title: Specific memory B cell response and participation of CD4+central and effector memory T cells in mice immunized with liposome encapsulated recombinant NE protein based Hepatitis E vaccine candidate.
abstract: Liposome encapsulated neutralizing epitope protein of Hepatitis E virus (HEV), rNEp, our Hepatitis E vaccine candidate, was shown to be immunogenic and safe in pregnant and non-pregnant mice and yielded sterilizing immunity in rhesus monkeys.
  
  
  
  The current study in Balb/c mice assessed the levels and persistence of anti-HEV IgG antibodies by ELISA, frequencies of B, memory B, T and memory T cells by flow cytometry and HEV-specific IgG secreting memory B cells by ELISPOT till 420days post immunization (PI) with 5?g rNEp encapsulated in liposome based adjuvant (2 doses, 4weeks apart). Mice immunized with a lower dose (1?g) were assessed only for anamnestic response post booster dose.
  
  
  
  Vaccine candidate immunized mice (5?g dose) elicited strong anti-HEV IgG response that was estimated to persist for lifetime. At day 120 PI, frequency of memory B cells was higher in immunized mice than those receiving adjuvant alone. Anti-HEV IgG titers were lower in mice immunized with 1?g dose. A booster dose yielded a heightened antibody response in mice with both high (>800GMT, 5?g) and low (?100GMT, 1?g) anti-HEV IgG titers. At day 6th post booster dose, HEV-specific antibody secreting plasma cells (ASCs) were detected in 100% and 50% of mice with high and low anti-HEV IgG titers, respectively, whereas the frequencies of CD4+central and effector memory T cells were high in mice with high anti-HEV IgG titers only.
  
  
  
  Taken together, the vaccine candidate effectively generates persistent and anamnestic antibody response, elicits participation of CD4+memory T cells and triggers memory B cells to differentiate into ASCs upon boosting. This approach of assessing the immunogenicity of vaccine candidate could be useful to explore the longevity of HEV-specific memory response in future HEV vaccine trials in human.
authors.affiliation: Hepatitis Group, National Institute of Virology, Pune, 130/1, Sus Road, Pashan, Pune 411021, Maharashtra, India.
authors.forename: Shruti P
authors.initials: SP
authors.lastname: Kulkarni
authors.affiliation: Hepatitis Group, National Institute of Virology, Pune, 130/1, Sus Road, Pashan, Pune 411021, Maharashtra, India.
authors.forename: Subrat
authors.initials: S
authors.lastname: Thanapati
authors.affiliation: Interactive Research School in Health Affairs (IRSHA), Bharati Vidyapeeth Deemed University, Pune-Satara Road, Katraj-Dhankawadi, Pune 411043, Maharashtra, India. Electronic address: varankalle@yahoo.com.
authors.forename: Vidya A
authors.initials: VA
authors.lastname: Arankalle
authors.affiliation: Hepatitis Group, National Institute of Virology, Pune, 130/1, Sus Road, Pashan, Pune 411021, Maharashtra, India. Electronic address: anuradhastripathy@hotmail.com.
authors.forename: Anuradha S
authors.initials: AS
authors.lastname: Tripathy
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes / Q000276:immunology; D006508:Hepatitis Antibodies / Q000097:blood; D016751:Hepatitis E / Q000517:prevention & control*; D016752:Hepatitis E virus / Q000737:chemistry / Q000276:immunology*; D007117:Immunization, Secondary; D000071497:Immunogenicity, Vaccine; D007074:Immunoglobulin G / Q000097:blood; D007156:Immunologic Memory; D008081:Liposomes / Q000737:chemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D014761:Viral Hepatitis Vaccines / Q000008:administration & dosage / Q000737:chemistry / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D000939:Epitopes; D006508:Hepatitis Antibodies; D007074:Immunoglobulin G; D008081:Liposomes; D014761:Viral Hepatitis Vaccines
keywords: Anamnestic response; CD4(+) memory T cells; Functional memory B cells; Hepatitis E vaccine