any member of a family of DNA viruses that cause hepatitis B in humans and other animals; the human pathogens are in genus Orthohepadnavirus
Hea teada
nt. B‑hepatiidi viirus
Hea teada
Hepadnaviruses have small, enveloped, spherical virions (virus particles) that are about 40–48 nm (1 nm = 10−9 metre) in diameter. The capsid (the protein shell surrounding the viral nucleic acids) contains a circular double-stranded DNA molecule with a single-stranded DNA region and a DNA-dependent DNA polymerase. ... There are two recognized genera of hepadnavirus: Orthohepadnavirus and Avihepadnavirus. The former includes hepatitis B viruses that have been isolated from mammals, including humans, woodchucks, ground squirrels, Arctic squirrels, and woolly monkeys. The second genus, Avihepadnavirus, consists of hepatitis B viruses that infect birds, including ducks, herons, cranes, and storks. ... Humans and other animals that become infected with hepatitis B virus may develop a severe and long-lasting form of liver disease known as hepatitis. In humans the condition may occur as an acute disease, or in about 5 to 10 percent of cases it may become chronic and lead to permanent liver damage. Symptoms usually appear from 40 days to 6 months after exposure to the virus. Those persons at greatest risk for contracting hepatitis B include intravenous drug users, sexual partners of individuals with the disease, health care workers who are not adequately immunized, and recipients of organ transplants or blood transfusions. A safe and effective vaccine against the virus is available and provides protection for at least five years.
