Two envelope glycoproteins, the H and F proteins forming an H/F protein complex [12], have roles in receptor binding and membrane fusion, respectively, to introduce the ribonucleoprotein (RNP) complex, composed of the RNA genome and the N, P and L proteins, into the host cell by fusing the viral envelope with the plasma membrane (envelope fusion) and thus initiating infection [13–17]. The gene discussed is RNPC3; the disease is infection.