Epidemiological presentation of EBV infection and characterization of NK subpopulationsin the tonsils of pediatric patients compared with non-infected patients

FERRESSINI N; MOYANO A; CALDIROLA MS; GAILLARD MI; DE MATTEO E; PRECIADO, M. V.; PAOLA ANDREA CHABAY

Trieste

Congreso; ICGEB DNA Tumour Virus Meeting ? 50th Anniversary; 2019

ICGEB

Several studies demonstrated the keyrole of NK cells in the control of early infection and EBV-mediated transformationin children from developed countries. Therefore, our aim wasto characterize EBV infectionin relation to NK cell subsets at the tonsils,site of viral entry and reactivation, in children from Argentina.We analyzed 76patients (1-15 years,median5) undergoing tonsillectomy. EBV primary infection (PI), reactivation (R), carrier (HC), or non-infected (NI) status was defined by serology. Viral load(VL) was evaluated by qPCR.Viralantigen expression was assessed by Immunohistochemistry (IHC) for LMP1, LMP2A, EBNA2 and BMRF1, and byEBERS in situ Hybridization (ISH). CD56, CD16, IFNand GrzBIHC (expressed as positive cells/mm2) was performed tocharacterize NK cells. CD3,CD56,CD16, NKG2A and NKG2DNK subsets were identifiedin 44patients by Flow Cytometry (FC).EBV typification was performed using primers directed against EBNA3C gene.Twenty-three PI patients,38HC,10 R patients and 5 NI patients were discriminated. No significant differencesregarding age andVL among groups were demonstrated(p> 0.05) even though PI patients had a higher VL mean. Unexpectedly, latency III pattern was observed exclusively in HC (p=0.0342, X2 test). CD56+ and IFN+ cells by IHC displayed a positive correlation between them in the whole series (r=0.3009, p=0,0256) and specifically in PI (r=0.5298, p=0.0163). FC analysis revealed no specific NK cell population in the three groups of EBV- infected patients (p>0.05), while a negative correlation between CD56+ and VL in all patients (r=-0,6623, p=0.005) and particularly in PI (r=-0,6623, p=0.005) was proved. In PI we observed correlation between age and NKG2A+NKG2D+ NK cells (r=0,6685, p=0.0245).Regarding EBV types in cases with good quality DNA, EBV1 was prevalent in the whole series, given that 19 patients were positive for EBV-1, 6 for EBV-2 and one PI patient was co- infected, moreover, EBV1 was statistically distributed in patients younger than 10 years (p=0.0468, Fisher exact test)The low viralinoculum along with restricted expression of EBV latent and lytic proteins was found in PI, maybe related to the lack of symptoms. Even though no specific NK subpopulation was described,IFN- producing NK cells may be involved the control of viral infection in all EBV-infected patients