Magnitude and breadth of antibody cross-reactivity induced by recombinant influenza hemagglutinin trimer vaccine is enhanced by combination adjuvants

Abstract

The effects of adjuvants for increasing the immunogenicity of influenza vaccines are well known. However, the effect of adjuvants on increasing the breadth of cross-reactivity is less well understood. In this study we have performed a systematic screen of different toll-like receptor (TLR) agonists, with and without a squalene-in-water emulsion on the immunogenicity of a recombinant trimerized hemagglutinin (HA) vaccine in mice after single-dose administration. Antibody (Ab) cross-reactivity for other variants within and outside the immunizing subtype (homosubtypic and heterosubtypic cross-reactivity, respectively) was assessed using a protein microarray approach. Most adjuvants induced broad IgG profiles, although the response to a combination of CpG, MPLA and AddaVax (termed ‘IVAX-1’) appeared more quickly and reached a greater magnitude than the other formulations tested. Antigen-specific plasma cell labeling experiments show the components of IVAX-1 are synergistic. This adjuvant preferentially stimulates CD4 T cells to produce Th1>Th2 type (IgG2c>IgG1) antibodies and cytokine responses. Moreover, IVAX-1 induces identical homo- and heterosubtypic IgG and IgA cross-reactivity profiles when administered intranasally. Consistent with these observations, a single-cell transcriptomics analysis demonstrated significant increases in expression of IgG1, IgG2b and IgG2c genes of B cells in H5/IVAX-1 immunized mice relative to naïve mice, as well as significant increases in expression of the IFNγ gene of both CD4 and CD8 T cells. These data support the use of adjuvants for enhancing the breath and durability of antibody responses of influenza virus vaccines.

Protein Nanoparticle-Mediated Delivery of Recombinant Influenza Hemagglutinin Enhances Immunogenicity and Breadth of the Antibody Response

“…Although HA trimers may present quaternary epitopes not found in monomers and thereby elicit antibodies from a broader repertoire of B cell clones, , we aim to construct H1–E2 using HA monomers to facilitate synthesis, which is an important consideration for future nanoparticle vaccine scale-up. Moreover, we have also published IgG cross-reactivity profiles against different drift variants for mice that were administered monomeric or trimeric H5; we found that these datasets are highly correlated ( R 2 = 0.92), suggesting the immunogenicity of monomeric HA is broadly overlapping with trimeric HA …”

“…Moreover, we have also published IgG cross-reactivity profiles against different drift variants for mice that were administered monomeric or trimeric H5; we found that these datasets are highly correlated ( R 2 = 0.92), suggesting the immunogenicity of monomeric HA is broadly overlapping with trimeric HA. 78 …”

“…This relatively broader response to full length (HA0) compared to HA1 fragment by protein microarray ( Figure 6 ) has been seen in other studies where the breadth of the response induced by adjuvanted HA was examined using the microarray platform. 78 , 102 One possibility is the stem is immunodominant over the head, at least when recombinant HA protein is delivered in adjuvant. This contrasts with the response to natural infection where the head is usually immunodominant.…”

“…Moreover, we have also published IgG crossreactivity profiles against different drift variants for mice that were administered monomeric or trimeric H5; we found that these datasets are highly correlated (R 2 = 0.92), suggesting the immunogenicity of monomeric HA is broadly overlapping with trimeric HA. 78 To attach the His-tagged H1 to E2, we chelated tNTA-E2 with Ni(II) and incubated it with the His 6 -tagged H1. The H1− E2 product was then separated from unbound H1 by size exclusion chromatography (SEC), resulting in protein elution within two distinct peaks (Figure 2A,B).…”

Evaluation of Pre-Pandemic Trivalent COBRA HA Vaccine in Mice Pre-Immune to Historical H1N1 and H3N2 Influenza Viruses

“…In this study, the COBRA HA antigens were formulated with AddaVax TM , a squalene-based MF-59-like adjuvant [ 52 , 53 ]. This adjuvant induces predominantly Th2-type humoral responses, preferentially stimulates CD4+ T cells to help B cell differentiation into IgG1-secreting cells in the presence of IL-4 and other anti-inflammatory cytokines by attracting more immune cells to site of injection, and upregulates antigen trafficking and presentation [ 54 , 55 ]. Intranasal infection with influenza viruses results in a more Th1-biased immune response, as observed in pre-immune, but mock-vaccinated mice ( Figure 6 ).…”