Potent inhibition of human immunodeficiency virus type 1 replication by conditionally replicating human immunodeficiency virus-based lentiviral vectors expressing envelope antisense mRNA.

We describe an HIV-based lentiviral vector that expresses a 1-kb antisense mRNA directed against the HIV-1 mRNAs containing env sequences. The expression of antisense env mRNAs (envAS) does not inhibit the synthesis of p24 expressed from the HIV-1 helper plasmid used to package the vector, as this helper has a deletion in the env gene. This allows the production of high-titer VSV-G pseudotyped lentiviral particles. In challenge experiments using unselected populations of SupT1 cells transduced with this vector, a complete inhibition of HIV-1 replication was observed for long periods of in vitro culture, even at high HIV-1 infectious doses. The potent inhibition of HIV-1 replication by this vector correlated with a low occurrence of mobilization of the vector to previously untransduced cells. The infectivity of the wild-type HIV-1 that escapes inhibition was highly inhibited, suggesting that the vector is providing HIV-1 inhibition of replication not only due to its antisense effect but also by competing for encapsidation and mobilization to noninfected cells.