The innate immune system plays a pivotal role in pathogen recognition and the initiation of innate immune responses through its Pathogen Recognition Receptors (PRRs), which detect Pathogen-Associated Molecular Patterns (PAMPs). Nucleic acids, including RNA and DNA, are recognized as particularly significant PAMPs, especially in the context of viral pathogens. During RNA virus infections, specific sequences in the viral RNA mark it as non-self, enabling host recognition through interactions with RNA sensors, thereby triggering innate immunity. Given that some of the most lethal viruses are RNA viruses, they pose a severe threat to human and animal health. Therefore, understanding the immunobiology of RNA PRRs is crucial for controlling pathogen infections, particularly RNA virus infections. In this chapter, we will introduce a "pull-down" method for identifying RIG-I-like receptors, related RNA helicases, Toll-like receptors, and other RNA sensors.