Influences on the design and purification of soluble, recombinant native-like HIV-1 envelope glycoprotein trimers by Ringe, R, Yasmeen, A, Ozorowski, G, Go, E, Pritchard, L, Guttman, M, Ketas, T, Cottrell, C, Wilson, I, Sanders, R, Cupo, A, Crispin, M, Lee, K, Desaire, H, Ward, A, Klasse, P, Moore, J