpot. Ad5-CSP/Ad4-CSP, Ad4-CSP/Ad4-CSP, and Ad4-CSP/A5-CSP vaccinated Ad5 immune animals all had significantly higher numbers of NYDNAGTNL responsive IFNγ secreting cells present when compared to the Ad5-CSP/Ad5-CSP cohort or the non-vaccinated animals (Figure 6). However, as compared to Ad5 naive animals, overall induction of NYDNAGTNL responsive, IFNγ secreting splenocytes was notably diminished in Ad5 immune animals despite use of Ad4-CSP in some of the regimens (Table 1). The reductions prevented detection of significant differences between the treatments when ICS of the splenocytes for IFNγ, TNF, and Granzyme B was undertaken ( Additional file4A-C).

Bottom Line: Priming with Ad4-CSP followed by a homologous boost resulted in significantly less CSP specific humoral responses than any other vaccination regimen tested in Ad naïve animals.In Ad5 immune animals use of Ad4-CSP improved CSP specific immune responses as compared to repeated use of Ad5-CSP, but could not achieve the levels of immunogenicity observed when the same vaccine regimens were used in Ad naïve animals.Based on these results, it is suggested that future studies should undertake similarly stringent analyses of alternative Ad serotypes to establish their effectiveness as replacements for Ad5.

View Article: PubMed Central - HTML - PubMed

Affiliation: Genetics Program, Michigan State University, 2240 E Biomedical and Physical Sciences Building, East Lansing, MI 48824, USA.

ABSTRACT

Background: Induction of potent long lasting effector T cell responses against liver stage malaria antigens strongly correlates with protection from malaria. While Adenovirus serotype 5 (Ad5) based malaria vaccine platforms have the ability to induce potent effector T cell responses against transgenes, high rates of pre-existing Ad5 immunity in malaria endemic regions has prompted study of alternative Ad serotype based malaria vaccines as replacements for Ad5 based malaria vaccines. The research described in this article examines the utility of alternative serotype adenovirus serotype 4 (Ad4) expressing a sporozoite surface protein (circumsporozoite protein (CSP)) (Ad4-CSP) to induce immune responses against CSP. The immunogenicity of Ad4-CSP was also tested in homologous and heterologous prime boost vaccinations in both Ad5 naïve and Ad5 immune backgrounds as compared to use of Ad5-CSP.

Results: In Ad5 naïve animals, use of Ad4-CSP priming vaccinations followed by boosting with Ad5-CSP (Ad4-CSP/Ad5-CSP) maximally increased the numbers of CSP specific cytokine secreting cytotoxic T cells relative to repeated use of Ad5-CSP. The Ad4-CSP/Ad5-CSP regimen also induced equivalent levels of CSP specific cell killing as did homologous prime-boost vaccinations with Ad5-CSP, despite stimulating lower numbers of CSP specific cytotoxic T cells. Priming with Ad4-CSP followed by a homologous boost resulted in significantly less CSP specific humoral responses than any other vaccination regimen tested in Ad naïve animals. In Ad5 immune animals, addition of Ad4-CSP in homologous or heterologous prime boost resulted in inductions of higher CSP specific responses than animals repeatedly vaccinated with Ad5-CSP alone. However, the observed responses were well below those observed in similarly treated Ad naïve mice.

Conclusions: While the Ad4-CSP/Ad5-CSP and Ad5-CSP/Ad5-CSP vaccination regimens resulted in equivalent CSP specific killing in Ad naïve animals, Ad4-CSP/Ad5-CSP achieved this result with a lower percentage of CSP specific CD8+ T cells and a higher number of IFNγ secreting cells, suggesting that the Ad4-CSP/Ad5-CSP vaccination regimen elicits more efficient cytotoxic T cells. In Ad5 immune animals use of Ad4-CSP improved CSP specific immune responses as compared to repeated use of Ad5-CSP, but could not achieve the levels of immunogenicity observed when the same vaccine regimens were used in Ad naïve animals. These data indicate the existence of some level of immunological cross-reactivity between these two adenovirus subgroups. Based on these results, it is suggested that future studies should undertake similarly stringent analyses of alternative Ad serotypes to establish their effectiveness as replacements for Ad5.

Show MeSH
Related in: MedlinePlus