In contrast, the minimal independent binding unit in G13-Tz-ECD100 is a tetrameric ECD containing 4 CRDs. The CRD positions are fixed in each ECD unit and cannot readily adjust relative positions to adapt to viral surface glycans, making it difficult to form strong multivalent binding. In fact, most natural multimeric lectins have fixed CRD presentations, allowing them to recognize specific, spatially matched multivalent glycans. However, their CRDs often lack the flexibility and adaptability required to achieve complete viral inhibition, making them ineffective as antiviral reagents. The G13-OH control showed no significant inhibition as expected, demonstrating that viral inhibition is due to specific lectinglycan interactions. Camostat (an inhibitor of the SARS-CoV-2 S protein activating protease TMPRSS2) exhibited no inhibitory effect even at 100 µM, as expected, since Vero cells do not express TMPRSS2. In contrast, chloroquine displayed significant inhibition at ~100 µM, as expected.