Cryo-EM structure of enteric adenovirus HAdV-F41 highlights structural variations among human adenoviruses
Enteric adenoviruses, one of the main causes of viral gastroenteritis in the world, must withstand the harsh conditions found in the gut. This requirement suggests that capsid stability must be different from that of other adenoviruses. We report the 4-Å-resolution structure of a human enteric adenovirus, HAdV-F41, and compare it with that of other adenoviruses with respiratory (HAdV-C5) and ocular (HAdV-D26) tropisms. While the overall structures of hexon, penton base, and internal minor coat proteins IIIa and VIII are conserved, we observe partially ordered elements reinforcing the vertex region, which suggests their role in enhancing the physicochemical capsid stability of HAdV-F41. Unexpectedly, we find an organization of the external minor coat protein IX different from all previously characterized human and nonhuman mastadenoviruses. Knowledge of the structure of enteric adenoviruses provides a starting point for the design of vectors suitable for oral delivery or intestinal targeting ; This work was supported by grants PID2019-104098GB-I00/AEI/10.13039/501100011033 and BFU2016-74868-P, cofunded by the Spanish State Research Agency and the European Regional Development Fund; BFU2013-41249-P and BIO2015-68990-REDT (the Spanish Adenovirus Network, AdenoNet) from the Spanish Ministry of Economy, Industry, and Competitiveness; and the Agencia Estatal CSIC (2019AEP045) to C.S.M. The CNB-CSIC is further supported by a Severo Ochoa Excellence grant (SEV 2017-0712). Work in M.B's. lab was supported by grant 194562-08 from the Natural Sciences and Engineering Research Council of is a recipient of a Juan de la Cierva postdoctoral contract funded by the Spanish State Research Agency. M.P.-I. holds a predoctoral contract from La Caixa Foundation (ID 100010434), under agreement LCF/BQ/SO16/52270032. Access to CEITEC was supported by iNEXT, project number 653706, funded by the Horizon 2020 Programme of the European Union. The CEITEC Cryo-electron Microscopy and Tomography core facility is supported by MEYS CR (LM2018127)