3 ms·

I think that the commonly used virus is a variant of rabies, which can definitely cross the blood brain barrier.

• mattkrause 10y ago
  This paper uses AAV (adeno-associated virus), which is probably the most common viral vector for optogenetics. There are several other options, including lentivirus and--yes, rabies. They all have slightly different properties in terms of their propensity to infect different cell types, payload capacity, and so on. Rabies has the interesting ability to move trans-synaptically. Specifically, it moves "backwards" from a post-synaptic cell into its presynaptic partners. This makes it very useful for studies where you want to label or manipulate connections between areas. On the other hand, this would make it more difficult to study all cells or all cells of a specific type in one area. Incidentally, I'm not sure if rabies crosses the blood-brain barrier per se. It moves up to the brain via peripheral nerves instead of circulating through the blood. In fact, the blood brain barrier may be a problem for rabies because it prevents immune cells from cleaning out the virus inside the central nervous system.