[Advance in the study on delta agent].
D000818:Animals; D006509:Hepatitis B / Q000150:complications* / Q000276:immunology; D006515:Hepatitis B virus / Q000276:immunology; D003699:Hepatitis D / Q000150:complications* / Q000453:epidemiology / Q000276:immunology; D003698:Hepatitis Delta Virus / Q000032:analysis / Q000276:immunology*; D006801:Humans