Determining molecular and genetic markers for severe EBV-mononucleosis

Abstract

Epstein—Barr virus (EBV) is one of the etiological agents causing infectious mononucleosis. A severe form of the disease can result in developing serious complications, which risk might also depend on the state of patient’s immune system. To date, no specific tests for assessing a risk of developing severe disease form are available. Our study was aimed at identifying molecular genetic markers of severe EBV-infectious mononucleosis (EBV-IM) in immunocompetent peripheral blood cells. Expression of 483 genes and gene transcripts regulating apoptosis, proliferation and differentiation of immunocompetent cells was measured in the peripheral blood leukocytes from patients with severe and moderate EBV-IM as well as apparently healthy donors. A DNA-microarray designed by us and subsequent data processing were carried out by using custom-made “MiDA” software. To identify markers of a severe form of the pathology, expression of each gene and transcript was compared in EBV-IM patients and apparently healthy donors. For each gene and transcript, the level of expression fold change and significance for binary classification were determined. Genes and transcripts, characterized by the maximum values of two determined parameters while comparing patients with severe infection and healthy donors, as well as patients with severe and moderate EBV-IM forms, were selected as markers of severe EBV-IM. Genes and transcripts with differed expression in patients with moderate EBV-IM and healthy donors, were excluded from the list of markers. In addition, sex- and age-linked markers with differed expression were excluded as well. The markers for severe EBV-IM consisted of apoptosis regulators (BCL2L11, BIRC3 genes and XIAP.NM_001167 transcript) and splicing factors (CELF6 gene and SF1.NM_201995 transcript). Compared with donors and patients with a moderate form of the disease, a decreased expression of BCL2L11, BIRC3 genes, transcripts SF1.NM_201995 and XIAP.NM_001167, as well as increased expression of the CELF6 gene were detected in the blood of patients with severe EBV-IM. The functional role of identified molecular markers suggests that severe EBV-IM is characterized by suppressed mitochondrial and activated TRAF-dependent apoptosis pathways in immunocompetent cells. The expression pattern for select markers is specific for severe EBV-MI, not associated with patient sex and age. Thus, study data may be used to develop specific tools for assessing a risk of developing complications of EBV mononucleosis.