Tweet
J Virol. 2014 Jul 16. pii: JVI.00800-14. [Epub ahead of print]
Prolidase (PEPD) is required for early trafficking events during influenza A virus entry.
Pohl MO1, Edinger TO1, Stertz S2.
Author information
Abstract
Influenza A virus (IAV) entry is a multi-step process that requires the interaction of the virus with numerous host factors. In this study, we demonstrate that prolidase (PEPD) is a cellular factor required by IAV for successful entry into target cells. PEPD was selected as a candidate during an entry screen performed on non-validated primary hits from previously published genome-wide siRNA screens. siRNA-mediated depletion of PEPD resulted in decreased growth of IAV during mono- and multi-cycle growth. This growth defect was independent of cell type or virus strain. Furthermore, IAV restriction was apparent as early as 3h post-infection and experiments in the absence of protein biosynthesis revealed that nuclear import of viral ribonucleoprotein complexes (vRNPs) was already blocked in the absence of PEPD. These results led us to investigate which step during entry was affected. Receptor expression, IAV attachment or internalization were not dependent on the presence of PEPD. However, when looking at the distribution of incoming IAV particles in PEPD knockdown cells, we found a localization pattern that differed compared to control cells: IAV mostly localized to the cell periphery and consequently, viral particles displayed reduced co-localization with early and late endosome markers and fusion between viral and endosomal membranes was strongly reduced. Finally, experiments using a competitive inhibitor of PEPD catalytic activity suggest that the enzymatic function of the dipeptidase is required for its proviral effect on IAV entry. In sum, this study establishes PEPD as a novel entry factor required for early endosomal trafficking of IAV.
IMPORTANCE:
Influenza A virus (IAV) continues to be a constant threat to public health. As IAV relies on its host cell for replication the identification of host factors required by the virus is of importance: First, such studies often reveal novel functions of cellular factors and can extend our knowledge of cellular processes. Second, we can further our understanding of processes that are required for entry of IAV into target cells. Third, the identification of host factors that contribute to IAV entry will enlarge the number of potential targets for the development of novel antiviral drugs that are of urgent need. Our study identifies prolidase (PEPD) as a novel entry factor of IAV required for correct routing within the endosomal compartment following virus internalization. Thereby, we link PEPD which has been shown to play a role during collagen recycling and growth factor signaling, to early events of viral infection.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
25031340
[PubMed - as supplied by publisher]
Prolidase (PEPD) is required for early trafficking events during influenza A virus entry.
Pohl MO1, Edinger TO1, Stertz S2.
Author information
Abstract
Influenza A virus (IAV) entry is a multi-step process that requires the interaction of the virus with numerous host factors. In this study, we demonstrate that prolidase (PEPD) is a cellular factor required by IAV for successful entry into target cells. PEPD was selected as a candidate during an entry screen performed on non-validated primary hits from previously published genome-wide siRNA screens. siRNA-mediated depletion of PEPD resulted in decreased growth of IAV during mono- and multi-cycle growth. This growth defect was independent of cell type or virus strain. Furthermore, IAV restriction was apparent as early as 3h post-infection and experiments in the absence of protein biosynthesis revealed that nuclear import of viral ribonucleoprotein complexes (vRNPs) was already blocked in the absence of PEPD. These results led us to investigate which step during entry was affected. Receptor expression, IAV attachment or internalization were not dependent on the presence of PEPD. However, when looking at the distribution of incoming IAV particles in PEPD knockdown cells, we found a localization pattern that differed compared to control cells: IAV mostly localized to the cell periphery and consequently, viral particles displayed reduced co-localization with early and late endosome markers and fusion between viral and endosomal membranes was strongly reduced. Finally, experiments using a competitive inhibitor of PEPD catalytic activity suggest that the enzymatic function of the dipeptidase is required for its proviral effect on IAV entry. In sum, this study establishes PEPD as a novel entry factor required for early endosomal trafficking of IAV.
IMPORTANCE:
Influenza A virus (IAV) continues to be a constant threat to public health. As IAV relies on its host cell for replication the identification of host factors required by the virus is of importance: First, such studies often reveal novel functions of cellular factors and can extend our knowledge of cellular processes. Second, we can further our understanding of processes that are required for entry of IAV into target cells. Third, the identification of host factors that contribute to IAV entry will enlarge the number of potential targets for the development of novel antiviral drugs that are of urgent need. Our study identifies prolidase (PEPD) as a novel entry factor of IAV required for correct routing within the endosomal compartment following virus internalization. Thereby, we link PEPD which has been shown to play a role during collagen recycling and growth factor signaling, to early events of viral infection.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
25031340
[PubMed - as supplied by publisher]
