Effect of polypurine tract (PPT) mutations on human immunodeficiency virus type 1 replication: a virus with a completely randomized PPT retains low infectivity.
Miles LR, Agresta BE, Khan MB, Tang S, Levin JG, Powell MD. Effect of polypurine tract (PPT) mutations on human immunodeficiency virus type 1 replication: a virus with a completely randomized PPT retains low infectivity. J Virol. 2005 Jun; 79(11):6859-67.