Sortida del virus de l’hepatitis a dels hepatòcits: implicacions en la selecció d’antivirals

• Autores: Montserrat de Castellarnau Serra
• Directores de la Tesis: Rosa María Pintó Solé (dir. tes.), Albert Bosch i Navarro (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2018
• Idioma: español
• Tribunal Calificador de la Tesis: Miguel Ángel Martínez de la Sierra (presid.), Enric Ribes Mora (secret.), Josep Quer Sivila (voc.)
• Programa de doctorado: Programa de Doctorado en Biotecnología por la Universidad de Barcelona
• Materias:
  • Ciencias de la vida
    • Microbiología
    • Virología
      • Enterovirus
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• Resumen

  • Hepatitis A virus (HAV) is a hepatotropic member of the Picornaviridae family with very special molecular features. Among these features, an unexpected exit pathway through its envelopment into exosomes has been recently described. The mechanism of HAV sorting into the exosome-containing multi-vesicular bodies involves the interaction with the ALIX protein. In the present work using two HAV strains, which differ in their replication capacity, we show that indeed ALIX plays a role in the formation of HAV quasi-enveloped particles in human hepatocytes. Human hepatocytes (Huh7-AI cell line) show an increased level of expression of ALIX over time, and they respond to virus replication by increasing the levels of ALIX mRNA synthesis. Huh7-AI cells infected with a fast-growing strain of HAV (HM175-HP; HP) showed an increase of ALIX expression compared to cells infected with a slow-growing strain (HM175-L0; L0). Additionally, the HP strain showed to be much less sensitive to ALIX silencing than the L0 strain. Analysis of quantitative confocal microscopy of the capsid protein and ALIX, in Huh7-AI cells, revealed a higher proportion of HP capsids rather than L0 capsids co-localizing with ALIX. These results point out to a more efficient interaction of HP capsids with ALIX, which correlates with a higher release of capsid containing-exosomes in the HP population. The fast-growing phenotype of the HP strain respond to a combination of features including a more efficient IRES, an optimized codon usage and a more efficient system to egress from the cell. Moreover, this work shows how the mechanism of virus egress could be a potential target for new antiviral therapy.