Mice were housed in individually ventilated cages during the MHV68 infection period. MHV68 stocks were grown and quantified by plaque assay as previously described (Adler et al., 2000). Mice were infected intranasally (i.n.) with 5 × 10∗4 plaque forming units of MHV68 diluted in PBS in a total volume of 30 μl. Prior to i.n. infection, mice were anesthetized with medetomidine–midazolam–fentanyl. At the predetermined time points, mice were sacrificed by cervical dislocation and lung tissue was processed for subsequent experiments. All lobes were removed, minced and transferred for mild enzymatic digestion for 20-30 min at 37°C in an enzymatic mix containing Dispase (50 caseinolytic U/mL), Collagenase (2 mg/mL), Elastase (1 mg/mL), and DNase I (30 μg/mL). Single cells were harvested by straining the digested tissue suspension through a 70μm strainer. After centrifugation at 300 x g for 5 min, single cells were counted, and prepared as a single cell suspension. For Drop-seq, cells were aliquoted in PBS supplemented with 0.04% of bovine serum albumin at a final concentration of 100 cells/μl.