Browsing by Author "Ferreira, Filipe"
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- Influenza A virus ribonucleoproteins form liquid organelles at endoplasmic reticulum exit sitesPublication . Alenquer, Marta; Vale-Costa, Sílvia; Etibor, Temitope Akhigbe; Ferreira, Filipe; Sousa, Ana Laura; Amorim, Maria JoãoInfluenza A virus has an eight-partite RNA genome that during viral assembly forms a complex containing one copy of each RNA. Genome assembly is a selective process driven by RNA-RNA interactions and is hypothesized to lead to discrete punctate structures scattered through the cytosol. Here, we show that contrary to the accepted view, formation of these structures precedes RNA-RNA interactions among distinct viral ribonucleoproteins (vRNPs), as they assemble in cells expressing only one vRNP type. We demonstrate that these viral inclusions display characteristics of liquid organelles, segregating from the cytosol without a delimitating membrane, dynamically exchanging material and adapting fast to environmental changes. We provide evidence that viral inclusions develop close to endoplasmic reticulum (ER) exit sites, depend on continuous ER-Golgi vesicular cycling and do not promote escape to interferon response. We propose that viral inclusions segregate vRNPs from the cytosol and facilitate selected RNA-RNA interactions in a liquid environment.
- KIF13A mediates influenza a virus ribonucleoproteins traffickingPublication . Ramos-Nascimento, Ana; Kellen, Bárbara; Ferreira, Filipe; Alenquer, Marta; Vale-Costa, Silvia; Raposo, Graça; Delevoye, Cédric; Amorim, Maria JoãoInfluenza A is a rapid evolving virus, successful in provoking periodic epidemics and occasional pandemics in humans. Viral assembly is complex as the virus incorporates an eight-partite segmented genome of RNA (in the form of viral ribonucleoproteins, vRNPs). Genome assembly, with implications to public health, is not completely understood. It was reported that vRNPs are transported to the cell surface on Rab11 vesicles using microtubules, but no molecular motor has been assigned to the process. Here, we have identified KIF13A, a member of the kinesin-3 family, as the first molecular motor efficiently transporting vRNP-Rab11 vesicles during IAV infection. Depletion of KIF13A resulted in reduced viral titres and less accumulation of vRNPs at the cell surface, without interfering with the levels of other viral proteins at sites of viral assembly. In addition, in overexpression conditions and using two artificial methods able to displace vRNP-Rab11 vesicles, KIF13A augmented vRNP levels at the plasma membrane. Together our results show that KIF13A is an important host factor promoting influenza A vRNP transport, which is a crucial step for viral assembly.