title: Serological response to trivalent inactivated influenza vaccine in HIV-infected adults in Singapore.
abstract: A cohort of 81 HIV-infected participants received seasonal trivalent inactivated influenza vaccine (TIV) and their humoral responses were monitored using hemagglutination inhibition (HAI) assay and enzyme-linked immunosorbent assay (ELISA). Three weeks after the vaccination, the percentage of the cohort that had an HAI titer of >1:40 was 35% (for H1N1), 43% (for H3N2) and 19% (for influenza B). An increase in HAI titer can be achieved by an increase in magnitude of the antibody responses, which can be measured by an increase in ELISA titer; as well as a quality improvement of the antibody responses through increased avidity to the virus. For some individuals, an increase in avidity alone is sufficient to reach the sero-protective titer. Notably, a number of volunteers showed an increase in ELISA titer without a rise in HAI titer. A total of 24 participants (30%) did not show any significant increase in both HAI and ELISA tests after vaccination. Apart from a lower peripheral CD4+T cell count, the non responders' peripheral blood mononuclear cells (PBMC) also had a higher IL-10 mRNA expression after TIV vaccination ex vivo. Cytokine profiling demonstrated that, apart from a weaker MCP-1 expression in the non-responder group, PBMC from both groups responded comparably to lipopolysaccharide (LPS) stimulation in vitro. Since only 3 participants developed sero-protective titers against all 3 subtypes after vaccination, our study highlights a need to enhance the immunogenicity of the subunit vaccine for this population, potentially through harnessing the innate immunity with an external adjuvant.
authors.affiliation: a Host-pathogen Interactions Laboratory, DMERI , DSO National Laboratories , The Republic of Singapore.|b Program in Emerging Infectious Diseases , Duke-NUS Medical School , The Republic of Singapore.
authors.forename: Yuk-Fai
authors.initials: YF
authors.lastname: Lau
authors.affiliation: a Host-pathogen Interactions Laboratory, DMERI , DSO National Laboratories , The Republic of Singapore.
authors.forename: Lay-Hoon
authors.initials: LH
authors.lastname: Tang
authors.affiliation: c Communicable Disease Centre , Tan Tock Seng Hospital , Singapore.|d Yong Loo Lin School of Medicine , National University of Singapore , Singapore.
authors.forename: David
authors.initials: D
authors.lastname: Chien Lye
authors.affiliation: b Program in Emerging Infectious Diseases , Duke-NUS Medical School , The Republic of Singapore.
authors.forename: Eng-Eong
authors.initials: EE
authors.lastname: Ooi
authors.affiliation: c Communicable Disease Centre , Tan Tock Seng Hospital , Singapore.|d Yong Loo Lin School of Medicine , National University of Singapore , Singapore.|e Saw Swee Hock School of Public Health , National University of Singapore , Singapore.
authors.forename: Yee-Sin
authors.initials: YS
authors.lastname: Leo
mesh_terms: D000328:Adult; D000368:Aged; D000917:Antibody Formation; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D016207:Cytokines / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D012846:Singapore; D014838:Volunteers; D055815:Young Adult
chemical_list: D016207:Cytokines; D007252:Influenza Vaccines
keywords: HIV; seasonal influenza vaccine