Assessment of neutralizing and non-neutralizing antibody responses against Porcine circovirus 2 in vaccinated and non-vaccinated farmed pigs.

Vaccination is the most efficacious procedure to curtail Porcine circovirus 2 (PCV2)-associated diseases (PCVAD). Experimental studies indicate that PCV2 vaccine-induced virus-neutralizing antibodies play a major role in protection from PCVAD. However, the immune response to PCV2 vaccination of pigs on farms is less clear. Analysing groups of age-matched vaccinated and non-vaccinated farmed pigs, we found significantly increased levels of virus-neutralizing antibodies only in vaccinated pigs belonging to the age group with the highest risk for developing PCVAD. Serum levels of PCV2 genomes were not different between corresponding age groups. Levels of antibodies directed against a linear peptide from the PCV2 capsid protein correlated with those of virus-neutralizing antibodies and reached the highest levels in older, non-vaccinated animals, pointing towards an intense interaction between PCV2-infected cells and the immune system. In conclusion, current PCV2 vaccines are in need of improvement to induce stronger and more rapid immunity to prevent PCV2 infection.

Acute BVDV-2 infection in beef calves delays humoral responses to a non-infectious antigen challenge.

Immunosuppressive effects of an intranasal challenge with non-cytopathic bovine viral diarrhea virus (BVDV) 2a (strain 1373) were assessed through acquired and innate immune system responses to ovalbumin (OVA). Concurrent BVDV infection was hypothesized to delay and reduce the humoral response to ovalbumin (administered on days 3 and 15 post-inoculation). Infected animals followed the expected clinical course. BVDV titers, and anti-BVDV antibodies confirmed the course of infection and were not affected by the administration of OVA. Both the T-helper (CD4(+)) and B-cell (CD20(+)) compartments were significantly (P < 0.05) reduced in infected animals, while the gamma-delta T-cell population (Workshop cluster 1+, WC1(+)) decreased slightly in numbers. Infection with BVDV delayed the increase in OVA IgG by approximately 3 d from day 12 through day 21 post-inoculation. Between days 25 and 37 post-inoculation following BVDV infection the IgM concentration in the BVDV- group decreased while the OVA IgM titer still was rising in the BVDV+ animals. Thus, active BVDV infection delays IgM and IgG responses to a novel, non-infectious antigen.

Une infection aiguë par le BVDV-2 chez les veaux retarde les réponses humorales face à un test à l'aide d'un antigène non infectieux. Les effets immunosuppressifs d'une inoculation défin intranasale à l'aide du virus non cytopathogène de la diarrhée virale bovine (VBVD) 2a (souche 1373) ont été évalués par les réactions acquises et innées du système immunitaire à l'ovalbumine (OVA). On a émis l'hypothèse que l'infection concomitante par le VBVD retardait et réduisait la réaction humorale à l'ovalbumine (administrée aux jours 3 et 15 après l'inoculation). Les animaux infectés ont suivi le cheminement clinique prévu. Les titres de BVDV et les anticorps anti-BVDV ont confirmé le déroulement de l'infection et ils n'ont pas été affectés par l'administration d'OVA. Les compartiments des lymphocytes T auxiliaires (CD4+) et des cellules B (CD20+) étaient significativement réduits (P < 0,05) chez les animaux infectés, tandis que la numération de la population de cellules T gamma-delta (WC1+) a diminué légèrement. L'infection par le VBVD a retardé l'augmentation de l'OVA IgG d'environ 3 jours, à compter du jour 12 jusqu'au jour 21 après l'inoculation. Entre les jours 25 et 37 après l'inoculation suivant l'infection par le BVDV, la concentration d'IgM dans le groupe VBVD a diminué tandis que le titre d'OVA IgM augmentait toujours chez les animaux positifs pour le VBVD. Par conséquent, l'infection active par le VBVD retarde les réactions IgM et IgG face à un antigène non infectieux nouveau.(Traduit par Isabelle Vallières).

Post-transcriptional down-regulation of Toll-like receptor signaling pathway in umbilical cord blood plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (PDCs) from human umbilical cord blood (UCB) produce lower amounts of IFN-α upon TLR stimulation compared with adult counterparts. This difference may play a role in the low graft-versus-host disease rate after UCB transplantation and in the impaired immune response of the neonate to pathogens. Comparing UCB PDC to their adults counterparts, we found that they exhibited a mature surface phenotype and a normal antigen uptake. They upregulated costimulatory molecules upon activation, although with delayed kinetics. Protein, but not ARN, levels of TLR-9, MyD88, IRAK1 and IRF-7, involved in the TLR-9 signaling pathway were reduced. The expression levels of miR-146a and miR-155, known to be involved in the post-transcriptional down-regulation of immune responses, were higher. These data point out a post-transcriptional down-regulation of the TLR-9/IRF-7 signaling pathway in UCB PDC.

Evaluation of suitable reference genes for gene expression studies in bronchoalveolar lavage cells from horses with inflammatory airway disease.

BACKGROUND: The stability of reference genes has a tremendous effect on the results of relative quantification of genes expression by quantitative polymerase chain reaction. Equine Inflammatory Airway Disease (IAD) is a common condition often treated with corticosteroids. The diagnosis of IAD is based on clinical signs and bronchoalveolar lavage (BAL) fluid cytology. The aim of this study was to identify reference genes with the most stable mRNA expression in the BAL cells of horses with IAD irrespective of corticosteroids treatment. RESULTS: The expression stability of seven candidate reference genes (B2M, HPRT, GAPDH, ACTB, UBB, RPL32, SDHA) was determined by qRT-PCR in BAL samples taken pre- and post- treatment with dexamethasone and fluticasone propionate for two weeks in 7 horses with IAD. Primers' efficiencies were calculated using LinRegPCR. NormFinder, GeNorm and qBasePlus softwares were used to rank the genes according to their stability. GeNorm was also used to determine both the ideal number and the best combination of reference genes. GAPDH was found to be the most stably expressed gene with the three softwares. GeNorm ranked B2M as the least stable gene. Based on the pair-wise variation cut-off value determined with GeNorm, the number of genes required for optimal normalization was four and included GAPDH, SDHA, HPRT and RPL32. CONCLUSION: The geometric mean of GAPDH, HPRT, SDHA and RPL32 is recommended for accurate normalization of quantitative PCR data in BAL cells of horses with IAD treated with corticosteroids. If only one reference gene can be used, then GAPDH is recommended.

Cytotoxicity of ORF3 proteins from a nonpathogenic and a pathogenic porcine circovirus.

Porcine circovirus type 2 (PCV2) infection is associated with significant and serious swine diseases worldwide, while PCV1 appears to be a nonpathogenic virus. Previous studies demonstrated that the ORF3 protein of PCV2 (PCV2ORF3) was involved in PCV2 pathogenesis via its proapoptotic capability (J. Liu, I. Chen, Q. Du, H. Chua, and J. Kwang, J. Virol. 80:5065-5073, 2006). If PCV2ORF3-induced apoptosis is a determinant of virulence, PCV1ORF3 is hypothesized to lack this ability. The properties of PCV1 and PCV2 ORF3, expressed as fusion proteins to an enhanced green fluorescent protein (eGFP), were characterized with regard to their ability to cause cellular morphological changes, detachment, death, and apoptosis. PCV1ORF3 significantly induced more apoptotic cell death and was toxic to more different cell types than PCV2ORF3 was. PCV1ORF3-associated cell death was caspase dependent. PCV1ORF3 also induced poly(ADP-ribose) polymerase 1 (PARP) cleavage; however, whether PARP was involved in cell death requires further studies. Truncation of PCV1 and elongation of PCV2 ORF3 proteins revealed that the first 104 amino acids contain a domain capable of inducing cell death, whereas the C terminus of PCV1ORF3 contains a domain possibly responsible for enhancing cell death. These results suggest that the pathogenicity of PCV2 for pigs is either not determined or not solely determined by the ORF3 protein.

Loss of Ubiquitin Carboxy-Terminal Hydrolase L1 Impairs Long-Term Differentiation Competence and Metabolic Regulation in Murine Spermatogonial Stem Cells.

Spermatogonia are stem and progenitor cells responsible for maintaining mammalian spermatogenesis. Preserving the balance between self-renewal of spermatogonial stem cells (SSCs) and differentiation is critical for spermatogenesis and fertility. Ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1) is highly expressed in spermatogonia of many species; however, its functional role has not been identified. Here, we aimed to understand the role of UCH-L1 in murine spermatogonia using a Uch-l1-/- mouse model. We confirmed that UCH-L1 is expressed in undifferentiated and early-differentiating spermatogonia in the post-natal mammalian testis. The Uch-l1-/- mice showed reduced testis weight and progressive degeneration of seminiferous tubules. Single-cell transcriptome analysis detected a dysregulated metabolic profile in spermatogonia of Uch-l1-/- compared to wild-type mice. Furthermore, cultured Uch-l1-/- SSCs had decreased capacity in regenerating full spermatogenesis after transplantation in vivo and accelerated oxidative phosphorylation (OXPHOS) during maintenance in vitro. Together, these results indicate that the absence of UCH-L1 impacts the maintenance of SSC homeostasis and metabolism and impacts the differentiation competence. Metabolic perturbations associated with loss of UCH-L1 appear to underlie a reduced capacity for supporting spermatogenesis and fertility with age. This work is one step further in understanding the complex regulatory circuits underlying SSC function.

Stirred Suspension Bioreactor Culture of Porcine Induced Pluripotent Stem Cells.

Induced pluripotent stem cells (iPSCs) are an attractive cell source for regenerative medicine and the development of therapies, as they can proliferate indefinitely under defined conditions and differentiate into any cell type in the body. Large-scale expansion of cells is limited in adherent culture, making it difficult to obtain adequate cell numbers for research. It has been previously shown that stirred suspension bioreactors (SSBs) can be used to culture mouse and human stem cells. Pigs are important preclinical models for stem cell research. Therefore, this study investigated the use of SSBs as an alternative culture method for the expansion of iPSCs. Using an established porcine iPSC (piPSC) line as well as a new cell line derived and characterized in the current study, we report that piPSCs can grow in SSB while maintaining characteristics of pluripotency and karyotypic stability similar to cells grown in traditional two-dimensional static culture. This culture method provides a suitable platform for scale-up of cell culture to provide adequate cell numbers for future research applications involving piPSCs.

Analyses of the prognostic significance of the Epstein-Barr virus transactivator ZEBRA protein and diagnostic value of its two synthetic peptides in nasopharyngeal carcinoma.

BACKGROUND: Although numerous serological studies have determined the diagnostic and prognostic values of Epstein-Barr virus (EBV) antibodies in adult patients with nasopharyngeal carcinoma (NPC), little data about the anti-EBV immune response in children with NPC is available. OBJECTIVES: To examine the diagnostic value of IgG antibodies against BamHI Z Epstein-Barr replication activator (ZEBRA) protein and two related synthetic peptides (Zp125 and Zp130). To compare the prognostic value of IgA antibodies against early antigens (EA) and viral capsid antigen (VCA), and IgG antibodies against ZEBRA protein, of Moroccan children treated for NPC with their prognostic value for young and adult NPC patients. STUDY DESIGN: Sera were collected from 255 newly diagnosed Moroccan NPC patients and 226 healthy donors. IgA antibody against VCA and EA was measured by immunofluorescence assays. IgG antibody against ZEBRA, Zp125, and Zp130 was measured by ELISA. RESULTS: No significant difference in the detection of IgG-Zp125 and Zp130 antibodies was observed in children with NPC. IgG-Zp130 were detected less frequently than IgG-Zp125 in young and adult patients, as compared to children. High specificity of IgG-Zp125 and -Zp130 antibodies was found in the three age groups. A decrease in IgG-ZEBRA was observed in patients with NPC in clinical remission, whereas patients with NPC who died or developed metastases maintained or had an increase in these titers. CONCLUSION: IgG-ZEBRA is a better diagnostic and post-therapeutic prognostic marker in children with NPC, who showed very low titers of IgA -VCA and -EA.

[Neonatal immunology and cord blood transplantation]. / Immunologie néonatale et greffe de sang de cordon.

The increased susceptibility of human newborns to infections is usually ascribed to the immaturity of the neonatal immune system. The neonatal immune system has never met microbial antigens, and thus the repertoire of its adaptative arm (T and B cells) is entirely pre-immune, or "naïve". However this neonatal pre-immune repertoire is similar to the adult pre-immune repertoire, and cord blood natural killer cells studies show that the innate immunity cells harbor the full killing machinery that characterize mature cells. Moreover, human neonates are able to show an adult-like allogeneic response. Taken together, several lines of evidence suggest that the neonatal immune system, although naïve, is fully mature. However, newborns display phenotypic and functional differences with adults in both adaptative and innate arms. Specific properties may explain these differences, as high number of regulatory T cells, low plasmacytoid dendritic cell response to stimuli and high IL-10 production. These properties are in line with the high susceptibility of newborns to infections and the low incidence of graft-versus-host-disease after cord blood transplantation. To explain these differences, we introduce a new model. Although naive, the neonatal immune system is mature, and these functional differences are due to a message originating from the placenta and aimed at inducing the foetus tolerance to its mother. Full understanding of the involved mechanisms will help to protect the newborn against infections and to improve cord blood transplantation outcome.

Expression of T helper cell-associated inflammatory mediator mRNAs in cells of bronchoalveolar lavage fluid samples and oxygen concentration in arterial blood samples from healthy horses exposed to hyperbaric oxygen.

OBJECTIVE To evaluate the mRNA expression of T helper (Th)1, Th2, and Th17 cell-associated inflammatory mediators in cells of bronchoalveolar lavage fluid samples collected from healthy horses exposed to hyperbaric oxygen (HBO) and to monitor blood oxygen concentration during and following HBO therapy. ANIMALS 8 healthy horses. PROCEDURES In a randomized controlled crossover design study, each horse was exposed (beginning day 1) to 100% oxygen at a maximum of 3 atmospheres absolute (304 kPa) daily for 10 days or ambient air at atmospheric pressure in the HBO chamber for an equivalent amount of time (control). Bronchoalveolar lavage fluid samples were collected on days 0 and 10. After validation of candidate reference genes, relative mRNA expressions of various innate inflammatory, Th1 cell-derived, Th2 cell-derived (including eotaxin-2), Th17 cell-derived, and regulatory cytokines were measured by quantitative PCR assays. For 3 horses, arterial blood samples were collected for blood gas analysis during a separate HBO session. RESULTS The optimal combination of reference genes was glyceraldehyde-3-phosphate dehydrogenase, hypoxanthine ribosyltransferase, and ribosomal protein L32. Compared with day 0 findings, expression of eotaxin-2 mRNA was significantly lower (0.12-fold reduction) and the percentage of neutrophils in bronchoalveolar lavage fluid samples was significantly lower on day 10 when horses received HBO therapy. Values of Pao2 rapidly increased (> 800 mm Hg) but immediately decreased to pretreatment values when HBO sessions ended. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that HBO therapy does not increase mRNA expression of inflammatory cytokines, but reduces eotaxin-2 mRNA transcription. The Pao2 increase was transient with no cumulative effects of HBO.

Porcine circovirus-2 capsid protein induces cell death in PK15 cells.

Studies have shown that Porcine circovirus (PCV)-2 induces apoptosis in PK15 cells. Here we report that cell death is induced in PCV2b-infected PK15 cells that express Capsid (Cap) protein and this effect is enhanced in interferon gamma (IFN-γ)-treated cells. We further show that transient PCV2a and 2b-Cap protein expression induces cell death in PK15 cells at rate similar to PCV2 infection, regardless of Cap protein localization. These data suggest that Cap protein may have the capacity to trigger different signaling pathways involved in cell death. Although further investigation is needed to gain deeper insights into the nature of the pathways involved in Cap-induced cell death, this study provides evidence that PCV2-induced cell death in kidney epithelial PK15 cells can be mapped to the Cap protein and establishes the need for future research regarding the role of Cap-induced cell death in PCV2 pathogenesis.

Human papillomavirus detection in moroccan patients with nasopharyngeal carcinoma.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a malignant tumor which arises in surface epithelium of the posterior wall of the nasopharynx. There's is evidence that Epstein Barr virus (EBV) is associated to NPC development. However, many epidemiologic studies point to a connection between viral infections by the human papillomavirus (HPV) and NPC. METHOD: Seventy Moroccan patients with NPC were screened for EBV and HPV. EBV detection was performed by PCR amplification of BZLF1 gene, encoding the ZEBRA (Z Epstein-Barr Virus Replication Activator) protein, and HPV infection was screened by PCR amplification with subsequent typing by hybridization with specific oligonucleotides for HPV types 16, 18, 31, 33, 35, 45 and 59. RESULTS: The age distribution of our patients revealed a bimodal pattern. Sixty two cases (88.9%) were classified as type 3 (undifferentiated carcinoma), 6 (8.6%) as type 2 (non keratinizing NPC) and only 2 (2.9%) cases were classified as type 1 (keratinizing NPC). EBV was detected in all NPC tumors, whereas HPV DNA was revealed in 34% of cases (24/70). Molecular analysis showed that 20.8% (5/24) were infected with HPV31, and the remaining were infected with other oncogenic types (i.e., HPV59, 16, 18, 33, 35 and 45). In addition, statistical analysis showed that there's no association between sex or age and HPV infection (P > 0.1). CONCLUSION: Our data indicated that EBV is commonly associated with NPC in Moroccan patients and show for the first time that NPC tumours from Moroccan patients harbour high risk HPV genotypes.

IL-7 enhances survival of human CD56bright NK cells.

Lymphoid differentiation and activation critically depend on cytokine stimulation and the interleukin-7 (IL-7) signaling in particular. Although it has been demonstrated that IL-7 may play a role in natural killer (NK) cell maturation, the effect of IL-7 stimulation on mature human NK cells has not been studied. We, therefore, investigated the expression and functional activity of IL-7Ralpha on mature NK populations from adult blood. In this article, we demonstrate that IL-7Ralpha is specifically expressed in the CD56bright noncytotoxic cytokine-producing NK subset. Importantly, this expression is thymus independent, contrary to what is observed in mice. In addition, we show that IL-7Ralpha is expressed at higher levels on NKG2A+CD56bright NK cells. In contrast to IL-15 stimulation, IL-7 does not increase NK cell cytotoxicity, interferon-gamma production, or the expression of activation markers, indicating that these cytokines play different functions in NK homeostasis and activation. However, IL-7 promotes the survival of the CD56bright NK subset and inhibits apoptosis by increasing BCL2 expression. These data should be taken into account when considering the clinical use of IL-7, particularly after stem cell transplantation.

Binding of thymoglobulin to natural killer cells leads to cell activation and interferon-gamma production.

Thymoglobulin is an antithymocyte globulin preparation used in hematopoietic stem cell transplantation (HSCT) to prevent rejection and graft-versus-host disease. Because natural killer (NK)-cell alloreactivity improves HSCT outcome, but only in patients receiving thymoglobulin, we investigated the in vitro effects of thymoglobulin on purified NK cells. Thymoglobulin binding to NK cells and NK-cell activation were assessed by flow cytometry. NK surface targets for thymoglobulin were determined by competition inhibition assays using monoclonal antibodies. Chromium 51 (Cr) release assay, Annexin V combined with 7-amino-actinomycin D staining, and carboxyfluorescein diacetate succinimidyl ester staining were used to study cytotoxic activity, apoptosis/cell death, and NK-cell proliferation, respectively. Interferon (IFN)-gamma production was determined by ELISA. Thymoglobulin, thymoglobulin derived-F(ab')2 fragments as well as rabbit IgG bound NK cells, and competed strongly with anti-CD16. Thymoglobulin enhanced the expression of activation (CD69 and NKG2D) and degranulation (CD107a) markers on NK cells. It competed with CD18 binding and decreased NK activity, but not interleukin-15-induced killer activity. Effects on apoptosis/cell death and proliferation were minimal. F(ab')2 fragments and rabbit IgG strongly induced IFN-gamma production by NK cells. Thymoglobulin binds to NK cells by CD16 by its variable and constant regions. The decrease in NK-cell cytotoxic activity is restored by interleukin-15, and contrasts sharply with the induction of activation, degranulation, and IFN-gamma production. These data support the hypothesis that thymoglobulin treatment is required to observe the improvement in HSCT outcome by NK-cell alloreactivity.

High frequency of latent membrane protein-1 30-bp deletion variant with specific single mutations in Epstein-Barr virus-associated nasopharyngeal carcinoma in Moroccan patients.

Latent membrane protein 1 (LMP-1) is an Epstein-Barr virus-encoded oncoprotein expressed in approximately 50-70% of nasopharyngeal carcinoma (NPC). Previous studies have shown that NPC-derived LMP-1 variants carrying 30 bp deletion and specific mutations in the 3'C-terminal region confer high oncogenic potential and a weak immunogenicity. Although numerous polymorphism studies of LMP-1 have been carried out so far in the Asian population with NPC, very little is known in this regard on NPC patients from Northern Africa where there is a significantly high occurrence of this tumor. In our study, we examined the frequency of different LMP-1 sequence variants derived from Moroccan NPC patients. As compared to healthy donors, NPC patients showed a high prevalence of the 30bp deletion variant of LMP-1 (i.e. 84% vs. 36%; p<0.0005). Moreover, the del-LMP-1 variant derived from NPC tumors shared identical amino acid substitutions at positions 322, 334, 338, 352 and 366 with the Mediterranean (Med) variant, whereas those derived from peripheral blood mononuclear cells (PBMC) had similar mutation pattern as China1 variant. Additional mutations within the 342-352 regions (identified in LMP-1 variants without deletion derived from NPC tumors) were not found in healthy donors' PBMC. Our results support the assumption that the distribution of LMP-1 variants in NPC tumors co-segregate with geographic regions. Indeed, Med variant is found more frequently in tumors from NPC Moroccan patients, whereas China1 variant is more prevalent in tumors from NPC patients in endemic regions for NPC.