In James Binley and John P. Moore's News and Views article of 22 May (“HIV-cell fusion: The viral mousetrap” Nature 387, 346–348; 1997), acknowledgement for the origin of Fig. 2 should have appeared as “Adapted from Fig. 2 of reference 5” (Gallaher, W. R., Ball, J. M., Garry, R. F., Griffin, M. C. & Montelaro, R. C. “A general model for the transmembrane proteins of HIV and other retroviruses”, AIDS Res. Hum. Retroviruses 5, 431-440; 1989). In the same article, the references in the passage, “Moreover, soluble CD4 can activate fusion of ⃛ HIV-2 (ref. 13) and some primary forms of HIV-1 (ref. 12)⃛” were transposed and should have been printed as they are here.