Rkia Dardari - Academia.edu (original) (raw)

Papers by Rkia Dardari

iPSCs from Diverse Species, 2021

Porcine circovirus associated disease (PCVAD) has caused considerable economic impact worldwide s... more Porcine circovirus associated disease (PCVAD) has caused considerable economic impact worldwide since its fi rst description on a Canadian pig farm in the 1990s. PCVAD, a wasting and immunosuppressive disease in post-weaned pigs, is caused by Porcine circovirus type 2 (PCV2). Despite the availability of eff ective vaccines, little is known about the molecular pathogenesis of the disease. Belonging to the Circoviridae family, PCV2 and PCV1 are closely-related viruses with a 1.7kb, ambisensed and circular ssDNA genome 1. While PCV2 is pathogenic, PCV1 is not. Investigating the diff erences in the genomic composition of these viruses will provide clues to the molecular pathogenesis of PCVAD. ORF3 is a good candidate as a determinant of PCV pathogenicity because PCV1 and PCV2 ORF3 share only 60.6% amino acid (aa) sequence identity in the translated region. In addition, a consistent single nucleotide (nt) substitution in the PCV2ORF3 coding region resulted in a stop codon, leading to PCV...

Cells, 2021

Spermatogonia are stem and progenitor cells responsible for maintaining mammalian spermatogenesis... more 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 i...

Induced pluripotent stem cells (iPSCs) are an attractive cell source for regenerative medicine an... more 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 pre-clinical 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 line as well as a new cell line derived and characterized in the current study, we report that porcine iPSCs (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 met...

American Journal of Veterinary Research, 2016

OBJECTIVE To evaluate the mRNA expression of T helper (Th)1, Th2, and Th17 cell–associated inflam... more 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...

The Canadian veterinary journal. La revue vétérinaire canadienne, 2015

Immunosuppressive effects of an intranasal challenge with non-cytopathic bovine viral diarrhea vi... more 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 w...

The Journal of general virology, 2015

Vaccination is the most efficacious procedure to curtail Porcine circovirus 2 (PCV2) associated d... more 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 (NAs) play a major role in protection from PCVAD. However, the immune response to PCV2 vaccination of pigs on farms is less clear. Analyzing groups of age matched vaccinated and non-vaccinated farmed pigs, we found significantly increased levels of NAs only in vaccinated pigs belonging to the age group with 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 NAs and reached 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...

Médecine et Maladies Infectieuses, 2002

Étudier les raisons de la recrudescence de rage humaine au Maroc. Résultats : Les personnes vacci... more Étudier les raisons de la recrudescence de rage humaine au Maroc. Résultats : Les personnes vaccinées testées présentaient un taux d'anticorps supérieur à 0,5 UI/ml. Le contrôle du vaccin et du sérum antirabique administrés a montré une bonne efficacité. Les résultats du typage moléculaire des souches rabiques ont indiqué que la souche marocaine appartenait au groupe Afrique 1, génétiquement très proches des souches vaccinales classiques. Les résultats de l'enquête sur la qualité de la prise en charge ont montré que les cas mortels semblaient plutôt être liés à une action prophylactique insuffisante. Conclusion : La virulence de la rage au Maroc n'aurait aucun rapport avec la variabilité génétique du virus circulant, ni avec l'échec de la vaccination ou une mauvaise qualité du vaccin et du sérum, mais plutôt avec une prise en charge thérapeutique insuffisante et inadéquate.

Virology, 2014

Studies have shown that Porcine circovirus (PCV)-2 induces apoptosis in PK15 cells. Here we repor... more 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.

Carcinogenesis, Diagnosis, and Molecular Targeted Treatment for Nasopharyngeal Carcinoma, 2012

highest incidence rates of NPC are found among the southern Chinese population and in isolated no... more highest incidence rates of NPC are found among the southern Chinese population and in isolated northern populations such as Eskimos and Greenlanders (30 to 80 cases per 100,000 per year) (Parkin & Muir 1992). Intermediate incidence (8 to 12 cases per 100,000 per year) was reported in the Mediterranean basin, especially among the Arabic populations of North Africa (7-10% of all cancers among men), where NPC is also the commonest tumour of the ear, nose and throat region (Benider et al. 1995). The aetiology of NPC seems to be multifactorial with evidence that genetic susceptibility, environmental factors and viral infection with EBV reactivation and HPV infection are involved together or separately, simultaneously or consecutively (Hildesheim & Levine 1993). The increased risk of NPC in North African population was associated with the consumption of rancid butter and rancid sheep fat. In fact, higher level of N-nitrosamines in rancid fat has not been demonstrated, which suggests some other disease causing chemicals in this population. A possible compound is butyric acid, which is also named n-Butanoic Acid. The glyceride form of butyric acid makes up 3 to 4% of butter, and is released into free butyric acid by hydrolysis when it becomes rancid (Feng et al. 2007). Butyric acid is known to be able to activate EBV in the B-lymphoid cells into lyric cycle (Takimoto et al. 1984), and therefore, could be related to NPC. In addition, Marijuana smoking was associated significantly to high NPC risk independently of cigarette smoking which suggests dissimilar carcinogenic mechanisms between cannabis and tobacco. Genetic traits play a significant role in the development of NPC. Specific human leukocyte antigen (HLA) haplotypes have been reported to be associated with high risk for NPC, namely HLA-B13 in Tunisians, HLA-A3, B5 and B15 in Algerians and HLA-B18 allele in Moroccans population. In contrast, HLA-Aw33,-B14 and A9 were associated to low risk of NPC in Tunisians, Algerians and Moroccans, respectively. Retrospectives and prospectives epidemiologic studies have indicated that assocaition between EBV, an ubiquitous human herpesvirus, and the development of different malignancies, such as Burkitt's lymphoma, 40%-50% of Hodgkin's disease, B-cell lymphoma in immunocompromised individuals, and NPC (Rickinson 2002). Undifferentiated NPC is one of the most striking examples of human malignancies that have been found strongly associated with the EBV, and interest in HPV as a cofactor in NPC occurrences has emerged over the last few years (Punwaney et al. 1999). 2. EBV life cycle in brief During primary infection, EBV initially undergoes a brief replication in the epithelial cells of the oropharynx and salivary glands (Young & Rickinson 2004). The virus subsequently infects trafficking B-cells where the virus establishes a lifelong persistence and proceeds periodic spontaneous reactivation, resulting in lytic replication, infectious virus production and transmission (Cohen 2000). Upon reactivation, EBV can productively infect oropharyngeal epithelium, leading to infectious virus production and transmission (Jenkins, Binne & Farrell 2000). In latent infection, EBV genomic DNA exists as an episome, replicating only once during S phase and partitioning accurately into daughter cells during the mitotic phase. In lytic state, the EBV genomic DNA is linear. The initiation of lytic replication process greatly depends on the expression of two EBV immediate-early (IE)

Cancer/Radiothérapie, 1997

Transplantation, 2009

Thymoglobulin is an antithymocyte globulin preparation used in hematopoietic stem cell transplant... more 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 (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)-␥ 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-␥ 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-␥ production. These data support the hypothesis that thymoglobulin treatment is required to observe the improvement in HSCT outcome by NK-cell alloreactivity.

Journal of Virology, 2010

Porcine circovirus type 2 (PCV2) infection is associated with significant and serious swine disea... more 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 involv...

Journal of Immunotherapy, 2010

Journal of Clinical Virology, 2008

Background: Although numerous serological studies have determined the diagnostic and prognostic v... more 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.

Journal of Clinical Microbiology, 2001

Serological tests based on the antibodies directed against the Epstein-Barr virus early antigen (... more Serological tests based on the antibodies directed against the Epstein-Barr virus early antigen (EA) and viral capsid antigen (VCA), which have been recognized as tumor markers for nasopharyngeal carcinoma (NPC), are routinely used to help in the diagnosis of this malignancy. The detection of these antibodies reveals very low titers, found only in a small proportion of young compared with older NPC patients. This is a problem for the diagnosis of NPC, especially among Maghrebians, among whom young people are also affected, and emphasizes the necessity to search for more reliable markers. The present study reports results of immunoglobulin G (IgG) and IgA responses of NPC patients to recombinant EA antigens p54 (BMRF1) and p138 (BALF2), VCA complex antigens p18 (BFRF3) and p23 (BLRF2), and EBNA antigen p72 (BKRF1). Our results show that IgA-EA-p54 and -p138 (IgA-EA-p54+138) antibodies have a diagnostic value for detection of NPC (70%), compared with IgA-VCA-p18+23 and IgA-EBNA-p72, w...

International Journal of Cancer, 2005

Latent membrane protein 1 (LMP-1) is an Epstein-Barr virusencoded oncoprotein expressed in 50-70%... more Latent membrane protein 1 (LMP-1) is an Epstein-Barr virusencoded oncoprotein expressed in 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 0 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.