Targeted Genetics reports the issuance of a patent that describes the use of adeno-associated virus (AAV) vectors that more efficiently express therapeutic genetic constructs. "The issuance of Targeted Genetics' latest patent adds to a portfolio of intellectual property that enhances the utility of AAV vectors in two important ways,” points out Barrie J. Carter, Ph.D., executive vp, CSO, and inventor on the patent. “First, for expressing therapeutic genes in order to add back necessary proteins to prevent or correct a disease state, and second, for expressing therapeutic RNA molecules, such as RNAi, which can silence or block the expression of abnormal proteins associated with other disease states.
“Abnormal production of proteins is the cause of many human diseases, and RNAi naturally occurs within cells to regulate gene expression, thus blocking or silencing the production of specific disease causing proteins,” Dr. Carter explains. “The use of AAV Vectors described in this patent to express these specific double-stranded therapeutic RNAs, such as RNAi, may specifically block the expression of these abnormal proteins associated with disease.”
For the therapeutic gene of interest to be expressed, single-stranded DNA vectors like AAV require conversion to a double-stranded DNA form. The AAV vector DNA is about 4.7 Kb in size. However, a significant number of either genes used in gene therapy or genetic constructs, such as expressed RNA or RNAi, are approximately half this size or less.
This patent is the first to demonstrate that AAV vectors containing genetic sequences that are roughly half the size of an AAV payload can form intrastrand-based pairing, rapidly converting the therapeutic construct to an expressible form, explains Targeted Genetics. "The key is that utilizing these vectors may allow us to treat disease by essentially turning on or turning off gene expression associated with disease states," asserts H. Stewart Parker, president and CEO.