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1.
J Immunol ; 184(1): 303-14, 2010 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-19949089

RESUMO

Despite multiple lines of evidence suggesting their involvement, the precise role of CD8(+) T cells in controlling HIV replication remains unclear. To determine whether CD8(+) T cells can limit retroviral replication in the absence of other immune responses, we transferred 1-13 x 10(9) allogeneic in vitro expanded SIV-specific CD8(+) T cell clones matched for the relevant restricting MHC-I allele into rhesus macaques near the time of i.v. SIV challenge. Additionally, in vitro expanded autologous SIV-specific CD8(+) T cell clones were infused 4-9 mo postinfection. Infused cells did not appreciably impact acute or chronic viral replication. The partially MHC-matched allogeneic cells were not detected in the blood or most tissues after 3 d but persisted longer in the lungs as assessed by bronchoalveolar lavage (BAL). Autologous cells transferred i.v. or i.p. were found in BAL and blood samples for up to 8 wk postinfusion. Interestingly, despite having a nominally activated phenotype (CD69(+)HLA-DR(+)), many of these cells persisted in the BAL without dividing. This suggests that expression of such markers by T cells at mucosal sites may not reflect recent activation, but may instead identify stable resident memory T cells. The lack of impact following transfer of such a large number of functional Ag-specific CD8(+) T cells on SIV replication may reflect the magnitude of the immune response required to contain the virus.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Quimiotaxia de Leucócito/imunologia , Ativação Linfocitária/imunologia , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Vírus da Imunodeficiência Símia/imunologia , Transferência Adotiva , Animais , Antígenos de Diferenciação de Linfócitos T/imunologia , Antígenos de Diferenciação de Linfócitos T/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Doença Crônica , Células Clonais , Citometria de Fluxo , Antígenos de Histocompatibilidade Classe I/imunologia , Macaca mulatta , Replicação Viral/imunologia
2.
J Immunol ; 184(1): 315-26, 2010 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-19949091

RESUMO

Plasma viremia decreases coincident with the appearance of virus-specific CD8(+) T cells during acute HIV or SIV infection. This finding, along with demonstrations of viral mutational escape from CD8(+) T cell responses and transient increase in plasma viremia after depletion of CD8(+) T cells in SIV-infected monkeys strongly suggest a role for CD8(+) T cells in controlling HIV/SIV. However, direct quantitative or qualitative correlates between CD8(+) T cell activity and virus control have not been established. To directly assess the impact of large numbers of virus-specific CD8(+) T cells present at time of SIV infection, we transferred in vitro expanded autologous central and effector memory-derived Gag CM9-, Nef YY9-, and Vif WY8-specific CD8(+) T cell clones to acutely infected rhesus macaques. The cells persisted in PBMCs between 4 and 9 d, but were not detected in gut-associated lymphoid tissue or lymph nodes. Interestingly, a high frequency of the infused cells localized to the lungs, where they persisted at high frequency for >6 wk. Although persisting cells in the lungs were Ag reactive, there was no measurable effect on virus load. Sequencing of virus from the animal receiving Nef YY9-specific CD8(+) T cells demonstrated an escape mutation in this epitope <3 wk postinfection, consistent with immune selection pressure by the infused cells. These studies establish methods for adoptive transfer of autologous SIV-specific CD8(+) T cells for evaluating immune control during acute infection and demonstrate that infused cells retain function and persist for at least 2 mo in specific tissues.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Quimiotaxia de Leucócito/imunologia , Memória Imunológica , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Vírus da Imunodeficiência Símia/imunologia , Transferência Adotiva , Animais , Sequência de Bases , Células Clonais , DNA Viral/genética , Mapeamento de Epitopos , Epitopos de Linfócito T/genética , Epitopos de Linfócito T/imunologia , Citometria de Fluxo , Evasão da Resposta Imune/genética , Ativação Linfocitária/imunologia , Macaca mulatta , Dados de Sequência Molecular , Mutação , Reação em Cadeia da Polimerase , Síndrome de Imunodeficiência Adquirida dos Símios/genética , Vírus da Imunodeficiência Símia/genética , Viremia/imunologia
3.
Immunol Invest ; 37(4): 279-91, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18569071

RESUMO

Detection of cytokines secreted by ex vivo antigen-stimulated peripheral blood mononuclear cells (PBMC) by ELISA is hampered by low frequencies of specific T cells and cellular receptor consumption. We investigated if ELISpot, measuring cytokine production at the single cell level, facilitated a better detection of the Th2 cytokines IL-4 and IL-5. PBMC from nickel-allergic (n = 31) and non-allergic subjects (n = 10) were stimulated with nickel or tetanus toxoid (TT) and cytokine production assessed by ELISpot and ELISA. By IL-4 ELISpot, 74% of the allergic and 0% control subjects responded to nickel and 56% of all subjects to TT. ELISA detected IL-4 after nickel stimulation only in 13% of the allergic subjects. Also detection of TT-induced IL-5 was improved by ELISpot with 54% subjects responding versus 24% in ELISA. In contrast, detection of nickel-induced IL-5 was more comparable between methods, most likely due to the 7-fold higher IL-5 production per cell in response to nickel versus TT. The low IL-5 response to TT was associated with a higher induction of the down-regulatory cytokine IL-10 by TT as compared to nickel (p < 0.001). Overall, ELISpot displayed a better detection of IL-4 as well as low intensity IL-5 responses thus emphasizing the importance of selecting suitable methods for the measurement of cytokine production ex vivo.


Assuntos
Ensaio de Imunoadsorção Enzimática , Hipersensibilidade/imunologia , Técnicas Imunoenzimáticas , Interleucina-10/análise , Interleucina-4/análise , Interleucina-5/análise , Linfócitos T/imunologia , Adulto , Idoso , Alérgenos/imunologia , Feminino , Humanos , Leucócitos Mononucleares/imunologia , Ativação Linfocitária , Masculino , Pessoa de Meia-Idade , Níquel/imunologia , Toxoide Tetânico/imunologia , Células Th2/imunologia , Células Th2/metabolismo
4.
PLoS One ; 13(3): e0195246, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29590210

RESUMO

[This corrects the article DOI: 10.1371/journal.pone.0023703.].

5.
Int J Infect Dis ; 9(3): 159-69, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15840457

RESUMO

OBJECTIVES: In this study, the effect of maternal peripheral and placental Plasmodium falciparum parasitaemia on the level of antibody and cytokine immune responses in the neonate was investigated. METHODS: Malaria parasites were detected by light microscopy. Levels of malaria-specific isotypic antibodies were measured in maternal and cord blood by indirect ELISA. The numbers of IFN-gamma and IL-4 cells produced by maternal/cord blood after in vitro stimulation were enumerated using the ELISPOT assay. RESULTS: Malaria parasite rate of maternal, placental biopsy and cord blood was 32.8%, 33.7% and 7.8% respectively. Overall, ELISA seropositivity rates for P. falciparum-specific IgG, IgM, IgE and IgA in the maternal plasma samples were 71%, 85%, 29.3%, and 0% respectively, while those for the cord samples were 69%, 6.0%, 4.4% and 0% respectively. Mean IgM ELISA OD(405) values of neonates born from positive placentas, or whose mothers had peripheral malaria parasitaemia were higher than those who were parasite negative. The mean number of maternal cells producing IFN-gamma was higher (P=0.0001) than that of the paired cord samples. The mean number of IL-4 producing cells of neonates born of mothers who were positive (P<0.05) or from malaria-positive placentas (P<0.025) was higher than from those who were malaria negative. Neonates born of malaria-positive mothers or from parasitized placentas mounted predominantly Th2 type immune responses. CONCLUSION: It appears from this study that neonates born from malaria-infected mothers or placentas may relatively be more susceptible to malaria attack during the first years of life.


Assuntos
Anticorpos Antiprotozoários/sangue , Sangue Fetal/imunologia , Isotipos de Imunoglobulinas/sangue , Interferon gama/sangue , Interleucina-4/sangue , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Adolescente , Adulto , Animais , Camarões , Ensaio de Imunoadsorção Enzimática , Feminino , Sangue Fetal/parasitologia , Humanos , Isotipos de Imunoglobulinas/imunologia , Recém-Nascido , Interferon gama/imunologia , Interferon gama/metabolismo , Interleucina-4/imunologia , Interleucina-4/metabolismo , Malária Falciparum/sangue , Parasitemia/imunologia , Placenta/parasitologia , Gravidez
6.
Acta Trop ; 90(1): 107-14, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-14739029

RESUMO

Plasmodium falciparum-infected erythrocytes have been reported to sequester in the placenta by adhering to chondroitin 4-sulfate during pregnancy. Earlier studies have highlighted higher susceptibility of primigravidae to P. falciparum compared to multigravidae living within the same endemic areas. The haptoglobin phenotype (Hp1-1) has been associated with susceptibility to severe P. falciparum malaria and the presence of Hp in human endometrium has been reported. The possible role of different Hp phenotypes in susceptibility to or protection from placental infection by P. falciparum in both primigravid and multigravid women at delivery in western Cameroon was investigated in this study. Only the three major haptoglobin phenotypes; Hp1-1, Hp2-1 and Hp2-2, were found in the study population with the Hp1-1 phenotype being the predominant (53%). There was no significant difference in the distribution of the three Hp phenotypes between the two gravidity groups. Women carrying the Hp1-1 phenotype had higher parasite prevalences in both peripheral blood (21.6% against 9.1%) and placentas (42% against 16.7%) when compared to those with the Hp2-2 phenotype. The difference in the parasite density between women carrying the Hp1-1 and Hp2-2 phenotypes was statistically significant for placental infection (P=0.001) but not for maternal peripheral blood infection. Placental parasitaemias without peripheral blood parasitaemias were detected in 42.6% of all the P. falciparum positive women while 27.7% of the women had peripheral blood parasitaemias in the absence of placental infection and 29.8% of the women had both placental and peripheral blood parasitaemias. A statistically significant difference was observed between the primigravidae and multigravidae in the parasite density in placental biopsies (P=0.02) but not for maternal peripheral blood parasitaemia. Our data suggest that the Hp1-1 phenotype may play a role in susceptibility to placental infection by P. falciparum during pregnancy.


Assuntos
Haptoglobinas/genética , Malária Falciparum/sangue , Adulto , Camarões/epidemiologia , Parto Obstétrico , Suscetibilidade a Doenças/sangue , Suscetibilidade a Doenças/parasitologia , Eletroforese em Gel de Poliacrilamida , Feminino , Sangue Fetal/parasitologia , Humanos , Malária Falciparum/epidemiologia , Malária Falciparum/prevenção & controle , Fenótipo , Placenta/parasitologia , Gravidez , Prevalência
7.
Vaccine ; 32(50): 6847-54, 2014 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-24530403

RESUMO

NuThrax™ (Anthrax Vaccine Adsorbed with CPG 7909 Adjuvant) (AV7909) is in development. Samples obtained in a phase Ib clinical trial were tested to confirm biomarkers of innate immunity and evaluate effects of CPG 7909 (PF-03512676) on adaptive immunity. Subjects received two intramuscular doses of commercial BioThrax(®) (Anthrax Vaccine Adsorbed, AVA), or two intramuscular doses of one of four formulations of AV7909. IP-10, IL-6, and C-reactive protein (CRP) levels were elevated 24-48 h after administration of AV7909 formulations, returning to baseline by Day 7. AVA (no CPG 7909) resulted in elevated IL-6 and CRP, but not IP-10. Another marker of CpG, transiently decreased absolute lymphocyte counts (ALCs), correlated with transiently increased IP-10. Cellular recall responses to anthrax protective antigen (PA) or PA peptides were assessed by IFN-γ ELISpot assay performed on cryopreserved PBMCs obtained from subjects prior to immunization and 7 days following the second immunization (study day 21). One-half of subjects that received AV7909 with low-dose (0.25mg/dose) CPG 7909 possessed positive Day 21 T cell responses to PA. In contrast, positive T cell responses occurred at an 11% average rate (1/9) for AVA-treated subjects. Differences in cellular responses due to dose level of CPG 7909 were not associated with differences in humoral anti-PA IgG responses, which were elevated for recipients of AV7909 compared to recipients of AVA. Serum markers at 24 or 48 h (i.e. % ALC decrease, or increase in IL-6, IP-10, or CRP) correlated with the humoral (antibody) responses 1 month later, but did not correlate with cellular ELISpot responses. In summary, biomarkers of early responses to CPG 7909 were confirmed, and adding a CpG adjuvant to a vaccine administered twice resulted in increased T cell effects relative to vaccine alone. Changes in early biomarkers correlated with subsequent adaptive humoral immunity but not cellular immunity.


Assuntos
Adjuvantes Imunológicos/administração & dosagem , Vacinas contra Antraz/imunologia , Antraz/prevenção & controle , Imunidade Inata , Oligodesoxirribonucleotídeos/administração & dosagem , Linfócitos T/imunologia , Antraz/imunologia , Vacinas contra Antraz/administração & dosagem , Anticorpos Antibacterianos/sangue , Proteína C-Reativa/análise , Citocinas/sangue , Método Duplo-Cego , ELISPOT , Humanos , Imunoglobulina G/sangue , Injeções Intramusculares , Vacinação/métodos
8.
PLoS One ; 6(8): e23703, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21886812

RESUMO

BACKGROUND: The SIV/rhesus macaque model for HIV/AIDS is a powerful system for examining the contribution of T cells in the control of AIDS viruses. To better our understanding of CD8(+) T-cell control of SIV replication in CD4(+) T cells, we asked whether TCRs isolated from rhesus macaque CD8(+) T-cell clones that exhibited varying abilities to suppress SIV replication could convey their suppressive properties to CD8(+) T cells obtained from an uninfected/unvaccinated animal. PRINCIPAL FINDINGS: We transferred SIV-specific TCR genes isolated from rhesus macaque CD8(+) T-cell clones with varying abilities to suppress SIV replication in vitro into CD8(+) T cells obtained from an uninfected animal by retroviral transduction. After sorting and expansion, transduced CD8(+) T-cell lines were obtained that specifically bound their cognate SIV tetramer. These cell lines displayed appropriate effector function and specificity, expressing intracellular IFNγ upon peptide stimulation. Importantly, the SIV suppression properties of the transduced cell lines mirrored those of the original TCR donor clones: cell lines expressing TCRs transferred from highly suppressive clones effectively reduced wild-type SIV replication, while expression of a non-suppressing TCR failed to reduce the spread of virus. However, all TCRs were able to suppress the replication of an SIV mutant that did not downregulate MHC-I, recapitulating the properties of their donor clones. CONCLUSIONS: Our results show that antigen-specific SIV suppression can be transferred between allogenic T cells simply by TCR gene transfer. This advance provides a platform for examining the contributions of TCRs versus the intrinsic effector characteristics of T-cell clones in virus suppression. Additionally, this approach can be applied to develop non-human primate models to evaluate adoptive T-cell transfer therapy for AIDS and other diseases.


Assuntos
Linfócitos T CD8-Positivos/metabolismo , Genes Codificadores dos Receptores de Linfócitos T/genética , Macaca mulatta/imunologia , Vírus da Imunodeficiência Símia/imunologia , Especificidade do Receptor de Antígeno de Linfócitos T/imunologia , Transdução Genética , Replicação Viral/imunologia , Animais , Antígenos Virais , Técnicas de Cultura de Células , Células Clonais/imunologia , Humanos , Macaca mulatta/genética
9.
Virology ; 409(1): 132-40, 2011 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-21035160

RESUMO

Studies using transformed human cell lines suggest that most SIV strains use CCR5 as co-receptor. Our analysis of primary rhesus macaque CD4(+) T-cell clones revealed marked differences in susceptibility to SIV(mac)239 infection. We investigated whether different levels of CCR5 expression account for clonal differences in SIV(mac)239 susceptibility. Macaque CD4(+) T-cells showed significant CCR5 downregulation 1-2days following CD3 mAb stimulation, which gradually recovered at resting state, 7-10days after activation. Exposure of clones to SIV(mac)239 during their CCR5(low) or CCR5(high) expression states revealed differences in SIV susceptibility independent of surface CCR5 levels. Furthermore, a CCR5 antagonist similarly reduced SIV(mac)239 infection of clones during their CCR5(low) or CCR5(high) expression states. Our data suggest a model where i) very low levels of CCR5 are sufficient for efficient SIV infection, ii) CCR5 levels above this threshold do not enhance infection, and iii) low level infection can occur in the absence of CCR5.


Assuntos
Linfócitos T CD4-Positivos/metabolismo , Regulação para Baixo , Receptores de Antígenos de Linfócitos T/imunologia , Receptores CCR5/metabolismo , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Vírus da Imunodeficiência Símia/patogenicidade , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/metabolismo , Antagonistas dos Receptores CCR5 , Complexo CD3/imunologia , Complexo CD3/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/virologia , Linhagem Celular , DNA Viral/análise , Feminino , Produtos do Gene gag/genética , Produtos do Gene gag/imunologia , Produtos do Gene gag/metabolismo , Humanos , Macaca mulatta , Masculino , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/metabolismo , Receptores CCR5/genética , Síndrome de Imunodeficiência Adquirida dos Símios/virologia
10.
Vaccine ; 28(30): 4827-36, 2010 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-20451642

RESUMO

Naïve Indian rhesus macaques were immunized with a mixture of optimized plasmid DNAs expressing several SIV antigens using in vivo electroporation via the intramuscular route. The animals were monitored for the development of SIV-specific systemic (blood) and mucosal (bronchoalveolar lavage) cellular and humoral immune responses. The immune responses were of great magnitude, broad (Gag, Pol, Nef, Tat and Vif), long-lasting (up to 90 weeks post third vaccination) and were boosted with each subsequent immunization, even after an extended 90-week rest period. The SIV-specific cellular immune responses were consistently more abundant in bronchoalveolar lavage (BAL) than in blood, and were characterized as predominantly effector memory CD4(+) and CD8(+) T cells in BAL and as both central and effector memory T cells in blood. SIV-specific T cells containing Granzyme B were readily detected in both blood and BAL, suggesting the presence of effector cells with cytolytic potential. DNA vaccination also elicited long-lasting systemic and mucosal humoral immune responses, including the induction of Gag-specific IgA. The combination of optimized DNA vectors and improved intramuscular delivery by in vivo electroporation has the potential to elicit both cellular and humoral responses and dissemination to the periphery, and thus to improve DNA immunization efficacy.


Assuntos
Imunidade Celular/imunologia , Imunidade Humoral/imunologia , Imunidade nas Mucosas/imunologia , Vacinas de DNA/imunologia , Animais , Anticorpos Antivirais/análise , Anticorpos Antivirais/sangue , Especificidade de Anticorpos , Líquido da Lavagem Broncoalveolar/imunologia , Citocinas/sangue , Sistemas de Liberação de Medicamentos , Eletroporação , Citometria de Fluxo , Produtos do Gene gag/imunologia , Vetores Genéticos/genética , Vetores Genéticos/imunologia , Imunoglobulina A/imunologia , Imunoterapia Adotiva , Injeções Intramusculares , Macaca mulatta , Vacinas contra a SAIDS/genética , Vacinas contra a SAIDS/imunologia , Linfócitos T/imunologia , Vacinação/métodos , Vacinas de DNA/administração & dosagem , Vacinas de DNA/genética
11.
Virology ; 391(1): 130-9, 2009 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-19555986

RESUMO

CD8(+) T lymphocytes (CTL) play a role in controlling HIV/SIV infection. CTL antiviral activity is dependent on recognition of antigenic peptides associated with MHC class I molecules on infected target cells, and CTL activation can be impaired by Nef-mediated down-regulation of MHC class I molecules. We tested the ability of a series of rhesus macaque CD8(+) T-cell clones specific for the SIV Gag CM9 peptide to suppress SIV infection of autologous CD4(+) T cells. We used a set of SIV(mac)239 viruses with either wild-type Nef or Nef mutations that impair MHC class I down-regulation. All CTL clones efficiently suppressed virus replication in cells infected with mutant viruses with altered Nef function, phenotypically MHC class I(high) or MHC class I(intermediate). However, the ability of the clones to suppress virus replication was variably reduced in the presence of wild-type Nef (MHC class I(low)) despite the observations that all CTL clones showed similar IFN-gamma responses to titrated amounts of cognate peptide as well as to SIV-infected cells. In addition, the CTL clones showed variable CD107a (CTL degranulation marker) responses that did not correlate with their capacity to suppress virus replication. Thus, the clonal differences are not attributable to TCR avidity or typical effector responses, and point to a potential as yet unknown mechanism for CTL-mediated suppression of viral replication. These data emphasize that current assays for evaluating CTL responses in infected or vaccinated individuals do not fully capture the complex requirements for effective CTL-mediated control of virus replication.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Produtos do Gene nef/metabolismo , Antígenos de Histocompatibilidade Classe I/imunologia , Vírus da Imunodeficiência Símia/imunologia , Animais , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/virologia , Linfócitos T CD8-Positivos/virologia , Células Cultivadas , Regulação para Baixo , Regulação da Expressão Gênica , Interferon gama/imunologia , Proteína 1 de Membrana Associada ao Lisossomo/imunologia , Macaca mulatta/imunologia , Macaca mulatta/virologia , RNA Viral/metabolismo , Vírus da Imunodeficiência Símia/fisiologia , Replicação Viral
12.
Virology ; 372(2): 430-41, 2008 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-18068748

RESUMO

CD8(+) cytotoxic T lymphocyte (CTL) responses play an important role in controlling the replication of primate lentiviruses. Induction of these responses is a key objective for most current AIDS vaccine approaches. Despite a variety of approaches for measuring properties and activities of CTL, the functions responsible for controlling viral replication in vivo have not been clearly identified. Assays measuring CTL-mediated suppression of viral replication in vitro are beginning to be used as possible correlates of in vivo virus suppressive activity, but the utility and interpretive value of these assays are typically limited by properties of the cells that have been used. We investigated the capacity of SIV-specific CTL clones (effectors), immortalized by transduction with human telomerase reverse transcriptase (hTERT), to suppress SIV replication in autologous hTERT immortalized CD4(+) T-cell clones (targets). Immortalized and non-immortalized SIV-specific effector cells showed IFN-gamma production and degranulation in response to viral antigen specific stimulation and significantly inhibited SIV(mac)239 replication (2 to 4 log decrease in viral RNA or cell-associated proviral DNA) (p<0.0005). Our in vitro assays of inhibition of viral replication, using T-cell clones as effectors and targets, provide a well-defined approach for evaluating possible mechanisms of CTL-mediated control of viral production which may involve direct killing of infected target cells and/or release of proinflammatory cytokines such as IFN-gamma and TNF-alpha. The use of hTERT immortalized effector and target cells for such assays preserves relevant functional properties while providing a convenient, reproducible means of conducting studies over time.


Assuntos
Linfócitos T CD4-Positivos/virologia , Linfócitos T CD8-Positivos/imunologia , Vírus da Imunodeficiência Símia/imunologia , Replicação Viral/imunologia , Animais , Linhagem Celular , Regulação da Expressão Gênica , Proteína 1 de Membrana Associada ao Lisossomo/metabolismo , Macaca mulatta , Vírus da Imunodeficiência Símia/fisiologia
13.
Virology ; 375(1): 307-14, 2008 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-18328525

RESUMO

CD8(+) cytotoxic T lymphocytes (CTL) play an important role in controlling virus replication in HIV- and SIV-infected humans and monkeys, respectively. Three well-studied SIV CTL determinants are the two Mamu A()01-restricted epitopes Gag CM9 and Tat SL8, and the Mamu B()17-restricted epitope Nef IW9. Point mutations leading to amino acid replacements in these epitopes have been reported to mediate SIV escape from CTL control. We found that synthetic peptides containing mutations in SIV Gag CM9 and Tat SL8 were no longer recognized by the respective CTL. On the other hand, the described I-to-T replacement at the N-terminal amino acid residue of the SIV Nef IW9 epitope only moderately affected CTL recognition of the variant peptide, TW9. In an attempt to dissect the mechanism of escape of the Nef TW9 mutation, we investigated the effect of this mutation on CTL recognition of CD4(+)T cells infected with an engineered SIV(mac)239 that contained the TW9 mutation in Nef. Although, the wild type and mutant virus both infected and efficiently replicated in rhesus macaque CD4(+)T cells, the TW9 mutant virus failed to induce IFN-gamma expression in an SIV Nef IW9-specific CTL clone. Thus, unlike escape from Gag CM9- or Tat SL8-specfic CTL control presumably by loss of epitope binding, these results point to a defect at the level of processing and/or presentation of the variant TW9 epitope with resultant loss of triggering of the cognate TCR on CTL generated against the wild type peptide. Our data highlight the value of functional assays using virus-infected target cells as opposed to peptide-pulsed APC when assessing relevant escape mutations in CTL epitopes.


Assuntos
Substituição de Aminoácidos , Epitopos de Linfócito T/genética , Epitopos de Linfócito T/imunologia , Vírus da Imunodeficiência Símia/imunologia , Proteínas Virais Reguladoras e Acessórias/genética , Proteínas Virais Reguladoras e Acessórias/imunologia , Replicação Viral , Animais , Linfócitos T CD4-Positivos/virologia , Células Cultivadas , Interferon gama/biossíntese , Macaca mulatta , Mutação de Sentido Incorreto , Vírus da Imunodeficiência Símia/fisiologia , Linfócitos T Citotóxicos/imunologia , Replicação Viral/fisiologia
14.
J Trop Pediatr ; 51(3): 182-90, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15855302

RESUMO

In malaria endemic areas, young children are protected against malaria attack during the first few weeks of life partially by transplacentally acquired antibodies. In this study, we show, using an in vitro assay, that part of these antibodies are involved with blocking the re-invasion of host red blood cells by erythrocytic merozoites. One hundred consecutive paired maternal-cord blood samples were collected at delivery and their plasma assayed for total IgG antibodies against crude blood stage antigens by the ELISA. The Ig fraction were precipitated from the plasma samples with (NH(4))(2)SO(4), purified on PD10 columns and used in vitro in determining the re-invasion inhibitory capacities. The mean (+/-SD) ELISA OD(405) IgG antibodies to crude blood stage antigens of maternal (0.476 +/- 0.48) and cord (0.421 +/- 0.39) plasma samples was not significantly different. However, the mean total protein concentration of the Ig fractions for maternal samples (15.82 +/- 3.85) was significantly higher (p=0.005) than that of paired cord samples (12.87 +/- 2.86 mg/ml). There was no correlation between anti-Plasmodium falciparum-specific IgG levels and total protein concentrations of the Ig fractions of both maternal and cord samples. The entire test Ig fractions were strongly inhibitory (>50 per cent) except for four paired maternal cord samples, which were moderately inhibitory (21--50 per cent) at the highest concentration tested (1:2 dilution). Furthermore, there was no correlation between maternal IgG levels and percentage re-invasion inhibition at the 1:2 dilution. The results suggest that mothers resident in malaria endemic areas possess naturally acquired re-invasion inhibitory antibodies and their foetuses can acquire these antibodies transplacentally, which may contribute to the relative protection observed in infants during their first few weeks of life.


Assuntos
Anticorpos Antiprotozoários/imunologia , Imunidade Materno-Adquirida/imunologia , Malária Falciparum/imunologia , Plasmodium falciparum/isolamento & purificação , Complicações Parasitárias na Gravidez/imunologia , Adolescente , Adulto , Animais , Anticorpos Antiprotozoários/análise , Camarões/epidemiologia , Distribuição de Qui-Quadrado , Estudos de Coortes , Ensaio de Imunoadsorção Enzimática , Feminino , Sangue Fetal , Seguimentos , Humanos , Recém-Nascido , Modelos Lineares , Malária Falciparum/diagnóstico , Malária Falciparum/epidemiologia , Masculino , Plasmodium falciparum/imunologia , Gravidez , Complicações Parasitárias na Gravidez/diagnóstico , Probabilidade , Medição de Risco
15.
Acta Paediatr ; 94(7): 917-23, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16188815

RESUMO

AIM: The impact of maternal, umbilical cord and placental malaria parasitaemia on the incidence of low birthweight was investigated in pregnant women reporting for delivery at the Mutengene Maternity Centre, Fako Division, South West Province, Cameroon. METHODS: The malaria parasitaemia status of 770 umbilical cords, parturient women and placental impression smears were determined by light microscopy using blood samples collected between June 1999 and September 2001. The birthweights (BW) of the newborns were recorded soon after delivery. RESULTS: The results show that malaria parasites were present in the blood samples of 57 out of 730 (7.8%), 233/711 (32.8%) and 248/735 (33.7%) cord, maternal and placental biopsies respectively. Low birthweight (LBW) was recorded in 72 (9.6%) newborns, and the incidence was higher in primiparae. Newborns of mothers who had malaria parasites in their peripheral blood (12.4%) had a higher incidence (p=0.014) of LBW when compared with malaria parasite-free mothers (6.8%). Similarly, neonates born from malaria-positive placentas (13.5%) had a significantly higher incidence of LBW (p=0.006) than those from parasite-negative placentas (6.8%). Furthermore, newborns of malaria parasite-positive mothers, umbilical cords, placentas and primiparae had lower mean birthweight than malaria-negative mothers, placentas, umbilical cords and multiparae. CONCLUSION: We suggest that parity and maternal and placental malaria parasitaemia at delivery have an important negative impact on birthweight, especially in first pregnancies. This observation emphasizes the need for appropriate aggressive intervention strategies such as the use of insecticide-treated bed nets or intermittent preventive treatment to control malaria in pregnancy in the study area.


Assuntos
Peso ao Nascer , Sangue Fetal/parasitologia , Recém-Nascido de Baixo Peso , Malária Falciparum/complicações , Doenças Placentárias/parasitologia , Complicações Parasitárias na Gravidez , Adolescente , Adulto , Camarões , Feminino , Humanos , Recém-Nascido , Paridade , Gravidez
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