Electron micrographs of LASV VLP budding from the surface of HEK-293T/17 cells expressing LASV Z alone or in combination with GPC and NP genes, and high magnification of LASV pseudoparticles. Cells expressing LASV Z (6A), Z+NP (6B), or Z+NP+GPC (6C) were harvested at 72 hours post transfection, fixed in glutaraldehyde, and embedded in agarose plugs. Cell pellets were processed for EM analysis and were imaged. Images were printed on photographic paper and were subsequently scanned and saved as high resolution tiff files. LASV Z VLP budded from the surface of cells as empty particles, noted by the lack of electron dense cores (6A). By contrast, LASV Z+NP and Z+NP+GPC appear as electron dense particles containing subcellular structures (6A and 6B). LASV VLP budding from the surface of transfected cells or approaching the cell surface are marked by black arrows. Budded LASV Z+NP+GPC VLP appeared as round, dense structures enveloped in a bilayer structure, presumably a lipid envelope, and were associated with electron dense subcellular organelles (6D). These organelles were not identified as ribosomes in these studies. Cellular ribosomes are known to associate with and be packaged into native LASV virions. The bar in each Figure equals 100 nm.
Branco et al. Virology Journal 2010 7:279 doi:10.1186/1743-422X-7-279