Biology subjects

Pohlmann, S.

Publications and source records attributed to Pohlmann, S..

4 recordsLinked to original sources

bioRxiv2024

Macrophage- and CD4+ T cell-derived SIV differ in glycosylation, infectivity and neutralization sensitivity

The human immunodeficiency virus (HIV) envelope protein (Env) mediates viral entry into host cells and is the primary target for the humoral immune response. Env is extensively glycosylated, and these glycans shield underlying epitopes from neutralizing antibodies. The glycosylation of Env is influenced by the type of host cell in which the virus is produced. Thus, HIV is distinctly glycosylated by CD4+ T cells, the major target cells, and macrophages. However, the specific differences in glycosylation between viruses produced in these cell types have not been explored at the molecular level. Moreover, the impact of these differences on viral spread and neutralization sensitivity remains largely unknown. To address these questions, we employed the simian immunodeficiency virus (SIV) model. Glycan analysis revealed higher relative levels of oligomannose-type N-glycans in SIV from CD4+ T cells (T-SIV) compared to SIV from macrophages (M-SIV), and the complex-type N-glycans profiles differed between the two viruses. Notably, M-SIV demonstrated greater infectivity than T-SIV, even when accounting for Env incorporation, suggesting that host cell-dependent factors influence infectivity. Further, M-SIV was more efficiently disseminated by HIV binding cellular lectins. We also evaluated the influence of cell type-dependent differences on SIVs vulnerability to carbohydrate binding agents (CBAs) and neutralizing antibodies. T-SIV demonstrated greater susceptibility to mannose-specific CBAs, possibly due to its elevated expression of oligomannose-type N-glycans. In contrast, M-SIV exhibited higher susceptibility to neutralizing sera in comparison to T-SIV. These findings underscore the importance of host cell-dependent attributes of SIV, such as glycosylation, in shaping both infectivity and the potential effectiveness of intervention strategies.

microbiology↗

bioRxiv2021

A pair of non-competing neutralizing human monoclonal antibodies protecting from disease in a SARS-CoV-2 infection model

TRIANNI mice carry an entire set of human immunoglobulin V region gene segments and are a powerful tool to rapidly generate human monoclonal antibodies. After immunizing these mice against the spike protein of SARS-CoV-2, we identified 29 hybridoma antibodies that reacted with the SARS-CoV-2 spike protein. Nine antibodies neutralized SARS-CoV-2 infection at IC50 values in the subnanomolar range. ELISA-binding studies and DNA sequence analyses revealed one cluster of clonally related neutralizing antibodies that target the receptor-binding domain and compete with the cellular receptor hACE2. A second cluster of neutralizing antibodies binds to the N-terminal domain of the spike protein without competing with the binding of hACE2 or cluster 1 antibodies. SARS-CoV-2 mutants selected for resistance to an antibody from one cluster are still neutralized by an antibody from the other cluster. Antibodies from both clusters markedly reduced viral spread in mice transgenic for human ACE2 and protected the animals from SARS-CoV-2 induced weight loss. Thus, we report two clusters of potent non-competing SARS-CoV-2 neutralizing antibodies providing potential candidates for therapy and prophylaxis of COVID-19. The study further supports the use of transgenic animals with human immunoglobulin gene repertoires in pandemic preparedness initiatives.

immunology↗

bioRxiv2020

LY6E impairs coronavirus fusion and confers immune control of viral disease

Zoonotic coronaviruses (CoVs) are significant threats to global health, as exemplified by the recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)1. Host immune responses to CoV are complex and regulated in part through antiviral interferons. However, the interferon-stimulated gene products that inhibit CoV are not well characterized2. Here, we show that interferon-inducible lymphocyte antigen 6 complex, locus E (LY6E) potently restricts cellular infection by multiple CoVs, including SARS-CoV, SARS-CoV-2, and Middle East respiratory syndrome coronavirus (MERS-CoV). Mechanistic studies revealed that LY6E inhibits CoV entry into cells by interfering with spike protein-mediated membrane fusion. Importantly, mice lacking Ly6e in hematopoietic cells were highly susceptible to murine CoV infection. Exacerbated viral pathogenesis in Ly6e knockout mice was accompanied by loss of hepatic and splenic immune cells and reduction in global antiviral gene pathways. Accordingly, we found that Ly6e directly protects primary B cells and dendritic cells from murine CoV infection. Our results demonstrate that LY6E is a critical antiviral immune effector that controls CoV infection and pathogenesis. These findings advance our understanding of immune-mediated control of CoV in vitro and in vivo, knowledge that could help inform strategies to combat infection by emerging CoV.

microbiology↗

bioRxiv2018

Development and use of Lentiviral Vectors Pseudotyped with Influenza B Haemagglutinins: application to vaccine immunogenicity, mAb potency and sero-surveillance studies

Influenza B viruses cause respiratory disease epidemics in human populations and are included in seasonal influenza vaccines. Serological methods are employed to evaluate vaccine immunogenicity prior to licensure. However, the haemagglutination inhibition assay, which represents the gold standard for assessing the immunogenicity of influenza vaccines, has been shown to be relatively insensitive for the detection of antibodies against influenza B viruses. Furthermore, this assay, and the serial radial haemolysis assay are not able to detect stalk-directed cross-reactive antibodies. For these reasons there is a need to develop new assays that can overcome these limitations. The use of replication-defective viruses, such as lentiviral vectors pseudotyped with influenza A haemagglutinins, in microneutralization assays is a safe and sensitive alternative to study antibody responses elicited by natural infection or vaccination. We have produced Influenza B haemagglutinin-pseudotypes using plasmid-directed transfection. To activate influenza B haemagglutinin, we have explored the use of proteases by adding relevant encoding plasmids to the transfection mixture. When tested for their ability to transduce target cells, the newly produced influenza B pseudotypes exhibit tropism for different cell lines. Subsequently the pseudotypes were evaluated as surrogate antigens in microneutralization assays using reference sera, monoclonal antibodies, human sera collected during a vaccine immunogenicity study and surveillance sera from seals. The influenza B pseudotype virus neutralization assay was found to effectively detect neutralizing and cross-reactive responses despite lack of significant correlation with the haemagglutinin inhibition assay.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=61 SRC=\"FIGDIR/small/492785_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (19K):\norg.highwire.dtl.DTLVardef@d5d8e7org.highwire.dtl.DTLVardef@1934a06org.highwire.dtl.DTLVardef@e0d0b8org.highwire.dtl.DTLVardef@1a717e0_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗