Chemical cross-linking stabilizes native-like HIV-1 envelope glycoprotein trimer antigens per Schiffner, T, de Val, N, Russell, RA, de Taeye, SW, de la Peña, AT, Ozorowski, G, Kim, HJ, Nieusma, T, Brod, F, Cupo, A, Sanders, RW, Moore, JP, Ward, AB, Sattentau, QJ