Fig. 3

Novel polyadenylation site usage for preVI. a The transcript structure of transcripts coding for three proteins classically considered to be L3 proteins viz preVI, hexon and 23K proteinase. The three vertical boxes on the left represent the tripartite exons, labelled TPL1, TPL2 and TPL3, and normally included in all major late transcripts generated by mammalian adenoviruses. The L3 transcripts would classically share the same L3 polyadenylation site (indicated on the diagram). In this diagram, the dominant transcripts seen in ChAdOx1 nCoV-19-infected 293 cells for each ORF are coloured red. This figure includes, in black, the transcript structure for observed transcripts that would both code for preVI and fit the canonical transcript structure for an L3 transcript, utilising the L3 polyadenylation site. In the case of 293 cells, however, there are only 192 copies of this transcript compared to 403 copies of the novel preVI transcript indicated in red at the bottom of a. b The sequences at the proposed polyadenylation site on ChAdOx1 showing the location of the polyadenylation signal and the GU-rich region that is often present downstream of a polyadenylation signal. c The equivalent regions in the genome of human adenoviruses 5 (a species C adenovirus) and human adenovirus type 4 which is, like ChAdOx1, a species E adenovirus. Taken together, b, c and d illustrate the similarities between the two species E adenovirus genomes and their distinction from a species C adenovirus genome