Our goal was to analyze the changes in morphology and physiological function (phagocytosis, migratory capabilities, humoral and cellular response, and nitric oxide secretion) of murine macrophages after labeling with a clinically used superparamagnetic iron oxide (SPIO), ferucarbotran. In SPIO-treated macrophages, nanoparticles were taken up in the cytoplasm and accumulated in a membrane-bound organelle. Macrophage proliferation and viability were not modified after SPIO labeling. Phagocytic function decreased after labeling with only 10 microg Fe/mL SPIO, whereas other functions including migration and production of tumor necrosis factor-alpha and nitric oxide increased at the highest SPIO concentration (100 microg Fe/mL).

The X-ray crystallographic structure of HIV-1 capsid protein suggests that the dimer interface of the dimerization domain is mainly formed from a putative a-helix structure of 14 amino acids (Gag residues 311-324) and lies directly C-terminal to the capsid major homology region. We found that a deletion mutation in the a-helix drastically reduces virus particle production.