The genetic stability of a conditional live HIV-1 variant can be improved by mutations in the Tet-On regulatory system that restrain evolution.
Live attenuated human immunodeficiency virus type 1 (HIV-1) vaccines are considered unsafe because more quickly replicating pathogenic virus variants may evolve after vaccination. As an alternative vaccine approach, we have previously presented a doxycycline (dox)-dependent HIV-1 variant that was constructed by incorporating the tetracycline-inducible gene expression system (Tet-On system) into the viral genome. Replication of this HIV-rtTA variant is driven by the dox-inducible transcriptional activator rtTA and can be switched on and off at will. A large scale evolution study was performed to test the genetic stability of this conditional live vaccine candidate. In several long term cultures, we selected for HIV-rtTA variants that no longer required dox for replication. These evolved variants acquired a typical amino acid substitution either at position 19 or 37 in the rtTA protein. Both mutations caused rtTA activity and viral replication in the absence of dox. We designed a novel rtTA variant with a higher genetic barrier toward these undesired evolutionary routes. The corresponding HIV-rtTA variant did not lose dox control in long term cultures, demonstrating its improved genetic stability.
Zhou
Xue
X
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Vink
Monique
M
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Klaver
Bep
B
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Verhoef
Koen
K
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Marzio
Giuseppe
G
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Das
Atze T
AT
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
Berkhout
Ben
B
Department of Human Retrovirology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands. Electronic address: b.berkhout@amc.uva.nl.
D016915:AIDS Vaccines / Q000737:chemistry / Q000235:genetics*; D003062:Codon; D004318:Doxycycline / Q000378:metabolism; D019143:Evolution, Molecular; D015967:Gene Expression Regulation, Viral; D014644:Genetic Variation; D015658:HIV Infections / Q000517:prevention & control*; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D013752:Tetracycline / Q000494:pharmacology; D014613:Vaccines, Attenuated; D014779:Virus Replication
D016915:AIDS Vaccines; D003062:Codon; D014613:Vaccines, Attenuated; D013752:Tetracycline; D004318:Doxycycline