Many viruses cause hepatitis. Of these, five medically important viruses are commonly described as “hepatitis viruses” because their main site of infection is the liver. These five are hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV, delta virus), and hepatitis E virus (HEV) (Tables 41–1 and 41–2). Other viruses, such as Epstein–Barr virus (the cause of infectious mononucleosis), cytomegalovirus, and yellow fever virus, infect the liver but also infect other sites in the body and therefore are not exclusively hepatitis viruses. They are discussed elsewhere.
TABLE 41–1Glossary of Hepatitis Viruses and Their Serologic Markers ||Download (.pdf) TABLE 41–1 Glossary of Hepatitis Viruses and Their Serologic Markers
|Abbreviation ||Name and Description |
|HAV ||Hepatitis A virus, a picornavirus (nonenveloped RNA virus) |
|IgM HAV Ab ||IgM antibody to HAV; best test to detect acute hepatitis A |
|HBV ||Hepatitis B virus, a hepadnavirus (enveloped, partially double-stranded DNA virus); also known as Dane particle |
|HBsAg ||Antigen found on surface of HBV, also found on noninfectious particles in patient’s blood; positive during acute disease; continued presence indicates carrier state |
|HBsAb ||Antibody to HBsAg; provides immunity to hepatitis B |
|HBcAg ||Antigen associated with core of HBV |
|HBcAb ||Antibody to HBcAg; positive during window phase; IgM HBcAb is an indicator of recent disease |
|HBeAg ||A second, different antigenic determinant in the HBV core; important indicator of transmissibility |
|HBeAb ||Antibody to e antigen; indicates low transmissibility |
|Non-A, non-B ||Hepatitis viruses that are neither HAV nor HBV |
|HCV ||Hepatitis C virus, a flavivirus (enveloped RNA virus); one of the non-A, non-B viruses |
|HDV ||Hepatitis D virus, small RNA virus with HBsAg envelope; defective virus that replicates only in HBV-infected cells |
|HEV ||Hepatitis E virus, a hepevirus (nonenveloped RNA virus); one of the non-A, non-B viruses |TABLE 41–2Important Properties of Hepatitis Viruses ||Download (.pdf) TABLE 41–2 Important Properties of Hepatitis Viruses
|Virus ||Genome ||Replication Defective ||DNA Polymerase in Virion ||HBsAg in Envelope ||Virus Family |
|HAV ||ssRNA ||No ||No ||No ||Picornavirus |
|HBV ||dsDNA1 ||No ||Yes ||Yes ||Hepadnavirus |
|HCV ||ssRNA ||No ||No ||No ||Flavivirus |
|HDV ||ssRNA2 ||Yes ||No ||Yes ||Deltavirus |
|HEV ||ssRNA ||No ||No ||No ||Calicivirus |
Additional information regarding the clinical aspects of infections caused by the viruses in this chapter is provided in Part IX, titled Infectious Diseases.
Note that these viruses belong to different viral families; some are DNA viruses, whereas others are RNA viruses, and some are enveloped, whereas others are nonenveloped. They are united by their ability to infect hepatocytes because they have proteins on their surface that attach to receptors on the surface of hepatocytes.
Note also that these viruses are all noncytotoxic (i.e., they do not kill hepatocytes directly). ...