The GPΔ and therefore GPΔ-Res lack the mucin-like domain that is nonessential for the viral infection of cells [85,86] in the signal peptide for glycoprotein transport at the late stages of viral replication in the infected cells and in the C-terminal transmembrane region for anchoring in the lipid bilayer of virion particles (Figure 6A). The gene discussed is MUC5AC; the disease is viral infectious disease.