Macrophage?s role in the microenvironment against Epstein Barr Virus (EBV) in tonsils from pediatrics patients

MOYANO A; FERRESSINI GERPE, NM; DE MATTEO E; PRECIADO MV; PAOLA ANDREA CHABAY

Congreso; 19th International Congress on Infectious Diseases; 2020

International Society for Infectious Diseases

In Argentina, our group demonstrated that 72% of children are infected by EBV, usually without showing symptoms. Furthermore, in our country EBV-associated lymphomas prevail in patients under 10 years old. In order to better understand EBV pathogenesis, our aim was to describe the characteristics of EBV infection in pediatric patients at the site of viral entry and reactivation, the tonsils. We analyzed 32 patients (age range 2-15 years, median) undergoing tonsil surgery due to non-reactive hyperplasia. EBV serological status was defined by Anti-EBV VCA-IgM, VCA-IgG, Anti-Early Antigen (EA)-IgG and Anti-EBNA1 IgG, or order to assess if the patients were undergoing primary infection, reactivation, or if they were healthy carriers. The viral load was measured by real rime PCR. To characterize viral latency, we performed Immunohistochemistry (IHC) in formalin fixed paraffin-embedded tonsil biopsies for viral antigens (LMP1, EBNA2 and BMRF1), and EBERS in Situ Hybridization (ISH). We identified 18 patients with EBV primary infection (IgM+/IgG+/-) (mean 6 years), 11 carriers (VCA-IgM-/VCA-IgG+/EA-IgG-/EBNA-IgG+) (age mean 7+ 3 years old), 3 patients with viral reactivation (VCA-IgM+/-/VCA-IgG+/EA-IgG+ /EBNA-IgG+) (age mean 7+ 1 years old) and no EBV-seronegative patients. No significant differences in age or viral load between groups were demonstrated (p> 0.05, Kruskal-Wallis test). However,in primary infected patients there was a negative correlation between age and viral load (p=0.0335, r=-0.5, Spearman correlation test). Unexpectedly, EBV-infected cells showed Latency I or II patterns even in patients undergoing primary infection or viral reactivation. Only pediatric healthy carriers showed BMRF1 lytic antigen expression.Conclusions: In adults undergoing EBV primary infection with symptoms, high viral load together with latency III pattern and lytic antigen expression was described. In contrast, in our primary infected patients the lack of symptoms could be related to a low viral inoculum, together with the lack of latency III and lytic viral antigens. Furthermore, viral characteristics in the primary infected group are similar to patients with viral reactivation and healthy carriers. In addition, lower viral load in older patients may reflect a recruitment of immune cells to successfully control EBV infection at the site of viral entry and reactivation, perhaps as a consequence of maturity of the immune system.