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Vitro Infection (vitro + infection)
Selected AbstractsB-lymphocyte subpopulations are equally susceptible to Epstein,Barr virus infection, irrespective of immunoglobulin isotype expressionIMMUNOLOGY, Issue 4 2003Barbro Ehlin-Henriksson Summary While Epstein,Barr virus (EBV) is known to establish latency in the memory B-cell compartment, there is controversy as to whether the memory or the naïve B cell is the initial target for infection. Here we have explored the infectability of the B-cell subsets contained in peripheral blood and tonsils, as distinguished by their surface expression of the immunoglobulin isotypes that help to define naïve and memory pools. First we show that both CD21 and major histocompatibility complex (MHC) class II molecules , respectively, the major receptor and co-receptor for EBV on B cells , are expressed at similar levels on blood and tonsillar B cells, irrespective of surface immunoglobulin class, indicating that each of the subsets demonstrate an equal potential, at least for infection. Then, following in vitro infection of total tonsillar B cells, we found that the relative frequencies of immunoglobulin (Ig)M-, IgG- and IgA-positive cells containing EBV-encoded Epstein,Barr virus nuclear antigen 5 (EBNA5) protein at 48 hr were similar to those of the starting population. However, IgD expression was uniformly decreased, probably as a consequence of cellular activation. These data indicate that recirculating B cells have both the potential for, and susceptibility to, initial infection by EBV, irrespective of the immunoglobulin isotype expressed. [source] Dendritic cell susceptibility to hepatitis C virus genotype 1 infectionJOURNAL OF MEDICAL VIROLOGY, Issue 2 2002Maria-Cristina Navas Abstract In vitro infection of human monocyte-derived dendritic cells was carried out to study their susceptibility to hepatitis C virus (HCV) infection. Immature dendritic cells and mature dendritic cells were incubated overnight at 37°C with HCV-positive (genotype 1) serum samples; the presence of the viral genome associated with the production of its replicative intermediate was used as evidence of infection. In immature dendritic cells, HCV RNA was detectable from days 1,10 post-infection (p.i.), and de novo synthesis of negative-strand HCV RNA could be demonstrated by a strand-specific rTth reverse transcription-polymerase chain reaction at day 2. In mature dendritic cells, the positive-strand form was detectable from days 1,5 p.i., while the negative-strand HCV RNA appeared at days 1 and 2 p.i. Quasispecies present in the inoculum and 6 days p.i. were analyzed by sequencing hypervariable region 1 of the E2 protein. Only two of seven HVR variants present in the inoculum were found in HCV-infected immature dendritic cells. Another two HVR variants not found in the inoculum were recovered from infected immature dendritic cells, suggesting serum minor variants selection or virus evolution during in vitro replication. Analysis by single-strand conformation polymorphism assay of 5, untranslated region of HCV sequences showed that the patterns obtained from the inoculum and infected immature dendritic cells and mature dendritic cells differed slightly. These findings indicate that both immature dendritic cells and mature dendritic cells are susceptible to HCV genotype 1 infection, supporting at least HCV RNA replication. This model should be a valuable tool for the study of modulation of dendritic cell functions in HCV infection. J. Med. Virol. 67:152,161, 2002. © 2002 Wiley-Liss, Inc. [source] Expression of interferon-, subtypes in peripheral mononuclear cells from patients with chronic hepatitis C: a role for interferon-,5JOURNAL OF VIRAL HEPATITIS, Issue 2 2001E. Larrea Interferon (IFN)-, is a family of antiviral proteins encoded by different genes. The biological significance of the existence of various IFN-, subtypes is not clear. We have investigated the interferon system in chronic hepatitis C virus (HCV) infection, a disease that responds to interferon-,2 therapy in only a limited proportion of cases. We analysed the expression of interferon regulatory factor (IRF)-1, IRF-2, and IFN-, subtypes in nonstimulated and Sendai virus-stimulated peripheral blood mononuclear cells (PBMC) from HCV infected patients and healthy controls. We observed that the IRF-1 mRNA and IRF-1/IRF-2 ratios were increased in PBMC from hepatitis C patients with respect to normal subjects. Sendai virus stimulation of PBMC led to a significant increase in the levels of IRF-1, IRF-2 and IFN-, mRNAs and in the production of IFN-, protein with respect to basal values in healthy controls as well as in patients with HCV infection. In addition, we found that while natural HCV infection induced increased IFN-,5 expression in PBMC, in vitro infection of these cells with Sendai virus caused a raise in the expression of IFN-,8 in both patients and normal controls. In summary, our results indicate that virus-induced activation of the IFN system in human PBMC is associated with selective expression of individual IFN-, subtypes, IFN-,5 being the specific subtype induced in PBMC from patients with chronic HCV infection. [source] Schistosomiasis delays lesion resolution during Leishmania major infection by impairing parasite killing by macrophagesPARASITE IMMUNOLOGY, Issue 7 2002Anne Camille La Flamme Summary Infection of mice with Schistosoma mansoni delays the resolution of cutaneous lesions and parasitaemia during Leishmania major infection. In contrast, L. major infection does not appear to alter the course of schistosomiasis. Analysis of the cytokine responses in the draining lymph nodes (LN) indicates that, while L. major infection had no effect on schistosome-specific interleukin (IL)-4 production by mesenteric LN (MLN) cells, coinfection with S. mansoni resulted in decreased leishmania-induced interferon (IFN)-,, tumour necrosis factor-, and nitric oxide production by popliteal LN (PLN) cells 4 weeks after L. major infection. In addition, PLN cells produced higher levels of IL-4 4 weeks after L. major infection in coinfected mice. Finally, IFN-,-stimulated macrophages isolated from S. mansoni -infected mice were impaired in their ability to kill L. major after in vitro infection. These results suggest that pre-existence of a strong Th2 response-dominated infection can alter the responses to Th1-inducing pathogens at peripheral sites and impair Th1-mediated effector functions. [source] The CGGGG insertion/deletion polymorphism of the IRF5 promoter is a strong risk factor for primary Sjögren's syndromeARTHRITIS & RHEUMATISM, Issue 7 2009Corinne Miceli-Richard Objective Interferon regulatory factor 5 is a transcription factor involved in type I interferon (IFN) secretion. This study was undertaken to investigate whether a 5-bp (CGGGG insertion/deletion) promoter polymorphism is involved in genetic predisposition to primary Sjögren's syndrome (SS) and to assess the functional consequences of this polymorphism. Methods The exploratory cohort consisted of 185 patients with primary SS and 157 healthy controls, and the replication cohort consisted of 200 patients with primary SS and 282 healthy controls. Levels of IRF5 messenger RNA (mRNA) were assessed at baseline and after in vitro infection with reovirus in peripheral blood mononuclear cells (PBMCs) from 30 patients with primary SS and from salivary gland epithelial cells that had been cultured for 4 weeks from patients with primary SS or sicca symptoms. Results Carriage of the IRF5 4R CGGGG allele was associated with a greatly increased risk of primary SS in both cohorts (odds ratio 2.00 [95% confidence interval 1.5,2.7], P = 6.6 × 10,6). The CGGGG insertion/deletion polymorphism alone was sufficient to explain the association of primary SS with IRF5. The level of IRF5 mRNA in PBMCs depended significantly on genotype (P = 0.002) and was correlated with the levels of mRNA for the IFN-induced genes MX1 and IFITM1. Cultured salivary gland epithelial cells from patients carrying the 4R CGGGG IRF5 allele showed a high level of IRF5 mRNA (P = 0.04), which was amplified after reovirus infection (P = 0.026). Conclusion Our findings indicate an association of the CGGGG insertion/deletion polymorphism of the IRF5 promoter with primary SS. Patients carrying the 4R CGGGG IRF5 allele had a high level of mRNA for IRF5 in PBMCs and salivary gland epithelial cells, mainly after in vitro viral infection. Patients with high levels of mRNA for IRF5 also had high levels of mRNA for type I IFN,induced genes in PBMCs. [source] | ||||||||||