Hepatitis viruses Flashcards
Hepatitis
Inflammation of the liver
Causes of hepatitis - 2
Infectious
Non infection
Infectious causes of hepatitis
Viral
bacterial
fungal
parasitic
Symptoms and signs of hepatitis
Jaundice Malaise Dark urine Fatty stools Specific serology tests
Non infectious causes of hepatitis
Alcohol
Drugs
Autoimmune
Metabolic diseases
Virus structure recap
Strand of nucleic acid - DNA or RNA
surrounded by protective protein coat
further membrane of lipid
Major hepatitis viruses and spread
HAV - FO HBV - BB HCV - BB, IV DRUG ABUSE HDV - ASSOCIATED WITH HBV HEV - FO
Hep A Genotypes Spread Duration Vaccine
RNA Picornavirus 7 genotypes I-III and VII related to human disease I and III most prevalent GI -> blood --> liver Liver bile --> faeces Poor sanitation 2 week incubation 4-10 days early symptoms resolves in a few weeks vaccine - formalin killed virus
Hep A
Global distribution
Epidemiology
1.5M worldwide
Children often asymptomatic
Severity increases with age
IgM/IgG
IgM produced first time host is exposed to an antigen
Eventually declines
Host produces IgG - lasts much longer
IgM detection indicates acute or primary infection
IgG indicates past infection or immunity
Hep B
Parenteral
dsDNA - resides in hepatocytes
Most patients recover in a few weeks
Some develop chronic carrier state
Two types of chronic carried hep B
Chronic persistent hepatitis
Chronic active hepatitis
3 forms of Hep B
Filament
Spheres
Dane particle (whole virion) - infectious
HbeAg is marker of Hep B
breakdown product of HbcAg (core protein)
Only core gene is…
transcribed to produced core antigen
Core antigen produced at same time as e antigen
Course of infection of Hep B
High Alt++ indicates damaged liver cells lysing
OR
chronic persistent viraemia
Lab diagnosis of Hep B
Detection of Hep B surface antigen HBsAg
HBsAg
surface protein of virus
soluble
comes off and goes into blood and triggers immune response of IgM
HBcAg not detected on serological testing - found on core protein of virus
HBeAg
Marker of high levels of replication of virus
Found on surface of infected liver cells
Chronic infection of hepatitis B is characterized by the
persistence of HBsAg for at least 6 months (with or without concurrent HBeAg). Persistence of HBsAg is the principal marker of risk for developing chronic liver disease and liver cancer (hepatocellular carcinoma) later in life.
Hep B epidemiology
transmission
infection early in life =
10% of chronic infection
5% carriage in africa/asia
vertical, parenteral, sexual
increased chance of chronicity
chronic liver disease
Hep D
Caused by defective RNA co exists with HBV small virus outer coat derived from HBsAg 5% HBV are HDV +ve
HBV and HDV
SUPERINFECTION on HBV
Infection co incident HDV influenced by replication of HBV superinfection - Ideal for rapid HDV replication commonly chronic 15 million cases of HDV worldwide
Hep C
type of virus
released
core
HEPACIVIRUS member of flavivirus 10 genes - polyprotein virus released by budding Small enveloped SSRNA virus core of genetic material RNA surrounded by capsid two viral envelope glycoproteins
HCV epidemiology
Transmission
180 million carriers worldwide
5 million in W Europe
IV drug abuse needle sticks, tattoos, ear piercing
Minor routes
