Fig. 4.

Shape and stability of native mavirus virions and recombinantly generated VLPs. (A) Negative stain EM of purified native mavirus virions (Left) and VLPs (Right). For VLPs, the expressed MCP variant and additionally coexpressed proteins are indicated in the image. (Scale bars: 50 nm.) For the MCPΔC/penton coexpression, sucrose gradient fractions were imaged since no VLP light scattering band was detected in these gradients for extraction and further purification. (B) Thermal disassembly of mavirus and VLPs. T_dis, disassembly temperatures for flMCP/penton-VLPs (yellow), flMCP/penton/MVP-VLPs (purple), and native mavirus (turquoise). Average and SD (error bars) are shown (n = 3). No T_dis could be determined for flMCP/penton-VLPs at pH 4.0 although intact VLPs were observed under this condition by negative stain EM. Thus, it is assumed that disassembly and aggregation were not resolved by the measurement. Similarly, we detected disassembly neither for flMCP-VLPs nor MCPΔC-VLPs.