Delivery of tamoxifen to Pdgfrα-CreERT2 :: RphiGT transgenic mice induces the expression of TVA and RVG in PDGFRα+ OPCs, renders OPCs susceptible to infection and labeling by the SADΔG-GFP-(EnvA) virus, and allows the monosynaptic transfer of the virus to label neurons that directly synapse with the labeled OPCs in vivo (Mount et al., 2019). The gene discussed is PDGFRA; the disease is infection.