Thanks for your response John, that helps me a lot. 6 years is a long time. I looked a little further, and found an indication in brain injected tissue that intact vector persists there too for at least 1 month. This report suggested the intact vector was not still active as transfection of nearby tissue did not occur after destroying the transfected cells….

I will be careful with my terminology! 

Hello Karin.  That is a good question and one that, unfortunately there is not a clear answer for.  Systemic AAV (outside of cells) is usually neutralized as soon as the animal makes an antibody response to the vector (1-2 weeks).  You will no longer be able to find vector in the blood or other fluids.  As for vector in the tissue, unfortunately I don't know what the answer is.  After transduction, the majority of vector accumulates around the nucleus in perinuclear vesicles.  I think these can persist for quite a while.  In the retina, intact AAV particles have been shown to persist for up to 6 years (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835079/).   Whether or not this perinuclear AAV is still infectious is a question that I don't know the answer to. 

I would also be hesitant of using the word 'infectious' when referring to AAV vector (especially when discussing with a safety committee that might not be familiar with the difference between a vector and a virus).  Infection infers invasion and multiplication in a host.  AAV vectors contain no viral genes, so there is no chance of replication. 

Good luck,

John

Thanks for your response John, that helps me a lot. 6 years is a long time. I looked a little further, and found an indication in brain injected tissue that intact vector persists there too for at least 1 month. This report suggested the intact vector was not still active as transfection of nearby tissue did not occur after destroying the transfected cells….

I will be careful with my terminology!