Complex sentence: These receptors are critical to the first line of immunological defense against a broad range of pathogens, and normally double-stranded RNA molecules from an infection with RNA viruses bind to TLR-3 receptors.
Split into simpler sentences: These receptors are critical to the first line of immunological defense against a broad range of pathogens. Normally double-stranded RNA molecules from an infection with RNA viruses bind to TLR-3 receptors.