Trimeric HIV-1-env structures define glycan shields from clades A, B, and G di Stewart-Jones, G, Soto, C, Lemmin, T, Chuang, G, Druz, A, Kong, R, Thomas, P, Wagh, K, Zhou, T, Behrens, A, Bylund, T, Choi, C, Davison, J, Georgiev, I, Joyce, M, Kwon, Y, Pancera, M, Taft, J, Yang, Y, Zhang, B, Shivatare, S, Shivatare, V, Lee, C, Wu, C, Bewley, C, Burton, D, Koff, W, Connors, M, Crispin, M, Baxa, U, Korber, B, Wong, C, Mascola, J, Kwong, P