Minor species of non-genomic nucleic acid are some times also found in virions. The encapsidated nucleic acid is mainly of genomic origin, but virions may also contain subgenomic RNA. The complete genome is 7450 nucleotides long. The genome has a guanine + cytosine content of 49.3–50.1 %. The 5' end of the genome has a usually genome-linked protein (VPg), or methylated nucleotide cap (in the case of Hepatitis E virus). The 3' terminus has a poly (A) tract. Each virion contains a full length copy, or defective interfering copies. The viral genome encodes viral structural protein. Virions consist of 1 structural protein(s) (major species located in the capsid. Viral structural protein: Capsid protein has a molar mass of 59000–71000 Da; is the coat protein. Capsid protein has a molecular mass of minor 'soluble' 28–30 kDa. Cross-reactivity is found. Cross-reactivity between species of the same serotype, but not with species of another serotype and some species of the same serotype, but not with all. Although the degree of antigenic specificity varies with the degree of relatedness, the antigenicity is distinct from serogroups of the same genus. Most species in the genus are related antigenically. They are sharing some epitopes in the structural proteins.