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SUMMARY:External Seminar Petr CHLANDA "Influenza A Virus Morphology-Depend
 ent Spread and Assembly revealed by in situ cryo-electron tomography"
DTSTART:20260605T080000Z
DTEND:20260605T090000Z
DTSTAMP:20260625T071700Z
UID:indico-event-420@indico.i2bc.paris-saclay.fr
DESCRIPTION:Speakers: Petr CHLANDA (Center for Quantitative Analysis of Mo
 lecular and Cellular System- BioQuant\, Heidelberg University\, Germany - 
 Department of Infectious Diseases – Virology\, Heidelberg University Hos
 pital\, Germany)\n\nPetr CHLANDA\, Center for Quantitative Analysis of Mol
 ecular and Cellular System- BioQuant\, Heidelberg University\, Germany - D
 epartment of Infectious Diseases – Virology\, Heidelberg University Hosp
 ital\, Germany\n \nTitle : "Influenza A Virus Morphology-Dependent Sprea
 d and Assembly revealed by in situ cryo-electron tomography"\n \nAbstract
  :\nInfluenza A viruses (IAV) form pleomorphic virions\, ranging from sph
 erical to filamentous shapes. These morphologies influence viral entry\, 
 spread\, and immune evasion. Laboratory-adapted strains are mostly spheri
 cal\, but the determinants of morphology in physiological conditions rema
 in unclear. To investigate this\, we generated fluorescent reporter virus
 es with identical glycoproteins but distinct morphologies and applied cor
 relative light and scanning electron microscopy. Filamentous IAV spread mo
 re slowly across cell lines\, consistent with delayed entry observed by i
 n situ cryo-electron tomography (cryo-ET)\, explaining the predominance o
 f spherical forms in labs. Spread was not affected by cellular junction i
 ntegrity\, neuraminidase (NA) activity\, or mucin\, but filamentous virio
 ns had an advantage under hemagglutinin (HA)-targeted neutralizing antibo
 dies.IAV is a segmented negative-sense RNA virus\, with eight genomic segm
 ents assembled into helical viral ribonucleoprotein complexes (vRNPs) in 
 the nucleus. vRNPs traffic via Rab11 to the plasma membrane\, where assem
 bly is orchestrated by matrix protein 1 (M1)\, HA\, and NA. Using in situ
  cryo-ET\, we found that HA-containing membranes cluster vRNPs in Rab11a 
 dependent manner. Our data show that in the absence of HA\, vRNPs cluster
  on NA-containing membranes and virus assembly remains intact\, indicating
  that vRNP clustering and trafficking are membrane-assisted but HA indepe
 ndent. Surprisingly\, M1 forms multilayered helical complexes in the nucl
 eus and cytosol\, distinct from budding virions\, and M1 layer formation 
 precedes membrane attachment and vRNP bundle formation. We further reveal
 ed that the canonical 7+1 vRNP arrangement is established only during vir
 us budding on the plasma membrane concomitantly with M1 layer formation.C
 ontact: Emmanuelle Quemin (emmanuelle.quemin@i2bc.paris-saclay.fr)\n\nht
 tps://indico.i2bc.paris-saclay.fr/event/420/
LOCATION:B21-N0-00 - Auditorium (I2BC CNRS Gif)
URL:https://indico.i2bc.paris-saclay.fr/event/420/
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