The guanine nucleotide exchange factor GBF1 participates in rotavirus replication

José L. Martínez; Francesca Arnoldi; Elisabeth M. Schraner; Catherine Eichwald; Daniela Silva-Ayala; Eunjoo Lee; Elizabeth Sztul; Óscar R. Burrone; Susana López; Carlos F. Arias

expression by RNA interference, or inhibiting its activity by treatment with Brefeldin A 23 (BFA) or Golgicide A (GCA) significantly reduce the yield of infectious viral progeny. This 24 reduction in virus yield was related to a block in virus assembly since in the presence of either 25 BFA or GCA the assembly of infectious mature triple-layered virions was significantly 26 prevented and only doubled layered-particles were detected. We report that the catalytic 27 activity of GBF1, but not the activation of Arf1, is essential for the assembly of the outer 28 capsid of rotavirus. We show that both BFA and GCA, as well as interfering with the 29 synthesis of GBF1, alter the electrophoretic mobility of glycoproteins VP7 and NSP4 and 30 block the trimerization of the virus surface VP7, a step required for its incorporation into 31 virus particles. Although a post-translational modification of VP7 (other than glycosylation) 32 could be related to the lack of trimerization, we found that NSP4 might also be involved in 33 this process, since knocking-down its expression reduces VP7 trimerizarion. In support, The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/619924 doi: bioRxiv preprint and VP4. The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/619924 doi: bioRxiv preprint