Hepatitis D Virus

Slide 1 · Hepatitis D Virus

Viral dependence · clinical patterns · liver injury

Dr Abu Suraih Sakhri

MBBS, MD (Pathology)

www.abusuraihsakhri.com

Slide 2 · Learning objectives

Explain why HDV requires hepatitis B virus.

Contrast simultaneous HBV–HDV infection with HDV superinfection.

Interpret source-described viral markers and hepatic injury patterns.

Connect clinical course with cirrhosis and HCC risk.

Slide 3 · HDV is an HBV-dependent RNA virus

HDV is also called the delta agent.

It requires hepatitis B virus for its life cycle.

HBV dependence distinguishes it from autonomous hepatitis viruses.

Slide 4 · HDV dependence: The causal chain

HBV infection

HBsAg available

HDV particle formation

HDV infection sustained

Dependency is on HBV envelope antigen for the HDV life cycle.

Slide 5 · HDV and HBV are distinct viruses

Hepatitis B virus

Hepatitis D virus

Partially double-stranded DNA genome

Circular single-stranded RNA genome

Makes multiple viral proteins

Encodes delta antigen (HDAg)

HBV supplies surface antigen

HDV uses the HBV-derived coat

Reverse transcription in replication

Host RNA polymerase supports RNA synthesis

Slide 6 · HDV particle: Envelope and interior

Circular

SsRNA

HBsAg-containing outer coat

Delta antigen (HDAg) assembly

Circular single-stranded RNA

Slide 7 · The viral particle is approximately 35 nm

HDV as a 35-nm, double-shelled particle.

An external coat surrounds an internal polypeptide assembly.

The interior contains delta antigen and the RNA genome.

Slide 8 · HBsAg enables HDV particle assembly

The HDV external coat contains hepatitis B surface antigen.

The surface protein supply is why HBV infection matters.

HDV cannot complete its infectious life cycle independently.

Slide 9 · HDV has very limited coding capacity

Delta antigen (HDAg) is the only protein produced by HDV.

The genome is circular, single-stranded RNA.

Host and HBV products therefore contribute essential functions.

Slide 10 · RNA replication uses host machinery

Circular HDV RNA

Host RNA polymerase

RNA-directed RNA synthesis

New HDV RNA

Replication description is mechanistic; Not a full molecular pathway.

Slide 11 · HDV replication versus HBV replication

HDV RNA replication

HBV DNA replication

Circular single-stranded RNA

Partially double-stranded DNA

RNA-directed RNA synthesis

Reverse transcription via RNA intermediate

Uses a host RNA polymerase

Encodes a viral polymerase

Depends on HBV for its coat

Produces its own surface proteins

Slide 12 · Hepatocyte injury has unresolved mechanisms

The basis of HDV-associated disease flares is not well understood.

Direct viral cytopathic injury has been proposed.

Enhanced cytotoxic responses of the host have also been proposed.

Slide 13 · Two proposed mechanisms of flares

Direct cytopathic hypothesis

Enhanced host response

Hepatocytes may be injured by HDV-related processes

Immune-mediated killing may increase

Discussed as a proposed mechanism

Discussed as a proposed mechanism

Not established as the sole cause

Not established as the sole cause

Slide 14 · HDV transmission is predominantly parenteral

Exposure to infected blood is the central route.

Intravenous drug use is a described transmission setting.

Multiple blood transfusions are another described setting.

Slide 15 · Exposure history: Important clues

Shared injection equipment

Parenteral exposure is central to the HDV transmission pattern.

Blood transfusion history

Repeated transfusion exposure is listed as a risk setting.

Slide 16 · Reported geographical concentration

High prevalence is described in the Amazon basin and central Africa.

The Middle East and Mediterranean basin are also highlighted.

Lower frequency in Southeast Asia and China.

Slide 17 · Epidemiology: Interpret estimates carefully

Fraction among HBV-infected

The textbook estimates that approximately 5% have HDV co-infection.

Estimated global burden

The textbook estimates approximately 15 million persons with HDV.

Slide 18 · Two sequences of infection

Coinfection

Superinfection

HBV and HDV acquired together

HDV acquired after established HBV

Acute hepatitis may resolve

Severe acute or exacerbated hepatitis

Usually both viruses clear

Chronic HDV is frequent

Chronicity less typical

Chronicity >80% (Robbins)

Slide 19 · Coinfection: Simultaneous acquisition

No established HBV

Exposure to HBV + HDV

Acute hepatitis

Often both cleared

This is coinfection, not superinfection.

Slide 20 · Coinfection resembles acute hepatitis B

Acute disease can be clinically indistinguishable from hepatitis B.

Exposure introduces both HBV and HDV.

Clinical features alone cannot establish the viral combination.

Slide 21 · Coinfection is commonly self-limited

Acute hepatitis may resolve after the simultaneous infection.

Clearance of both viruses usually follows.

The usual outcome contrasts with HDV superinfection.

Slide 22 · Coinfection can still be dangerous

A higher rate of acute hepatic failure in intravenous drug users.

That complication is a risk, not the usual course of all coinfections.

Severity and likelihood of chronicity are different outcome dimensions.

Slide 23 · Superinfection: Two-stage acquisition

Established HBV carrier

New HDV exposure

HDV superinfection

High chronicity risk

The host has HBV before acquiring HDV.

Slide 24 · Superinfection: Clinical onset

Baseline

Chronic HBV carrier

New exposure

HDV acquisition

30–50 days

Hepatitis may become evident

Interval is reported for superinfection, not a universal incubation range.

Slide 25 · Previously silent HBV may become symptomatic

A carrier with no symptoms may develop severe acute hepatitis.

The new clinical event follows acquisition of HDV.

Recognize an abrupt shift in illness rather than assuming stable HBV.

Slide 26 · Established chronic hepatitis may worsen

HDV can exacerbate a pre-existing chronic hepatitis B illness.

This is another clinical presentation of superinfection.

A disease flare does not by itself determine which virus is replicating.

Slide 27 · Superinfection frequently becomes chronic

Chronic HDV infection follows >80% of superinfections.

This is a distinctive contrast with usual coinfection outcomes.

Persistent infection creates a setting for progressive liver injury.

Slide 28 · Superinfection: Possible two-phase pattern

Early / active HDV phase

HDV replication active

HBV replication suppressed

Serum transaminases high

Later / chronic phase

HDV replication decreases

HBV replication increases

Transaminases fluctuate

Schematic disease-course pattern; Individual courses vary.

Slide 29 · HBV and HDV activity need not move together

The proposed phases can show opposing viral replication patterns.

High aminotransferases do not uniquely quantify either viral activity.

The phase model describes possibilities, not an immutable sequence.

Slide 30 · Chronic HBV–HDV infection carries risks

HBV–HDV coinfection is associated with progression to cirrhosis.

Risk of hepatocellular carcinoma is increased.

Risk is clinically important even without distinctive histology.

Slide 31 · Progression: Infection to clinical consequences

Persistent hepatitic injury

Inflammation and fibrosis

Cirrhosis

HCC risk context

Progression is possible, not an inevitable individual outcome.

Slide 32 · Symptoms do not establish HDV etiology

Acute HDV coinfection may resemble acute HBV infection.

A chronic HBV carrier may experience a severe flare after HDV exposure.

Serologic and molecular evidence is needed to identify infection.

Slide 33 · Serologic windows in hepatitis D

Before / early symptoms

HDV RNA detectable

Blood and liver

Recent exposure

IgM anti-HDV

May appear late; Transient

Chronic delta hepatitis

HBsAg present

Anti-HDV persists

Distinct detection contexts; Not a required chronological sequence.

Slide 34 · HDV RNA: An early direct marker

HDV RNA can be detected in blood and liver just before illness.

Detection also occurs in the early days of symptomatic disease.

Its presence is direct molecular evidence of HDV.

Slide 35 · IgM anti-HDV: Recent exposure marker

Robbins calls IgM anti-HDV the most reliable indicator of recent exposure.

Its appearance may be late.

The detectable interval is frequently short-lived.

Slide 36 · Chronic delta hepatitis: Persistent markers

HBsAg remains present in serum.

Anti-HDV antibodies can persist for months or longer.

Persistent antibody is not identical to a viral replication measurement.

Slide 37 · Interpret the markers by their target

Marker

Main information

HBsAg

HBV surface-antigen presence; Necessary context

HDV RNA

Direct evidence of HDV genetic material

IgM anti-HDV

Recent HDV exposure; Late or transient

Persistent anti-HDV

History/persistence of antibody response

Slide 38 · A conceptual diagnostic reasoning path

Hepatitis syndrome

Evaluate HBV context

Assess HDV RNA / antibody

Integrate timing + course

Educational logic; Not a formal diagnostic protocol.

Slide 39 · Diagnostic pitfall: A negative IgM window

IgM anti-HDV may not appear promptly after exposure.

It may also disappear after a short interval.

A single antibody result must be interpreted in temporal context.

Slide 40 · HDV must be distinguished from other injury

Common hepatitic findings

Etiologic confirmation

Portal or lobular lymphocytes

Serology and molecular tests

Necrosis or apoptosis

Context of HBV and HDV markers

Fibrosis in chronic hepatitis

Etiology cannot be read from fibrosis alone

Slide 41 · Acute viral hepatitis: Common pattern

Portal compartment

Hepatocyte lobule

Pale green = hepatocytes; Pink = injury

Lobular inflammation + hepatocyte injury

Blue circles = lymphocytes

Schematic only — common hepatitis pattern; No HDV-specific morphology.

Slide 42 · Acute hepatitis: Portal and lobular inflammation

Lymphocytes predominate in the inflammatory infiltrate.

Plasma cells and eosinophils may be variably present.

HDV cannot be diagnosed from these shared findings alone.

Slide 43 · Hepatocyte death: Apoptosis and necrosis

Hepatocyte injury may produce necrosis or apoptosis.

Pigmented macrophages scavenge cellular debris.

These changes establish injury rather than the viral subtype.

Slide 44 · Severe acute hepatitis: Confluent necrosis

Necrosis may involve groups of adjacent hepatocytes.

Severe cases can show bridging or panlobular necrosis.

Massive necrosis may accompany acute liver failure.

Slide 45 · Chronic viral hepatitis: Common pattern

Portal compartment

Hepatocyte lobule

Interface activity

Pale green = hepatocytes

Portal lymphocytes + interface injury

Blue circles = lymphocytes

Schematic only — common hepatitis pattern; No HDV-specific morphology.

Slide 46 · Chronic hepatitis: Portal inflammation

Portal lymphocytic or lymphoplasmacytic infiltration is characteristic.

Inflammation may breach the limiting plate.

Periportal hepatocyte injury is termed interface activity.

Slide 47 · Fibrosis progression in chronic injury

Portal and periportal fibrosis

Portoportal bridging fibrosis

Architectural remodeling

Cirrhosis

Slide 48 · Histology is rarely virus-specific

Viral hepatitis patterns overlap with autoimmune hepatitis.

Drug reactions and Wilson disease can also resemble hepatitis.

Serology and molecular studies help establish etiology.

Slide 49 · Do not confuse HBV morphology with HDV

HBV-associated feature

HDV diagnostic implication

HBsAg-filled ER can make ground-glass hepatocytes

This points to HBV, not uniquely to HDV

HBsAg or HBcAg immunostains support HBV

HDV remains a separate diagnostic question

Chronic inflammation and fibrosis may coexist

Morphology alone cannot identify HDV

Slide 50 · Biopsy: Grade and stage are different

Inflammatory activity represents disease grade.

Fibrosis extent represents disease stage.

Morphology characterizes injury but does not replace etiologic testing.

Slide 51 · HBV vaccination prevents HDV infection

HDV depends on HBV for its life cycle.

Preventing HBV infection also prevents HDV infection.

This is a direct clinical consequence of the dependency mechanism.

Slide 52 · Therapeutic evidence: Respect source limits

Interferon-based treatment with limited clearance.

It also discusses viral entry and replication as therapeutic targets.

Specific regimens and current approvals require separate verification.

Slide 53 · Case 1: Simultaneous viral exposure

Clinical scenario

A person develops acute hepatitis after a single exposure event involving HBV and HDV. Clinical features resemble acute hepatitis B.

Question: Coinfection or superinfection? What is the usual outcome?

Slide 54 · Case 1: Interpretation

This is HBV–HDV coinfection because both were acquired together.

Acute hepatitis may be indistinguishable from acute HBV.

Usual recovery with clearance of both viruses.

Slide 55 · Case 2: HBV carrier with acute hepatitis

Clinical scenario

An asymptomatic chronic HBsAg-positive carrier has a new parenteral exposure. Severe hepatitis develops about 40 days later.

Question: Which HDV acquisition pattern best fits?

Slide 56 · Case 2: Interpretation

New HDV exposure in an established HBV carrier is superinfection.

Onset about 30–50 days after the inoculum.

Superinfection is associated with a high likelihood of chronic HDV.

Slide 57 · Case 3: Fluctuating laboratory activity

Clinical scenario

A person with chronic HBV–HDV has an early severe flare with high transaminases. Later aminotransferase levels fluctuate.

Question: Can this correspond to the possible two-phase course?

Slide 58 · Case 3: Interpretation

The early phase may have active HDV and suppressed HBV replication.

In a later phase, HDV may decrease as HBV replication increases.

This model is possible, not required for all patients.

Slide 59 · Final synthesis: Four discriminating ideas

Question

Core answer

What makes HDV different?

An RNA virus dependent on HBV

Why is superinfection important?

Persistent chronic HDV is common

What establishes etiology?

HBV context plus HDV serology / RNA

Why follow long term?

Fibrosis, cirrhosis, HCC risk

Slide 60 · Core references and source limitations

Robbins, Cotran & Kumar: Pathologic Basis of Disease, 11th ed. (2026).

Hepatitis D Virus and adjacent Hepatitis B Virus sections.

General viral hepatitis syndromes, morphology, and Table 18.3.

Original chapter PDF and authentic licensed tissue images were unavailable.