Hepatitis B and hepatitis D virus- causes, symptoms, diagnosis, treatment, pathology

                                                                                                                                                                                                                                     Hepatitis b virus or hep b virus for

 short 

is a member of the hepadnavirus family 

hepatitis d 

virus or hep d virus is a delta virus 

they both cause hepatitis or inflammation of the liver 

even though they both cause hepatitis 

hepatitis d virus cannot cause the 

disease by itself 

and needs hepatitis b virus to replicate 

both hep b and d viruses are enveloped 

so they're surrounded by a membrane 

to make things interesting the membrane 

of both viruses contains hepatitis b 

viral proteins specifically they both 

have a surface antigen called hbs beneath the membrane there's a protein shell called a capsid which has more antigens hb core or hbc is in the capsid of hepatitis b there's also an hb envelope or hope antigen for short which is a variant of hpc but it's not really part of the virus it's secreted and can be found in infected individual serum delta antigen or hdag for short is in the capsid of hepatitis d virus inside the capsid there's the viral genetic material now hepb is a dna virus which means that its capsid contains partial double-stranded circular DNA which is made of a long and short strand so there's a part where the long strand is single-stranded and it also has dna polymerase which is an enzyme with DNA and rna-dependent activity meaning it can convert dna to rna and vice versa on the other hand hep-d is a rna virus so its capsid contains single-stranded circular rna bin a rod-like folded structure which is why host cell enzymes can use it as double-stranded DNA the main source of hepatitis b virus is blood but it can also be found in other bodily fluids like milk amniotic fluid vaginal secretions and semen 

so routes of transmission include sexual  contact contaminated blood either following transfusions or injections with contaminated needles the latter being more common in people who use intravenous drugs the virus can also be passed from an infected mother to the baby during childbirth rarely during the pregnancy the virus can pass through the placental barrier which is a kind of very thin wall that brings the mothers and fetuses blood very close and allows them to exchange some substances like oxygen 

igg antibodies waste products and 

unfortunately certain microbes more commonly the virus can pass from an infected individual to the child during birth because of the close contact between individual blood and secretions with the child it's still not certain if a c-section can protect against this kind of transmission hepatitis d virus spreads the same way but it only causes disease in individuals with an active hepatitis b infection all right now both these viruses target the liver which is made of functional units called hepatic lobules the main cells are called hepatocytes they pick up and detoxify harmful substances like drugs or alcohol help maintain a normal blood glucose level synthesize a variety of important 

proteins like albumin and coagulation 

factors 

store certain vitamins in some minerals 

and convert cholesterol into bile salts 

which along with water and bilirubin 

make up the bile 

hepatitis b virus enters the hepatocytes 

by fusing its membrane with the cell 

membrane and releasing the capsid into 

the cell 

the cell's polymerase elongates the shorter strand of the viral DNA so that it now forms a complete double-stranded DNA with the long strand it then travels to the nucleus there it's transcribed by the cell's transcription elements into multiple mRNAs which leave the nucleus and use the cell's ribosomes to create viral proteins like DNA polymerase and viral antigens HBS HB core and be antigen the largest mrna is used by the viral DNA polymerase to replicate viral DNA viral antigens HBS and HB core are assembled into new viral particles be however isn't included in the viral particle but leaves the cell and can be found in the serum the viral DNA is replicated and packaged into the capsid at the same time which is why its replication is interrupted and the virus gets partial double-stranded DNA the capsid is then enveloped and released without damaging the cell which is why the infection can persist for a long time without causing liver damage the damage actually comes from the body's immune system t cells to find and eliminate infected hepatocytes which cause liver damage b cells to react to the virus in the bloodstream and secrete antibodies against hep b antigens bilirubin with bile salts is released from the destroyed cells into the bloodstream and impregnate the tissue causing jaundice which is the yellowish pigmentation of the skin mucosa and whites of the eyes the bile salts into the skin and cause itching 

the bilirubin from the blood is filtered 

by the kidneys and ends up in the urine 

instead of the stool 

making it dark while the stool becomes 

pale 

an insufficient t cell response or if 

large amounts of hbs antigen bind to 

neutralizing antibodies  can lead to chronic hepatitis acute hepatitis b becomes chronic in about five to ten percent of cases in some cases liver damage can progress to scarring cirrhosis and liver failure chronic hepatitis also increases the risk of liver cancer called hepatocellular carcinoma hepatitis d virus enters the cell in the nucleus in the same way however it uses the host cell's RNA polymerase to copy itself and sells ribosomes to create delta antigens viral rna is packaged into the capsid but to make a complete viral particle it must use hbs antigen and get enveloped it then leaves the cell now delta antigens are harmful to the cell and cause cell death and liver damage so unlike heb hep d damages the cells directly hep d virus causes acute hepatitis in one of two ways first there's co-infection with hep b when the two viruses infect the liver at the same time in the second there's a super infection which is when hep d infects individuals with chronic hepatitis b which is more severe hep d increases the severity of the hep b infection these individuals are more likely to develop fulminant hepatitis massive liver necrosis and hepatic encephalopathy when the brain function is affected hep b has a long incubation period of one to six months usually two to three months abouttwo-thirds of affected individuals develop mild asymptomatic acute hepatitis that's usually undetected symptomatic hepatitis usually starts as a pre-icteric phase with fever 

fatigue body aches and nausea lasts a 

few days to a week and is followed by 

the icteric phase 

with jaundice and dark urine usually 

lasts one to two weeks after which the recovery phase happens very rarely an individual can develop fulminant hepatitis with liver failure usually marked by sudden fever abdominal pain vomiting jaundice confusion and even 

coma 

symptoms of chronic hep b are typically 

similar to acute hepatitis but 

milder 

the diagnosis of hep b or b and d 

co-infection 

is based on the antigen and antibody 

findings in the blood 

hbs antigen is the first to appear and 

can be detected in the first one to two weeks after exposure hope antigen appears shortly after but clears quickly shortly after its clearing hope antibodies appear anti-HB core IgM antibodies usually appear shortly before the symptoms followed by anti-hp core igg antibodies one to two weeks after anti-hbs antibodies appear during recovery hepatitis b DNA can be detected at any time during the disease now in acute hepatitis b infection anti-HB core IgM has antigen be an antigen and viral DNA can be found hb core igg is usually present depending on the time of testing in the recovery phase also called the window phase only anti-hb core igm and anti-hbe antibodies can be detected in chronic hepatitis b anti-hb core igm is negative while anti-hb core igg antibodies and hbs antigen are present for longer than 6 months and viral dna can also be detected hpe antigen and antibody can be present as well anti-hb core igg antibody is the marker of resolved hepatitis anti-hbs and hpe antibodies can also be present but no antigens anti-hb core igm or viral dna are present serum alanine and aspartate immunotransferase or alt and last are elevated during the active acute and chronic infection but alt is more elevated than last finally vaccinated individuals have only anti-hbs antibodies present a liver biopsy can be done to confirm the diagnosis of chronic hepatitis b and evaluate the damage it usually shows hepatocytes with granular cytoplasm called ground-class hepatocytes in severe cases hepatitis b and d co-infection super infection can be suspected the presence of hepatitis d rna delta antigen or antihepatitis d antibodies confirm the suspicion acute hepatitis b infection usually requires no treatment severe cases like fulminant hepatitis and chronic hepatitis are treated with antiviral medication and immune system modulators like interferon alpha and pegylated interferon for hepatitis b prevention is much more important screening of donated blood for hepatitis 

b is done to prevent the spread of the 

virus 

individuals can avoid a lifestyle that 

puts them at risk of infection 

like unprotected sex and the use of intravenous drugs finally high-risk individuals like babies of mothers with chronic hepatitis b intravenous drug users people who have multiple sex partners individuals on dialysis healthcare providers and so on can be vaccinated against the disease however if the individual is exposed to the virus hepatitis b immune globulin can be given within a week after exposure to prevent the disease there's no specific treatment for hepatitis d because it's dependent on hepatitis b treatment and prevention of hepatitis b also protects from hepatitis d virus all right as a quick recap hepatitis b virus is a DNA virus transmitted by the blood sexually or during birth that causes acute or chronic hepatitis by infecting liver cells while the damage is caused by the immune system initial symptoms of acute hepatitis include fever fatigue body aches and nausea after which jaundice develops rarely severe fulminant hepatitis can develop chronic hepatitis has similar symptoms but is milder 

and it increases the risk of 

hepatocellular carcinoma 

diagnosis is based on the clinical course 

and antigen and antibody findings 

it can be prevented by avoiding risky 

behavior and vaccination 

acute hepatitis usually requires no 

treatment but severe cases and chronic hepatitis can be treated by antiviral drugs in interferons hepatitis d is an RNA virus transmitted similarly to hepatitis b virus it can only infect individuals with active hepatitis b infection and increases the severity and a chance of fulminant hepatitis 

it's diagnosed by antigen and antibody 

findings 

no special treatment is required as 

treating and preventing hepatitis b treats hepatitis d.