Toward the understanding of DSG2 and CD46 interaction with HAdV-11 fiber, a super-complex analysis

Abstract

ABSTRACT Among human species B adenovirus, HAdV-11, has the particular feature of exploiting two primary receptors, desmoglein 2 (DSG2) and CD46, to mediate cell attachment. This serotype represents a particularly promising class of oncolytic viral vaccines. For instance, Enadenotucirev, a species B HAdV-11/HAdV-3 chimeric adenoviral vector, demonstrated preclinical tumor-selective cytotoxicity. Understanding the mechanism of HAdV-11 entry is a major challenge for the development of powerful vectors. Interactions between HAdV-11 and CD46 are well-characterized and clearly depend on the fiber protein, but the mechanism whereby HAdV-11 engages DSG2 has been still unresolved. In this study, we described a new cryo-EM structure of the HAdV-11 fiber in complex with DSG2. Kinetic interaction studies demonstrated that the binding stability of the HAdV-11 in complex with DSG2 was significantly lower than with CD46. Furthermore, competition assays with pseudotyped viruses suggested that the interaction of the HAdV-11 fiber with DSG2 was not required for infection but that DSG2 could serve as a receptor in the absence of CD46. Unexpectedly, we succeeded to isolate a HAdV-11 fiber/DSG2/CD46 “super complex” showing that these two receptors could simultaneously bind to the same trimeric HAdV-11K. Our work deciphers the use of two independent receptors by HAdV-11 from a biochemical and structural point of view, which can have an impact for future vectors design. IMPORTANCE The main limitation of oncolytic vectors is neutralization by blood components, which prevents intratumoral administration to patients. Enadenotucirev, a chimeric HAdV-11p/HAdV-3 adenovirus identified by bio-selection, is a low seroprevalence vector active against a broad range of human carcinoma cell lines. At this stage, there’s still some uncertainty about tropism and primary receptor utilization by HAdV-11. However, this information is very important, as it has a direct influence on the effectiveness of HAdV-11-based vectors. The aim of this work is to determine which of the two receptors, DSG2 and CD46, is involved in the attachment of the virus to the host, and what role they play in the early stages of infection.