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Nonreplicating influenza A virus vaccines confer broad protection against lethal challenge.

Baz M, Boonnak K, Paskel M, Santos C, Powell T, Townsend A, Subbarao K - MBio (2015)

Bottom Line: We compared the efficacies of two intranasally delivered nonreplicating influenza virus vaccines (H1 and H5 S-FLU) that are based on the suppression of the hemagglutinin signal sequence, with the corresponding H1N1 and H5N1 cold-adapted (ca) live attenuated influenza virus vaccines in mice and ferrets.Currently licensed influenza vaccines are based on immunity to the hemagglutinin protein that is highly variable.In this study, two nonreplicating pseudotyped influenza virus vaccines were compared with their corresponding live attenuated influenza virus vaccines, and both elicited robust protection against homologous and heterosubtypic challenge in mice and ferrets, making them promising candidates for further evaluation in humans.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Infectious Diseases, NIAID, NIH, Bethesda, Maryland, USA.

No MeSH data available.


Related in: MedlinePlus

Protective efficacy of H1 S-FLU and H1 ca vaccines against lethal homologous and heterologous challenge in BALB/c mice. (A and D) Weight loss in mice (five mice in each group) inoculated intranasally with one or two doses of 50 µl of VGM containing 3.42 × 105 TCID50 of H1 S-FLU vaccine or 106 TCID50 of H5 ca vaccine and challenged with 106 TCID50/50 µl of CA/09 (H1N1) or 105 TCID50/50 µl of the tl/97 (H6N1) virus. Animals were monitored daily for weight loss, and mortality was recorded over a period of 14 days. Mice were euthanized when they lost 25% of their original body weight. A † symbol indicates that a mouse died on the specified day. (B, C, E, and F) Protection conferred by the H1 S-FLU and H1 ca vaccines against homologous virus (B and C) and heterologous virus (E and F) challenge. Animals (four mice in each group) were i.n. inoculated with either VGM (mock) or one or two doses of 3.42 × 105 TCID50 of H1 S-FLU or 106 TCID50 of H1 ca vaccines and challenged 28 days following the last vaccine dose with 106 TCID50/50 µl of CA/09 virus or 105 TCID50/50 µl of the tl/97 virus. Virus titers were determined on day 2 (d2) and day 4 (d4) postchallenge in the nasal turbinates (NTs) or lungs of mice. In panels B, C, E, and F, each symbol represents the titer for an individual mouse, and each horizontal bar depicts the mean titer for a group of mice. The dotted horizontal line shows the lower limit of detection (101.8 TCID50/g for NTs and 101.5 TCID50/g for lungs).
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fig1: Protective efficacy of H1 S-FLU and H1 ca vaccines against lethal homologous and heterologous challenge in BALB/c mice. (A and D) Weight loss in mice (five mice in each group) inoculated intranasally with one or two doses of 50 µl of VGM containing 3.42 × 105 TCID50 of H1 S-FLU vaccine or 106 TCID50 of H5 ca vaccine and challenged with 106 TCID50/50 µl of CA/09 (H1N1) or 105 TCID50/50 µl of the tl/97 (H6N1) virus. Animals were monitored daily for weight loss, and mortality was recorded over a period of 14 days. Mice were euthanized when they lost 25% of their original body weight. A † symbol indicates that a mouse died on the specified day. (B, C, E, and F) Protection conferred by the H1 S-FLU and H1 ca vaccines against homologous virus (B and C) and heterologous virus (E and F) challenge. Animals (four mice in each group) were i.n. inoculated with either VGM (mock) or one or two doses of 3.42 × 105 TCID50 of H1 S-FLU or 106 TCID50 of H1 ca vaccines and challenged 28 days following the last vaccine dose with 106 TCID50/50 µl of CA/09 virus or 105 TCID50/50 µl of the tl/97 virus. Virus titers were determined on day 2 (d2) and day 4 (d4) postchallenge in the nasal turbinates (NTs) or lungs of mice. In panels B, C, E, and F, each symbol represents the titer for an individual mouse, and each horizontal bar depicts the mean titer for a group of mice. The dotted horizontal line shows the lower limit of detection (101.8 TCID50/g for NTs and 101.5 TCID50/g for lungs).

Mentions: First, we immunized mice i.n. with one or two doses of H1 S-FLU or H1 ca viruses and collected sera on day 28 after each vaccine dose. Mice were challenged i.n. with the homologous A/California/07/2009 (CA/09) or heterologous tl/97 (H6N1) virus 28 days after vaccination and were monitored for weight loss for 14 days. Another group of mice was challenged, and virus titers in the nasal turbinates (NTs) and lungs were measured on days 2 and 4 postchallenge (p.c.) (Fig. 1A to F). There were no deaths in the mice immunized with one dose of H1 S-FLU vaccine, while mock-vaccinated mice challenged with CA/09 and tl/97 showed mortality rates of 100 and 80%, respectively (Fig. 1A and D). Mice that received a single dose of H1 S-FLU vaccine had transient weight loss and ruffled fur after homologous or heterologous virus challenge, but they recovered rapidly. Although one dose of H1 ca vaccine was more efficacious than one dose of H1 S-FLU vaccine, two doses of either vaccine were highly effective in controlling replication of the homologous or heterologous challenge viruses in the respiratory tract; virus titers in the NTs and lungs were very low or undetectable by day 4 p.c. (Fig. 1B, C, E, and F). Because S-FLU is a pseudotyped vaccine virus that does not synthesize HA, the only HA-specific antibody response is due to the HA coating the particles in the viral inoculum. Therefore, as expected, the H1 S-FLU vaccine did not elicit an antibody response against the homologous virus or cross-reactive antibodies against the heterologous virus (see Fig. S2A in the supplemental material). To investigate the cellular immune response to the H1 S-FLU vaccine, the induction of conserved nucleoprotein (NP147) CTL epitope-specific CD8+ CTLs in the lungs of mice was examined by flow cytometry (Fig. 2). Eight days after the first dose of H1 S-FLU, 4.8% of pulmonary CD8+ T cells were NP147 specific, and this percentage increased to 30.3% (P = 0.008) after the second dose of vaccine (see Fig. S1 for gating strategy). The immunogenicity and efficacy of the H1 S-FLU vaccine validated our earlier findings with PR8 S-FLU (12), and the nonreplicating pseudotyped H1 S-FLU virus compared well with the corresponding LAIV in mice.


Nonreplicating influenza A virus vaccines confer broad protection against lethal challenge.

Baz M, Boonnak K, Paskel M, Santos C, Powell T, Townsend A, Subbarao K - MBio (2015)

Protective efficacy of H1 S-FLU and H1 ca vaccines against lethal homologous and heterologous challenge in BALB/c mice. (A and D) Weight loss in mice (five mice in each group) inoculated intranasally with one or two doses of 50 µl of VGM containing 3.42 × 105 TCID50 of H1 S-FLU vaccine or 106 TCID50 of H5 ca vaccine and challenged with 106 TCID50/50 µl of CA/09 (H1N1) or 105 TCID50/50 µl of the tl/97 (H6N1) virus. Animals were monitored daily for weight loss, and mortality was recorded over a period of 14 days. Mice were euthanized when they lost 25% of their original body weight. A † symbol indicates that a mouse died on the specified day. (B, C, E, and F) Protection conferred by the H1 S-FLU and H1 ca vaccines against homologous virus (B and C) and heterologous virus (E and F) challenge. Animals (four mice in each group) were i.n. inoculated with either VGM (mock) or one or two doses of 3.42 × 105 TCID50 of H1 S-FLU or 106 TCID50 of H1 ca vaccines and challenged 28 days following the last vaccine dose with 106 TCID50/50 µl of CA/09 virus or 105 TCID50/50 µl of the tl/97 virus. Virus titers were determined on day 2 (d2) and day 4 (d4) postchallenge in the nasal turbinates (NTs) or lungs of mice. In panels B, C, E, and F, each symbol represents the titer for an individual mouse, and each horizontal bar depicts the mean titer for a group of mice. The dotted horizontal line shows the lower limit of detection (101.8 TCID50/g for NTs and 101.5 TCID50/g for lungs).
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fig1: Protective efficacy of H1 S-FLU and H1 ca vaccines against lethal homologous and heterologous challenge in BALB/c mice. (A and D) Weight loss in mice (five mice in each group) inoculated intranasally with one or two doses of 50 µl of VGM containing 3.42 × 105 TCID50 of H1 S-FLU vaccine or 106 TCID50 of H5 ca vaccine and challenged with 106 TCID50/50 µl of CA/09 (H1N1) or 105 TCID50/50 µl of the tl/97 (H6N1) virus. Animals were monitored daily for weight loss, and mortality was recorded over a period of 14 days. Mice were euthanized when they lost 25% of their original body weight. A † symbol indicates that a mouse died on the specified day. (B, C, E, and F) Protection conferred by the H1 S-FLU and H1 ca vaccines against homologous virus (B and C) and heterologous virus (E and F) challenge. Animals (four mice in each group) were i.n. inoculated with either VGM (mock) or one or two doses of 3.42 × 105 TCID50 of H1 S-FLU or 106 TCID50 of H1 ca vaccines and challenged 28 days following the last vaccine dose with 106 TCID50/50 µl of CA/09 virus or 105 TCID50/50 µl of the tl/97 virus. Virus titers were determined on day 2 (d2) and day 4 (d4) postchallenge in the nasal turbinates (NTs) or lungs of mice. In panels B, C, E, and F, each symbol represents the titer for an individual mouse, and each horizontal bar depicts the mean titer for a group of mice. The dotted horizontal line shows the lower limit of detection (101.8 TCID50/g for NTs and 101.5 TCID50/g for lungs).
Mentions: First, we immunized mice i.n. with one or two doses of H1 S-FLU or H1 ca viruses and collected sera on day 28 after each vaccine dose. Mice were challenged i.n. with the homologous A/California/07/2009 (CA/09) or heterologous tl/97 (H6N1) virus 28 days after vaccination and were monitored for weight loss for 14 days. Another group of mice was challenged, and virus titers in the nasal turbinates (NTs) and lungs were measured on days 2 and 4 postchallenge (p.c.) (Fig. 1A to F). There were no deaths in the mice immunized with one dose of H1 S-FLU vaccine, while mock-vaccinated mice challenged with CA/09 and tl/97 showed mortality rates of 100 and 80%, respectively (Fig. 1A and D). Mice that received a single dose of H1 S-FLU vaccine had transient weight loss and ruffled fur after homologous or heterologous virus challenge, but they recovered rapidly. Although one dose of H1 ca vaccine was more efficacious than one dose of H1 S-FLU vaccine, two doses of either vaccine were highly effective in controlling replication of the homologous or heterologous challenge viruses in the respiratory tract; virus titers in the NTs and lungs were very low or undetectable by day 4 p.c. (Fig. 1B, C, E, and F). Because S-FLU is a pseudotyped vaccine virus that does not synthesize HA, the only HA-specific antibody response is due to the HA coating the particles in the viral inoculum. Therefore, as expected, the H1 S-FLU vaccine did not elicit an antibody response against the homologous virus or cross-reactive antibodies against the heterologous virus (see Fig. S2A in the supplemental material). To investigate the cellular immune response to the H1 S-FLU vaccine, the induction of conserved nucleoprotein (NP147) CTL epitope-specific CD8+ CTLs in the lungs of mice was examined by flow cytometry (Fig. 2). Eight days after the first dose of H1 S-FLU, 4.8% of pulmonary CD8+ T cells were NP147 specific, and this percentage increased to 30.3% (P = 0.008) after the second dose of vaccine (see Fig. S1 for gating strategy). The immunogenicity and efficacy of the H1 S-FLU vaccine validated our earlier findings with PR8 S-FLU (12), and the nonreplicating pseudotyped H1 S-FLU virus compared well with the corresponding LAIV in mice.

Bottom Line: We compared the efficacies of two intranasally delivered nonreplicating influenza virus vaccines (H1 and H5 S-FLU) that are based on the suppression of the hemagglutinin signal sequence, with the corresponding H1N1 and H5N1 cold-adapted (ca) live attenuated influenza virus vaccines in mice and ferrets.Currently licensed influenza vaccines are based on immunity to the hemagglutinin protein that is highly variable.In this study, two nonreplicating pseudotyped influenza virus vaccines were compared with their corresponding live attenuated influenza virus vaccines, and both elicited robust protection against homologous and heterosubtypic challenge in mice and ferrets, making them promising candidates for further evaluation in humans.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Infectious Diseases, NIAID, NIH, Bethesda, Maryland, USA.

No MeSH data available.


Related in: MedlinePlus