The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.for more details please visit  www.indiandentalacademy.com

1. Pathogenicity
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

2. Mode of
transmission
Parenteral perinatal sexual
www.indiandentalacademy.com

3. The course of acute HBV infection can be divided into 3 phases:
1
• Preicteric phase
2
• Icteric phase
3
• Convalescent phase
www.indiandentalacademy.com

4. Preicrteric phase
• After incubation of 6 wks to 6 months pt.
develops malaise, anorexia,nausea, vomiting
and pain in upper rt.abdominal quadrant.
• few pts. develop maculopapular rashes,
polyarteritis nodosa and glomerulonephritis.
• It is due to circulating immune complex.
www.indiandentalacademy.com

5. Icteric phase
• 2 days to 2 wks following initial symptoms pt.
develops jaundice ,pale stool, dark urine,
hepatocellular damage.
www.indiandentalacademy.com

6. Convalescent phase
• This phase is long and drawn out with malaise
and fatigue lasting for several weeks.
www.indiandentalacademy.com

7. • Genome:
• Nucleocapsid encloses 2 linear strands of
DNA.
• Plus strand and minus strand.
• Plus strand is incomplete and associated with
viral DNA polymerase, which can repair the
gap in plus strand.
www.indiandentalacademy.com

8. The genome has 4 overlapping genes:
• S gene
• C gene
• P gene
• X gene
www.indiandentalacademy.com

9. www.indiandentalacademy.com

10. • S gene consist of s region, pre s1,s2 regions.
• It codes for surface Ag, HBsAg and major
protein S.
• C gene consists of 2 regions c and pre c.
• C region codes for core antigen HBcAg.
• This Ag is demonstrated in hepatocytes.
• C and pre c region encodes for HBeAg , a non
particulate Ag.
www.indiandentalacademy.com

11. • P gene is largest & codes for DNA polymerase
enzyme.
• X gene codes for HBxAg , nonparticulate
protein which leads to enhanced replication of
HBV.
www.indiandentalacademy.com

12. • HBV virus interferes with the function of liver by
replicating in hepatocytes.
• The virions bind to host cell via preS domain of viral
surface antigen and subsequently internalized by
endocytosis.
The viral genomic DNA is transferred to the cell
nucleus by host proteins called chaperones.
The partially double stranded viral DNA is then made
fully double stranded and transformed into closed
circular DNA that serves as a template for
transcription of four viral mRNAs.www.indiandentalacademy.com

13. • HBV-preS – Specific receptors are present on
hepatocytes , however viral DNA and protein have
also been detected in extra hepatic sites such as
bone marrow spleen , lymph nodes.
.
•These four viral transcripts undergo additional
processing and go on to form progeny virions
•The virion P protein (the DNA polymerase)
synthesizes DNA via its reverse transcriptase
activity.
www.indiandentalacademy.com

14. • During HBV infection, host immune response
causes both hepatocellular damage and viral
clearance.
• Cytotoxic T- lymphocytes contibutes to liver
injury which is initiated and mediated by CTLs ,
antigen – non specific inflammatory cells and can
worsen CTL- induced immunopathology .
• CTLs also help in viral clearance by killing infected
cells and producing antiviral cytokines .
www.indiandentalacademy.com