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bioRxiv2022

A cell-based, spike protein binding assay highlights differences in antibody neutralising capacity for SARS-CoV-2 variants

The engagement of the SARS-CoV-2 spike protein with ACE2 is a critical step for viral entry to human cells and accordingly blocking this interaction is a major determinant of the efficacy of monoclonal antibody therapeutics and vaccine-elicited serum antibodies. The emergence of SARS-CoV-2 variants necessitates the development of adaptable assays that can be applied to assess the effectiveness of therapeutics. Through testing of a range of recombinant spike proteins, we have developed a cell based, ACE2/spike protein binding assay that characterises monoclonal anti-spike protein antibodies and neutralising antibodies in donor serum. The assay uses high-content imaging to quantify cell bound spike protein fluorescence. Using spike proteins from the original Wuhan SARS-CoV-2 virus, as well as the delta and omicron variants, we identify differential blocking activity of three monoclonal antibodies directed against the spike receptor binding domain. Importantly, biological activity in the spike binding assay translated to efficacy in a SARS-CoV-2 infection assay. Hence, the spike binding assay has utility to monitor anti-spike antibodies against the major known SARS-CoV-2 variants and is readily adaptable to quantify impact of antibodies against new and emerging SARS-CoV-2 variants.

cell biology↗

bioRxiv2020

Variation in a pleiotropic regulatory module drives evolution of head shape and eye size in Drosophila

Revealing the mechanisms underlying the breath-taking morphological diversity observed in nature is a major challenge in Biology. It has been established that recurrent mutations in hotspot genes cause the repeated evolution of rather simple morphological traits, such as body pigmentation or the gain and loss of structures. To date, however, it remains elusive whether hotspot genes contribute to natural variation in complex morphological traits, such as the size and shape of organs. Since natural variation in head morphology is pervasive in Drosophila, we studied the molecular and developmental basis of differences in compound eye size and head shape in two closely related Drosophila species. We show that differences in both traits are established late during head development and we applied comparative transcriptomics and chromatin accessibility data to identify the GATA transcription factor Pannier (Pnr) as central factor regulating these differences. Although the genetic manipulation of Pnr affected multiple aspects of dorsal head development, the effect of natural variation is restricted to a subset of the phenotypic space. We present data suggesting that this developmental constraint is caused by the co-evolution of expression of pnr and its co-factor u-shaped (ush). We propose that natural variation in highly connected developmental regulators with pleiotropic functions is a major driver for morphological evolution and we discuss implications on gene regulatory network evolution. In comparison to previous findings, our data strongly suggests that evolutionary hotspots do not contribute to the repeated evolution of eye size and head shape in Drosophila.

evolutionary biology↗