Research ArticleVACCINES

A respiratory syncytial virus (RSV) F protein nanoparticle vaccine focuses antibody responses to a conserved neutralization domain

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Science Immunology  01 May 2020:
Vol. 5, Issue 47, eaba6466
DOI: 10.1126/sciimmunol.aba6466
  • Fig. 1 Sc-pre-F-NP structure.

    Linear diagram of sc-pre-F-NP antigen. Residue numbers corresponding to the N terminus of each segment are indicated below the segment. Domains 1 to 3 are indicated (DI, DII, and DIII), heptad repeat region A (HRA) is in red, and heptad repeat region B (HRB) is in blue. Δp27 and FP (fusion peptide) indicates where the p27 and FP have been deleted and replaced with the single-chain linker. A yellow bracket labeled Cys-Cys shows the engineered disulfide bond. The green segment indicates the ferritin particle moiety, as labeled below. (A) Negative-stained EM image of sc-pre-F-NP showing that the molecule forms homogeneous nanoparticles. (B) 2D EM class averages of pre-F-NP show the expected symmetry of eight spherical F spikes consistent with the pre-F nanoparticle structural model.

  • Fig. 2 Glycans block nonneutralizing epitopes on pre-F-NP.

    Linear diagram of pre-F-NP labeled and colored as in Fig. 1. The engineered proline residue capping the central helix, as well as the sites for the three engineered glycan sites, are indicated above. (A) Structural model of the single-chain F protomer showing the engineered proline in blue and single-chain linker buried in the F head in red. The three native glycans are shown in green. (B) Modeled structure of the single-chain F trimer spike, with native glycans colored in green and three engineered glycan sites shown in magenta. Known neutralizing epitopes are colored and labeled for reference.

  • Fig. 3 NAb responses to pre-F-NP in mice and NHPs.

    (A) Pre-F–binding Ab titers after immunization with pre-F-NP or post-F with adjuvant in mice measured using Octet. In all panels, immunogens, injection number, and adjuvant use are indicated below the graph. (B) NAb titers induced by pre-F-NP or post-F with adjuvant in mice represented as PRNT60. (C) Pre-F–binding Ab titers after immunization with pre-F-NP with or without adjuvant in NHPs measured by ELISA. (D) NAb titers induced by pre-F-NP in NHPs with or without adjuvant are represented as PRNT60. Each mouse group represents five mice, and each NHP group represents four NHPs.

  • Fig. 4 Blocking nonfunctional epitopes with glycans on pre-F-NP focuses Ab responses toward pre-F epitopes in mice.

    (A) NAb titers induced by immunization with pre-F-NP or pre-F-NPΔglyc in mice represented as PRNT60. In all panels, response is after three injections with adjuvant. (B) Post-F–binding Ab titers elicited by immunization with pre-F-NP or pre-F-NPΔglyc. (C) Ratio of RSV NAb to post-F–binding Ab titer elicited by immunization with pre-F-NP or pre-F-NPΔglyc. Each group represents five mice.

  • Fig. 5 NAb responses to pre-F and pre-F-NP in mice is dependent on immunogen dose.

    NAb titers induced by two immunizations with pre-F-NP or pre-F with adjuvant in mice represented as PRNT60. Immunogen dose is plotted on the x axis with limit of detection (LOD) as illustrated. Each point represents a geometric mean of eight mice per group. Fold differences in geometric mean titers for each dose and statistical analysis are provided in fig. S3C.

  • Fig. 6 Pre-F-NP elicits pre-F–directed NAbs in the MIMIC system.

    (A) Pre-F–binding titers were measured after stimulating cells with post-F, pre-F, or pre-F-NP. In each panel, immunogen used for stimulation is indicated below the graph. Each dot represents a response from individual donor, the bar indicates the geometric mean, and the percentage of individual donors who responded to stimulation is indicated. For pre-F–binding titer, a responder is considered an individual donor whose titer rose at least fivefold after stimulation. (B) NAb titers were measured after stimulating cells as above. The titer is given as 50% reduction in neutralizing titer, and a responder is considered an individual whose titer is at least 25, as indicated by the dotted line. (C) Measured ratios between pre-F– and post-F–binding Ab titers. A responder is considered an individual whose pre-F:post-F binding ratio is greater than 1, as indicated by the dotted line. For comparison, the untreated control is labeled as none.

  • Fig. 7 Preexisting Ab titer in human individuals is strongly correlated with the magnitude of the RSV immune response in MIMIC system.

    (A) Rise in pre-F titers is shown on the basis of serologic status for 16 donors with the lowest and highest preexisting pre-F Ab titers after stimulation with post-F, pre-F, or pre-F-NP antigens. Data are presented as fold change of pre-F titer over unstimulated baseline titer. Each dot represents a response from an individual donor. Below the graph, the geometric mean fold change in titer after stimulation is shown for each immunogen. (B) Rise in NAb titers is shown on the basis of serologic status for 13 donors with the lowest and highest preexisting pre-F Ab titers after stimulation with F antigens. Each dot represents a response from an individual donor. The titer is given as 50% reduction in neutralizing titer, and a responder is considered an individual whose titer is at least 25, as indicated by the dotted line.

Supplementary Materials

  • immunology.sciencemag.org/cgi/content/full/5/47/eaba6466/DC1

    Fig. S1. Durability of pre-F response elicited in NHP immunized with pre-F-NP and AF03 adjuvant.

    Fig. S2. Homogeneity and antigenicity of CHO-derived pre-F-NP.

    Fig. S3. NAb responses to pre-F and pre-F-NP in mice is dependent on immunogen dose.

    Fig. S4. Representation of pre-F–binding titers stimulated by RSV antigens for all individuals tested in the MIMIC system.

    Fig. S5. Similar RSV-specific Ab and CD4+ T cell responses are elicited in adult and elderly donors after in vitro vaccination in the MIMIC system.

    Table S1. Raw data file (Excel spreadsheet).

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Durability of pre-F response elicited in NHP immunized with pre-F-NP and AF03 adjuvant.
    • Fig. S2. Homogeneity and antigenicity of CHO-derived pre-F-NP.
    • Fig. S3. NAb responses to pre-F and pre-F-NP in mice is dependent on immunogen dose.
    • Fig. S4. Representation of pre-F–binding titers stimulated by RSV antigens for all individuals tested in the MIMIC system.
    • Fig. S5. Similar RSV-specific Ab and CD4+ T cell responses are elicited in adult and elderly donors after in vitro vaccination in the MIMIC system.

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    Other Supplementary Material for this manuscript includes the following:

    • Table S1. Raw data (Excel spreadsheet).

    Files in this Data Supplement:

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