Takashi Odawara

Yeast-derived human immunodeficiency virus type 1 p55(gag) virus-like particles activate dendritic cells (DCs) and induce perforin expression in Gag-specific CD8(+) T cells by cross-presentation of DCs.

ABSTRACT To evaluate the immunogenicity of human immunodeficiency virus (HIV) type 1 p55gag virus-like particles (VLPs) released by budding from yeast spheroplasts, we have analyzed the effects of yeast VLPs on monocyte-derived dendritic cells (DCs). Yeast VLPs were efficiently incorporated into DCs via both macropinocytosis and endocytosis mediated by mannose-recognizing receptors, but not the mannose receptor. The uptake of yeast VLPs induced DC maturation and enhanced cytokine production, notably, interleukin-12 p70. We showed that yeast membrane components may contribute to DC maturation partly through Toll-like receptor 2 signaling. Thus, Gag particles encapsulated by yeast membrane may have an advantage in stimulating Gag-specific immune responses. We found that yeast VLPs, but not the control yeast membrane fraction, were able to activate both CD4+ and CD8+ T cells of HIV-infected individuals. We tested the effect of cross-presentation of VLP by DCs in two subjects recruited into a long-term nonprogressor-slow progressor cohort. When yeast VLP-loaded DCs of these patients were cocultured with peripheral blood mononuclear cells for 7 days, approximately one-third of the Gag-specific CD8+ T cells were activated and became perforin positive. However, some of the Gag-specific CD8+ T cells appeared to be lost during in vitro culture, especially in a patient with a high virus load. Our results suggest that DCs loaded with yeast VLPs can activate Gag-specific memory CD8+ T cells to become effector cells in chronically HIV-infected individuals, but there still remain unresponsive Gag-specific T-cell populations in these patients.

Targeted infection of a retrovirus bearing a CD4-Env chimera into human cells expressing human immunodeficiency virus type 1.

We constructed a hybrid Moloney murine leukaemia virus (MoMLV) bearing both a chimeric CD4 and the wild-type MoMLV envelope protein (Env) on its surface. The chimeric molecule, consisting of a surface domain of CD4 and the C-terminal two-thirds of MLV Env, was expressed on the cell surface. When expressed in MoMLV-infected cells, the CD4-Env chimera was incorporated into the virion as efficiently as the wild-type MoMLV Env. The hybrid MoMLV could infect human HeLa cells (although not with high efficiency) only if the cells were expressing human immunodeficiency virus type 1 genome. This method of ligand incorporation into a virion may lead to a development of a cell-specific retroviral vector for targeting gene therapy.

Proline 78 is crucial for human immunodeficiency virus type 1 Nef to down-regulate class I human leukocyte antigen.

ABSTRACT Human immunodeficiency virus type 1 Nef down-regulates human leukocyte antigen class I (HLA-I) in T lymphocytes, and the down-regulation involves the Nef proline-rich domain (PRD) containing four prolines at positions 69, 72, 75, and 78. We used a Sendai virus vector with nef and examined regulation by Nef of HLA-I and CD4 in suspension cultures of cells such as T lymphocytes. Analyses of a series of PRD substitution mutants indicated that, because the substitution of Pro78 with Ala abolished down-regulation of HLA-I but not of CD4, Pro78 is important for HLA-I down-regulation in T lymphocytes.

Induction of protective immunity against pathogenic simian immunodeficiency virus by a foreign receptor-dependent replication of an engineered avirulent virus

In AIDS vaccine strategies, live attenuated vaccines can confer good resistance against pathogenic virus infections but have the potential risk of inducing disease, whereas safer replication-negative strategies such as DNA vaccinations have so far failed to prevent the disease onset. Here, we developed a novel DNA vaccine strategy to induce restricted replication of an avirulent virus and evaluated it in a simian immunodeficiency virus (SIV) infection model. We generated a chimeric SIV, FMSIV, by replacing SIV env with ecotropic Friend murine leukemia virus (FMLV) env to confine its replication to FMLV receptor (mCAT1)-expressing cells. In primate cells lacking mCAT1, FMSIV did not replicate unless mCAT1 was introduced exogenously. Vaccination to macaques with both the FMSIV DNA and the mCAT1-expression plasmid DNA induced SIV Gag-specific cellular immune responses and resistance against pathogenic SIV(mac239) challenge more efficiently than the replication-negative control vaccination with the FMSIV DNA alone. This strategy may be useful for development of safe and effective vaccines against various kinds of pathogenic viruses.

Changes in impact of HLA class I allele expression on HIV-1 plasma virus loads at a population level over time

HLA class I allele types have differential impacts on the level of the pVL and outcome of HIV‐1 infection. While accumulations of CTL escape mutations at population levels have been reported, their actual impact on the level of the pVL remains unknown. In this study HLA class I types from 141 untreated, chronically HIV‐1 infected Japanese patients diagnosed from 1995–2007 were determined, and the associations between expression of individual HLA alleles and level of pVL analyzed. It was found that the Japanese population has an extremely narrow HLA distribution compared to other ethnic groups, which may facilitate accumulation of CTL escape mutations at the population level. Moreover while they uniquely lack the most protective HLA‐B27/B57, they commonly express the alleles that are protective in Caucasians (A11:10.4%, A26:11.55%, B51:8.6% and Cw14:12.7%). Cross‐sectional analyses revealed no significant associations between expression of individual alleles and the level of the pVL. The patients were then stratified by the date of HIV diagnosis and the analyses repeated. It was found that, before 2001, B51+ individuals displayed significantly lower pVL than the other patients (median: 5150 vs. 18 000 RNA copies/ml, P= 0.048); however thereafter this protective effect waned and disappeared, whereas no changes were observed for any other alleles over time. These results indicate that, at a population level, some HLA alleles have been losing their beneficial effects against HIV disease progression over time, thereby possibly posing a significant challenge for HIV vaccine development. However such detrimental effects may be limited to particular HLA class I alleles.

Whole brain radiation alone produces favourable outcomes for AIDS‐related primary central nervous system lymphoma in the HAART era

Primary central nervous system lymphoma (PCNSL) related to acquired immunodeficiency syndrome (AIDS) is a lethal disorder, but the recent application of highly active antiretroviral therapy (HAART) has significantly improved prognosis. This retrospective cohort study of AIDS‐related PCNSL examined the actual clinical outcomes and prognostic variables affecting overall survival (OS) in the HAART era. Twenty‐three newly diagnosed AIDS‐related PCNSL at 12 regional centre hospitals for HIV/AIDS in Japan between 2002 and 2008 were consecutively enrolled. The estimated 3‐yr OS rate of the entire cohort was 64% (95%CI, 41.0–80.3%). Whole brain radiation therapy (WBRT) had an independent positive impact on survival (WBRT ≥30 Gy vs. others, P = 0.02). Nine of 10 patients with a good performance status (PS) (0–2) remained alive with complete response, whereas 10 (77%) of 13 of those with a poor PS (3–4) died mostly after a short period. The estimated 3‐yr OS rate of the groups with a good and poor PS was 100% and 38% (95%CI, 14–63%), respectively (P = 0.01). Leukoencephalopathy (grade ≥ 2) developed in 21% of those that survived more than 12 months after radiation. The patients receiving a curative intent radiation dose (≥30 Gy) of WBRT achieved prolonged survival while maintaining a good quality of life in the HAART era, especially among patients with a favourable PS.

Highly restricted T-cell receptor repertoire in the CD8+ T-cell response against an HIV-1 epitope with a stereotypic amino acid substitution.

Objective:In peripheral blood mononuclear cells (PBMCs) from HIV-1-positive patients, we sought to identify CD8+ T-cell populations and the corresponding T-cell receptor (TCR) repertoires that react to an immunogenic cytotoxic T lymphocyte (CTL) epitope with or without an escape mutation. Methods:PBMCs from HLA-A*2402(A24)-positive patients were stimulated with peptides representing a wild-type CTL epitope in the HIV-1 Nef protein [Nef138-10(wt)] or an escape mutant with a Y to F (Y139F) substitution at the second position [Nef138-10(2F)]. Cultured PBMCs were stained with peptide-major histocompatibility complex tetramers containing Nef138-10(wt) or Nef138-10(2F) sequences. After in-vitro stimulation of PBMCs with cognate peptides, the CD8+ T-cell population was sorted into different fractions: positive only to the wild-type tetramer (wt-positive), positive only to the mutant tetramer (2F-positive), and positive to both wt-tetramers and mutant-tetramers (dual-positive). TCR repertoires of sorted epitope-specific CD8+ T-cell populations were determined by sequencing. Results:A 2F-positive population was rarely observed under our culture and staining conditions. The wt-positive CD8+ T-cell populations had a diverse TCR repertoire, but the TCR repertoires in dual-positive CD8+ populations were highly restricted. In the dual-positive CD8+ T-cell populations, most clonotypes used the TRBV4-1 and TRBJ2-7 gene segments for the TCR β-chain and the TRAV8-3 and TRAJ40-1 for the TCR α-chain. The CDR3 region of the TCR β-chain showed little variation. Conclusion:These results provide an example of restricted TCR repertoire in a specific CTL response against the escaping epitope. We speculate that impairment of antigen presentation in escaping viruses may underlie the restricted repertoire.

Molecular Analysis of Human Herpesvirus 8 by Using Single Nucleotide Polymorphisms in Open Reading Frame 26

ABSTRACT Human herpesvirus 8 (HHV-8) can be classified into distinct subtypes on the basis of sequence polymorphisms in several open reading frames (ORFs). We analyzed the subtypes of HHV-8 in 59 human immunodeficiency virus-infected Japanese patients by using polymorphisms in ORF26 and found that over two-thirds of the HHV-8 isolates fell into major subtype A. We also found that single nucleotide polymorphisms (SNPs) at nucleotide positions 1032 (C-to-A substitution) and 1055 (G-to-T substitution) in HHV-8 ORF26 were correlated with increased susceptibility to Kaposis sarcoma, compared to the results obtained with HHV-8 with wild-type nucleotides at these positions (P = 0.0106). This observation suggests that molecular heterogeneity of the HHV-8 genome affects the biological properties of HHV-8, resulting in different clinical phenotypes of HHV-8 infection. Since sensitive PCR of ORF26 allowed us to analyze the SNPs by using peripheral blood from HHV-8-infected patients, the ORF26 SNPs will be a potent tool for investigating the pathogenesis of HHV-8 infection.

Actual status of AIDS-related lymphoma management in Japan

Recently, with the widespread use of highly active antiretroviral therapy (HAART), the occurrence of opportunistic infections as an acquired immunodeficiency syndrome (AIDS)-defining illness (ADI) has declined dramatically [1]. Decreases in the incidence of AIDSrelated lymphoma (ARL) are not as evident compared with other ADI, so lymphoma has now become one of the most common ADIs [2]. Lymphoma has also become a more common cause of mortality due to AIDS. Management of ARL is starting to represent a critical problem in the total care of the Human Immunodeficiency virus (HIV)-infected

Non-AIDS-defining hematological malignancies in HIV-infected patients: An epidemiological study in Japan

Objective:To clarify the incidence and clinical outcomes of non-AIDS-defining hematological malignancies (NADHMs), excluding non-Hodgkins lymphomas, in HIV-infected patients. Design:A nationwide epidemiological study was conducted to evaluate the incidence and clinical outcomes of NADHMs. Methods:Questionnaires were sent to 429 regional AIDS centers and 497 educational hospitals certified by the Japanese Society of Hematology. Data from 511 institutes were obtained. Results:From 1991 to 2010, 47 patients with NADHMs were detected (median age, 42.0 years; male, 93.6%). The median CD4-positive T-cell count was 255/&mgr;l, and the median duration from the diagnosis of HIV infection to development of hematological malignancy was 28.0 months. Most patients with acute leukemia were treated with standard induction chemotherapy. Complete remission rates and median overall survival periods for acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL) were 70.0 and 85.7% and 13 and 16 months, respectively. Three of four patients with chronic-phase chronic myeloid leukemia (CML-CP) were well controlled with imatinib. Five patients (2 AML, 1 ALL, 1 accelerated-phase CML, and 1 myeloma) were treated with autologous or allogeneic stem-cell transplantation. Comparison of patients over the two periods (1991–2000 and 2001–2009) revealed a 4.5-fold increase in the incidence of hematological malignancies. Conclusion:The incidence of NADHMs has increased in the past decade. The prognosis of these patients was similar to that of HIV-negative patients; therefore, standard chemotherapy may be a feasible treatment option for HIV-infected patients with hematological malignancies.