Lactic dehydrogenase virus (LDV) impairs the antigen-presenting capacity of macrophages yet fails to affect their phagocytic activity

The effect of acute infection of mice with lactic dehydrogenase virus (LDV) on two major functions of peritoneal macrophages was tested. Using a macrophage-dependent T cell proliferative assay to test the antigen-presenting capacity of LDV-infected macrophages we found that LDV impairs the capacity of antigen-presenting cells to trigger memory T lymphocytes. Endocytosis of antigen by LDV-infected macrophages was similar to that of uninfected cells. In addition, the proportion of intracellular antigen versus membrane-bound antigen in LDV-infected cells were similar to that observed in uninfected mice. It appears therefore, that the impaired immunogenic effect of LDV-infected macrophages results from reduced immunogenicity of the membrane-bound antigen.Testing the phagocytic activity of peritoneal macrophages we found that the uptake of radiolabeled antibody-coated sheep erythrocytes or bacteria (E. coli) by infected cells was similar to that by uninfected macrophages. In addition, LDV failed to affect the ability of peritoneal macrophages in a nitroblue tetrazolium reduction reaction which serves as an alternative parameter for measuring phagocytic activity. Our results support the assumption that LDV, which probably propagates in the cells of the reticuloendothelial system, impairs some of the immunogenic functions of macrophages and thereby affects macrophage-dependent immune responses.     

Zika virus diagnosis: challenges and solutions

Background

Since its sudden appearance and link to microcephaly in 2015, the number of PubMed references for Zika virus (ZIKV) has risen from 181 to 5163, at time of writing, with a vast proportion focused on the consequences of ZIKV infection during pregnancy. This level of attention underlies increased demand for sensitive and specific diagnostic tools able to assess risk to an unborn child, as well as to understand the dynamics and consequences of viral persistence.

Differential plasticity and fate of brain-resident and recruited macrophages during the onset and resolution of neuroinflammation

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Molecular and biological analysis of echovirus 9 strain isolated from a diabetic child

The full-length infectious cDNA clone was constructed and sequenced from the strain DM of echovirus 9, which was recently isolated from a 6-week-old child at the clinical onset of type 1 diabetes. Parallel with the isolate DM, the full-length infectious cDNA clone of the prototype strain echovirus 9 Barty (Barty-INF), was constructed and sequenced. Genetic relationships of the sequenced echo 9 viruses to the other members of the human enterovirus type B species were studied by phylogenetic analyses. Comparison of capsid protein sequences showed that the isolate DM was closely related to both prototype strains: Hill and Barty-INF. The only exception was the inner capsid protein VP4 where serotype specificity was not evident and the isolate DM clustered with the strain Hill and the strain Barty-INF with echovirus 30 Bastianni. Likewise, the nonstructural protein coding region, P2P3, of isolate DM was more similar to strain Hill than to strain Barty-INF. However, like echovirus 9 Barty, the isolate DM contained the RGD-motif in the carboxy terminus of capsid protein VP1. By blocking experiments using an RGD-containing peptide and a polyclonal rabbit antiserum to the alpha(v)beta(3)-integrin, it was shown that this molecule works as a cellular receptor for isolate DM. By using primary human islets, it was shown that the isolate DM is capable of infecting insulin-producing beta-cells like the corresponding prototype strains did. However, only isolate DM was clearly cytolytic for beta-cells. The infectious clones that were made allow further investigations of the molecular features responsible for the diabetogenicity of the isolate DM.     

Characterization of cytokine production in infectious mononucleosis studied at a single-cell level in tonsil and peripheral blood.

Cytokine profile and production was studied at a single-cell level in cells obtained from 14 patients with acute infectious mononucleosis (IM), with less than 7 days of symptomatic disease, by use of cytokine-specific MoAbs and indirect immunofluorescence technique. In producer cells, all the studied cytokines, except IL-1, accumulated in the Golgi system, which resulted in a characteristic morphology of the staining. Less than one in a thousand mononuclear cells obtained directly from IM blood and stained within 2 h of sampling produced IL-2, interferon-gamma (IFN-gamma), IL-4, IL-5, IL-6, IL-10, GM-CSF, tumour necrosis factor-alpha (TNF-alpha) or TNF-beta, spontaneously. However, these cells were induced to cytokine synthesis by T cell receptor ligation in vitro using immobilized anti-CD3 MoAbs for 2-3 h restimulation under conditions which did not activate normal cells. By this approach 168 +/- 120 cells/10,000 peripheral blood mononuclear cells produced IFN-gamma as compared with 10 +/- 8 cells/10,000 non-stimulated cultured cells obtained from IM patients (P < 0.001) and 1/10,000 cells obtained from healthy controls, respectively. No induced production of IL-2, IL-3, IL-4, IL-5, IL-10, GM-CSF or TNF-beta was detected in IM cells obtained from peripheral blood by this restimulation. In contrast, a spontaneous cytokine production was evident in tonsil material obtained from four IM patients tonsilectomized because of respiratory obstruction. From this site 160 +/- 40 cells/10,000 cells produced IL-2, 40 +/- 30 cells IL-6, 30 +/- 30 cells TNF-beta and 35 +/- 25 cells IFN-gamma, respectively. No such spontaneous IL-2, IL-6, TNF-beta or IFN-gamma production was evident in control cells obtained from patients tonsilectomized because of chronic tonsil hyperplasia.     

Absence of Epstein-Barr virus-specific, HLA class II-restricted CD4+ cytotoxic T lymphocytes in infectious mononucleosis.

Cytotoxic T lymphocytes (CTL) with the CD4+ phenotype that recognize major histocompatibility complex (MHC) class II antigens are detectable very frequently in cultures of human alloreactive or virus-specific T cells. The significance of these CD4+ CTL for an immune reaction in vivo is not clear. Since Epstein-Barr virus (EBV) transformed B cells express HLA-class I and class II antigens equally well both CD8+ and CD4+ CTL should be stimulated during an acute EBV infection. We analysed the MHC specificity and the phenotype of EBV-specific CTL from patients with infectious mononucleosis (IM). When tested directly without any previous culture, T cells from patients in the acute phase of IM showed specific MHC-restricted cytotoxicity against the autologous B cell line. Addition of a HLA class I specific monoclonal antibody (MoAb) but not of a HLA class II specific MoAb resulted in a complete blocking of the lytic activity. Cell sorting revealed that the entire cytotoxic activity was present in the CD8+ fraction whereas no specific CTL were detectable in the CD4+ fraction. The absence of cytotoxicity in CD4+ cells was not due to a lack of activation of these cells since both CD8+ and CD4+ cells were activated in situ, showing spontaneous growth in interleukin-2 (IL-2) and expressing the activation marker TP103. Frequency estimation revealed that 1/300-1/600 CD8+ but only 1/2000-1/4000 CD4+ T cells gave rise to a specific CTL colony after 10 days. If CD4+ colonies were tested repeatedly for cytotoxicity we found that CD4+ CTL acquired their cytotoxicity during in vitro culture. In addition, we isolated EBV-specific CD4+ T cell clones able to lyse their stimulator cells in the presence but not in the absence of lectin, even after a long period of culture. Taken together our results show that cytotoxicity mediated by CD4+ T cells does not play a role in an anti-viral immune response.     

Improved outcome of chronic Pseudomonas aeruginosa lung infection is associated with induction of a Th1-dominated cytokine response

Repeated challenge with antigen is involved in the pathogenesis of a variety of pulmonary diseases. Patients with cystic fibrosis (CF) experience recurrent pulmonary colonization with Pseudomonas aeruginosa before establishment of chronic lung infection. To mimic recurrent lung infections in CF patients, the lungs of susceptible BALB/c mice were re-infected with P. aeruginosa 14 days after the initial infection. Singly-infected BALB/c mice, as well as non-infected mice, were used as controls. Decreased mortality and milder lung inflammation in re-infected BALB/c mice, as well as a tendency for improved clearance of bacteria, was observed when compared with singly-infected mice. The improved outcome in re-infected mice correlated with changes in CD4 cell numbers. Surface expression of LFA-1 on pulmonary CD4 cells was increased in re-infected compared with singly-infected mice. Moreover, resistance to re-infection was paralleled by a shift towards a Th1-dominated response and increased IL-12 production. No significant increase in serum IgG was observed in the re-infected mice. In conclusion, these results indicate a protective role for a Th1-dominated response, independent of antibody production, in chronic P. aeruginosa lung infection in CF.     

EIAV减毒疫苗诱导马外周血单个核细胞Th1型细胞因子的转录

目的：探讨马传染性贫血病毒驴白细胞减毒疫苗免疫马后,外周血单个核细胞中Th1型细胞因子转录水平与免疫保护应答的关系,揭示DLV的免疫保护机制。方法：应用分子克隆及实时定量RT-PCR技术,建立了马PBMC中IFNγ-、IL-2、IL-12 mRNA转录水平的定量检测方法,定期观察4组（疫苗免疫组、阴性对照组、强毒株阳性对照组、自然感染组）12匹马外周血PBMC中细胞因子的转录水平及分布特征,同时监测体温变化等指标。疫苗株免疫动物8个月后,用EIAV强毒株攻击,观察攻击前后细胞因子转录水平的变化。结果：DLV免疫马,在免疫后3周外周血PBMC中IFN-γ、IL-2转录量显著高于阴性对照组及自然感染组（P〈0.01）;免疫后用EIAV强毒株攻击,IFNγ-、IL-2和IL-12转录的量明显升高,免疫马获得完全保护;强毒株攻击阳性对照马IFN-γ、IL-2转录量随疾病进展波动,发热期下降。结论：本研究首次证明EIAV减毒疫苗可诱导马外周血PBMC中IFN-γ、IL-2、IL-12基因高效转录,其转录水平与DLV的免疫保护密切相关,此结果在分子水平为阐明DLV的免疫保护机制提供了新的实验依据。     

Influence of epidemiological factors on blood transfusion

The prevalence, incidence and risk factors of infectious diseases observed in the general population have been described to directly influence transfusion medicine, especially the blood selection. The objective is to ensure the blood safety. The characterization of modes of transmission influences the donor selection: the risk factors of the main blood‐borne infections have permitted to adapt the pre‐donation questionnaire in order to exclude at‐risk donors. The prevalence of infections also has an impact on the blood screening strategy. For example, anti‐HBc antibody (Ab) screening is currently performed only in countries where the HBV prevalence is compatible with a reasonable number of donor exclusions. HTLV Ab screening is implemented in countries in which the rate of donors originating from endemic areas could represent a risk for blood components. Measurement of incidence which contributes to the residual risk has led to the introduction of nucleic acid testing (NAT) for HIV, HCV and in some cases for HBV in viral screening strategy in many countries worldwide. The observed NAT yield differs according to the incidence of the infection and according to the country. Finally, the putative blood transmission of new and emerging pathogens has led to implement specific and non‐specific measures in order to enhance blood safety. Conversely, although the blood donor population is selected, the data observed in this population have also contributed to better understand epidemiology and pathogenesis of infection. Moreover, owing to the recent progress in developing modelling approaches for estimating risk, we are able to anticipate a transfusion transmission threat by introducing, when necessary, specific measures intended for reduce this risk.     

Optimizing vaccine design for cellular processing,MHC binding and TCR recognition

In this review we describe the methods and processes that our group have developed while aiming to test and design multiepitope vaccines for infectious diseases and cancer. Testing the performance of vaccines composed of epitopes restricted by human leukocyte antigen (HLA) molecules is accomplished by in vitro antigenicity assays, as well as in vivo immunogenicity assays in HLA transgenics. The efficiency by which multiepitope vaccines are processed is optimized by spacer residues, which are designed to facilitate generation by natural processing of the various class I- and class II-restricted epitopes. Methods and strategies to test and optimize HLA binding affinity, patient coverage from the vaccine construct, and TCR recognition of HLA/epitope complexes are also discussed.