Blood samples were collected and tested for antibodies against common murine pathogens. Each column represents an animal. Each row indicates a pathogen. Filled boxes indicate positive results, lighter shaded boxes indicate equivocal (weak positive) results. White boxes indicate negative results. a, Serology results from representative pet store (n = 8), cohoused B6 (n = 26) and F1 IL-5v (n = 11) mice cohoused for approximately two weeks at the time of blood collection. b, Serology results from representative pet store and cohoused B6, F1 IL-5v, and BALB/c mice cohoused for at least two months at the time of blood collection (n = 26/group). CPIL = Clostridium piliforme, ECUN = Encephalitozoon cuniculi, EDIM = rotavirus, LCMV = lymphocytic choriomeningitis virus, MAV1+2 = mouse adenovirus 1 and 2, MCMV = murine cytomegalovirus, MHV = mouse hepatitis virus, MNV = murine norovirus, MPUL = Mycoplasma pulmonis, MPV1+2 = mouse parvovirus type 1 and type 2, MVM = minute virus of mice, POLY = polyoma virus, PVM = pneumonia virus of mice, REO = reovirus, SEND = murine respirovirus (Sendai virus), TCMV = GDVII Theiler’s murine encephalomyelitis virus. c. Representative flow cytometry histograms of protein expression of lung ILC2 in age-matched SPF (blue) and CoH (red) mice at 2wk and >2mo. Vertical gray lines are added to aid in comparison of expression among groups.