Structure

Transmission

Pathogenesis

Clinical findings

Laboratory diagnosis

Treatment

Family: herpevirus

Genome: linear double-strand DNA.

Size: 100m

Icosahedral nucleoapsid

Lipoprotein envelope

Single serotype

Structurally and morphologically identical to other herpesviruses, but is antigenically different.

Viral capsid antigen (VCA) used often in diagnostic tests.

Neutralizing activity against viral membrane antigen.

Transmitted primarily by exchange of saliva during kissing.

One of the most common infections worldwide.

Enters B lymphocytes at site of C3 receptor.

Infects oropharynx, then spreads to blood where it infects B lymphocytes.

EBV remains latent within B lymphocytes:

- a few copies of EBV DNA are integrated into cell genome.

- many copies of circular EBV DNA are found in cytoplasm.

Lifelong immunity against second episodes of infectious mononucleosis is based on antibody against viral membrane antigen.

Incubation period: 4-7 weeks.

Clinical symptoms:

- fever, sore throat.

- lymphadenopathy, splenomegaly.

- anorexia, lethargy.

Mononucleosis:

- atypical lymphocytes

- enlarged misshapen nuclei and excess cytoplasm.

- cytotoxic T cells: lobulated nucleus, vacuolated basophilic cytoplasm.

Duration: 2-3 weeks, spontaneous recovery.

EBV infections in the immunosuppressed can cause severe lymphoproliferative disease, which may be fatal and is characterized by infiltration of organs and tissues by immature B lymphocytes.

Chronic fatigue syndrome: fatigue, fever, sore throat, painful lymphadenopathy, muscle weakness, memory loss.

Association with:

- Burkitt’s lymphoma

- B cell lymphoma

- nasopharyngeal carcinoma.

Sequelae:

- Guillian-Barr syndrome.

- meningitis.

- pharyngitis.

- maculopapular rash

Paul-Bunnell test:

- heterophil antibodies to sheep erythrocytes appear in blood in infectious mononucleosis.

- monospot test used to detect the heterophil antibody.

Serology:

- early illness: IgM VCA antibody response.

- prior infection: IgG VCA antibody response.

Demonstration of EBV-specific IgM by immunofluorescence test, with VCA and antibody to early antigen.

No antiviral therapy needed for uncomplicated infectious mononucleosis.