INTRODUCTION TO EPSTEIN-BARR VIRUS (EBV)
In 1964, a virus was observed in cultured lymphoma cells by Epstein, Barr & Achong, a new type of Herpesvirus, named the EB virus or Epstein-Barr Virus, specifically affecting cells of the B lymphocyte lineage.
INFECTIONS CAUSED BY EPSTEIN-BARR VIRUS
⇒ The source of the infection is usually the saliva of infected persons.
⇒ Intimate oral contact, as in Kissing, appears to be the main mode of infection.
⇒ It mainly causes Infectious Mononucleosis or Glandular fever.
⇒ EBV has Oncogenic properties & may cause Burkitt’s lymphoma and nasopharyngeal carcinoma.
CLINICAL FEATURES OF EPSTEIN-BARR VIRUS
⇒ The incubation period of Epstein – Barr virus is 4-8 weeks.
⇒ The disease is characterized by
- Sore throat
⇒ A mild transient rash may be present.
⇒ Presence of abnormal lymphocytes in peripheral blood smears.
⇒ A number of other complications have been recorded, including hematological, neurological, cardiac & pulmonary conditions.
LABORATORY DIAGNOSIS OF EPSTEIN-BARR VIRUS
⇒ Blood examination:- During initial phase leucopenia may be observed due to a drop in the number of polymorphs. Later there is prominent leucocytosis, with the appearance of abnormal mononuclear cells.
⇒ Paul-Bunnell test:– It is the standard diagnostic procedure for infectious mononucleosis. In infectious mononucleosis, heterophile antibodies appear and capable to agglutinate sheep erythrocytes. Such antibodies may also occur after injections of sera, sometimes in normal individuals. Infectious mononucleosis antibodies may be differentiated by absorption tests. For this, inactivated serum (56°C for 30 minutes) in doubling dilutions is mixed with equal volumes of a 1% suspension of sheep erythrocytes. After incubation at 37°C for four hours the tubes are examined for agglutination. An agglutination titer of 100 or above is suggestive of infectious mononucleosis.
⇒ EBV specific antibodies:- Anti EBV antibodies can be demonstrated by indirect immunofluorescence or ELISA.
⇒ Antigen detection:– EBV antigen can be detected by immunofluorescence using monoclonal antibodies.
⇒ Virus isolation:– Saliva or throat washings and peripheral blood cells can be inoculated onto lymphocytes. If the specimen contains EBV, it produces a lymphoblastoid cell line.
⇒ Polymerase chain reaction:– The DNA of Epstein Barr virus can be detected by PCR.