Journal: Advanced Materials (Deerfield Beach, Fla.)

Article Title: Hydrogel‐Based Slow Release of a Receptor‐Binding Domain Subunit Vaccine Elicits Neutralizing Antibody Responses Against SARS‐CoV‐2

doi: 10.1002/adma.202104362

Figure Lengend Snippet: Polymer‐nanoparticle (PNP) hydrogel is suitable for subcutaneous delivery of RBD and combinations of clinically de‐risked adjuvants. a) Schematic showing the entire SARS‐CoV‐2 virus (≈60‐140 nm), the spike trimer on its surface (≈7.5 nm), and the receptor‐binding domain (RBD; ≈5 nm) that is used as the antigen in these studies. b) RBD expression levels greatly exceed (≈100X) spike trimer expression levels. Bars show the approximate range of expression levels found in the literature. [ ⁸ , ²² ] c) Dodecyl‐modified hydroxypropylmethylcellulose (HPMC‐C 12 ) is combined with poly(ethylene glycol)‐ b ‐poly(lactic acid) (PEG‐PLA) and vaccine cargo (RBD, CpG, and Alum) to form PNP hydrogels. Dynamic, multivalent noncovalent interactions between the polymer and nanoparticles (NPs) leads to physical crosslinking within the hydrogel that behaves like a molecular velcro. d) HPMC‐C 12 is loaded into one syringe (blue) and the NP solution and vaccine components are loaded into the other (yellow). By connecting the syringes with an elbow i) and rapidly mixing ii), a homogenous, solid‐like gel is formed iii). The gel is then easily injected through a 21‐guage needle iv) before self‐healing and reforming a solid depot v) in the subcutaneous space.

Article Snippet: We found that a standard bolus injection of the adjuvants Alum (Alhydrogel), AddaVax (an MF59‐like squalene emulsion), and CpG + Alum (similar to Dynavax's CpG/Alum adjuvant) were not sufficient to improve RBD titers after one immunization and were still unable to afford neutralizing responses following both a prime and boost.

Techniques: Binding Assay, Expressing, Modification, Injection

Journal: Advanced Materials (Deerfield Beach, Fla.)

Article Title: Hydrogel‐Based Slow Release of a Receptor‐Binding Domain Subunit Vaccine Elicits Neutralizing Antibody Responses Against SARS‐CoV‐2

doi: 10.1002/adma.202104362

Figure Lengend Snippet: Material properties of PNP hydrogels allow for easy injection, subcutaneous depot formation, and slow release of vaccine cargo. a) Frequency‐dependent oscillatory shear rheology of a PNP hydrogel with or without Alum. b) Shear‐dependent viscosities of PNP hydrogels with or without Alum. c) Oscillatory amplitude sweeps of PNP hydrogels with or without Alum. The yield stresses were determined by the crossover points and are both around 1300 Pa. d) Step‐shear measurements of hydrogels with or without Alum over three cycles of alternating high shear (gray; 10 s −1 ) and low shear (white; 0.1 s −1 ) rates. e) Percent of CpG retained in the hydrogel in a glass capillary in vitro release study over time. The points were fit with a one‐phase decay in GraphPad Prism and the half‐life of release was determined. f) Percent of RBD retained in the same hydrogels as in part e. The points were fit with a linear fit in GraphPad Prism and the half‐life of release was determined. e,f) Each point represents a separate hydrogel ( n = 3). g) Representative images demonstrating the different duration of release of Alexa‐fluor 647‐labeled RBD antigen given as a bolus or gel subcutaneous immunization over 18 days. h) Fluorescent signal from Alexa‐fluor 647‐labeled RBD (representative images shown in g) for 3 weeks following immunization as determined by an In Vivo Imaging System (IVIS) ( n = 5). The points were fit with a one phase‐decay in GraphPad Prism and the half‐lives were determined. h) Data are shown as mean ± SEM.

Article Snippet: We found that a standard bolus injection of the adjuvants Alum (Alhydrogel), AddaVax (an MF59‐like squalene emulsion), and CpG + Alum (similar to Dynavax's CpG/Alum adjuvant) were not sufficient to improve RBD titers after one immunization and were still unable to afford neutralizing responses following both a prime and boost.

Techniques: Injection, In Vitro, Labeling, In Vivo Imaging

Journal: Advanced Materials (Deerfield Beach, Fla.)

Article Title: Hydrogel‐Based Slow Release of a Receptor‐Binding Domain Subunit Vaccine Elicits Neutralizing Antibody Responses Against SARS‐CoV‐2

doi: 10.1002/adma.202104362

Figure Lengend Snippet: Hydrogel RBD vaccine increases antibody titers compared to bolus vaccine. a) Timeline of mouse immunizations and blood collection for different assays. Mice were immunized on day 0 and day 56. Serum was collected over time to determine IgG titers. IgM titers were assessed on day 7 (Figure , Supporting Information). IgG1, IgG2b, IgG2c titers were quantified, and neutralization assays were conducted on day 28 and day 84 serum. b) Anti‐RBD IgG ELISA titers before and after boosting (arrow) of several controls and the CpG + Alum + Gel group of interest. P values listed were determined using a 2way ANOVA with Tukey's multiple comparisons test. P values for comparisons between the CpG + Alum + Gel group and all other groups for day 28 and day 84 are shown above the points. c‐d) Anti‐RBD IgG1 (c) and IgG2c (d) titers from serum collected 4 weeks after mice were boosted. P values listed were determined using a one‐way ANOVA with Tukey's multiple comparisons between the CpG + Alum + Gel group and each control group. e) The ratio of Anti‐RBD IgG2c to IgG1 post‐boost titers. Lower values (below 1) suggest a Th2 response or skewing towards a stronger humoral response. All data are shown as individual mouse titer values ( n = 5) and the mean.

Article Snippet: We found that a standard bolus injection of the adjuvants Alum (Alhydrogel), AddaVax (an MF59‐like squalene emulsion), and CpG + Alum (similar to Dynavax's CpG/Alum adjuvant) were not sufficient to improve RBD titers after one immunization and were still unable to afford neutralizing responses following both a prime and boost.

Techniques: Neutralization, Enzyme-linked Immunosorbent Assay

Journal: Advanced Materials (Deerfield Beach, Fla.)

Article Title: Hydrogel‐Based Slow Release of a Receptor‐Binding Domain Subunit Vaccine Elicits Neutralizing Antibody Responses Against SARS‐CoV‐2

doi: 10.1002/adma.202104362

Figure Lengend Snippet: Hydrogel RBD vaccine elicits neutralizing antibodies in mice. a) Percent infectivity for Alum, CpG + Alum, and CpG + Alum + Gel treatments at a range of serum dilutions as determined by a SARS‐CoV‐2 spike‐pseudotyped viral neutralization assay. Week 12 serum samples were tested for all groups. b) Percent infectivity for the same treatment groups at a 1 in 50 serum dilution. Convalescent human serum collected 9–10 weeks after the onset of symptoms is also shown for comparison. c) IC 50 values determined from the neutralization curves in (a). Samples with neutralizing activity that was undetectable at a 1:50 dilution are excluded. a) Data shown are mean ± SEM ( n = 5). Samples were run in technical duplicate on two separate occasions and values were averaged to determine the mean at each serum dilution. b,c) Data are shown as individual mouse or human titer values ( n = 5) and the mean. P values listed were determined in GraphPad Prism software using a one‐way ANOVA with Tukey's multiple comparison test and correspond to comparisons to CpG + Alum + Gel.

Article Snippet: We found that a standard bolus injection of the adjuvants Alum (Alhydrogel), AddaVax (an MF59‐like squalene emulsion), and CpG + Alum (similar to Dynavax's CpG/Alum adjuvant) were not sufficient to improve RBD titers after one immunization and were still unable to afford neutralizing responses following both a prime and boost.

Techniques: Infection, Neutralization, Activity Assay, Software

Journal: Human Vaccines & Immunotherapeutics

Article Title: Exploring the possible use of saponin adjuvants in COVID-19 vaccine

doi: 10.1080/21645515.2020.1833579

Figure Lengend Snippet: Activity exhibited by licensed adjuvants

Article Snippet: Several platforms, including non-replicating viral vector vaccine, inactivated vaccine, RNA or DNA vaccine, protein subunit vaccine and virus-like particle vaccine, with (like Matrix M, Advax, MF59, CpG 1018, GlaxoSmithKline adjuvants) or without adjuvants are being investigated.

Techniques: Activity Assay, Injection, Expressing