TLR-9 agonist and CD40-targeting vaccination induces HIV-1 envelope-specific B cells with a diversified immunoglobulin repertoire in humanized mice

Abstract

The development of HIV-1 vaccines is challenged by the lack of relevant models to accurately induce human B- and T-cell responses in lymphoid organs. In humanized mice reconstituted with human hematopoietic stem cells (hu-mice), human B cell-development and function are impaired and cells fail to efficiently transition from IgM B cells to IgG B cells. Here, we found that CD40-targeted vaccination combined with CpG-B adjuvant overcomes the usual defect of human B-cell switch and maturation in hu-mice. We further dissected hu-B cell responses directed against the HIV-1 Env protein elicited by targeting Env gp140 clade C to the CD40 receptor of antigen-presenting cells. The anti-CD40.Env gp140 vaccine was injected with CpG-B in a homologous prime/boost regimen or as a boost of a NYVAC-KC pox vector encoding Env gp140 clade C. Both regimens elicited Env-specific IgG-switched memory hu-B cells at a greater magnitude in hu-mice primed with NYVAC-KC. Single-cell RNA-seq analysis showed gp140-specific hu-B cells to express polyclonal IgG1 and IgG3 isotypes and a broad Ig VH/VL repertoire, with predominant VH3 family gene usage. These cells exhibited a higher rate of somatic hypermutation than the non-specific IgG+ hu-B-cell counterpart. Both vaccine regimens induced splenic GC-like structures containing hu-B and hu-Tfh-like cells expressing PD-1 and BCL-6. We confirmed in this model that circulating ICOS+ memory hu-Tfh cells correlated with the magnitude of gp140-specific B-cell responses. Finally, the NYVAC-KC heterologous prime led to a more diverse clonal expansion of specific hu-B cells. Thus, this study shows that CD40-targeted vaccination induces human IgG production in hu-mice and provides insights for the development of a CD40-targeting vaccine to prevent HIV-1 infection in humans.

Targeting SARS-CoV-2 receptor-binding domain to cells expressing CD40 improves protection to infection in convalescent macaques

“…The results in the hu-mice model are consistent with those of our previous CD40-targeted in uenza and HIV vaccine studies 13,14,18,19 and demonstrate that αCD40.RBD is a potent prime or boost vaccine for eliciting RBD-speci c T-and B-cell responses similar in magnitude to previously reported protective responses 11 . In addition, we previously showed that nanomolar amounts of αCD40 vaccines can elicit in vitro recall responses in PBMCs collected from individuals primed by the natural viral infection 18,22 .…”

“…Direct delivery of the antigen, which can additionally activate cell receptors, may also evoke a danger signal, stimulating an immune response without the need of additional immune stimulants, such as adjuvants. Among the various DC receptors tested, including lectins and scavenger receptors, we reported the superiority of vaccines targeting diverse viral antigens to CD40 expressing antigen-presenting cells in evoking strong antigen-speci c T-and B-cell responses [12][13][14][15][16] . Drawing from this knowledge, we developed a vaccine that targets the receptor-binding domain (RBD) of the SARS-CoV-2 spike antigen to the CD40 receptor (αCD40.RBD).…”

TLR9- and CD40-Targeting Vaccination Promotes Human B Cell Maturation and IgG Induction via pDC-Dependent Mechanisms in Humanized Mice

“…The antigen we used in this study was not HIV envelop protein so that we were not able to evaluate the neutralization activity of antibody induced by our vaccination stratagem. In another recent study, we proved that TLR-9 agonist plus CD40-targeting HIV envelop vaccination induced HIV-1 envelop-specific IgG with a diversified immunoglobulin repertoire and circulating Env-specific IgG-switched memory human B cells that exhibit clear signs of antigen-driven antibody affinity maturation ( 41 ).…”

Advances in Humanized Mouse Models to Improve Understanding of HIV-1 Pathogenesis and Immune Responses

“…Additionally, single-cell RNA-sequencing was used in this model to characterize human innate immune cells in lymphoid tissues ( 83 ). Interestingly, despite the lack of isotype-switched mature B cells, hu-NRGs can still be a useful tool for certain vaccine investigations ( 84 ).…”