1.] Hepatitis – B virus [HBV] the cause of ”serum hepatitis” is the most versatile of the hepatotropic viruses.
2.] It has an longer incubation period of about 30 – 180 days and is basically transmitted such as in recipient of blood and blood products.
3.] HBV can produce severe form of illness that includes :-
- acute hepatitis B
- chronic hepatitis
- progression to cirrhosis
- fulminate (severe and sudden in onset) hepatitis
- asymptomatic carrier stage
4.] HBV plays role in the development of hepatocellular carcinoma (most common primary malignant tumor of the liver).
MODE OF TRANSMISSION :-
- HBV is an hardy virus and can withstand extremes of temperature and the humidity.
- HBV can spread primarily through blood and body fluids.
- Virus may also spread through contact with body secretion, such as semen, saliva, sweat, tears, breast milk and pathologic effusions.
- During the active acute chronic hepatitis, HBV is present in all physiologic and pathologic body fluids with the exception of stool.
HEPATITIS – B VIRUS [HBV] :-
1.] HBV shows three forms of viral particles of 2 sizes :-
- Small (spheres and tubules/filaments)
- Large (spheres)
2.] Small particles are numerous and exist in two forms – as 22 nm sphere, and as tubules 22 nm in diameter and 100 nm long.
3.] Large particles, 42 nm in diameter, are double – shelled spherical particles, also called dane particles.
4.] The genomic structure of HBV is quite compact and complex. The HBV DNA consist of 4 overlapping genes which encode for multiply proteins :-
- S gene code for the surface envelope protein, hepatitis B surface antigen (HBsAg) this protein in the major protein. Pre S -1 and Pre S – 2 region of genome are the upstream of S – gene and code for pre – S gene protein products that include receptor on the HBV surface and for hepatocyte membrane protein.
- P gene is the largest and codes for the DNA polymerase.
- C gene codes for two nucleotide protein HBeAg and a core protein termed as HBcAg.
- X gene codes for HBxAg which is a small non – particulate protein. HBxAg has a role in transactivation of the transcription of both viral and cellular genes.
Expression of HBxAg and its antibodies associated with enhanced HBV DNA replication has been implicated in a hepatocellular carcinoma in patients of chronic hepatitis.
There are certain evidence which links immune pathogenesis with the hepatocellular damage :-
- When HBV is not directly cytopathic (refers to structural change in host cell that are caused by viral invasion) that means a carrier state of hepatitis B without the hepatocellular damage exists.
- It has been observed that individuals with defect or deficiency of the cellular immunity have more persistent, hepatitis B diseases.
- In support of cell mediated mechanism in hepatocellular damage by HBV comes from the observation that viral antigens are attacked by host cytoxin CD8+T lymphocytes.
- The host response of CD8+T lymphocytes by elaboration of antiviral cytokines is variable in different individuals, that determines whether an HBV – infected person recovers, develops mild or severe disease, or progresses to chronic disease.
A.] Oral Antiviral drugs for Hepatitis – B :
Tenofovir disoproxil (Viread)
Tenofovir alafenamide (Vemlidy)
Telbivudine (Tyzeka or Sebivo)
Adefovir Dipivoxil (Hepsera)
Lamivudine (Epivir-HBV, Zeffix, or Heptodin)
B.] Immune modulators (Interferon) for Hepatitis – B :
Pegylated Interferon (Pegasys)
Interferon Alpha (Intron A)
MULTIPLE CHOICE QUESTIONS :-
1.] Which of the following hepatitis virus is not RNA virus ?
a. Hepatitis – A virus
b. Hepatitis – B virus
c. Hepatitis – E virus
d. Hepatitis – G virus
2.] Which of the following nucleic acid is present in hepatitis – B virus ?
3.] The most serious infection is ?
a. super infection of an HBsAg carrier by HDV
b. infection with HBV and HDV
c. coinfection of HBV and HDV
d. None of the above
4.] Which of the following specimen contains hepatitis B virus in an infected person ?
d. All of the above
5.] Which of the following antigenic type of hepatitis B virus is present in the envelope ?
6.] The development of hepatocellular carcinoma is associated with ?
a. ground squirrel hepatitis virus
b. hepatitis B virus
c. woodchuck hepatitis virus
d. all of the above
7.] Which of the following antigenic type of hepatitis B virus is prevalent in India ?
8.] Which of the following virus can be transmitted by parental route ?
d. All of the above
9.] Incubation period of HBV virus ?
a. 30 – 180 days
b. 2 days
c. 1 week
d. 10 days
10.] The tubule of small viral particle has a diameter of about ?
a. 23 nm
b. 30 nm
c. 22 micro meter
d. 22 nm
1.] (b) hepatitis – B virus
2.] (a) dsDNA
3.] (a) super infection of an HBsAg carrier by HDV
5.] (a) HbsAg
7.] (c) Ayw
9.] (a) 30 – 180 days
10.] (d) 22 nm
1.] Textbook Of Pathology By Harsh Mohan; 7th edition; Page no. 591 – 592.
2.] Robbin’s Basic Pathology; 5th edition; Page no. 844 – 846.