Epstein–Barr virus in humans can cause either of the following types of infections:
a) Primary infections by replication of viruses in B cells and epithelial cells.
b) Latent infection of B cells and presence of competent T cells.
c) Transformation of B cells to immortal plasmacytoid cells leading to malignancies.
Epstein–Barr virus infection first occurs in the oropharynx and then spreads to the blood causing infection of B lympho-cytes. The virus is, therefore, present in large numbers in oro-pharyngeal secretions. Hence, the infection is most commonly transmitted through infected saliva often as a result of kissing.
Therefore, the infectious mononucleosis is also commonly called as the kissing disease.
The virus infection induces a strong immune response, com-prising circulating antibodies against many virus-specific proteins, cell-mediated immune responses, and production of lymphokines. The humoral immunity is characterized by the appearance of IgM antibodies first against the viral membrane antigen, followed by the IgG antibodies, which persist for life. These antibodies against viral membrane antigen confer lifelong immunity against the second attack of infectious mononucleosis. The CMI plays an important role in controlling chronic infection and limiting primary infection.