Figure 1.

Modifications of HIV-1 genome for developing a vector plasmid with improved safety. Various critical accessory and regulatory components within the HIV-1 genome are removed or substituted in order to construct a safe viral vector. LTR, long-terminal repeats; gag, group-specific antigen; pol, DNA polymerase; vif, viral infectivity factor; vpr, viral protein R; vpu, viral protein u; nef, negative regulator factor; env, viral envelope; RRE, rev response element; tat, transactivator of transcription; rev, transactivating protein; CMV, cytomegalovirus; RSV, respiratory syncytial virus.