Researchers at Texas A&M AgriLife Research have essentially done a large scale screen of neurons to see which genes play a key role in sensitivity to Rabies virus infection. In a very ambitious, 5 year project, they utilized murine embryonic stem cells from a previously generated library of mutant stem cells that is classically used to generate knockout mice. Thus, they had thousands of different lines of stem cells, each theoretically containing a mutation in a different gene. The researchers then differentiated each of these stem cell lines into neurons so they could test their varying susceptibility to rabies virus infection.
Fluorescently labeled rabies virus was given to each of these neuronal cell lines containing a single genetic mutation. Then, after a few days, they analyzed the amount of fluorescence in each of the rabies infected cell lines. Lots of fluorescence correlates with high sensitivity to rabies, while little fluorescence implies a resistance against the virus. With this method, the researchers at Texas A&M AgriLife Research were able to identify 63 candidate genes that may play a role in the progression of rabies virus in the body.
While rabies virus was used in this case, this technique of screening stem cells can be applied to a lot of different infectious agents in order to help us better understand how these pathogens interact with different human genes.