Spite the structural similarity, human sera containing high anti-Ad5 neutralization titers (.1000) show no or marginal neutralization capacity on PanAd3. Moreover, in a screening study, PanAd3 was shown to be a potent vector in mice and in primates [34]. We show here that aHighly Immunogenic Simian Adenovirus VectorFigure 5. T cell responses to different doses of PanAd3-NPM1. Mice were immunized as in Figure 3. Four weeks Indolactam V post-immunization, T -cells of three mice per group were assayed by IFN-c ELISPOT. Results shown are for lung T cells, and are reported as number of IFN-c secreting cells per 106 cells. Bars show mean 6 SEM of results for lungs of individual mice. doi:10.1371/journal.pone.0055435.gsingle administration of PanAd3-NPM1 influenza vaccine given i.n. provided highly effective protection against lethal challenge with mouse-adapted A/FM, with greatly reduced morbidity and mortality compared to controls. Protection was comparable to that in previously published studies of Ad5 expressing conserved influenza virus antigens for the same challenge virus and dose [20,21]. The PanAd3 vaccine induced both antibody and T cell responses to NP. As mentioned earlier, the T cell response to NP is well-known to contribute to protection [5,8?0], and recentstudies have reported that antibodies to NP can also contribute to protection [12]. The fusion protein of NP with M1 expressed by the PanAd3 vaccine has the advantage of including another major target of human immunity. Using multiple target antigens may invoke different immune mechanisms, reduce the likelihood of generating escape mutants, and provide a larger range of epitopes that may be suitable for different MHC types. Although M1 is not expected to play much of a role in protection in mice, it is a prominent target of T cell immunity in humans [3], and might contribute to the performance of the PanAd3-NPM1 vaccine in humans.Figure 6. Protection against lethal influenza challenge by PanAd3-NPM1. Mice were immunized as in Figure 3. Approximately 9 weeks post-immunization, mice were challenged with influenza virus A/FM at a dose of 104 TCID50 (100 LD50) per mouse, and monitored for body weight and mortality. Survival of the PanAd3-NPM1 group at the dose of 109 vp differs significantly (p,0.05) from the PanAd3-RSV control group. Error bars indicate mean 6 SEM. doi:10.1371/journal.pone.0055435.gHighly Immunogenic Simian Adenovirus VectorThe results presented here support the use of the PanAd3 vector as a vaccine candidate that is highly effective at inducing T cell and antibody immunity, while at the same time having the advantage that it is not neutralized by human sera [34]. Thus PanAd3, when used to express conserved influenza virus antigens, has promise as a “universal” influenza vaccine candidate.the studies were conducted according to the principles of the Declaration of Helsinki and in accordance with Good Clinical Practice. (DOC)AcknowledgmentsWe thank Anthony Ferrine, Mary Belcher and the CBER animal facility staff for care of experimental animals, and Marian Major and MedChemExpress ML 281 Andrew Byrnes for review of the manuscript.Supporting InformationTable S1 Sera from healthy human individuals from different geographical areas in Europe and the United States had been screened previously for neutralizing activity to Ad5 [34]. Selected sera with high Ad5 neutralizing activity (titers .1000) were tested for neutralization of PanAd3 as described in Materials and Methods, using vectors expressing th.Spite the structural similarity, human sera containing high anti-Ad5 neutralization titers (.1000) show no or marginal neutralization capacity on PanAd3. Moreover, in a screening study, PanAd3 was shown to be a potent vector in mice and in primates [34]. We show here that aHighly Immunogenic Simian Adenovirus VectorFigure 5. T cell responses to different doses of PanAd3-NPM1. Mice were immunized as in Figure 3. Four weeks post-immunization, T -cells of three mice per group were assayed by IFN-c ELISPOT. Results shown are for lung T cells, and are reported as number of IFN-c secreting cells per 106 cells. Bars show mean 6 SEM of results for lungs of individual mice. doi:10.1371/journal.pone.0055435.gsingle administration of PanAd3-NPM1 influenza vaccine given i.n. provided highly effective protection against lethal challenge with mouse-adapted A/FM, with greatly reduced morbidity and mortality compared to controls. Protection was comparable to that in previously published studies of Ad5 expressing conserved influenza virus antigens for the same challenge virus and dose [20,21]. The PanAd3 vaccine induced both antibody and T cell responses to NP. As mentioned earlier, the T cell response to NP is well-known to contribute to protection [5,8?0], and recentstudies have reported that antibodies to NP can also contribute to protection [12]. The fusion protein of NP with M1 expressed by the PanAd3 vaccine has the advantage of including another major target of human immunity. Using multiple target antigens may invoke different immune mechanisms, reduce the likelihood of generating escape mutants, and provide a larger range of epitopes that may be suitable for different MHC types. Although M1 is not expected to play much of a role in protection in mice, it is a prominent target of T cell immunity in humans [3], and might contribute to the performance of the PanAd3-NPM1 vaccine in humans.Figure 6. Protection against lethal influenza challenge by PanAd3-NPM1. Mice were immunized as in Figure 3. Approximately 9 weeks post-immunization, mice were challenged with influenza virus A/FM at a dose of 104 TCID50 (100 LD50) per mouse, and monitored for body weight and mortality. Survival of the PanAd3-NPM1 group at the dose of 109 vp differs significantly (p,0.05) from the PanAd3-RSV control group. Error bars indicate mean 6 SEM. doi:10.1371/journal.pone.0055435.gHighly Immunogenic Simian Adenovirus VectorThe results presented here support the use of the PanAd3 vector as a vaccine candidate that is highly effective at inducing T cell and antibody immunity, while at the same time having the advantage that it is not neutralized by human sera [34]. Thus PanAd3, when used to express conserved influenza virus antigens, has promise as a “universal” influenza vaccine candidate.the studies were conducted according to the principles of the Declaration of Helsinki and in accordance with Good Clinical Practice. (DOC)AcknowledgmentsWe thank Anthony Ferrine, Mary Belcher and the CBER animal facility staff for care of experimental animals, and Marian Major and Andrew Byrnes for review of the manuscript.Supporting InformationTable S1 Sera from healthy human individuals from different geographical areas in Europe and the United States had been screened previously for neutralizing activity to Ad5 [34]. Selected sera with high Ad5 neutralizing activity (titers .1000) were tested for neutralization of PanAd3 as described in Materials and Methods, using vectors expressing th.
