Dear community,
We use viral vectors to deliver genes in optogenetic experiments in rats. I have recently read a claim that lentiviral vectors result in more localized expression as compared to AAV (e.g., Yizhar et al, Neuron 2011; Hirai, Cerebellum 2008). We usually work with AAVs as it is more simple (especially with regard to safety protocols).
1. What is your experience with this issue - did you observe such differences in your preparations?
2. If this is indeed the case, does anyone have an idea of the mechanism underlying this difference in the level of localization?
Thanks,
Roni
Hi Roni,
In the the lab I'm working in, we tried Lentiviral vectors and AAVs. Lentiviral delivery produce more consistent, and more importantly, longer lasting expression. This is unpublished data, as in the end AAVs were chosen for clinical reasons.The reason for this is that Lentiviruses integrate the DNA into the host cells, whereas AAVs are expressed episomally, and will eventually be cleared from the cells.
In regard to localization, are you talking of localization to a brain region or within a neuron?
Here is a review from our lab which might be helpful.
DOI: 10.1002/bies.201400094
best,
d
Thanks Diego, I will take a look at the paper
To clarify, I was referring to localization within a brain region
Dear Roni,
Do you deliver the virus by stereotaxis? Lentiviral normally show a restricted expression near the site of injection, while AAV spreading depends highly on the serotype you are using, as infection efficiency in different cell types depends on the serotype.
Yoy may be interested in this interesting article about the efficiency of diferent AAV serotypes to deliver genes in brain.
Yes, I deliver the virus stereotaxically.
Thanks for the paper, it should be quite helpful!
Lentiviral particles don't spread well after stereotaxic injection into brain because the particles are relatively large (~50nm if I recall correctly). In contrast, AAV particles spread more readily due to smaller size (~20nm). As mentioned, it has been stated that some AAV serotypes spread better than others in brain, for example, AAV5 is reported to spread exceptionally well when injected into striatum. Lastly, pretreatment with i.p. mannitol to your animal about 15 min ahead of viral injection has been reported to aid in spread of viral particles in the brain.
Same feedbacks,
- In my lab we did comparisons AAV/LV after stereotaxic injection (striatum, hippocampus / rat&mouse), the results show a better spreading with aav, but better level of expression with Lenti.
- I confirm the effect of the mannitol and also after LV injection in spinal cord
http://onlinelibrary.wiley.com/doi/10.1002/jnr.23468/full
Best,
Nicolas
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