Autoimmune Hepatitis Induced by Hepatitis Delta Virus: A Conundrum

Predominance of Genotype 5 Hepatitis Delta Virus Infection in a Portuguese Hepatology Unit

Hepatitis delta virus (HDV) infection is the most severe form of viral hepatitis. Genotype 1 (HDV-1) is by far the most prevalent in Europe and globally, while HDV-5 predominates in Western Africa. Data about HDV seroprevalence in Portugal are scarce and genotyping studies have not been performed yet. We aimed to assess the seroprevalence and genotypes of HDV in a large cohort of HBsAg-positive patients followed in our Hepatology Unit between 2012 and 2022. The anti-HDV-positive patients were subjected to a cross-sectional analysis, including blood sample collection for HDV RNA testing and genotype determination. In the cohort of HBsAg-positive patients, 57.5% (480/835) were born in African countries and 665/835 (79.6%) had been screened for anti-HDV antibodies. The HDV seroprevalence obtained was 6.5% (43/665). Twenty-one patients (age 41.2 ± 9.9 years; 57.1% male) were included in further molecular analyses. HDV RNA was positive in 8/21 (38.0%) and classified as HDV-5 in 7 patients (6 from Guinea-Bissau and 1 from Cape Verde) and HDV-1 in 1 patient (from Ukraine). In the largest and most comprehensive study performed in Portugal regarding HDV epidemiology to date, seroprevalence and genotype distribution of HDV (with predominance of HDV-5) were strongly influenced by immigration, notably from African countries.

Management of autoimmune hepatitis induced by hepatitis delta virus

Approximately 12-72 million people worldwide are co-infected with hepatitis B virus (HBV) and hepatitis delta virus (HDV). This concurrent infection can lead to several severe outcomes with hepatic disease, such as cirrhosis, fulminant hepatitis, and hepatocellular carcinoma, being the most common. Over the past few decades, a correlation between viral hepatitis and autoimmune diseases has been reported. Furthermore, autoantibodies have been detected in the serum of patients co-infected with HBV/HDV, and autoimmune features have been reported. However, to date, very few cases of clinically significant autoimmune hepatitis (AIH) have been reported in patients with HDV infection, mainly in those who have received treatment with pegylated interferon. Interestingly, there are some patients with HBV infection and AIH in whom HDV infection is unearthed after receiving treatment with immunosuppressants. Consequently, several questions remain unanswered with the challenge to distinguish whether it is autoimmune or "autoimmune-like" hepatitis being the most crucial. Second, it remains uncertain whether autoimmunity is induced by HBV or delta virus. Finally, we investigated whether the cause of AIH lies in the previous treatment of HDV with pegylated interferon. These pressing issues should be elucidated to clarify whether new antiviral treatments for HDV, such as Bulevirtide or immu-nosuppressive drugs, are more appropriate for the management of patients with HDV and AIH.