Similarities in the charge distribution patterns of different immunomodulatory viral sequences. Charge distribution patterns of different immunomodulatory viral sequences. Primary sequence analysis of proven and predicted immunomodulatory sequences of viral fusion protein regions and other domains shows a similarity in charge distribution pattern with two essential positively charged residues spaced apart by 4 (class I) or 8 (class III) amino acids or with three essential positively charged residues spaced apart by 3 amino acids (class II), suggesting a similarity of the SCHOOL-based mechanisms used by diverse viruses in their pathogenesis to modulate the host immune response. Abbreviations: TCR, T-cell receptor; CP, core peptide; HIV, human immunodeficiency virus; gp, glycoprotein; FP, fusion peptide/protein; TMD, transmembrane domain; CKS-17, a synthetic retroviral envelope heptadecapeptide; Fr-MLV, Friend murine leukemia virus; gp, glycoprotein; HHV-6 U24, human herpesvirus 6 U24 protein; HTLV-1, human T lymphotropic virus type 1; HVA, herpesvirus ateles; HVS, herpesvirus saimiri; ITAM, immunoreceptor tyrosine-based activation motif; LASV, Lassa virus; LCMV, lymphocytic choriomeningitis virus; MARV, Marburg virus; MOPV, Mopeia virus; SARS-CoV, severe acute respiratory syndrome coronavirus; SEBOV, Sudan Ebola virus; TACV, Tacaribe virus; Tip, tyrosine kinase interacting protein; Tio, two-in-one protein; TMD, transmembrane domain; ZEBOV, Zaire Ebola virus.