Biology subjects

Bachmann, M. F.

Publications and source records attributed to Bachmann, M. F..

6 recordsLinked to original sources

bioRxiv2021

Intranasal administration of a VLP-based vaccine against COVID-19 induces neutralizing antibodies against SARS-CoV-2 and Variants of Concerns

BackgroundThe highly contagious SARS-CoV-2 is mainly transmitted by respiratory droplets and aerosols. Consequently, people are required to wear masks and maintain a social distance to avoid spreading of the virus. Despite the success of the commercially available vaccines, the virus is still uncontained globally. Given the tropism of SARS-CoV-2, a mucosal immune reaction would help to reduce viral shedding and transmission locally. Only seven out of hundreds of ongoing clinical trials are testing the intranasal delivery of COVID-19 vaccines. MethodsIn the current study, we tested in murine model the immunogenicity of a conventional vaccine platform based on virus-like particles (VLPs) displaying RBD of SARS-CoV-2 for intranasal vaccination. The candidate vaccine, CuMVTT-RBD, has been immunologically optimized to incorporate tetanus-toxin and is self-adjuvanted with TLR7/8 ligands. ResultsCuMVTT-RBD elicited strong RBD- and spike- specific systemic IgG and IgA antibody responses of high avidity. Local immune responses were assessed and results demonstrate strong mucosal antibody and plasma cell production in lung tissue. The induced systemic antibodies could efficiently recognize and neutralize different Variants of Concerns of mutated SARS-CoV-2 RBDs. ConclusionIn summary, intranasal vaccination with CuMVTT-RBD shows high immunogenicity and induces protective systemic and local specific antibody response against SARS-CoV-2 and its variants. One sentence summaryEvaluation of an intransal administrated conventional VLP-based vaccine against COVID-19 in a murine model.

immunology↗

bioRxiv2021

Bedside formulation of a personalized multi-neoantigen vaccine against mammary carcinoma

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/440778v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@88f5d3org.highwire.dtl.DTLVardef@1c32c71org.highwire.dtl.DTLVardef@9abbedorg.highwire.dtl.DTLVardef@a7f41a_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO Individualized neoantigen vaccination against mammary carcinoma C_FIG BackgroundHarnessing the immune system to purposely recognize and destroy tumours represents a significant breakthrough in clinical oncology. Nonsynonymous mutations (neoantigenic peptides) were identified as powerful cancer targets. This knowledge can be exploited for further improvements of active immunotherapies, including cancer vaccines as T cells specific for neoantigens are not attenuated by immune tolerance mechanism and do not harm healthy tissues. The current study aimed at developing an optimized multi-target vaccine using short or long neoantigenic peptides utilizing virus-like particles (VLPs) as an efficient vaccine platform. MethodsHere we identified mutations of murine mammary carcinoma cells by integrating mass spectrometry-based immunopeptidomics and whole exome sequencing. Neoantigenic peptides were synthesized and covalently linked to virus-like nanoparticles using a Cu-free click-chemistry method for easy preparation of vaccines against mouse mammary carcinoma. ResultsAs compared to short peptides, vaccination with long peptides was superior in the generation of neoantigen-specific CD4+ and CD8+ T cells which readily produced IFN-{gamma} and TNF-. The resulting anti-tumour effect was associated with favourable immune re-polarization in the tumour microenvironment through reduction of myeloid-derived suppressor cells. Vaccination with long neoantigenic peptides also decreased post-surgical tumour recurrence and metastases, and prolonged mouse survival, despite the tumours low mutational burden. ConclusionIntegrating mass spectrometry-based immunopeptidomics and whole exome-sequencing is an efficient technique for identifying neoantigenic peptides. A multi-target VLP-based vaccine shows a promising anti-tumour results in an aggressive murine mammary carcinoma cell line. Future clinical application using this strategy is readily feasible and practical, as click-chemistry coupling of personalized synthetic peptides to the nanoparticles can be done at the bedside directly before injection.

immunology↗

bioRxiv2021

BNT162b2 mRNA COVID-19 vaccine induces antibodies of broader cross-reactivity than natural infection but recognition of mutant viruses is up to 10-fold reduced

BackgroundSeveral new variants of SARS-CoV-2 have emerged since fall 2020 which have multiple mutations in the receptor binding domain (RBD) of the spike protein. ObjectiveWe aimed to assess how mutations in RBD affected recognition of immune sera by antibodies induced by natural infection versus immunization with BNT162b2, a mRNA-based vaccine against COVID-19. MethodsWe produced SARS-CoV-2 RBD mutants with single mutations in the receptor binding domain (RBD) region (E484K, K417N, N501Y) or with all 3 mutations combined, as occurring in the newly emerged variants B.1.351 (South Africa) and P.1 (Brazil). Using standard and avidity ELISAs, we determined the binding capacities to mutant RBDs of antibodies induced by infection versus vaccination. ResultsThese binding assays showed that vaccination induced antibodies recognize both wildtype and mutant RBDs with higher avidities than those raised by infection. Nevertheless, recognition of mutants RBDK417N and RBDN501Y was 2.5-3-fold reduced while RBDE484K and the triple mutant were 10-fold less well recognized, demonstrating that the mutation at position 484 was key for the observed loss in cross-reactivity. ConclusionOur binding data demonstrate improved recognition of mutant viruses by BNT162b2-induced antibodies compared to those induced by natural infection. Recognition may, however, be 10-fold reduced for the variants B.1.351/P.1, suggesting that the development of a new vaccine is warranted. The E484K mutation is an key hurdle for immune recognition, convalescent plasma and monoclonal antibody therapy as well as serological assays based on the wildtype sequence may therefore seriously impaired. Capsule summaryBNT162b2 mRNA COVID-19 vaccine-induced antibodies recognize mutant viruses with up to 10-fold lower efficiency

immunology↗

bioRxiv2021

SARS-CoV-2 variant with higher affinity to ACE2 shows reduced sera neutralization susceptibility

BackgroundSeveral new variants of SARS-CoV-2 have emerged since fall 2020 which have multiple mutations in the receptor binding domain (RBD) of the spike protein. ObjectiveWe aimed to assess how mutations in the SARS-CoV-2 RBD affect receptor affinity to angiotensin-converting enzyme 2 (ACE2) and neutralization by anti-RBD serum antibodies. MethodsWe produced a SARS-CoV-2 RBD mutant (RBDmut) with key mutations (E484K, K417N, N501Y) from the newly emerged Brazilian variant. Using Biolayer Interferometry, we analyzed the binding of this mutant to ACE2, and the susceptibility to neutralization by sera from vaccinated mice and COVID-19 convalescent patients. ResultsKinetic profiles showed increased RBDmut - ACE2 affinity compared to RBDwt, and binding of vaccine-elicited or convalescent sera was significantly reduced. Likewise, both sera types showed significantly reduced ability to block RBDmut - ACE2 binding indicating that antibodies induced by RBDwt have reduced capability to neutralize mutant virus. ConclusionOur physiochemical data show enhanced infectivity and reduced neutralization by polyclonal antibodies of the Brazilian variant of SARS-CoV-2. Capsule summarySARS-CoV-2 variant with Brazilian RBD mutations shows increased ACE2 affinity and reduced susceptibility to blockage by vaccine-elicited and convalescent sera.

immunology↗

bioRxiv2020

The impact of size on particle drainage dynamics and antibody response

Vaccine-induced immune response can be greatly enhanced by mimicking pathogen properties. The size and the repetitive geometric shape of virus-like particles (VLPs) influence their immunogenicity by facilitating drainage to secondary lymphoid organs and enhancing interaction with and activation of B-cells and other innate humoral immune components. VLPs derived from the plant Bromovirus genus, specifically cowpea chlorotic mottle virus (CCMV), are T=3 icosahedron particles. They can be easily expressed in an E. coli host system and package ssRNA during the expression process. Recently, we have engineered CCMV-VLPs by incorporating the universal tetanus toxoid (TT) epitope at the N-terminus. The modified CCMVTT-VLPs successfully form icosahedral particles T=3, with a diameter of [~]30nm analogous to the parental VLPs. Interestingly, incorporating TT epitope at the C-terminus of CCMVTT-VLPs results in the formation of Rod-shaped VLPs, [~]1{micro}m in length and [~]30nm in width. In this study, we have investigated the draining kinetics and immunogenicity of both engineered forms (termed as Round-shaped CCMVTT-VLPs and Rod-shaped CCMVTT-VLPs) as potential B cell immunogens using different in vitro and in vivo assays. Our results reveal that Round-shaped CCMVTT-VLPs are more efficient in draining to secondary lymphoid organs to charge antigen-presenting cells as well as B-cells. Furthermore, compared to Rod-shaped CCMVTT-VLPs, Round-shaped CCMVTT-VLPs led to more than 100-fold increased systemic IgG and IgA responses accompanied by prominent formation of splenic germinal centers. Round-shaped CCMVTT-VLPs could also polarize the induced immune response towards TH1. Up to our knowledge, this is the first study investigating and comparing the draining kinetics and immunogenicity of one and the same VLP monomer forming nano-sized icosahedrons or rods in the micrometer size.

immunology↗

bioRxiv2020

Development of a COVID-19 vaccine based on the receptor binding domain displayed on virus-like particles

The ongoing coronavirus COVID-19 pandemic is caused by a new coronavirus (SARS-CoV-2) with its origin in the city of Wuhan in China. From there it has been rapidly spreading to many cities inside and outside China. Nowadays more than 33 millions with deaths surpassing 1 million have been recorded worldwide thus representing a major health issue. Rapid development of a protective vaccine against COVID-19 is therefore of paramount importance. Here we demonstrated that recombinantly expressed receptor binding domain (RBD) of the spike protein homologous to SARS binds to ACE2, the viral receptor. Higly repetitive display of RBD on immunologically optimized virus-like particles derived from cucumber mosaic virus (CuMVTT) resulted in a vaccine candidate that induced high levels of specific antibodies in mice which were able to block binding of spike protein to ACE2 and potently neutralized COVID-19 virus in vitro.

immunology↗