A) Amino acid sequences for the B22 family members in ECTV Moscow, VARV BG1975, CPXV Brighton Red or MPXV Zaire were analyzed for sequence similarity via pBLAST (NCBI), with sequence differences highlighted. Sequences were obtained from the Viral Bioinformatics Resource Centre. B-C) Either B) C57Bl/6 fibroblasts or C) BMDCs were infected with WT ECTV (GFP), ECTVΔC15 or ECTVrevC15 at a MOI of 3 in triplicate and infectious lysates were harvested at various times post infection and analyzed for infectious units via focus forming assay. Representative of two independent experiments. Significance analyzed by two way ANOVA, error bars signify SEM. D) BALB/c mice were infected with either ΔC15 ECTV or ECTVrevC15 and morbidity and mortality were assessed daily. Representative of two independent experiments. Significance analyzed by Kaplan-Meier estimate, **p<0.01.