Download Apical Transport of Influenza A Virus Ribonucleoprotein Requires

Apical Transport of Influenza A Virus Ribonucleoprotein
Requires Rab11-positive Recycling Endosome
Fumitaka Momose, Tetsuya Sekimoto, Takashi Ohkura, Yuko Morikawa et al.
22 June, 2011, PLoS ONE 6(6): e21123. doi:10.1371/journal.pone.0021123
Presenter: Chia-Yin Ho
Date/Time: 2011/11/17 17:10 -18:00
Commentator: Dr. Shainn-Wei Wang
Location: Room 601,Med College Building
Background:
Influenza A virus is a negative sense RNA virus, which encapsidates inside the budding eightsegmented viral ribonucleoprotein complexes (vRNPs) composed of vRNA, viral RNA dependent RNA
polymerase (RdRP) and nucleoprotein (NP) [1]. For genome packaging process, previous studies have
demonstrated that formed vRNP complexes is required to traffick to the apical plasma membrane (APM),
and the process is collaborated by
cytoskeleton, transport vesicles and/or motor proteins. Subsequent
budding of progeny influenza virus particles requires Rab11 system and related factors[2]. However, the
trafficking mechanism of the newly synthesized vRNPs during apical transport remains unclear.
Objective/Hypothesis:
To elucidate the transport mechanisms of newly synthesized vRNP and the key player that involved in
IAV egress pathway.
Results:
As revealed by combined with live cell imaging and dual color imaging, the mean velocity of IAV vRNPs
signal were initially observed similar to a microtubule- and motor protein-dependent vesicular transport.
Further confocol imaging and western blot analysis confirmed that vesicle transport- related protein
Rab11A were colocolized and coimmunoprecipitated with progeny vRNPs (or viral heterotrimeric RNA
polymerase, specifically). This colocolization accumulated to the Rab11A-positive recycling endosome (RE)
in active/ GTP-bound state, because in GDP-locked Rab11A mutation, S25N, the locolization of progeny
vRNPs signal to RE was disrupted. Furthermore, the infectivity of progeny virus produced in GDP-locked
mutation cell line was significantly reduced, indicated that active Rab11A were necessarily for the vRNP
trafficking and efficiently infectious virus production. However, the localization of vRNP to RE were
disrupted by overexpression of Rab binding domain (RBD) of Rab11 family interacting proteins (Rab11-FIPs).
Further experiment showed that class II Rab11-FIP3/4 ΔRBD did not exhibit the APM accumulation of vRNPs,
suggesting that not only targeting vRNP to RE but also functional apical recycling machinery are necessary
for the progeny vRNP trafficking and subsequent viral particle releasing.
Conclusion:
The researchers found out that with the interaction of active/GTPbound Rab11 and a heterotrimeric
form of viral RNA-dependent RNA polymerase, synthesized vRNP of influenza A virus moved along
microtubules, and finally transported to the APM, the sites of genome packaging/virion budding.
References:
1. Compans RW, Content J, Duesberg PH (1972) Structure of the ribonucleoprotein of influenza virus. J
Virol 10: 795–800.
2. Bruce EA, Digard P, Stuart AD (2010) The Rab11 pathway is required for influenza A virus budding and
filament formation. J Virol 84: 5848–5859.