Polymorphism and structural maturation of bunyamwera virus in Golgi and post-Golgi compartments.
The Golgi apparatus is the assembly site for a number of complex enveloped viruses. Using high-preservation methods for electron microscopy, we have detected two previously unknown maturation steps in the morphogenesis of Bunyamwera virus in BHK-21 cells. The first maturation takes place inside the Golgi stack, where annular immature particles transform into dense, compact structures. Megalomicin, a drug that disrupts the trans side of the Golgi complex, reversibly blocks transformation, showing that a functional trans-Golgi is needed for maturation. The second structural change seems to take place during the egress of viral particles from cells, when a coat of round-shaped spikes becomes evident. A fourth viral assembly was detected in infected cells: rigid tubular structures assemble in the Golgi region early in infection and frequently connect with mitochondria. In Vero cells, the virus induces an early and spectacular fragmentation of intracellular membranes while productive infection progresses. Assembly occurs in fragmented Golgi stacks and generates tubular structures, as well as the three spherical viral forms. These results, together with our previous studies with nonrelated viruses, show that the Golgi complex contains key factors for the structural transformation of a number of enveloped viruses that assemble intracellularly.
Salanueva
Iñigo J
IJ
Department of Macromolecular Structure, Centro Nacional de Biotecnología, CSIC, Cantoblanco, 28049 Madrid, Spain.
Novoa
Reyes R
RR
Cabezas
Pilar
P
López-Iglesias
Carmen
C
Carrascosa
José L
JL
Elliott
Richard M
RM
Risco
Cristina
C
D000818:Animals; D002042:Bunyamwera virus / Q000502:physiology* / Q000648:ultrastructure; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D005614:Freeze Fracturing; D006056:Golgi Apparatus / Q000187:drug effects / Q000648:ultrastructure / Q000821:virology*; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence