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Immunization with a live attenuated H7N9 influenza vaccine protects mice against lethal challenge.

Yang X, Zhao J, Wang C, Duan Y, Zhao Z, Chen R, Zhang L, Xing L, Lai C, Zhang S, Wang X, Yang P - PLoS ONE (2015)

Bottom Line: The emergence of severe cases of human influenza A (H7N9) viral infection in China in the spring of 2003 resulted in a global effort to rapidly develop an effective candidate vaccine.Intranasal immunization of female BALB/c mice with Ah01/AA ca twice at a 2-week interval induced robust humoral, mucosal, and cell-mediated immune responses in a dose-dependent manner.Taken together, these data support the further evaluation of this Ah01/AA ca candidate vaccine in primates.

View Article: PubMed Central - PubMed

Affiliation: Beijing Institute of Microbiology and Epidemiology, State Key Laboratory of Pathogen and Biosecurity, Beijing, China.

ABSTRACT
The emergence of severe cases of human influenza A (H7N9) viral infection in China in the spring of 2003 resulted in a global effort to rapidly develop an effective candidate vaccine. In this study, a cold-adapted (ca), live attenuated monovalent reassortant influenza H7N9 virus (Ah01/AA ca) was generated using reverse genetics that contained hemagglutinin (HA) and neuraminidase (NA) genes from a 2013 pandemic A H7N9 isolate, A/Anhui/01/2013 virus (Ah01/H7N9); the remaining six backbone genes derived from the cold-adapted influenza H2N2 A/Ann Arbor/6/60 virus (AA virus). Ah01/AA ca virus exhibited temperature sensitivity (ts), ca, and attenuation (att) phenotypes. Intranasal immunization of female BALB/c mice with Ah01/AA ca twice at a 2-week interval induced robust humoral, mucosal, and cell-mediated immune responses in a dose-dependent manner. Furthermore, the candidate Ah01/AA ca virus was immunogenic and offered partial or complete protection of mice against a lethal challenge by the live 2013 influenza A H7N9 (A/Anhui/01/2013). Protection was demonstrated by the inhibition of viral replication and the attenuation of histopathological changes in the challenged mouse lung. Taken together, these data support the further evaluation of this Ah01/AA ca candidate vaccine in primates.

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Related in: MedlinePlus

Analysis of IFN-γ and IL-4 by ELISPOT assays.On day 14 following the second immunization, mice were sacrificed and single-cell suspensions were prepared from the spleen, cultured for 48 h, and stimulated with 5 μg/mL purified Ah01/AA viral antigen. IFN-γ (A) and IL-4 (B) secretion by splenocytes was determined by ELISPOT in triplicate wells. Values and bars represent means ± SD. ** p<0.001 compared to the PBS group.
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pone.0123659.g004: Analysis of IFN-γ and IL-4 by ELISPOT assays.On day 14 following the second immunization, mice were sacrificed and single-cell suspensions were prepared from the spleen, cultured for 48 h, and stimulated with 5 μg/mL purified Ah01/AA viral antigen. IFN-γ (A) and IL-4 (B) secretion by splenocytes was determined by ELISPOT in triplicate wells. Values and bars represent means ± SD. ** p<0.001 compared to the PBS group.

Mentions: To determine the capacity of the Ah01/AA ca vaccine to elicit a cellular immune response, IFN-γ and IL-4–producing cells were enumerated using ELISPOT assays. Splenocytes were harvested at 14 days post boost and stimulated with purified H7N9 viral antigens in vitro. As shown in Fig 4A, Ah01/AA ca vaccination led to significantly higher levels of IFN-γ–producing T cells than compared the PBS-treated group; moreover, the effect was dose-dependent (p<0.001). Of particular note, no significant difference in the number of cytokine-producing T cells was observed between the 106 CCID50 and 105 CCID50 vaccinated groups. Additionally, treatment with the Ah01/AA ca vaccine induced significantly more IL-4–producing T cells, in a dose-dependent manner (p<0.001), compared to the control group (Fig 4B), suggesting that the Ah01/AA ca vaccine elicited both Th1 and Th2 immune responses. Thus, it would be interesting to measure the ratio of the Th1/Th2 response to assess the type of humoral response that leads to protection.


Immunization with a live attenuated H7N9 influenza vaccine protects mice against lethal challenge.

Yang X, Zhao J, Wang C, Duan Y, Zhao Z, Chen R, Zhang L, Xing L, Lai C, Zhang S, Wang X, Yang P - PLoS ONE (2015)

Analysis of IFN-γ and IL-4 by ELISPOT assays.On day 14 following the second immunization, mice were sacrificed and single-cell suspensions were prepared from the spleen, cultured for 48 h, and stimulated with 5 μg/mL purified Ah01/AA viral antigen. IFN-γ (A) and IL-4 (B) secretion by splenocytes was determined by ELISPOT in triplicate wells. Values and bars represent means ± SD. ** p<0.001 compared to the PBS group.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401572&req=5

pone.0123659.g004: Analysis of IFN-γ and IL-4 by ELISPOT assays.On day 14 following the second immunization, mice were sacrificed and single-cell suspensions were prepared from the spleen, cultured for 48 h, and stimulated with 5 μg/mL purified Ah01/AA viral antigen. IFN-γ (A) and IL-4 (B) secretion by splenocytes was determined by ELISPOT in triplicate wells. Values and bars represent means ± SD. ** p<0.001 compared to the PBS group.
Mentions: To determine the capacity of the Ah01/AA ca vaccine to elicit a cellular immune response, IFN-γ and IL-4–producing cells were enumerated using ELISPOT assays. Splenocytes were harvested at 14 days post boost and stimulated with purified H7N9 viral antigens in vitro. As shown in Fig 4A, Ah01/AA ca vaccination led to significantly higher levels of IFN-γ–producing T cells than compared the PBS-treated group; moreover, the effect was dose-dependent (p<0.001). Of particular note, no significant difference in the number of cytokine-producing T cells was observed between the 106 CCID50 and 105 CCID50 vaccinated groups. Additionally, treatment with the Ah01/AA ca vaccine induced significantly more IL-4–producing T cells, in a dose-dependent manner (p<0.001), compared to the control group (Fig 4B), suggesting that the Ah01/AA ca vaccine elicited both Th1 and Th2 immune responses. Thus, it would be interesting to measure the ratio of the Th1/Th2 response to assess the type of humoral response that leads to protection.

Bottom Line: The emergence of severe cases of human influenza A (H7N9) viral infection in China in the spring of 2003 resulted in a global effort to rapidly develop an effective candidate vaccine.Intranasal immunization of female BALB/c mice with Ah01/AA ca twice at a 2-week interval induced robust humoral, mucosal, and cell-mediated immune responses in a dose-dependent manner.Taken together, these data support the further evaluation of this Ah01/AA ca candidate vaccine in primates.

View Article: PubMed Central - PubMed

Affiliation: Beijing Institute of Microbiology and Epidemiology, State Key Laboratory of Pathogen and Biosecurity, Beijing, China.

ABSTRACT
The emergence of severe cases of human influenza A (H7N9) viral infection in China in the spring of 2003 resulted in a global effort to rapidly develop an effective candidate vaccine. In this study, a cold-adapted (ca), live attenuated monovalent reassortant influenza H7N9 virus (Ah01/AA ca) was generated using reverse genetics that contained hemagglutinin (HA) and neuraminidase (NA) genes from a 2013 pandemic A H7N9 isolate, A/Anhui/01/2013 virus (Ah01/H7N9); the remaining six backbone genes derived from the cold-adapted influenza H2N2 A/Ann Arbor/6/60 virus (AA virus). Ah01/AA ca virus exhibited temperature sensitivity (ts), ca, and attenuation (att) phenotypes. Intranasal immunization of female BALB/c mice with Ah01/AA ca twice at a 2-week interval induced robust humoral, mucosal, and cell-mediated immune responses in a dose-dependent manner. Furthermore, the candidate Ah01/AA ca virus was immunogenic and offered partial or complete protection of mice against a lethal challenge by the live 2013 influenza A H7N9 (A/Anhui/01/2013). Protection was demonstrated by the inhibition of viral replication and the attenuation of histopathological changes in the challenged mouse lung. Taken together, these data support the further evaluation of this Ah01/AA ca candidate vaccine in primates.

Show MeSH
Related in: MedlinePlus