Contributed Talk  - Wednesday, 15 September I 10:50 AM (CEST)

Mammalian orthoreoviruses (reoviruses), while not recognized as common human pathogens, were shown to play a role in triggering the development of celiac disease and, conversely, also owns oncolytic properties, making it an interesting tool in cancer therapy. Here, the focus will be on the primary attachment of T1L reovirus to host cellular surface receptors, which is mainly mediated by viral protein σ1. Following attachment to host cells through σ1 binding to sialic acid and JAM-A, virions must penetrate cell membranes and uncoat to activate the viral transcription machinery. In this study, in order to determine the functional importance of σ1 conformational mobility, we investigate interaction between JAM-A receptor and different T1L mutants, which present cysteine mutations in structurally adjacent sites in the σ1 tail, body, and head domains. Force Distance (FD) curve-based atomic force microscopy (AFM) techniques was first used on JAM-A model surfaces to investigate the dynamic mechanisms by which the T1L σ1 conformational mobility is crucial for JAM-A binding. In addition, FD curve-based AFM in combination with high-resolution microscopy was used to confirm our results on living cells. Overall, results suggest that Head mutants have a higher avidity and binding probability towards JAM-A in comparison with rsT1L and that Body and Tail mutants do not show enhanced kinetics in binding to the receptor. From a single-virus biophysical approach, we show that crosslinking the σ1 head enhances the avidity of reovirus T1L for JAM-A, offering new perspectives for the development of efficacious antiviral therapeutics and engineering improved oncolytic vectors.