Low expression of activation marker CD69 and chemokine receptors CCR5 and CXCR3 on memory T cells after 2009 H1N1 influenza A antigen stimulation in vitro following H1N1 vaccination of HIV-infected individuals.

Unlike well-studied antibody responses to pandemic 2009 H1N1 influenza A virus vaccines in human immunodeficiency virus-infected (HIV+) individuals, less well understood are cell-mediated immune (CMI) responses to this antigen in this susceptible population. We investigated such influenza-specific CMI responses in 61 HIV+ individuals and in 20 HIV-negative (HIV-) healthy controls. Each was vaccinated with a single licensed dose of inactivated, split-virion vaccine comprised of the influenza A/California/7/2009 (H1N1) virus-like strain. Cells collected just prior to vaccination and at 1 and 3 months afterwards were stimulated in vitro with dialyzed vaccine antigen and assayed by flow cytometry for cytokines TNF-α, IFN-γ, IL-2, and IL-10, for degranulation marker CD107a, as well as phenotypes of memory T-cell subpopulations. Comparable increases of cytokine-producing and CD107a-expressing T cells were observed in both HIV+ subjects and healthy HIV-controls. However, by 3 months post-vaccination, in vitro antigen stimulation of peripheral blood mononuclear cells induced greater expansion in controls of both CD4 and CD8 central memory and effector memory T cells, as well as higher expression of the activation marker CD69 and chemokine receptors CCR5 and CXCR3 than in HIV+ subjects. We concluded CD4+ and CD8+ memory T cells produce cytokines at comparable levels in both groups, whereas the expression after in vitro stimulation of molecules critical for cell migration to infection sites are lower in the HIV+ than in comparable controls. Further immunization strategies against influenza are needed to improve the CMI responses in people living with HIV.

Correlation of CYP2B6-516G > T Polymorphism with Plasma Efavirenz Concentration and Depression in HIV-Infected Adults in Northern Thailand.

BACKGROUND: Single nucleotide polymorphism of the hepatic cytochrome P450 isoenzyme 2B6 (CYP2B6) gene is a cause of variation in plasma efavirenz (EFV) concentrations. We aimed to determine the allelic distribution of CYP2B6 gene, plasma levels of EFV, the prevalence of clinical depression, and their correlations in northern Thai population. METHODS: This was a cross-sectional study of HIV-infected patients on EFV-containing antiretroviral regimens for ≥48 weeks. A single blood specimen was collected for determination of the mid-dose plasma EFV concentration and CYP2B6- 516G > T polymorphism. The presence and severity of depression were assessed. RESULTS: One hundred patients were enrolled [mean age (±SD) was 41.81±8.44 years, mean CD4 lymphocyte count 462±193 cells/ul]. The genotype CYP2B6-516 guanine/guanine (G/G), guanine/thymidine (G/T), and T/T were found in 49%, 37%, and 14% of patients, respectively. The allele frequency of CYP2B6-516 G to T replacement was 32.5%. The median plasma EFV concentration was 2,616 ng/mL (IQR 1,851-3,742); 79% had EFV plasma concentrations from 1,000 to 4,000 ng/mL. The mean EFV concentrations for those with G/G, G/T and T/T genotypes were 2,082±630, 3,166±1,074, and 11,196±6,265 ng/mL, respectively (p < 0.01). CYP2B6-516G > T polymorphism was the only factor associated with high plasma EFV levels. Nineteen patients had depression; 13 of 18 (72%) with mild and one with major depression had normal plasma EFV level. A weak correlation between plasma EFV concentrations and depression scores was observed (p=0.009, R2=0.059). CONCLUSIONS: The prevalence of CYP2B6-516G > T polymorphism in northern Thai population is high and strongly associated with inter-individual drug levels variation.

Immune response to 2009 H1N1 vaccine in HIV-infected adults in Northern Thailand.

BACKGROUND: In late 2009, the Thai Ministry of Public Health provided two million doses of the monovalent pandemic influenza H1N1 2009 vaccine (Panenza®, Sanofi Pasteur), which was the only vaccine formulation available in Thailand, to persons at risk of more severe manifestations of the disease including HIV infection. Several studies have shown poorer immune responses to the 2009 H1N1 vaccines in HIV-infected individuals. There are limited data in this population in resource-limited countries. RESULTS: At day 28 post-vaccination, seroconversion was found in 32.0% (95%CI 24.5 - 40.2) of the HIV-infected group and 35.0% (95%CI 15.4- 59.2) of the healthy controls (p = 0.79). Seroprotection rate was observed in 33.3% (95%CI 25.8-41.6) and 35.0% (95%CI 15.4-59.2) of the HIV-infected group and the control group, respectively (p = 0.88). Among HIV-infected participants, the strongest factor associated with vaccine response was age 42 y or younger (p = 0.05). METHODS: We evaluated the immunogenicity of a single, 15µg/0.5ml dose of a monovalent, non-adjuvanted 2009 H1N1 vaccine in 150 HIV-infected Thai adults and 20 healthy controls. Immunogenicity was measured by hemagglutination inhibition assay (HI) at baseline and 28 d after vaccination. Seroconversion was defined as 1) pre-vaccination HI titer < 1:10 and post-vaccination HI titer ≥ 1:40, or 2) pre-vaccination HI titer ≥ 1:10 and a minimum of 4-fold rise in post-vaccination HI titer. Seroprotection was defined as a post-vaccination HI titer of ≥ 1:40. CONCLUSIONS: A low seroconversion rate to the 2009 H1N1 vaccine in both study groups, corresponding with data from trials in the region, may suggest that the vaccine used in our study is not very immunogenic. Further studies on different vaccines, dosing, adjuvants, or schedule strategies may be needed to achieve effective immunization in HIV-infected population.