Characterization of EBV infection and NK subpopulations at the site of viral entry and reactivation in pediatric patients

FERRESSINI N; VISTAROP A; COHEN, M; CALDIROLA MS; GAILLARD MI; DE MATTEO E; PRECIADO MV; PAOLA ANDREA CHABAY

Madrid

Congreso; 28th European Congress of Clinical Microbiology and Infectious Diseases; 2018

European Society of Clinical Microbiology and Infectious Diseases

Several studies demonstrated the keyrole of NK cells in the control of early infection and EBV-mediated transformationin children from developed countries. Our aim was,in pediatric patients from a developing population, to characterize EBV infection related to NK cell subsets at the tonsils, site of viral entry and reactivation,.We analyzed 32 patients (2-15 years,median 5) undergoing tonsil surgery. EBV primary infection, reactivation or carrier status was defined by Anti-EBV VCA-IgM, VCA-IgG, Anti-EA-IgG and Anti-EBNA1 IgG. The viral load was measured by real rime PCR. Viral antigen expression was assessed by Immunohistochemistry (IHC) for LMP1, EBNA2 and BMRF1, and EBERS in Situ Hybridization (ISH). CD56, CD16, GRANZIME B (GrB), and IFN IHC (expressed as positive cells/mm2) was performed tocharacterize NK cells. CD3,CD56,CD16, NKG2A and NKG2DNK subsets were identifiedin 13 patients by Flow Cytometry (FC). Eighteen primary infected patients,11 healthy carriers, 3 patients with viral reactivation and no EBV-seronegative patients were described. No significant differencesin ageor viral load between groups were demonstrated(p> 0.05). In primary infected patients, there was a negative correlation between age and viral load (r=0.5, p=0.0335). EBV-infected cells showed Latency I or II patterns, in all patients (p>0.05). CD56+ and IFN+ cells correlated between them (r=0.7, p=0.002) and with viral load(r= 0.5, p=0.0188; r=0.5 p=0.0228, respectively). Neither statistical differences in NK subsets in the 3clustersby FC nor a correlation between NK cell subsets numberswith viral load wasestablished (p>0,05). In adults, symptomatically EBV primary infection display high viral load, latency III and lytic antigen expression, while low viral inoculum, restricted expression of EBV latent and lytic proteins was found in our 3 groups, maybe related to the lack of symptoms. Lower viral load in older patients may reflect a recruitment of immune cells to control EBV infection at the site of viral entry. The prevalence of IFN- producing NK cells in tonsils might be involved in restriction of EBV viral load. The lack of NKG2A+NKG2D+ NK cells prevalence in our primarily infected patients could be related to increased susceptibly to develop EBV-associated lymphomas