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In this paper we consider a two parameter ratio-product-ratio estimator for estimating population mean in case of post stratification following the estimator due to Chami et al (2012). The bias and mean squared error of proposed estimator are obtained to the first degree of approximation. We derive conditions under which the proposed estimator has smaller mean squared error than the sample mean , ratio estimator and product estimators . Empirical studies gives insight on the magnitude of the efficiency of the estimator developed.

In this paper we have considered the problem of estimating the population mean using auxiliary information in sample surveys. A class of dual to ratio estimators has been defined. Exact expressions for bias and mean squared error of the suggested class of dual to ratio estimator have been obtained. In particular, properties of some members of the proposed class of dual to ratio estimators have been discussed. It has been shown that the proposed class of estimators is more efficient than the sample mean, ratio estimator, dual to ratio estimator and some members of the suggested class of estimators in some realistic conditions. Some numerical illustrations are given in support of the present study.

In this paper we have suggested a generalized class of estimators for estimating the finite population mean ˉY of the study variable y using information on two auxiliary variables x and z. We have studied the properties of the proposed generalized class of estimators in simple random sampling without replacement scheme and in stratified random sampling up to the first order of approximation. It is shown that the suggested class of estimators is more efficient than the conventional unbiased estimator, ratio estimator, product estimator, traditional difference estimator, Srivastava (1967) estimator, Ray et al. (1979) estimator, Vos (1980) estimator, Upadhyaya et al. (1985) estimator, Rao (1991) estimator and Gupta and Shabbir (2008) estimator. Theoretical results are well supported through an empirical study.

This article addresses the problem of estimating the population mean using information on two auxiliary variables in presence of non-response on study variable only under stratified random sampling. A class of estimators has been defined. We have derived the bias and mean squared error up to first order of approximation. Optimum conditions are obtained in which the suggested class of estimators has minimum mean squared error. In addition to Chaudhury et al. (2009) estimator, many estimators can be identified as a member of the suggested class of estimators. It has been shown that the suggested class of estimators is better than the Chaudhury et al. (2009) estimator and other estimators. Results of the present study are supported through numerical illustration.

Progressive disease caused by pathogenic SIV/HIV infections is marked by systemic hyperimmune activation, immune dysregulation, and profound depletion of CD4+ T cells in lymphoid and gastrointestinal mucosal tissues. IL-17 is important for protective immunity against extracellular bacterial infections at mucosa and for maintenance of mucosal barrier. Although IL-17–secreting CD4 (Th17) and CD8 (Tc17) T cells have been reported, very little is known about the latter subset for any infectious disease. In this study, we characterized the anatomical distribution, phenotype, and functional quality of Tc17 and Th17 cells in healthy (SIV−) and SIV+ rhesus macaques. In healthy macaques, Tc17 and Th17 cells were present in all lymphoid and gastrointestinal tissues studied with predominance in small intestine. About 50% of these cells coexpressed TNF-α and IL-2. Notably, ∼50% of Tc17 cells also expressed the co-inhibitory molecule CTLA-4, and only a minority (

Here we investigate the effect of viremia and the influence of HAART on the frequency and quality of HIVspecfic T cells in an adolescent/young adult cohort. Measurements of viral loads and the magnitude and quality of antiviral cellular immune responses were performed on 14 HAART-naive and 8 treated HIV-1-infected adolescents. Cross-sectional correlations between viral load and cellular immune responses were determined and data were analyzed by viral load (4000, 4000-40,000, and40,000 copies/ml plasma) and patient treatment status. All 22 patients showed a broad IFN-gamma ELISPOT response that was proportional to viral load (r = 0.53, p = 0.02), recognizing an average of five to eight peptide pools throughout Gag, Pol, Env, Tat, Rev, and Nef. Intracellular cytokine staining was performed with pools of overlapping peptides corresponding to HIV Gag to distinguish CD8 response from CD4 response. Among untreated patients with increased viral load there was a constant IFN-gamma CD8 response but a declining IFN-gamma CD4 response. HIV-specific IL-2 production was consistently low in CD8 cells but inversely related to viral load in CD4 cells (r = -0.52, p = 0.02). In this crosssectional analysis, time on HAART was associated with an increased frequency of antiviral IFN-gamma- and IL-2-coproducing CD4 cells (r = 0.98, p0.001), but not of antiviral CD8 cells. Our results suggest that T cells coproducing IL-2 and IFN-gamma are a better marker for immunological competence than T cells producing IFN-gamma alone. They also suggest that HAART may be associated with an improved capacity for IL-2 production by antiviral CD4 T cells in a time-dependent manner. Longitudinal studies are clearly necessary to assess the impact of HAART on these parameters.

Malignant gliomas are heterogeneous, diffuse and highly infiltrating by nature. Despite wide surgical resection and improvements in radio- and chemotherapies, the prognosis of patients with glioblastoma multiforme remains extremely poor, with a median survival time of only 14.5 months from diagnosis to death. Particular challenges for glioblastoma multiforme therapy are posed by limitations in the extent of feasible surgical resections, distinct tumor heterogeneity, difficulties in drug delivery across the blood-brain barrier and low drug distribution within the tumor. Therefore, new paradigms permitting tumor-specific targeting and extensive intratumoral distribution must be developed to allow an efficient therapeutic delivery. This review highlights the latest advances in the treatment of glioblastoma multiforme and the recent developments that have resulted from the interchange between preclinical and clinical efforts. We also summarize and discuss novel therapies for malignant glioma, focusing on advances in the following main topics of glioblastoma multiforme therapy: immunotherapy, gene therapy, stem cell-based therapies and nanotechnology. We discuss strategies and outcomes of emerging therapeutic approaches in these fields, and the main challenges associated with the integration of discoveries that occur in the laboratory into clinical practice.

Brain tumors are a unique class of cancers since they are anatomically shielded from normal immunosurveillance by the blood-brain barrier, lack a normal lymphatic drainage system and reside in a potently immunosuppressive environment. Of the primary brain cancers, glioblastoma multiforme (GBM) is the most common and aggressive in adults. Although treatment options include surgery, radiation and chemotherapy, the average lifespan of GBM patients remains at only 14.6 months post-diagnosis.A review of key cellular and molecular immune system mediators in the context of brain tumors including TGF-β, cytotoxic T cells, Tregs, CTLA-4, PD-1 and IDO is discussed. In addition, prognostic factors, currently utilized immunotherapeutic strategies, ongoing clinical trials and a discussion of new or potential immunotherapies for brain tumor patients are considered.Current drugs that improve the quality of life and overall survival in patients with brain tumors, especially for GBM, are poorly effective. This disease requires a reanalysis of currently accepted treatment strategies, as well as newly designed approaches. Here, we review the fundamental aspects of immunosuppression in brain tumors, new and promising immunotherapeutic drugs as well as combinatorial strategies that focus on the simultaneous inhibition of immunosuppressive hubs, both in immune and brain tumor cells, which is critical to consider for achieving future success for the treatment of this devastating disease.

In SIV/HIV infection, the gastrointestinal tissue dominates as an important site because of the impact of massive mucosal CD4 depletion and immune activation-induced tissue pathology. Unlike AIDS-susceptible rhesus macaques, natural hosts do not progress to AIDS and resolve immune activation earlier. Here, we examine the role of dendritic cells (DCs) in mediating immune activation and disease progression. We demonstrate that plasmacytoid DCs (pDCs) in the blood up-regulate β7-integrin and are rapidly recruited to the colorectum after a pathogenic SIV infection in rhesus macaques. These pDCs were capable of producing proinflammatory cytokines and primed a T cytotoxic 1 response in vitro. Consistent with the up-regulation of β7-integrin on pDCs, in vivo blockade of α4β7-integrin dampened pDC recruitment to the colorectum and resulted in reduced immune activation. The up-regulation of β7-integrin expression on pDCs in the blood also was observed in HIV-infected humans but not in chronically SIV-infected sooty mangabeys that show low levels of immune activation. Our results uncover a new mechanism by which pDCs influence immune activation in colorectal tissue after pathogenic immunodeficiency virus infections.

The influence of preexisting immunity to viral vectors is a major issue for the development of viral-vectored vaccines. In this study, we investigate the effect of preexisting vaccinia virus immunity on the immunogenicity and efficacy of a DNA/modified vaccinia Ankara (MVA) SIV vaccine in rhesus macaques using a pathogenic intrarectal SIV251 challenge. Preexisting immunity decreased SIV-specific CD8 and CD4 T cell responses but preserved the SIV-specific humoral immunity. In addition, preexisting immunity did not diminish the control of an SIV challenge mediated by the DNA/MVA vaccine. The peak and set point viremia was 150- and 17-fold lower, respectively, in preimmune animals compared with those of control animals. The peak and set point viremia correlated directly with colorectal virus at 2 wk postchallenge suggesting that early control of virus replication at the site of viral challenge was critical for viral control. Factors that correlated with early colorectal viral control included 1) the presence of anti-SIV IgA in rectal secretions, 2) high-avidity binding Ab for the native form of Env, and 3) low magnitude of vaccine-elicited SIV-specific CD4 T cells displaying the CCR5 viral coreceptor. The frequency of SIV-specific CD8 T cells in blood and colorectal tissue at 2 wk postchallenge did not correlate with early colorectal viral control. These results suggest that preexisting vaccinia virus immunity may not limit the potential of recombinant MVA vaccines to elicit humoral immunity and highlight the importance of immunodeficiency virus vaccines achieving early control at the mucosal sites of challenge.

FOXP3+CD8+ T cells are present at low levels in humans; however, the function of these cells is not known. In this study, we demonstrate a rapid expansion of CD25+FOXP3+CD8+ regulatory T cells (Tregs) in the blood and multiple tissues following a pathogenic SIV infection in rhesus macaques. The expansion was pronounced in lymphoid and colorectal mucosal tissues, preferential sites of virus replication. These CD8 Tregs expressed molecules associated with immune suppressor function such as CTLA-4 and CD39 and suppressed proliferation of SIV-specific T cells in vitro. They also expressed low levels of granzyme B and perforin, suggesting that these cells do not possess killing potential. Expansion of CD8 Tregs correlated directly with acute phase viremia and inversely with the magnitude of antiviral T cell response. Expansion was also observed in HIV-infected humans but not in SIV-infected sooty mangabeys with high viremia, suggesting a direct role for hyperimmune activation and an indirect role for viremia in the induction of these cells. These results suggest an important but previously unappreciated role for CD8 Tregs in suppressing antiviral immunity during immunodeficiency virus infections. These results also suggest that CD8 Tregs expand in pathogenic immunodeficiency virus infections in the nonnatural hosts and that therapeutic strategies that prevent expansion of these cells may enhance control of HIV infection.

Methods Three groups of rhesus macaques, eight per group, were studied. The Dryvax-naive and Dryvax-immune groups received the DNA/MVA SIV vaccine (DNA at weeks 0 and 8, and rMVA at weeks 16 and 24). In addition, the Dryvaximmune group received the Dryvax vaccine 1.5 years prior to the DNA prime. The control group did not receive any vaccine. All macaques were challenged intrarectally with SIV251 at 9 months after the final MVA.

Following the U.S. monkeypox outbreak of 2003, blood specimens and clinical and epidemiologic data were collected from cases, defined by standard definition, and household contacts of cases to evaluate the role of preexisting (smallpox vaccine-derived) and acquired immunity in susceptibility to monkeypox disease and clinical outcomes. Orthopoxvirus-specific immunoglobulin G (IgG), IgM, CD4, CD8, and B-cell responses were measured at ∼7 to 14 weeks and 1 year postexposure. Associations between immune responses, smallpox vaccination, and epidemiologic and clinical data were assessed. Participants were categorized into four groups: (i) vaccinated cases, (ii) unvaccinated cases, (iii) vaccinated contacts, and (iv) unvaccinated contacts. Cases, regardless of vaccination status, were positive for orthopoxvirus-specific IgM, IgG, CD4, CD8, and B-cell responses. Antiorthopoxvirus immune responses consistent with infection were observed in some contacts who did not develop monkeypox. Vaccinated contacts maintained low levels of antiorthopoxvirus IgG, CD4, and B-cell responses, with most lacking IgM or CD8 responses. Preexisting immunity, assessed by high antiorthopoxvirus IgG levels and childhood smallpox vaccination, was associated (in a nonsignificant manner) with mild disease. Vaccination failed to provide complete protection against human monkeypox. Previously vaccinated monkeypox cases manifested antiorthopoxvirus IgM and changes in antiorthopoxvirus IgG, CD4, CD8, or B-cell responses as markers of recent infection. Antiorthopoxvirus IgM and CD8 responses occurred most frequently in monkeypox cases (vaccinated and unvaccinated), with IgG, CD4, and memory B-cell responses indicative of vaccine-derived immunity. Immune markers provided evidence of asymptomatic infections in some vaccinated, as well as unvaccinated, individuals.

Among the most effective vaccine candidates tested in the simian immunodeficiency virus (SIV)/macaque system, live attenuated viruses have been shown to provide the best protection from challenge. To investigate if preimmunization would increase the level of protection afforded by live attenuated SIVmac239Δnef (Δnef), macaques were given two priming immunizations of DNA encoding SIV Gag and Pol proteins, with control macaques receiving vector DNA immunizations. In macaques receiving the SIV DNA inoculation, SIV-specific cellular but not humoral responses were readily detectable 2 weeks after the second DNA inoculation. Following boosting with live attenuated virus, control of Δnef replication was superior in SIV-DNA-primed macaques versus vector-DNA-primed macaques and was correlated with higher levels of CD8 + /gamma-interferon-positive and/or interleukin-2-positive cells. Challenge with an intravenous inoculation of simian/human immunodeficiency virus (SHIV) strain SHIV89.6p resulted in infection of all animals. However, macaques receiving SIV DNA as the priming immunizations had statistically lower viral loads than control animals and did not develop signs of disease, whereas three of seven macaques receiving vector DNA showed severe CD4 + T-cell decline, with development of AIDS in one of these animals. No correlation of immune responses to protection from disease could be derived from our analyses. These results demonstrate that addition of a DNA prime to a live attenuated virus provided better protection from disease following challenge than live attenuated virus alone.

Here, we study immune responses in four DNA/MVA-vaccinated macaques following an SHIV-89.6P challenge and a subsequent CD8 cell depletion. Both post-challenge and post-depletion peaks of viremia contracted with the expansion, or re-emergence, of CD8 T cells. Post-depletion, CD8 cells expanded in the presence of higher levels of neutralizing Ab and CD4 help than post-challenge and had superior maturational characteristics as measured by expression of the anti-apoptotic protein Bcl-2, the IL-7 receptor CD127 and co-production of IFN-γ and IL-2. Pre-challenge and pre-depletion titers of neutralizing Ab correlated inversely with peaks of viremia and directly with peaks for anti-viral CD4 cells. Thus, our results reveal CD8 cells playing a central role, and neutralizing Ab, a supporting role in SHIV-89.6P control. They also suggest a dynamic relationship between neutralizing Ab, antigen load and anti-viral CD4 cells in the maturation of high-quality anti-viral CD8 T cells.

The allelic distribution of human leukocyte antigen (HLA) class I genes (HLA-A, HLA-B, and HLA-Cw) of the population from the State of Pernambuco in Northeastern Brazil was studied in a sample of 101 healthy unrelated individuals. Low to medium resolution HLA class I typing was performed using polymerase chain reaction-amplified DNA hybridized to sequence specific primers (PCR-SSPs). Twenty allele groups were detected for HLA-A, 28 for HLA-B, and 14 for HLA-Cw. The most frequent alleles were HLA-A*02(0.2871), HLA-B*15(0.1238), and HLA-Cw*04(0.2277), and the most frequent genotypes were A*02/A*02(0.0990), B*15/B*15(0.0594), and Cw*04/Cw*04 and Cw*07/Cw*07, both with a frequency of 0.0792. The observed heterozygosity for the studied loci was 79.21% for HLA-A, 87.13% for HLA-B, and 77.23% for HLA-Cw. The most frequent haplotype was A*02-Cw*04-B*35(0.0485), which is also present in Western European, Amerindian, and Brazilian Mulatto populations, but absent in African populations. Taken together, these data corroborate the historic anthropological evidences of the origin of the Northeastern Brazilian population from Pernambuco.

The currently used smallpox vaccine is associated with a high incidence of adverse events, and there is a serious need for a safe and effective alternative vaccine. Here, we carried out a longitudinal evaluation of vaccinia virus-specific CD4 and CD8 T cells in smallpox-vaccinated individuals by using a highly sensitive intracellular cytokine staining assay. Our results demonstrate that, in addition to the CD8 response, the smallpox vaccinations raised a robust CD4 response with a Th1-dominant cytokine profile. These CD4 T cells were stable and exhibited only a twofold contraction between peak effector and memory phases compared with an approximate sevenfold contraction for CD8 cells. A significant proportion of vaccinated individuals lost detectable CD8 memory while maintaining CD4 memory. After a booster immunization, these individuals generated a robust CD8 response, which some of them rapidly lost. Thus, the current smallpox vaccine provides long-lasting CD4 help that may be critical for long-lived B-cell memory. We suggest that the provision of adequate CD4 help for CD8 and humoral effector functions will be critical to the success of the next generation of smallpox vaccines.

Glioblastoma multiforme (GBM) is the most invasive form of brain tumors and average survival less than 14.6 months. Tumors in the central nervous system (CNS) are thought to be poorly immunogenic due to compartmentalization and immune specialization. However, presence of CD4+IL-17+ (Th17) and CD4+Foxp3+ regulatory T cells (Tregs) in GBM indicates that immune responses occur within the context of CNS-resident tumors. Inducible costimulator (ICOS) belongs to the CD28 family of costimulatory molecules. ICOS is upregulated on the surface of activated T cells and its interaction with ICOS ligand can shape diverse immune responses, such as differentiation of helper T cells and IL-10-secreting Tregs. Here, we hypothesized that ICOS plays a role in regulating T cell responses involved in tumor progression. To study the role of ICOS in tumor progression, wild-type (WT) and ICOS-deficient (ICOS-/-) mice were intracranially-implanted with murine GL261 glioma cells. The median survival of tumor-bearing ICOS-/- mice was reduced to 25 days from 30 days in WT mice. The data shows a two-fold reduction in frequency of intracranial Tregs in tumor-bearing ICOS-/- mice (p

Modified vaccinia Ankara (MVA) is being tested in humans as an alternative to the current smallpox vaccine Dryvax. Here, we compare the magnitude and longevity of protective immune responses elicited by a DNA/MVA HIV-1 vaccine with those elicited by Dryvax using a monkeypox virus/macaque model. The DNA/MVA vaccine elicited similar levels of vaccinia virus (VV)-specific antibody and 5–10-fold lower levels of VV-specific cellular responses than Dryvax. This MVA-elicited cellular and humoral immunity was long-lived. A subset of the DNA/MVA- and Dryvax-vaccinated macaques were subjected to a lethal monkeypox virus challenge at 3 years after vaccination. All of the vaccinated monkeys survived, whereas the unvaccinated controls succumbed to monkeypox. The viral control correlated with early postchallenge levels of monkeypox-specific neutralizing antibody but not with VV-specific cellular immune response. Thus, our results demonstrate the elicitation of long lasting protective immunity for a lethal monkeypox challenge by a DNA/MVA HIV-1 vaccine.