Hepatitis viruses. Features of structure and main biological

properties

Vinnitsa National Pirogov Memorial Medical University / Department of microbiology

The term “viral hepatitis” refers to a The term “viral hepatitis” refers to a primary infection of the liver by any primary infection of the liver by any one of a heterogeneous group of one of a heterogeneous group of “hepatitis viruses”. “hepatitis viruses”. It consists of It consists of types A, B, C, D, E, G.types A, B, C, D, E, G.

Hepatitis viruses are taxonomically Hepatitis viruses are taxonomically unrelated (DNA and RNA viruses). The unrelated (DNA and RNA viruses). The features common to them are:features common to them are:

1.1. hepatotropismhepatotropism

2.2. ability to cause a similar icteric illness ability to cause a similar icteric illness

By epidemiological and clinical criteria, By epidemiological and clinical criteria, two types of viral hepatitis had been two types of viral hepatitis had been recognised for long:recognised for long:

A first typeA first type (this type was called infective or (this type was called infective or infectious hepatitis)infectious hepatitis)

1.1. Occurred sporadically or as epidemics;Occurred sporadically or as epidemics;

2.2. Affecting mainly children and young Affecting mainly children and young adults;adults;

3.3. Transmitted by the fecal-oral route.Transmitted by the fecal-oral route. A second typeA second type (this type had been given (this type had been given

various names such as serum hepatitis or various names such as serum hepatitis or transfusion hepatitis) transmitted mainly transfusion hepatitis) transmitted mainly by parenteral routeby parenteral route

Type A virus hepatitis (HAV)Type A virus hepatitis (HAV)

Belongs to the Belongs to the Picornaviridae familyPicornaviridae family

Morphology.Morphology.

1.1. HAV is a spherical ss(+)RNA-HAV is a spherical ss(+)RNA-including virusincluding virus

2.2. 27-30 nm in diameter27-30 nm in diameter

3.3. Non envelopedNon enveloped

Classification of viral hepatitisClassification of viral hepatitis

Hepatitis A virusHepatitis A virus Hepatitis B virusHepatitis B virus Hepatitis C virusHepatitis C virus Hepatitis D virusHepatitis D virus Hepatitis E virusHepatitis E virus Hepatitis G virusHepatitis G virus

HAV is transmitted by the fecal-oral HAV is transmitted by the fecal-oral routeroute

PathogenesisPathogenesis

The clinical disease consists of The clinical disease consists of two stages: two stages: the prodromal (or preicteric) and the icteric the prodromal (or preicteric) and the icteric stagestage

Laboratory diagnosisLaboratory diagnosis1.1. IEMIEM

2.2. SerologySerology

3.3. Detection of viral antigens in stool Detection of viral antigens in stool samplessamples

ProphylaxisProphylaxis General prophylaxis consists of:General prophylaxis consists of: Specific prophylaxisSpecific prophylaxis1.1. ActiveActive2.2. PassivePassive

TreatmentTreatment is symptomatic. No specific is symptomatic. No specific antiviral drug is available antiviral drug is available

Type B hepatitis (HBV)Type B hepatitis (HBV)

Antigen StructureAntigen Structure HBsAgHBsAg

HBcAgHBcAg

HBeAgHBeAg

HBxAgHBxAg

There are three important modes of There are three important modes of transmission of HBV infection:transmission of HBV infection: parenteral, perinatal, sexualparenteral, perinatal, sexual

Laboratory diagnosisLaboratory diagnosis Detection of hepatitis B antigens and Detection of hepatitis B antigens and antibodies (viral markers).antibodies (viral markers).

ProphylaxisProphylaxis

Prophylaxis includes:Prophylaxis includes: General preventive measuresGeneral preventive measures ImmunisationImmunisation

1.1. PassivePassive 2.2. Active.Active.

Type C hepatitis (HCV)Type C hepatitis (HCV)

Hepatitis C virus belongs to the family Hepatitis C virus belongs to the family FlaviviridaeFlaviviridae

HCV is a 50-60 nm virus with a linear single HCV is a 50-60 nm virus with a linear single stranded RNA of positive polarity stranded RNA of positive polarity (ss(+)RNA)(ss(+)RNA)

Enclosed within a core and surrounded by Enclosed within a core and surrounded by an envelope, carrying glycoprotein spikesan envelope, carrying glycoprotein spikes

Laboratory diagnosisLaboratory diagnosis It can be established by detection of It can be established by detection of anti-HCVanti-HCV by by

ELISA. ELISA. Viral genome (HCV RNA) detectionViral genome (HCV RNA) detection

Type D (Delta) hepatitis (HDV)Type D (Delta) hepatitis (HDV) HDV is a HDV is a defective RNA virus defective RNA virus depending on depending on

the helper function of HBV for its replication the helper function of HBV for its replication and expression. It belongs to genus and expression. It belongs to genus DeltavirusDeltavirus

Its mode of transmission is the Its mode of transmission is the same as for HBVsame as for HBV

Two types of infection are recognizedTwo types of infection are recognized

1.1. CoinfectionCoinfection

2.2. SuperinfectionSuperinfection

Laboratory diagnosisLaboratory diagnosis Delta antigen Delta antigen Anti-delta antibodiesAnti-delta antibodies