Differential Biological Activities of E.coli Produced Murine IFN-Alpha Proteins on B16-F10 Cells
The mouse genome contains 14 interferon-α (IFN) genes that are temporally and differentially transcribed in a cell-type specific and stimulus dependent manner. The biological consequences of the inferred protein expression depend upon the activity of the subtypes expressed. Additionally, there is accumulating data suggesting that the biological activities between different IFN-α subtypes vary depending on the assay and cell line used for in vitro analysis. To examine this, we compared the hallmark IFN pleiotropic activities of 13 individual Mu IFN-α proteins expressed and purified from E.coli on the mouse B-16-F-10 melanoma cell line. The cytopathic protective effect (CPE) was tested by pre-treatment of cells with each IFN-α subtype preparation subsequently challenged with either EMCV or VSV. The specific activities were determined using the NIH mouse IFN-α protein standard (Ga02-901-511). The antiviral activity of each individual subtype was tested in both the B16-F-10/EMCV CPE assay as well as the standard L929/EMCV CPE assay. We observed a good correlation of the antiviral activities in both assays thus illustrating this mouse melanoma cell is an appropriate model for evaluation of mouse IFN biological activities. In addition, we performed antiproliferative testing on B-16-F-10 cells. While the antiviral and antiproliferative activities varied between the individual subtypes in each assay, we did observe a general correlation in both formats tested. For example, Mu IFN-α11 displayed the highest antiviral and antiproliferative activity while, in contrast, IFN-α7 produced the lowest values. These data suggest that the antiviral and antiproliferative activities of the recombinant mouse IFN-α subtypes are closely related in murine B16-F10 melanoma cells. We have begun developing a system which enables the dissection of the differential activities profile of the Murine IFN-α subtypes.