CD19 and disease arising from reactivation of latent virus: To define the relationship between mLANA expression in B cells and acute and latent infection, we evaluated O73.loxP and WT MHV68 infection in mice that express Cre recombinase under the control of the B cell-specific CD19 promoter [CD19Cre/+ [28]] allowing deletion of floxed ORF73 in B cells.