Epstein Barr Virus DNA viral load in tissue biopsies of nasopharyngeal carcinoma patients : a retrospective study

Abstract

The Epstein-Barr virus (EBV) was discovered in 1964 by Michael Anthony Epstein and Yvonne Barr. It is usually transmitted mainly through saliva and the symptoms are similar to those of the common cold. In some instances, especially in young adults and adolescents, it causes infectious mononucleosis. Since EBV tends to infect B lymphocytes and epithelial cells, it has been associated with causing different malignancies including nasopharyngeal carcinoma (NPC). NPC is a relatively rare but significant cancer originating in the nasopharynx. This cancer occurs worldwide but has a higher incidence in South-East Asia and norther African countries, whilst being rare in western countries. The exact causes of the gene mutations that lead to NPC are still not clearly identified. However, several studies have identified an association between EBV and the presence of NPC tumour cells, suggesting a direct role in the malignant transformation of epithelial cells. Nonetheless, similar studies have not been carried out on the Maltese population. This retrospective study intends to discover if there is an association between EBV and NPC, and what interplay other factors, such as environmental, lifestyle or genetic factors, play in its aetiology. This was done by conducting sample de-waxing and digestion, followed by DNA extraction by the spin column technique and real-time PCR for the latent membrane protein gene. A total of 45 NPC-confirmed cases, yielding 55 formalin-fixed paraffin-embedded tissue blocks, were examined. Out of the 45 cases, 43 tested positive for EBV-LMP. Viral loads ranged from undetectable to over 10,000 copies/ml and a 95% confidence interval for EBV positivity was calculated at 85.2%–98.8%, supporting a strong association between EBV and NPC. Thus, these findings support the hypothesis that EBV plays a significant role in NPC pathogenesis within this population.