CD8+ lymphocytes do not mediate protection against acute superinfection 20 days after vaccination with a live attenuated simian immunodeficiency virus. by Stebbings, R, Berry, N, Waldmann, H, Bird, P, Hale, G, Stott, J, North, D, Hull, R, Hall, J, Lines, J, Brown, S, D'Arcy, N, Davis, L, Elsley, W, Edwards, C, Ferguson, D, Allen, J, Almond, N