Virology: Hepatitis Viruses

Hepatitis

inflammation of the liver
-results in jaundice
-results in elevated levels of serum alanine aminotransferase levels (ALT)

Hepatitis: non-infectious causes

bacterial, fungal, parasites

Hepatitis: viral

hepatitis virus
yellow fever virus
some herpes virus

Hepatitis: types

A, B, C, D, E, & G
Predominant types: A, B, C
all have acute infections
Chronic infections: B, C, G

Hepatitis A: characteristics

+ss RNA virus
naked (non-enveloped)
human & primate hosts
-restricted to humans though

Hepatitis A: Transmission

fecal-oral: restaurants and frozen foods
-GI tract --> blood --> liver
-can also be found in other tissues (issue for organ transplants)

Hepatitis A: Disease

acute infection only
Incubation: 10-50 days
-starts w/ flu-like symptoms
-dose dependent (higher does --> earlier onset)
age effect

Hepatitis A: Age Effect

Children:
-subclinical infection (no disease)- 80-95%
-clinical infection (disease)- 5-20%
-recovery- 99%

Adult
-subclinical infection (no disease)- 10-25%
-clinical infection (disease)- 75-90%
-recovery- 99%

Hepatitis A: treatment

drugs: none

Hepatitis A: vaccine

whole inactivated --> standard for children
-previously only given to people traveling to endemic areas

Hepatitis A: passive immunization

works!

Hepatitis A: Prevention

vaccination, good hygiene, sanitation, clean needles

Hepatitis E: characteristics

originally thought to be Hep A
+ss RNA virus
Naked (non-enveloped)
human, primate, and swine hosts

Hepatitis E: transmission

fecal-oral

Hepatitis E: disease

acute infection only
Incubation: 10-50 days
-starts w/ flu-like symptoms
-dose dependent (higher dose-->earlier onset)
no age effect
Disease a bit more severe than Hep A
dangerous to pregnant women (mortality increase as pregnancy progresses)

Hepatitis E: passive immunization

does NOT work

Hepatitis E: vaccine

none

Hepatitis E: treatment

drugs: none

Hepatitis E: prevention

good hygiene, sanitation, cook pork

Hepatitis G: characteristics

aka GBV-C
15% of population is positive (seropositive)
+ss RNA virus
enveloped
same viral family as Hep C
human host
-infects hepatocytes and lymphocytes
-alters HIV infection (decrease HIV replication)

Hepatitis G: transmission

bodily fluids: sex, blood

Hepatitis G: disease

acute and chronic infections
no age effect

Hepatitis G: passive immunization

does NOT work

Hepatitis G: vaccine

none

Hepatitis G: treatment

drugs: none

Hepatitis G: prevention

safe sex, clean needles

Hepatitis B: characteristics

ds DNA virus (pseudo retrovirus)
enveloped
human host

Hepatitis B: transmission

bodily fluids: sex, blood, birth
-transmissibility related to viremia levels (viral load)
-10% chronically infected mothers will pass it on to their children

Hepatitis B: disease

acute and chronic infections
Incubation: 45-160 days
Age effect
chronic infection: reactivation (carrier state)
-latency

Hepatitis B: age effect

Newborns:
-acute: 5-10%
-chronic: 90-95%

Adults:
-acute: 90-95%
-chronic: 5-10%

Hepatitis B: chronic disease

cirrhosis, hepatocellular carcinoma

Hepatitis B: infection of non hepatocytes?

liver transplant does not eliminate the virus

Hepatitis B: vaccine

recombinant protein ("virus-like-particle" aka VLP)

Hepatitis B: treatment

drugs: yes (doesn't clear infection)

Hepatitis B: prevention

safe sex, clean needles, screen blood/blood products, decrease viral loads during birth

Hepatitis C: characteristics

AKA non-A, non-B
+ss RNA virus
enveloped
human and primate hosts

Hepatitis C: transmission

bodily fluids: sex, blood

Hepatitis C: disease

acute and chronic infections
Incubation: 5-50 days
-initial flu-like symptoms
no age effect
-15-30% acute
-70-85% chronic

Hepatitis C: Chronic infection

cirrhosis, hepatocellular carcinoma

Hepatitis C: infection of non-hepatocytes?

liver transplant does not eliminate the virus

Hepatitis C: vaccine

none

Hepatitis C: passive immunization

does NOT work
-tremendous genetic diversity (immune resistance)

Hepatitis C: treatement

drugs: yes
-cure infection by blocking continuous replication

Hepatitis C: How does chronic infection form?

results from continuous replication, not by latency

Hepatitis C: prevention

safe sex, screen blood/blood products, clean needles

Hepatitis D: characteristics

-ss RNA virus
associate virus
-defective (encodes no structural proteins)
-utilizes Hep B for structural proteins
enveloped
human hosts

Hepatitis D: transmission

bodily fluids: sex, blood

Hepatitis D: disease

acute and chronic infections
-acute- co-infection of B and D
-acute or chronic- superinfection of B then D
--chronic can result in cirrhosis
no age effect

Hepatitis D: vaccine

none

Hepatitis D: treatment

drugs: none

Hepatitis D: prevention

Hep B vaccination
-can't get D without B