THE ASSOCIATION OF EPSTEIN-BARR VIRUS AND ACUTE LEUKAEMIAS IN NAMIBIA

ABSTRACT

There are two viruses found to be direct aetiological agents of leukaemia, namely Epstein-Barr virus (EBV) and Human T-cell leukaemia virus. Viral infections were estimated to cause 15 – 20 % of all human cancers, by its capability to release virus-encoded proteins into its host. These proteins reprogram host cell signalling pathways within deoxyribonucleic acid (DNA), which are responsible for differentiation and proliferation. Furthermore, 90% of the world’s population is infected with EBV as a life-long and dormant infection of B lymphocytes. EBV is a considerably known an etiological factor in various tumours, but very little is known of the relationship between EBV and Acute Leukaemia (AL), taking into consideration any type of AL, gender or age. AL is a serious disease and the actual cause of cancer remains unknown. This study, therefore, aimed to establish the presence of Epstein-Barr virus in patients with Acute Leukaemias.

The patients who were previously diagnosed with AL and who visited the Oncology ward (Windhoek Central Hospital) within the specified time frame (01 March 2017 – 31 July 2018), were screened for the presence of EBV IgG and IgM antibodies, by the use of the Enzyme-linked Immunosorbent Assay (ELISA) method. The same Ethylene Diamine Tetra Acetic Acid (EDTA) samples, which were sent to Namibian Institute of Pathology (NIP) for routine AL check-up screening, were used for this study. Controls were randomly selected among non-AL patients of different ages. The AL patients which relapsed within the period of interest were screened for the presence of EBV DNA. The same amount of patients were picked as a control and also screened for EBV DNA by Real-Time Polymerase Chain Reaction (PCR). All variables were compared between cases and controls to determine any significant association of EBV with AL. Statistical differences between the AL patients and controls were determined by the use of Chi-square testing.

The AL patient group presented with the following results: 66 out of 95 (69%) were Acute Lymphoblastic Leukaemia (ALL) patients and 29 out of the 95 (31%) were Acute Myeloid Leukaemia (AML) patients. Additionally, 8 out of 95 (8%) relapsed within the period of interest. EBV IgG was the most common marker among the AL patients of which 95 out of the 95 (100%) patients were positive for EBV IgG following, EBV IgM of which 0 out of the 95 were positive for EBV IgM (0%). In the control group, 54 out of the 95 patients were positive for EBV IgG (57%) and 41 out of the 95 were negative for EBV IgG (43%). Furthermore, 17 out of the 95 were positive for EBV IgM (18%) and 78 patients out of the 95 were negative for EBV IgM (82%). Positive results were considered for titer concentrations of more than and equal to 1.2 for EBV IgG, and, more than and equal to 1.24 for EBV IgM. EBV DNA was based on qualitative measures. Chi-square results: EBV IgG p=0.0002*** for AL. EBV IgG

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p=0.0002*** for ALL. EBV IgG p=0.0002*** for AML. EBV DNA p=0.03* for the relapsed AL cases. A P- value less than or equal to 0.05 was considered statistically significant.

Overall it can be concluded that EBV is common amongst AL patients of Namibia, as a lifelong latent infection, which could have contributed to the development of AL regardless of the type of AL (ALL or AML), neither the age affected nor the gender. Furthermore, it’s concluded that there is also an association between EBV and relapsing AL. These conclusions broaden the knowledge that EBV can initially infect anyone and the consequences in the long term may be fatal. Prevention interventions considering EBV should already be taken at newborn infancy period. For those previously infected with EBV should maintain a strong immunity to prevent the EBV from going viral.