1Barts Liver Centre, Blizard Institute, Barts and The London, School of Medicine & Dentistry, Queen Mary University of London, London, United Kingdom.
Hepatitis delta virus (HDV) is known to cause the most aggressive and severe form of viral hepatitis, yet it remaind under-diagnosed, but does require early diagnosis for accurate disease staging. Antibody to HDV (anti-HDV) is the primary screening tool and should be assessed in patients with hepatitis B surface antigen (HBsAg) positivity, as HDV is a satellite RNA virus of hepatitis B. Additionally, the viral load (HDV RNA) should be assessed in those with positive anti-HDV, to differentiate between active infection and resolved hepatitis delta. Data regarding immune responses in HDV are limited, but show dysfunctional adaptive and innate immunity. Many studies however fail to distinguish between active and resolved infection. Limited treatments are available for HDV, but promise has been shown with the newly approved Bulevirtide, a first-in-class HBV entry-inhibitor. Thus immune response during therapy require further investigsation, alongwith additional targets for HDV cure.