Hepatitis D

00:01 Okay, after A, B and C, comes D.

00:04 So hepatitis D, or delta virus is an interesting entity.

00:09 It is a defective single stranded RNA virus like particle.

00:14 It doesn't have a membrane around it, it cannot on its own, making an active and proficient infection.

00:24 It requires and it can only propagate in the presence of hepatitis B.

00:30 And that's because Hepatitis B provides the envelope protein that allows the virus to mature and then potentially be passed along.

00:38 So it is a co-conspirator, it required, you would never get hepatitis D alone.

00:44 You only get it in the setting of pre existing Hepatitis B infection with a chronic infection or a brand new hepatitis B infection.

00:54 Concurrently with blood that is carrying hepatitis D.

00:58 It's a blood born pathogen.

00:59 Again, there's vertical and sexual transmission.

01:03 It is a severe acute disease.

01:07 In fact, there's a very high risk with hepatitis D of severe fulminant failure about 20% of cases.

01:16 There is also a higher incidence compared to hepatitis B of chronic infection.

01:21 So about 15 million people worldwide are chronically infected, but they also have to have Hepatitis B at the same time because you can't propagate the virus without being able to make the envelope protein.

01:34 The extra hepatic manifestations are again due to immune complex deposition, chronic virus, chronic antibody immune complex.

01:43 The labs include looking at the HDV antigen and looking at antibodies against the virus.

01:49 And there is a vaccine for hepatitis B.

01:53 And if you have that, then it's impossible once you have a good immune response to get hepatitis D.

01:59 So again, the same sort of schematic story with infection at time zero viral replication, then a response of the host to the virus.

02:12 If you clear it effectively, because you are making good antibody and T-cell responses, then everything goes away.

02:18 If you don't effectively clear it, then you can get continued replication of virus in the immune complex deposition problems, as well as the chronic hepatitis.