Article
Author: Aydin, Malik ; Baker, Alexander T ; Cerullo, Vincenzo ; Ciancaglini, Matias ; Sallard, Erwan ; Pinschewer, Daniel ; Wang, Xiaoyan ; Kreppel, Florian ; Schmidt, Natascha ; Zhang, Wenli ; Singharoy, Abhishek ; Pembaur, Daniel ; Jönsson, Franziska ; Grimm, Dirk ; Parker, Alan L ; Schröer, Katrin ; Viitala, Tapani ; Hamdan, Firas ; Weklak, Denice ; Ehrhardt, Anja ; Musielak, Carmen ; Schellhorn, Sebastian ; Bayer, Wibke ; Chan, Chun Kit ; Sarkar, Daipayan ; Scurti, Elena ; Feola, Sara ; Kemp, Vera ; Koukou, Georgia ; Manov-Bouard, Lucie ; Chabot, Elise ; Beaude, Nissai
The adenoviral vector-based AstraZeneca and Janssen COVID-19 vaccines have been associated with rare cases of thrombosis, believed to be triggered, among other factors, by vector binding to the blood protein platelet factor 4 (PF4). To identify vectors with lower thrombosis risk, we screened 50 natural and hexon-modified adenoviruses (Ads). Unlike the applied COVID-19 vaccines and most tested vectors, Ad34 and Ad80, as well as Ad5 vectors with deleted or chemically shielded hexon hyper-variable region 1 (HVR1), did not bind to PF4. Furthermore, interactions with PF4 substantially modified Ad5 infectivity in various immortalized and primary cells, suggesting that PF4 may influence existing vector tropism. Finally, HVR1-deleted Ad5 and Ad34 vectors expressing SARS-CoV-2 spike S1 domain were tested as vaccine candidates in mice and induced robust cellular immune responses. Therefore, the identified PF4 non-binding vectors may represent safe and efficient candidates for clinical applications.