RESUMO
The live attenuated simian immunodeficiency virus (SIV) SIVmac239Δnef is the most effective SIV/human immunodeficiency virus (HIV) vaccine in preclinical testing. An understanding of the mechanisms responsible for protection may provide important insights for the development of HIV vaccines. Leveraging the uniquely restricted genetic diversity of Mauritian cynomolgus macaques, we performed adoptive transfers between major histocompatibility complex (MHC)-matched animals to assess the role of cellular immunity in SIVmac239Δnef protection. We vaccinated and mock vaccinated donor macaques and then harvested between 1.25 × 10(9) and 3.0 × 10(9) mononuclear cells from multiple tissues for transfer into 12 naive recipients, followed by challenge with pathogenic SIVmac239. Fluorescently labeled donor cells were detectable for at least 7 days posttransfer and trafficked to multiple tissues, including lung, lymph nodes, and other mucosal tissues. There was no difference between recipient macaques' peak or postpeak plasma viral loads. A very modest difference in viral loads during the chronic phase between vaccinated animal cell recipients and mock-vaccinated animal cell recipients did not reach significance (P = 0.12). Interestingly, the SIVmac239 challenge virus accumulated escape mutations more rapidly in animals that received cells from vaccinated donors. These results may suggest that adoptive transfers influenced the course of infection despite the lack of significant differences in the viral loads among animals that received cells from vaccinated and mock-vaccinated donor animals.
Assuntos
Imunidade Celular/imunologia , Macaca fascicularis/virologia , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Vírus da Imunodeficiência Símia/imunologia , Carga Viral/imunologia , Vacinas Virais/imunologia , Reação de Fase Aguda/imunologia , Transferência Adotiva , Animais , Sequência de Bases , Biologia Computacional , ELISPOT , Citometria de Fluxo , Fluorescência , Leucócitos Mononucleares/imunologia , Complexo Principal de Histocompatibilidade/imunologia , Dados de Sequência Molecular , Análise de Sequência de DNA , Vírus da Imunodeficiência Símia/genéticaRESUMO
OBJECTIVES: To describe the use of pulse oximetry screening (POS) for critical congenital heart disease (CCHD). STUDY DESIGN: This observational study of Wisconsin out-of-hospital births was performed from January to November, 2013. Licensed midwives, Amish birth attendants, and public health nurses were trained in the use of pulse oximetry to detect CCHD, supplied with pulse oximeters, and reported screening results and clinical outcomes. RESULTS: Results of POS in 440 newborns were reviewed; 173/440 births were from Amish or Mennonite communities. Prenatal ultrasonography was performed in less than one-half of the pregnancies and in only 13% of Amish and Mennonite women. A total of 432 babies passed the screening, 5 babies were incorrectly assigned to have passed or failed, and 3 babies failed the screening. Two of the babies who failed the screening were treated for sepsis and the third had congenital heart disease. There was 1 false negative result (coarctation of the aorta and ventricular septal defect). CONCLUSIONS: This study provides information on the use of POS for CCHD in out-of-hospital births and shows that POS can be successfully implemented outside the hospital setting. Although the failure rate in this small sample was higher than reported in studies of hospital births, those babies failing the screening had significant disease processes that were identified more rapidly because of the screening.
Assuntos
Cardiopatias Congênitas/diagnóstico , Cardiopatias Congênitas/fisiopatologia , Parto Domiciliar , Triagem Neonatal/métodos , Oximetria , Estado Terminal , Feminino , Humanos , Recém-Nascido , Masculino , GravidezRESUMO
Simian immunodeficiency virus (SIV)-infected macaques are the preferred animal model for human immunodeficiency virus (HIV) vaccines that elicit CD8(+) T cell responses. Unlike humans, whose CD8(+) T cell responses are restricted by a maximum of six HLA class I alleles, macaques express up to 20 distinct major histocompatibility complex class I (MHC-I) sequences. Interestingly, only a subset of macaque MHC-I sequences are transcriptionally abundant in peripheral blood lymphocytes. We hypothesized that highly transcribed MHC-I sequences are principally responsible for restricting SIV-specific CD8(+) T cell responses. To examine this hypothesis, we measured SIV-specific CD8(+) T cell responses in MHC-I homozygous Mauritian cynomolgus macaques. Each of eight CD8(+) T cell responses defined by full-proteome gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay were restricted by four of the five transcripts that are transcriptionally abundant (>1% of total MHC-I transcripts in peripheral blood lymphocytes). The five transcriptionally rare transcripts shared by these animals did not restrict any detectable CD8(+) T cell responses. Further, seven CD8(+) T cell responses were defined by identifying peptide binding motifs of the three most frequent MHC-I transcripts on the M3 haplotype. Combined, these results suggest that transcriptionally abundant MHC-I transcripts are principally responsible for restricting SIV-specific CD8(+) T cell responses. Thus, only a subset of the thousands of known MHC-I alleles in macaques should be prioritized for CD8(+) T cell epitope characterization.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Vírus da Imunodeficiência Símia/imunologia , Animais , Expressão Gênica , Antígenos de Histocompatibilidade Classe I/genética , Macaca , Transcrição GênicaRESUMO
BACKGROUND: MHC class I proteins are partly responsible for shaping the magnitude and focus of the adaptive cellular immune response. In humans, conventional wisdom suggests that the HLA-A, -B, and -C alleles are equally expressed on the majority of cell types. While we currently have a thorough understanding of how total MHC class I expression varies in different tissues, it has been difficult to examine expression of single MHC class I alleles due to the homogeneity of MHC class I sequences. It is unclear how cDNA species are expressed in distinct cell subsets in humans and particularly in macaques which transcribe upwards of 20 distinct MHC class I alleles at variable levels. RESULTS: We examined MHC gene expression in human and macaque leukocyte subsets. In humans, while we detected overall differences in locus transcription, we found that transcription of MHC class I genes was consistent across the leukocyte subsets we studied with only small differences detected. In contrast, transcription of certain MHC cDNA species in macaques varied dramatically by up to 45% between different subsets. Although the Mafa-B134:02 RNA is virtually undetectable in CD4+ T cells, it represents over 45% of class I transcripts in CD14+ monocytes. We observed parallel MHC transcription differences in rhesus macaques. Finally, we analyzed expression of select MHC proteins at the cell surface using fluorescent peptides. This technique confirmed results from the transcriptional analysis and demonstrated that other MHC proteins, known to restrict SIV-specific responses, are also differentially expressed among distinct leukocyte subsets. CONCLUSIONS: We assessed MHC class I transcription and expression in human and macaque leukocyte subsets. Until now, it has been difficult to examine MHC class I allele expression due to the similarity of MHC class I sequences. Using two novel techniques we showed that expression varies among distinct leukocyte subsets of macaques but does not vary dramatically in the human cell subsets we examined. These findings suggest pathogen tropism may have a profound impact on the shape and focus of the MHC class I restricted CD8+ T cell response in macaques.
Assuntos
Antígenos de Histocompatibilidade Classe I/metabolismo , Leucócitos/imunologia , Alelos , Animais , Linfócitos T CD8-Positivos/imunologia , Regulação da Expressão Gênica , Haplótipos , Antígenos de Histocompatibilidade Classe I/genética , Humanos , Leucócitos/metabolismo , Macaca , Transcrição GênicaRESUMO
Simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infection results in an early and enduring depletion of intestinal CD4(+) T cells. SIV and HIV bind integrin alpha4beta7, thereby facilitating infection of lymphocytes that home to the gut-associated lymphoid tissue (GALT). Using an ex vivo flow cytometry assay, we found that SIVmac239-infected cells expressed significantly lower levels of integrin alpha4beta7 than did uninfected cells. This finding suggested a potential viral effect on integrin alpha4beta7 expression. Using an in vitro model, we confirmed that integrin alpha4beta7 was downregulated on the surfaces of SIVmac239-infected cells. Further, modulation of integrin alpha4beta7 was dependent on de novo synthesis of viral proteins, but neither cell death, the release of a soluble factor, nor a change in activation state was involved. Downregulation of integrin alpha4beta7 may have an unappreciated role in the CD4 depletion of the mucosal-associated lymphoid compartments, susceptibility to superinfection, and/or immune evasion.
Assuntos
Linfócitos T CD4-Positivos/química , Linfócitos T CD4-Positivos/virologia , Integrinas/biossíntese , Vírus da Imunodeficiência Símia/patogenicidade , Animais , Regulação para Baixo , Citometria de Fluxo , Humanos , Macaca fascicularis , Macaca mulattaRESUMO
Live-attenuated vaccination with simian immunodeficiency virus (SIV) SIVmac239Deltanef is the most successful vaccine product tested to date in macaques. However, the mechanisms that explain the efficacy of this vaccine remain largely unknown. We utilized an ex vivo viral suppression assay to assess the quality of the immune response in SIVmac239Deltanef-immunized animals. Using major histocompatibility complex-matched Mauritian cynomolgus macaques, we did not detect SIV-specific functional immune responses in the blood by gamma interferon (IFN-gamma) enzyme-linked immunospot assay at select time points; however, we found that lung CD8(+) T cells, unlike blood CD8(+) T cells, effectively suppress virus replication by up to 80%. These results suggest that SIVmac239Deltanef may be an effective vaccine because it elicits functional immunity at mucosal sites. Moreover, these results underscore the limitations of relying on immunological measurements from peripheral blood lymphocytes in studies of protective immunity to HIV/SIV.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Vacinas contra a SAIDS/imunologia , Vírus da Imunodeficiência Símia/fisiologia , Replicação Viral , Animais , Genes nef , Imunofenotipagem , Interferon gama/biossíntese , Pulmão/imunologia , Macaca fascicularis , Vacinação , Vacinas Atenuadas/imunologia , Vacinas Sintéticas/imunologiaRESUMO
Vaccines that elicit CD8(+) T-cell responses are routinely tested for immunogenicity in nonhuman primates before advancement to clinical trials. Unfortunately, the magnitude and specificity of vaccine-elicited T-cell responses are variable in currently utilized nonhuman primate populations, owing to heterogeneity in major histocompatibility (MHC) class I genetics. We recently showed that Mauritian cynomolgus macaques (MCM) have unusually simple MHC genetics, with three common haplotypes encoding a shared pair of MHC class IA alleles, Mafa-A*25 and Mafa-A*29. Based on haplotype frequency, we hypothesized that CD8(+) T-cell responses restricted by these MHC class I alleles would be detected in nearly all MCM. We examine here the frequency and functionality of these two alleles, showing that 88% of MCM express Mafa-A*25 and Mafa-A*29 and that animals carrying these alleles mount three newly defined simian immunodeficiency virus-specific CD8(+) T-cell responses. The epitopes recognized by each of these responses accumulated substitutions consistent with immunologic escape, suggesting these responses exert antiviral selective pressure. The demonstration that Mafa-A*25 and Mafa-A*29 restrict CD8(+) T-cell responses that are shared among nearly all MCM indicates that these animals are an advantageous nonhuman primate model for comparing the immunogenicity of vaccines that elicit CD8(+) T-cell responses.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Antígenos de Histocompatibilidade Classe I/genética , Macaca fascicularis/genética , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Alelos , Substituição de Aminoácidos , Animais , Antígenos Virais/genética , Antígenos Virais/imunologia , Linfócitos T CD8-Positivos/virologia , Epitopos de Linfócito T/imunologia , Frequência do Gene , Haplótipos , Antígenos de Histocompatibilidade Classe I/imunologia , Macaca fascicularis/imunologia , Repetições de Microssatélites , Vírus da Imunodeficiência Símia/genética , Vírus da Imunodeficiência Símia/imunologiaRESUMO
The presence of certain MHC class I alleles is correlated with remarkable control of HIV and SIV, indicating that specific CD8 T cell responses can effectively reduce viral replication. It remains unclear whether epitopic breadth is an important feature of this control. Previous studies have suggested that individuals heterozygous at the MHC class I loci survive longer and/or progress more slowly than those who are homozygous at these loci, perhaps due to increased breadth of the CD8 T cell response. We used Mauritian cynomolgus macaques with defined MHC haplotypes and viral inhibition assays to directly compare CD8 T cell efficacy in MHC-heterozygous and homozygous individuals. Surprisingly, we found that cells from heterozygotes suppress viral replication most effectively on target cells from animals homozygous for only one of two potential haplotypes. The same heterozygous effector cells did not effectively inhibit viral replication as effectively on the target cells homozygous for the other haplotype. These results indicate that the greater potential breadth of CD8 T cell responses present in heterozygous animals does not necessarily lead to greater antiviral efficacy and suggest that SIV-specific CD8 T cell responses in heterozygous animals have a skewed focus toward epitopes restricted by a single haplotype.
Assuntos
Apresentação de Antígeno/genética , Linfócitos T CD8-Positivos/virologia , Haplótipos , Heterozigoto , Antígenos de Histocompatibilidade/genética , Peptídeos/imunologia , Vírus da Imunodeficiência Símia/fisiologia , Alelos , Animais , Linfócitos T CD8-Positivos/imunologia , Antígenos de Histocompatibilidade/imunologia , Macaca fascicularis , Vírus da Imunodeficiência Símia/imunologia , Especificidade da Espécie , Replicação Viral/imunologiaRESUMO
The importance of a broad CD8 T lymphocyte (CD8-TL) immune response to HIV is unknown. Ex vivo measurements of immunological activity directed at a limited number of defined epitopes provide an incomplete portrait of the actual immune response. We examined viral loads in simian immunodeficiency virus (SIV)-infected major histocompatibility complex (MHC)-homozygous and MHC-heterozygous Mauritian cynomolgus macaques. Chronic viremia in MHC-homozygous macaques was 80 times that in MHC-heterozygous macaques. Virus from MHC-homozygous macaques accumulated 11 to 14 variants, consistent with escape from CD8-TL responses after 1 year of SIV infection. The pattern of mutations detected in MHC-heterozygous macaques suggests that their epitope-specific CD8-TL responses are a composite of those present in their MHC-homozygous counterparts. These results provide the clearest example of MHC heterozygote advantage among individuals infected with the same immunodeficiency virus strain, suggesting that broad recognition of multiple CD8-TL epitopes should be a key feature of HIV vaccines.