Unlike other alternative viral translation mechanisms that escape the use of Cape Town, we propose here a cap-dependent alternative possibility to initiate a translation of the mRN of the influenza virus. The results presented, which show a normal progression of influenza infection during cape-related functional impairment of the eIF4E factor, contradict a growing list of reports indicating decreased dependence on the cellular cap-smoothing factor for viral translation of cap-mRNA performed by different viruses with cap 5-inch structures (adenovirus, vesicular stomatitis virus and dengue virus). They also seem to indicate that this mechanism is more widespread than expected and that it could be a system developed by certain viruses to escape the requirement of a fully active initiation complex, which contributes to the suppression of the translation of the MRA from the host cell. Influenza virus polymerrase sub-units are associated with translation initiation complexes. (A) Cytosolic extracts of mocked or VIC-infected HEK293T cells were applied to sucrose gradients and treated as described in materials and methods. Samples were used for immunoprecipitation (IP) studies containing specific antibodies against the eIF4GI protein (I) or the preimunserum (C). (B) HEK293T cells were infected with the DelNS1 strain and cytosolic extracts were immunized as described above (A) to analyze the proteins associated with western blotting. (C) HEK293T cells were not transtransefleed (MOCK) or by co-transferring with plasmids that expressed PB1, PB2 and PA (PB1-PB2-PA) and cytosolic extracts were produced and immunized with the antiserum eIF4GI as described above. The polymer proteins associated with eIF4GI were analyzed by Western Blotting. The translation of cellular RNA is strongly inhibited in influenza-infected cells. Some of the viral activities exclude the translation of novo-synthesized cellular IRNM. Thus, infection reduces the synthesis of cellular MRNNs, probably as a result of induced cap-snatching viral activity, and inhibits nucleocytoplasic transport of cellular aRNs (32). Later in infection, there is cytoplasmic degradation of cellular NNNMs (2, 29).
In addition, the virus has developed mechanisms to selectively distinguish and translate its 5-capped and 3-polyadnyities mNAr among previously accumulated cellular IMNNs. As mentioned above, the NS1 protein plays an important role in the effective translation of lateviral RNIs. However, given the phenotypes presented by several viruses mutated by NS1, other viral mechanisms must work to effectively discriminate and translate viral NIRIs.