HEPATITIS B VIRUS (HBV)

Morphology

• Shape: Spherical in shape.

• Size: Approx. 42 nm nm.

• Envelope: Envelope present.

• Symmetry: Icosahedral symmetry.

• Hepatitis B virus is a partially double-stranded DNA virus.

• Core: Core of the virus contains the viral genome, which is a partially double-stranded DNA.The core is surrounded by the core antigen protein.

• Surface Proteins: Virus contains three surface proteins: small (S), medium (M), and large (L) surface antigens.

Antigenic structure

• HBsAg – surface antigen

• HBcAg – It is the core (nucleocapsid Ag. Of the virus)

• HBeAg – It appear in serum along with HbsAg but appear within a few week.

Pathogenesis

• Human are the only reservoir of infection

• Uncomplicated hepatitis is usually 8 - 10 weeks.

• Onset is slow but more severe

• Male homosexual are at higher risk of acquiring infection.

Ø Mode of transmission: Hepatitis B virus (HBV) is primarily transmitted through contact with infected blood, body fluid, etc. The modes of transmission include:

• 1. Parenteral transmission: Inoculation of blood, blood product or fluid containing HBV during medical surgical or dental procedure.

• 2. Perinatal transmission: transmission from mother to newborn during birth.

• 3. Sexual transmission: transmitted by sexual contact.

Ø Incubation period: 6 Week to 180 months

Ø Clinical feature: HBV can divide into 3 phases.

• 1. Preictric Phase – patient suffering with malaise, anorexia, weakness, myalgia, vomiting,etc.

• 2. Icteric phase – Patient develop jaundice, pale stool & dark urine.

• 3. Convalescent Phase – the phase is long & drawn with malaises & fatigue.

Ø Hepatitis B virus carrier: carrier of Hepatitis B virus (HBV) categories as

• 1. Asymptomatic Carrier:

  • They have HBV in their blood, but they do not exhibit symptoms of the infection. They can still transmit the virus to others.

• 2.Chronic Carrier:

  • Chronic carriers may or may not show symptoms, but they can spread the virus to others.

3. Chronic Active Carrier:

   • Chronic active carriers cause liver inflammation and damage.

4. Inactive Carrier:

   • Inactive carriers have chronic HBV infection, but their liver function remains normal & they do not exhibit symptoms. They can still transmit the virus to others.

Symptoms

• Hepatitis B virus (HBV) infection can manifest with a range of symptoms in some cases individuals may be asymptomatic. Common symptoms associated with Hepatitis B are:

• 1.Asymptomatic Phase:

  • Many people with Hepatitis B may not experience noticeable symptoms, especially during the early stages of infection.

• 2.Acute Hepatitis B:

  • Jaundice

  • Fatigue

  • Dark Urine

  • Pale-Colored Stools

  • Nausea and Vomiting

  • Loss of Appetite

• 3.Chronic Hepatitis B:

  • Many individuals with chronic Hepatitis B may be asymptomatic or have mild symptoms for years.

  • Chronic infection can lead to long-term liver damage, cirrhosis, & increased risk of liver cancer.

Laboratory Diagnosis

• Laboratory diagnosis of hepatitis B virus (HBV) involves detecting specific viral markers follow:

• 1. Specimen:

  • Blood

  • plasma

  • saliva

  • amniotic fluid

  • Liver biopsy

• 2. Collection & transport: immediately after specimen collection transport it to laboratory.

• 3. Viral marker:

  a. HBaAg –

  · Presence of HBsAg indicates acute or chronic HBV infection.

  · The initial and primary marker used for HBV diagnosis.

  · It is first marker to appear in blood after infection.

  b. HBcAg –

  · It is not detectable in the serum but can demonstrated in liver cell by immunofluorescence.

  c. HBeAg –

  · It appear in serum at same time as HBaAg.

  · Presence of anti-HBe may indicate a lower risk of transmission.

• 5. Molecular method:

  • Hepatitis B virus DNA level can be detected in serum by reverse transcriptase Polymerase chain reaction (RT-PCR).

• 6. Biochemical reaction.:

  • Serum glutamic pyruvic transaminase (SGPT/ALT)

  • Serum bilirubin

Treatment

• Treatment of Hepatitis B (HBV) depends on whether the infection is acute or chronic and the severity of the disease.

• Her the treatment options for Hepatitis B:

• 1. Acute Hepatitis B:

  • Acute Hepatitis B often resolves on its own without specific antiviral treatment.

• 2. Chronic Hepatitis B:

  • Antiviral Medications: For individuals with chronic Hepatitis B Common antiviral drugs include:

  • Entecavir

  • Tenofovir

  • Lamivudine

  • Adefovir

Prophylaxis

• Hepatitis B Vaccination:

  • The most effective form of prophylaxis for HBV is vaccination.

  • The hepatitis B vaccine is a safe and highly effective way to prevent HBV infection. It is typically administered in a series of doses.

• Perinatal Prophylaxis:

  • Newborns born to mothers with HBV receive prophylaxis within 12 hours of birth.

  • This involves administering the hepatitis B vaccine and HBIG to prevent mother-to-child transmission.