Figure 1. Membrane-enclosed structure containing multiple cores.

(a–c) Slices through a tomogram of a typical multi-core membrane-enclosed structure found in the supernatant of a HIV-1 BaL producing T-cell line culture. Each core is designated with the same digit in all slices. Envelope glycoproteins decorating the outer membrane are circled. (d) 3D rendering of the tomogram in a–c. Cores 1, 3 and 4 lay close to the membrane along their sides. Core 2 floats in the centre of the membrane-enclosed volume. Scale bars, 50 nm.