Differential expression patterns of type 1 interferon subtypes in mouse embryo fibroblasts: influence of genotype and viral inducer

Primary mouse embryo fibroblasts from 4 strains of mice (BALB/c, C57Bl/6, B6.C-H-28^c and CBA) were infected with either Newcastle disease virus or murine cytomegalovirus. The time course of the total type I interferon response was assessed and the presence of individual subtypes determined. The total type I interferon produced was titrated using the cytopathic effect reduction assay and the relative levels of type I interferon subtypes expressed (α1, α4, α5, α6 and β) were evaluated using a reverse transcription-polymerase chain reaction-based technique. In general, the patterns of type I interferon subtypes expressed appeared to be determined by the strain of mouse cells used rather than the inducing virus. However, the overall titre of type I interferons produced in response to a given virus was quite uniform across the strains of mice from which the mouse embryo fibroblasts were derived regardless of the subtype expression pattern. The latter observation fits the proposition that "cross-talk" or feedback between the type I interferon genes and their products is occurring and that the inducer determines the level of response.