New lentiviral platform eliminating packaging sequences from the transcribed DNA region

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All lentiviral vectors described to date contain packaging sequences necessary for the viral RNA genome to be assembled into viral particles. These sequences are unnecessarily reverse transcribed into DNA and permanently integrate into target cells. The researchers at UCL Institute of Child Health have developed a lentiviral platform which does not reverse transcribe the packaging sequences into the target cells.

The Technology and its Advantages

In all existing lentiviral vectors, packaging sequences (psi, Rev Response Element) are located between the two viral long terminal repeat (LTR) fragments and hence are within the region of the vector genome which is transcribed into host DNA. The packaging sequences are a signal necessary for assembling of the vector particle but are not needed in the target cells . Researchers at UCL Institute of Child Health developed a lentiviral vector platform which contains the packaging sequences downstream of the 3′ LTR. Such location makes them available for the packaging of viral particles but places them outside of the reverse transcribed part of the vector. Removal of the packaging sequences from the section of the vector genome which is reverse transcribed is important for many reasons. Firstly, as these sequences contain active splice acceptor sites, they pose a risk in host cells for potential splicing with other host genes leading to creation of aberrant fusion proteins. Secondly, they also enable remobilisation of self-inactivating retroviral vector genomes in cells expressing viral proteins – this poses a risk of unwanted remobilisation upon infection with HIV. Furthermore, packaging sequences also contain many CpG-rich regions undergoing DNA methylation which could potentially contribute to silencing of the transgene in target cells. Finally, removing the packaging sequences increases the transgene carrying capacity of the vector.

Market Opportunity

The technology addresses a problem faced by anyone working with lentiviral vectors, whether used for purely research purposes or in development of gene therapy. According to The Journal of Gene Medicine Clinical Trial site database, there were 1537 trials conducted until 2009. Until 2009, the seven major markets and Japan together accounted for 86% of all clinical trails conducted (Datamonitor). The greatest challenge in the development of gene therapies remains the safe delivery of genes into the target cells and this technology addresses this unmet clinical need.

Intellectual Property Status

Patent pending (PCT/GB2014/053102)

Further Information

Please contact Dr Chris Baker, Senior Business Manager|T:+44(0)20 7679 9000 |E:

The technology referred to herein is experimental in nature and UCL Business PLC makes no representations and gives no warranties of any kind, either express or implied, in relation to the technology and, in particular but without limiting the foregoing, UCL Business PLC gives no express or implied warranties of merchantability, satisfactory quality or fitness for a particular purpose.