Humoral and celular immune response 12 years after single dose vaccination against hepatitis A in Argentinian children

URUEÑA ANALIA; BADANO MARIA NOEL; ANDREA GÓMEZ RACCIO; PATRICIA BARÉ; GOLDSTEIN DE FINK SUSANA; VIZZOTTI CARLA

Ginebra

Congreso; Annual Meeting of the European Society for Paediatric Infectious DiseasesESPID 2021; 2021

ESPID

7/3/2021 #1664: HUMORAL AND CELLULAR IMMUNE MEMORY RESPONSE 12 YEARS AFTER SINGLE DOSE VACCINATION AGAINST...https://cpaper.ctimeetingtech.com/espid21/submission/preview/print?publication_id=1664 1/1Abstract 1664HUMORAL AND CELLULAR IMMUNE MEMORY RESPONSE 12 YEARS AFTER SINGLE DOSE VACCINATION AGAINSTHEPATITIS A IN ARGENTINIAN CHILDRENType: LB: Type 1: Clinical audit, prospective survey or retrospective studyTopic: General / 4. Immunology & immuno-compromised host / 4b. Host response diagnostics and imagingAuthors: A. Uruena1, M. Badano2, J. González3, P. Baré2, S. Fink2, C. Vizzotti1; 1ISALUD University, Centro deEstudios para la Prevención y Control de Enfermedades Transmisibles, Ciudad Autónoma De Buenos Aires,Argentina, 2Instituto de Medicina Experimental (IMEX)-CONICET. Academia Nacional de Medicina.,Laboratorio de Patogenia de Infecciones Virales, Ciudad Autónoma De Buenos Aires, Argentina, 3INEIANLIS ?Dr C. G. Malbran?, Departamento Virología, Ciudad Autónoma De Buenos Aires, ArgentinaBackgroundInfants? universal HAV single-dose vaccination has been highly effective for controlling HAV infection in Argentina,and in many other Latin-American countries that adopted that strategy. Although antibodies wane over time, thishas not been associated with HAV outbreaks or breakthrough infections, suggesting a relevant role for memoryimmunity. This study aimed to assess long term humoral and cellular immune memory response after HAV singledosevaccination.MethodsWe selected HAV-single dose vaccinated individuals known to have, in a 2015 study, protective (PAL)orunprotective antibody levels (UAL) against HAV. Humoral memory response was assessed by measuring anti-HAVAb titers at admission in both groups, and 30 days after a booster dose in the UAL group. Flow cytometry analysisof peripheral blood mononuclear cell (PBMC) sample stimulated with HAV antigen was performed to identifyactivated CD4+ memory T cells (CD3+CD4+CD69+CD45RO+) or CD8+ memory T cells(CD3+CD8+CD69+CD45RO+).Results48/52 (92%) individuals from UAL group who completed follow up reached protective levels after booster dose. Inthe PAL group, 2/27 (7%) individuals waned HAV Abs lacking seroprotection, while in 25/27 (93%) Abs remained>10 mUI/mL. HAV-specific memory CD4+ T cells were detected in 25/47 (53.2%) subjects while HAV-specific memory CD8+ T cells were observed in 16/47 (34.04%) individuals. HAV-specific memory CD4+ and CD8+ T-cells was observed in 14/25 (56%) individuals with non-detectable anti-HAV Ab levels, showing that the presence ofmemory T-cells was independent of the level or presence of anti-HAV antibodies.ConclusionsLong-term immunity demonstrated in the present work, including or not antibody persistence, suggests that individuals with waned Ab titers may still be protected and supports the single-dose HAV strategy.