The ability of pathogenic viruses like yellow fever virus (YFV) to evade the innate immune response is critical to their ability to survive in the host. Here we describe a method to examine the interaction of YFV nonstructural protein 5, NS5, with human signal transducer and activator of transcription 2 (STAT2) when cells expressing YFV NS5 protein are treated with type I or type III interferon. The use of a STAT2-deficient cell line combined with overexpression techniques and immunoprecipitation methods allowed us to examine the mechanism by which YFV NS5 binds human STAT2 when treated with interferon. This method has broad application in the study of virus-host interactions.