| Arenaviruses are enveloped, negative-strand RNA viruses. The release of their virions from the host membrane is thought to be promoted by the viral matrix protein Z through its interaction with components of the ESCRT (cellular endosomal sorting complex required for transport) machinery. During assembly, the nucleoprotein NP encapsidates the viral genome to form nucleocapsids, which are then recruited into newly forming viral particles. This process is currently poorly understood. The aim of my study is to understand the molecular mechanism of arenavirus assembly, specifically to indentify viral and host determinants of the incorporation of nucleocapsids into virions.;In Chapter 2, I focused on viral proteins and demonstrated that the expression of the Z and NP proteins of Mopeia virus resulted in the highly selective incorporation of NP protein into Z protein-induced virus-like particles (VLPs). I also found that Z protein actively promoted NP association with cellular membranes, suggesting that the association between NP, Z, and the membranes may facilitate efficient NP incorporation into VLPs. Further, by employing a series of NP deletion constructs and testing their VLP incorporation, I demonstrated an important role for the C-terminal half of NP in VLP incorporation.;In Chapter 3, I focused on the host factors involved in virus assembly. I found that ALIX/AIP1, an ESCRT-associated host protein, is required for the incorporation of NP into VLPs. I showed that the Bro1 domain of ALIX/AIP1 interacts with NP and Z simultaneously, and I identified residues 342-399 within NP as necessary for the NPALIX/AIP1 interaction. My observations suggest that ALIX/AIP1 facilitates the association between Mopeia NP and Z, promoting NP incorporation into VLPs.;In summary, my results imply that the association between the Mopeia virus NP and Z proteins and the ESCRT pathway is required for NP virion incorporation. |
