AAV PHP.eB-CMV-Cre

The blood-brain barrier (BBB) ​​is a physical lining between the circulatory system and the central nervous system (CNS) that prevents many water-soluble molecules and even large molecular weight lipid-soluble molecules from freely entering the CNS. Therefore, researchers have been eager to explore vectors that can effectively deliver therapeutic molecules through the blood-brain barrier to treat CNS diseases. Adeno-associated virus (AAV) is a non-enveloped single-stranded DNA molecule with a length of 4.7kb, which has attracted much attention due to its non-pathogenicity, low immunogenicity and persistent expression. AAV is commonly used in laboratory gene transfer and clinical trials of gene therapy. In humans and non-human primates, 12 AAV serotypes from AAV-1 to AAV-12 have been reported. Each of them is characterized by its tropism for specific cell types. Among them, AAV-9 has been shown to be able to penetrate the blood-brain barrier and transduce CNS cells. However, this BBB penetration only occurs when the viral load is very high and the CNS transduction efficiency is limited.

A recent study used a technique called Cre-recombination-based targeted evolution of AAV (CREATE) to create a new AAV variant, AAV-PHP.B, that was 40 times more efficient than AAV-9 in transferring genes to the CNS. However, its BBB penetration was strain- and species-dependent, being highly efficient in C57BL/6 mice and less efficient in BALB/c mice and marmosets. Subsequently, a novel variant, AAV-PHP.eB, was discovered that has DGT instead of AQT at amino acids 587-589 of the AAV-PHP.B capsid sequence and exhibits greater barrier penetration than AAV-PHP.B.