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Figure 2 | Infectious Agents and Cancer

Figure 2

From: Bovine papillomavirus E5 and E7 oncoproteins in naturally occurring tumors: are two better than one?

Figure 2

E5 and E7 can improve BPV activity by controlling the viral replication and persistence, and virus assembly. A schematic view of the expression of the BPV E5 and E7 genes in epithelium. BPV gene expression is tightly regulated and strictly linked to epithelial differentiation. In BPV naturally occurring epithelial tumours E5 and E7 colocalize in the basal layer. The expression of E5 and E7 in the basal layers of the epithelium, would lead to sustained cell proliferation to favour virus-infected cells. E5 also could contribute to a successful BPV infection establishment and persistence by inducing evasion of immune surveillance. In cutaneous fibropapillomas E7 is also expressed in the spinous layers suggesting its implications in viral DNA amplification, instead E5 is expressed in more differentiated granular layers suggesting its involvement in the late stages of virus life cycle (capsid synthesis). In fibropapillomas of the upper gastrointestinal tract E5 is expressed only in the basal layers, moreover E7 is expressed also in more differentiated spinous and granular layers suggesting its involvement in viral DNA amplification and in the late stages of virus life cycle. In bovine urinary bladder cancer E5 and E7 are expressed only in the basal layers.

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