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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

H1 S-FLU and H1 ca vaccines protect ferrets against homologous and heterologous virus challenge and prevent airborne transmission of the homologous challenge virus to naive ferrets housed in an adjacent cage. (A to D) Twelve-week-old ferrets were anesthetized with intramuscular injection of a ketamine-xylazine mixture prior to intranasal virus inoculation with one or two doses (28 days apart) of 3.42 × 106 or 107 TCID50 of H1 S-FLU or H1 ca vaccine, respectively. Mock-inoculated controls received virus growth medium (VGM) (DMEM with penicillin, streptomycin, and 0.1% BSA) alone. (A to D) Animals were challenged with 106 TCID50 of CA/09 (H1N1) virus (A and B) or tl/97 (H6N1) virus (C and D), and virus titers in the nasal turbinates (NTs) (A and C) and lungs (B and D) of the ferrets (three ferrets in each group) sacrificed on 2 and 4 days postinfection (dpi) are expressed as log10 TCID50/gram of tissue. Two animals immunized with the H1 ca vaccine did not recover from anesthesia after bleeding on day 28; therefore, there are only four ferrets in the group after dose 2. Each symbol represents the titer for an individual ferret, and each horizontal bar represents the mean titer for a group of ferret. The dotted horizontal line indicates the lower limit of detection, 101.5 TCID50 per gram for the NT and lungs. (E, i–iv) Three 5- to 8-month-old male adult ferrets were anesthetized as described above for panels A to D and immunized with one or two doses of 3.42 × 106 TCID50 of H1 S-FLU vaccine or one dose of 107 TCID50 H1 ca vaccine in 500 µl of VGM or VGM alone (mock immunized). Twenty-eight days after the first or second dose, ferrets were challenged with 106 TCID50 of CA/09 virus. Challenged ferrets were placed in the section of the cage closest to the air inlet the day of challenge. One day later, a naive ferret was placed into the cage on the other side of the divider. Nasal washes were collected every other day for 14 days, and virus titers in the experimentally infected ferrets and ferrets with airborne contact are presented. Each bar represents a single ferret.
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fig3: H1 S-FLU and H1 ca vaccines protect ferrets against homologous and heterologous virus challenge and prevent airborne transmission of the homologous challenge virus to naive ferrets housed in an adjacent cage. (A to D) Twelve-week-old ferrets were anesthetized with intramuscular injection of a ketamine-xylazine mixture prior to intranasal virus inoculation with one or two doses (28 days apart) of 3.42 × 106 or 107 TCID50 of H1 S-FLU or H1 ca vaccine, respectively. Mock-inoculated controls received virus growth medium (VGM) (DMEM with penicillin, streptomycin, and 0.1% BSA) alone. (A to D) Animals were challenged with 106 TCID50 of CA/09 (H1N1) virus (A and B) or tl/97 (H6N1) virus (C and D), and virus titers in the nasal turbinates (NTs) (A and C) and lungs (B and D) of the ferrets (three ferrets in each group) sacrificed on 2 and 4 days postinfection (dpi) are expressed as log10 TCID50/gram of tissue. Two animals immunized with the H1 ca vaccine did not recover from anesthesia after bleeding on day 28; therefore, there are only four ferrets in the group after dose 2. Each symbol represents the titer for an individual ferret, and each horizontal bar represents the mean titer for a group of ferret. The dotted horizontal line indicates the lower limit of detection, 101.5 TCID50 per gram for the NT and lungs. (E, i–iv) Three 5- to 8-month-old male adult ferrets were anesthetized as described above for panels A to D and immunized with one or two doses of 3.42 × 106 TCID50 of H1 S-FLU vaccine or one dose of 107 TCID50 H1 ca vaccine in 500 µl of VGM or VGM alone (mock immunized). Twenty-eight days after the first or second dose, ferrets were challenged with 106 TCID50 of CA/09 virus. Challenged ferrets were placed in the section of the cage closest to the air inlet the day of challenge. One day later, a naive ferret was placed into the cage on the other side of the divider. Nasal washes were collected every other day for 14 days, and virus titers in the experimentally infected ferrets and ferrets with airborne contact are presented. Each bar represents a single ferret.

Mentions: Therefore, we evaluated the H1 S-FLU vaccine in ferrets by immunizing groups of ferrets i.n. with one or two doses of H1 S-FLU or H1 ca vaccine and challenging them i.n. 28 days later with CA/09 virus (Fig. 3A and B) or tl/97 virus (Fig. 3C and D). One dose of either H1 S-FLU or H1 ca vaccine provided robust protection from pulmonary replication of the homologous and heterologous challenge viruses (Fig. 3B and D). In the NTs, one dose of H1 ca vaccine conferred better protection against homologous challenge than one dose of H1 S-FLU vaccine, although ferrets that received the S-FLU vaccine had significantly reduced (P < 0.006) titers of the CA/09 virus on day 4 p.c. than the mock-vaccinated animals did (Fig. 3A). Ferrets that received two doses of H1 S-FLU had significantly reduced tl/97 virus titers in the NTs (P < 0.022) by day 4 p.c., while the H1 ca vaccine conferred near-complete protection (Fig. 3C). We detected a modest homologous NtAb response after one dose of H1 S-FLU vaccine (geometric mean titer [GMT], 90), with a slight increase after the second dose (GMT, 158), but not against the heterologous H6N1 virus. The H1 ca vaccine elicited a robust homologous NtAb response with GMTs of 273 and 974 after the first and second dose, respectively, but again, cross-reactive antibodies against the H6N1 virus were not detected (see Fig. S2B in the supplemental material). Because the NAs of the tl/97 and CA/09 viruses are both of the N1 subtype and NA-inhibiting antibodies (NAI) are associated with protection against influenza and correlate with reduced viral shedding and disease symptoms (16, 17), we hypothesized that cross-reactive NA immunity could contribute to protection conferred by the H1 S-FLU vaccine. We measured NAI titers by enzyme-linked lectin assay (ELLA) and observed that ferrets immunized with two doses of H1 S-FLU vaccine had detectable, although lower, homologous NAI titers than those immunized with H1 ca vaccine, with GMTs of 50 and 113, respectively. However, NAI titers against the heterologous tl/97 virus were barely detected (GMT, 6.3) after two doses of H1 S-FLU vaccine, and a titer of 44 was observed after two doses of H1 ca vaccine (see Table S1 in the supplemental material). Thus, NAI antibodies are not likely to have played a role in H1 S-FLU-mediated heterosubtypic protection, and we infer that protection was conferred by cellular immunity. In summary, the H1 S-FLU vaccine conferred robust protection against pulmonary replication of homologous and heterologous challenge viruses, and one dose of H1 ca was more effective than one dose of H1 S-FLU. However, that may not be surprising, because ca vaccines induce antibodies as well as T cell responses.


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)

H1 S-FLU and H1 ca vaccines protect ferrets against homologous and heterologous virus challenge and prevent airborne transmission of the homologous challenge virus to naive ferrets housed in an adjacent cage. (A to D) Twelve-week-old ferrets were anesthetized with intramuscular injection of a ketamine-xylazine mixture prior to intranasal virus inoculation with one or two doses (28 days apart) of 3.42 × 106 or 107 TCID50 of H1 S-FLU or H1 ca vaccine, respectively. Mock-inoculated controls received virus growth medium (VGM) (DMEM with penicillin, streptomycin, and 0.1% BSA) alone. (A to D) Animals were challenged with 106 TCID50 of CA/09 (H1N1) virus (A and B) or tl/97 (H6N1) virus (C and D), and virus titers in the nasal turbinates (NTs) (A and C) and lungs (B and D) of the ferrets (three ferrets in each group) sacrificed on 2 and 4 days postinfection (dpi) are expressed as log10 TCID50/gram of tissue. Two animals immunized with the H1 ca vaccine did not recover from anesthesia after bleeding on day 28; therefore, there are only four ferrets in the group after dose 2. Each symbol represents the titer for an individual ferret, and each horizontal bar represents the mean titer for a group of ferret. The dotted horizontal line indicates the lower limit of detection, 101.5 TCID50 per gram for the NT and lungs. (E, i–iv) Three 5- to 8-month-old male adult ferrets were anesthetized as described above for panels A to D and immunized with one or two doses of 3.42 × 106 TCID50 of H1 S-FLU vaccine or one dose of 107 TCID50 H1 ca vaccine in 500 µl of VGM or VGM alone (mock immunized). Twenty-eight days after the first or second dose, ferrets were challenged with 106 TCID50 of CA/09 virus. Challenged ferrets were placed in the section of the cage closest to the air inlet the day of challenge. One day later, a naive ferret was placed into the cage on the other side of the divider. Nasal washes were collected every other day for 14 days, and virus titers in the experimentally infected ferrets and ferrets with airborne contact are presented. Each bar represents a single ferret.
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fig3: H1 S-FLU and H1 ca vaccines protect ferrets against homologous and heterologous virus challenge and prevent airborne transmission of the homologous challenge virus to naive ferrets housed in an adjacent cage. (A to D) Twelve-week-old ferrets were anesthetized with intramuscular injection of a ketamine-xylazine mixture prior to intranasal virus inoculation with one or two doses (28 days apart) of 3.42 × 106 or 107 TCID50 of H1 S-FLU or H1 ca vaccine, respectively. Mock-inoculated controls received virus growth medium (VGM) (DMEM with penicillin, streptomycin, and 0.1% BSA) alone. (A to D) Animals were challenged with 106 TCID50 of CA/09 (H1N1) virus (A and B) or tl/97 (H6N1) virus (C and D), and virus titers in the nasal turbinates (NTs) (A and C) and lungs (B and D) of the ferrets (three ferrets in each group) sacrificed on 2 and 4 days postinfection (dpi) are expressed as log10 TCID50/gram of tissue. Two animals immunized with the H1 ca vaccine did not recover from anesthesia after bleeding on day 28; therefore, there are only four ferrets in the group after dose 2. Each symbol represents the titer for an individual ferret, and each horizontal bar represents the mean titer for a group of ferret. The dotted horizontal line indicates the lower limit of detection, 101.5 TCID50 per gram for the NT and lungs. (E, i–iv) Three 5- to 8-month-old male adult ferrets were anesthetized as described above for panels A to D and immunized with one or two doses of 3.42 × 106 TCID50 of H1 S-FLU vaccine or one dose of 107 TCID50 H1 ca vaccine in 500 µl of VGM or VGM alone (mock immunized). Twenty-eight days after the first or second dose, ferrets were challenged with 106 TCID50 of CA/09 virus. Challenged ferrets were placed in the section of the cage closest to the air inlet the day of challenge. One day later, a naive ferret was placed into the cage on the other side of the divider. Nasal washes were collected every other day for 14 days, and virus titers in the experimentally infected ferrets and ferrets with airborne contact are presented. Each bar represents a single ferret.
Mentions: Therefore, we evaluated the H1 S-FLU vaccine in ferrets by immunizing groups of ferrets i.n. with one or two doses of H1 S-FLU or H1 ca vaccine and challenging them i.n. 28 days later with CA/09 virus (Fig. 3A and B) or tl/97 virus (Fig. 3C and D). One dose of either H1 S-FLU or H1 ca vaccine provided robust protection from pulmonary replication of the homologous and heterologous challenge viruses (Fig. 3B and D). In the NTs, one dose of H1 ca vaccine conferred better protection against homologous challenge than one dose of H1 S-FLU vaccine, although ferrets that received the S-FLU vaccine had significantly reduced (P < 0.006) titers of the CA/09 virus on day 4 p.c. than the mock-vaccinated animals did (Fig. 3A). Ferrets that received two doses of H1 S-FLU had significantly reduced tl/97 virus titers in the NTs (P < 0.022) by day 4 p.c., while the H1 ca vaccine conferred near-complete protection (Fig. 3C). We detected a modest homologous NtAb response after one dose of H1 S-FLU vaccine (geometric mean titer [GMT], 90), with a slight increase after the second dose (GMT, 158), but not against the heterologous H6N1 virus. The H1 ca vaccine elicited a robust homologous NtAb response with GMTs of 273 and 974 after the first and second dose, respectively, but again, cross-reactive antibodies against the H6N1 virus were not detected (see Fig. S2B in the supplemental material). Because the NAs of the tl/97 and CA/09 viruses are both of the N1 subtype and NA-inhibiting antibodies (NAI) are associated with protection against influenza and correlate with reduced viral shedding and disease symptoms (16, 17), we hypothesized that cross-reactive NA immunity could contribute to protection conferred by the H1 S-FLU vaccine. We measured NAI titers by enzyme-linked lectin assay (ELLA) and observed that ferrets immunized with two doses of H1 S-FLU vaccine had detectable, although lower, homologous NAI titers than those immunized with H1 ca vaccine, with GMTs of 50 and 113, respectively. However, NAI titers against the heterologous tl/97 virus were barely detected (GMT, 6.3) after two doses of H1 S-FLU vaccine, and a titer of 44 was observed after two doses of H1 ca vaccine (see Table S1 in the supplemental material). Thus, NAI antibodies are not likely to have played a role in H1 S-FLU-mediated heterosubtypic protection, and we infer that protection was conferred by cellular immunity. In summary, the H1 S-FLU vaccine conferred robust protection against pulmonary replication of homologous and heterologous challenge viruses, and one dose of H1 ca was more effective than one dose of H1 S-FLU. However, that may not be surprising, because ca vaccines induce antibodies as well as T cell responses.

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