Coinfection by multiple strains of Epstein-Barr virus in infectious mononucleosis in immunocompetent patients

Objective-A molecular study of Epstein-Barr virus (EBV)-induced infectious mononucleosis (IM) was performed. The presence of a 30-bp deletion on the latent membrane protein-1 (LMP-1) oncogene from EBV in Caucasian IM patients was evaluated. Material and Methods-Peripheral blood mononuclear cells were obtained from 27 IM patients and 18 adenoids, 28 tonsils and 16 EBV-related reactive lymphadenitis specimens were used as controls. DNA isolation, EBV polymerase chain reaction (PCR) and LMP-1 oncogene PCR analysis were performed. Results-The 30-bp deletion on LMP-1 was identified in 29.6% of IM patients, but was always seen in conjunction with full-length LMP-1. Although the LMP-1-deleted strain seemed to be more prevalent in IM (29.6%) and EBV-related reactive lymphadenitis (37.5%) than in adenoid (0%) or tonsil specimens (21.4%), these differences were not significant (p > 0.05; chi(2) ). Thus, a 30-bp deletion on LMP-1 was present in almost a third of Caucasian IM patients. Conclusion-The finding of coinfections in IM patients confirms that primary infection by more than one EBV strain is possible.