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M Naciri

Publications and source records attributed to M Naciri.

At least 19 recordsLinked to original sources
PubMed2001

Efficacy of halofuginone lactate in the prevention of cryptosporidiosis in suckling calves.

The efficacy of halofuginone lactate in the prevention of cryptosporidiosis in suckling calves was evaluated in a multicentre, control versus placebo, randomised, double-blind clinical trial. Seventy-eight six- to 48-hour-old calves were treated daily with 120 microg/kg bodyweight of halofuginone lactate administered orally for seven consecutive days, while 80 calves received a placebo. Faecal samples were collected on the first day of dosing and four, seven, 14 and 21 days later, and Cryptosporidium parvum oocysts were counted and faecal indices for diarrhoea were determined after a clinical examination. An analysis of variance for repeated measurements showed a highly significant difference in favour of halofuginone lactate for both the oocyst counts (P=0.0002) and the faecal diarrhoea indices (P=0.0001) throughout the trial. The difference was greatest after seven days, when the mean oocyst count of the placebo group was 2.5 times and its mean faecal index was twice the mean of the halofuginone lactate group. One day after the end of the treatment the calves which received halofuginone lactate excreted 44 per cent fewer C parvum oocysts and 44 per cent fewer of them had diarrhoea. The reduction was even greater (65 per cent) when liquid diarrhoea was assessed, with 32.5 per cent of the calves in the placebo group having liquid diarrhoea compared with 11.5 per cent in the halofuginone lactate group. The treatment was well tolerated and easily administered.

Administration, Oral↗
PubMed2001

Cryptosporidium parvum-specific mucosal immune response in C57BL/6 neonatal and gamma interferon-deficient mice: role of tumor necrosis factor alpha in protection.

Both neonatal and C57BL/6 gamma interferon (IFN-gamma) knockout (C57BL/6-GKO) mice are susceptible to Cryptosporidium parvum, but the course of infection is different. Neonatal mice are able to clear the parasite within 3 weeks, whereas C57BL/6-GKO mice, depending on age, die rapidly or remain chronically infected. The mechanism by which IFN-gamma leads to a protective immunity is yet poorly understood. In order to investigate the effect of IFN-gamma on other cytokines expressed in the intestinal mucosa during C. parvum infection, we studied cytokine mRNA expression in the neonates and GKO (neonatal and adult) mice by quantitative reverse transcription-PCR (RT-PCR) at 4 and 9 days after infection. IFN-gamma mRNA levels were quickly and strongly up-regulated in the mucosa of neonatal mice. In GKO mice, the Th1-type response was dramatically altered during the infection, whereas the mRNA expression levels of the Th2-type cytokines interleukin 4 (IL-4) and IL-10 were increased in both mouse models. In the absence of IFN-gamma, the adult knockout mice up-regulated the mRNA levels of inflammatory cytokines, such as IL-1beta, IL-6, and granulocyte-macrophage colony-stimulating factor, in the mucosa, but not tumor necrosis factor alpha (TNF-alpha), whereas all these cytokines were up-regulated in the infected neonatal mice. Further experiments indicated that injections of TNF-alpha into GKO adult mice significantly reduced oocyst shedding. The results of the present study indicate that the resolution of infection is dependent on the expression of Th1-type cytokines in the mucosa of C57BL/6 mice and that TNF-alpha may participate in the control of parasite development.

Animals↗
PubMed2000

Inhibition of Eimeria tenella replication after recombinant IFN-gamma activation in chicken macrophages, fibroblasts and epithelial cells.

We have previously shown that activation of primary cultures of chicken bone-marrow macrophages and embryo fibroblasts with supernatants of concanavaline A-stimulated or reticuloendotheliosis virus (REV)-transformed chicken spleen cells as source of IFN-gamma significantly decreases Eimeria tenella growth in vitro. In the present study, we used various chicken cell lines, HD11 macrophages and DU24 fibroblasts, both virally transformed, CHCC-OU2 fibroblasts and LMH hepatic epithelial cells, both chemically transformed, to replicate E. tenella in vitro. We confirmed the previous results by showing that HD11 macrophages pre-treated for 24h with recombinant chicken IFN-gamma (either produced in E. coli or by transfected COS cells), at doses ranging from 1000 to 10U/ml, drastically inhibited E. tenella replication as measured by [3H] uracil uptake after a further 70h of culture, as when treated with REV supernatant. Likewise the fibroblast and epithelial cell lines exhibited significant inhibitory activity on E. tenella replication after pre-treatment with recombinant chicken IFN-gamma, but were less sensitive (1000-100U/ml) than when treated with REV supernatant. Recombinant chicken IFN-alpha pre-treatment of all cell lines had no inhibitory effect on parasite development.

Animals↗
PubMed2000

Prevalence of Cryptosporidium infection in calves in France.

Two multicentre surveys were conducted in France to estimate the prevalence of Cryptosporidium infection in calves using qualitative ELISA for detection of Cryptosporidium coproantigens and oocysts. The first survey involved 4-12-day-old calves in six dairy-calf distribution centres, collecting calves from seven Administrative Regions (Aquitaine, Bretagne, Franche-Comté, Lorraine, Normandie, Nord, Pays de Loire). For each region, 20 calves were selected every month for 12 consecutive months (October 1995-September 1996). Prevalence of Cryptosporidium infection was 17.9% (Confidence Intervals (C.I.) 95%=[16.1%; 19.8%]) among the 1628 selected calves, of which only 5.3% had diarrhoea. The second survey conducted between November 1995 and May 1996 involved 4-21-day-old calves examined by veterinary practitioners who selected 189 livestock farms of dairy- or suckler-type in ten Administrative Departments (Allier, Cantal, Creuse, Doubs, Ille-et-Vilaine, Maine-et-Loire, Manche, Pas-de-Calais, Saône-et-Loire, Vendée). Cryptosporidia were detected in 105 (55.6%) of the farms. Among the 440 calves examined, of which 398 (90.5%) presented diarrhoea, cryptosporidia were found in 191 animals, i.e. a prevalence of 43.4% (C.I. 95%=[38. 8%; 48.0%]). Breed of calves and type of housing had very little impact on prevalence in this survey. Some regional variations could be noticed, even if cryptosporidia infection is widespread. Monthly variations could be related to seasonal peaks in calving with a lower infection rate during summer.

Animals↗
PubMed2000

Rapid detection and quantification of Cryptosporidium baileyi oocysts in feces and organs of chickens using a microscopic slide flotation method.

A simple semiquantitative microscopic slide flotation (MSF) method using modified Sheather's sugar solution (MSSS) is presented for the rapid detection and quantification of Cryptosporidium baileyi oocysts in the feces and mucosal and/or organ scrapings of chickens. Oocyst shedding was evaluated by examination of the surface of coverslips, and the average quantitative score (0-5) recorded for 10 microscopic fields (magnification x250) is reported. The equivalence between these scores and the actual number of oocysts counted per gram of feces was assessed (rs = 0.89; P < 0.001). The applicability of this method was tested by comparison of the kinetics of oocyst shedding in feces of inoculated chickens with those reported by other authors working under similar conditions. In organs the MSF method was compared to histology. Fewer false-negative results were obtained using MSF versus the histology method. The MSF method was particularly more efficient in tracheae with low levels of infection and in the lungs, regardless of the level of infection. The MSF method was also very efficient in detecting oocysts in air sacs from chickens with aerosacculitis. It provides a specific and sufficiently sensitive, simple, rapid, reliable, and low-cost means of diagnosing C. baileyi in the feces and organs of chickens. This method can be used in the routine diagnosis of cryptosporidia in chickens, and it could be extended to other avian species and used in epidemiology studies to evaluate the prevalence of cryptosporidiosis in fowl.

Animals↗
PubMed2000

Do discrepancies between microsatellite and allozyme variation reveal differential selection between sea and lagoon in the sea bass (Dicentrarchus labrax)?

In the present study the genetic structure of Dicentrarchus labrax (14 samples from the Mediterranean) was analysed at six microsatellite loci, in order to test the hypothesis that some enzymatic loci undergo selection between marine and lagoon habitat. Eight of the 14 samples were analysed at both microsatellite and allozyme markers. The analysis of the genetic variation among the Mediterranean samples showed that (i) &Fcirc;ST values obtained with the six microsatellite loci were much smaller than those obtained with the 28 allozymes and (ii) microsatellite loci seemed to reflect more the geographical proximity than an ecological one. Thirteen enzymatic loci exhibited moderate to high values compared with microsatellites. This was interpreted as evidence that these allozymes are non-neutral. However, only six loci seemed to be implicated in differentiation between marine and lagoon samples, the causes of selection being unknown for the others. A possible scenario of population dynamics of the sea bass between marine and lagoon habitat is suggested.

Adaptation, Physiological↗
PubMed1999

Role of Cryptosporidium parvum as a pathogen in neonatal diarrhoea complex in suckling and dairy calves in France.

This study was carried out to find the importance of Cryptosporidium parvum in diarrhoea of neonatal calves in two types of breeding - suckling and dairy calves - in France. Different agents causing neonatal diarrhoea, E. coli, rotavirus, coronavirus, Salmonella and Cryptosporidium were systematically researched in faeces. 1. Suckling calves: In 40 livestock farms selected for diarrhoea, 311 calves 4 to 10 days old which had diarrhoea for less than 24h or no diarrhoea, were included in the study. A prophylaxis of neonatal diarrhoea had been carried out in 21 of the 40 livestock farms. On D0 (inclusion day), the mean age was 6 days, 82% presented a good initial general condition and 76.2% had a good appetite; 48.6% were diarrhoeic but 91.3% presented no sign of dehydration. Only 6.1% were infected by E. coli K99, 14.3% by rotavirus, 6.8% by coronavirus, 0.3% by Salmonella but 50% excreted C. parvum oocysts. This later percentage increases up to 84% and 86% by D3 and D7, respectively . We note that 16% of the 4-day-old calves on D0 are excreting oocysts and this percentage increases as a function of the age of the calf on D0 to reach 90% to 95% by the age of 8 days. 10 out of 12 dead calves excreted C. parvum oocysts. From D0 to D14 the other pathogen agents show a relative or a decreasing stability. 2. Dairy calves: 382 calves which had diarrhoea for less than 24 h or no diarrhoea, aged 8 to 15 days coming from six industrial livestock farms were included in the study. On D0, 99% of the calves presented a good initial general condition, 99.7% had a good appetite and no calf was dehydrated. At this date (D0), 16.8% of the calves excreted cryptosporidia. This percentage increases up to 23% and 51.8% on D3 and D8, respectively, then decreases to 31.9% on D14. The pressure of the other pathogenicagents remains relatively stable, excepted for rotavirus on D7 (from 9.9% on D0 to 27.2% on D7, then 12.6% on D14) which does not explain the concomitantpeak in diarrhoea because the infection by rotavirus on D7 is more frequent in non-diarrhoeic calves than in diarrhoeic calves. Our results show that Cryptosporidium prevalence is higher in suckling than in dairy calves and C. parvum constitutes actually in both cases the major aetiological agent of neonatal diarrhoea.

Animals↗
PubMed1999

Protection of kids against Cryptosporidium parvum infection after immunization of dams with CP15-DNA.

In this study the effectiveness of a DNA vaccine to confer protection against cryptosporidiosis, an enteric infection of lifestock and humans, was evaluated. A vaccination protocol using a recombinant plasmid encoding the 15 kDa surface sporozoite protein of Cryptosporidium parvum was developed in adult pregnant goats. The present study reports that nasal immunization of pregnant goats with CP15-DNA led to a transfer of immunity to offspring conferring protection against C. parvum infection. Kids from CP15-DNA-vaccinated dams shed significantly fewer oocysts and over a shorter period than did kids from unvaccinated goats. The low level of parasite development in protected kids did not affect their growth whereas unprotected kids grew much slowly. There was still a significant difference in the weights of protected and unprotected kids after complete recovery. Anti-CP15 antibodies were present in serum and colostrum from vaccinated goats. Nevertheless, the precise immune mechanism of protection has still to be determined. This vaccine should reduce the economic losses due to cryptosporidiosis in ruminants, specially in small ruminants (calves, lambs, kids). It has also the potential to reduce environmental contamination by reducing oocyst shedding.

Animals↗
PubMed1999

Adjuvant effect of cholera toxin on systemic and mucosal immune responses in chickens infected with E. tenella or given recombinant parasitic antigen per os.

We investigated the adjuvant effect of cholera toxin (CT) on the intestinal and systemic immune systems of chickens. The CT was given orally, mixed with a non-replicating antigen, a recombinant Eimeria protein, IPEI, or with a replicating one, Eimeria tenella parasite. There were increases in the specific IgA and IgG responses to the recombinant protein IPEI, with a significant anti-1PE1 IgG response in the duodenum (p < 0.05) and caecum (p < 0.05) 4 weeks after immunization and a specific IgA (p < 0.05) response in the duodenum after 3 weeks. A transient anti-1PE1 IgG (p < 0.05) response was detected in the serum 1 week post-injection and an IgA response (p < 0.05) at 2 weeks. CT given with the replicative parasite caused no change in the intestinal and systemic immune responses with 1 or 3 immunizations although a specific antiparasitic in vitro proliferation of the spleen cells from infected chickens was observed. Nevertheless, 0.05 mg CT given per os to chickens was strongly immunogenic in both experiments. A strong serum IgG (p < 0.01) response was detected as soon as 1 week after the end of the immunization protocol with 1PE1 and 2 weeks after infection with E. tenella. Strong anti-CT IgG responses were also detected by the second week post-immunization in the duodenum and caeca (p < 0.01). Hence, CT can be used as a mucosal adjuvant in chickens to improve the intestinal immune response.

Adjuvants, Immunologic↗
PubMed1999

Comparison of the humoral and cellular immune responses to two preparations of Cryptosporidium parvum CP15/60 recombinant protein.

This study compares the immune responses produced by immunising mice and rabbits with two preparations of the recombinant 15/60 kDa protein of Cryptosporidium parvum. Genomic C. parvum DNA was amplified and the recombinant protein was synthesized as a fusion protein with glutathione-S-transferase in Escherichia coli and in the eukaryotic system of baculovirus/insect cells. Both recombinant proteins induced similar levels of serum antibodies against the fusion recombinant protein, but the eukaryotic recombinant protein triggered a stronger humoral response to C. parvum. Similarly, increased lymphoproliferation occurred only after stimulation of spleen cells from mice immunised with the eukaryotic recombinant protein. This suggests that the eukaryotic protein is a better candidate for immunological studies on cryptosporidiosis.

Animals↗
PubMed1999

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Journal Article↗
PubMed1998

Failure to differentiate Cryptosporidium parvum from C. meleagridis based on PCR amplification of eight DNA sequences.

In order to determine the specificities of PCR-based assays used for detecting Cryptosporidium parvum DNA, eight pairs of previously described PCR primers targeting six distinct regions of the Cryptosporidium genome were evaluated for the detection of C. parvum, the agent of human cryptosporidiosis, and C. muris, C. baileyi, and C. meleagridis, three Cryptosporidium species that infect birds or mammals but are not considered to be human pathogens. The four Cryptosporidium species were divided into two groups: C. parvum and C. meleagridis, which gave the same-sized fragments with all the reactions, and C. muris and C. baileyi, which gave positive results with primer pairs targeting the 18S rRNA gene only. In addition to being genetically similar at each of the eight loci analyzed by DNA amplification, C. parvum and C. meleagridis couldn't be differentiated even after restriction enzyme digestion of the PCR products obtained from three of the target genes. This study indicates that caution should be exercised in the interpretation of data from water sample analysis performed by these methods, since a positive result does not necessarily reflect a contamination by the human pathogen C. parvum.

Animals↗
PubMed1998

Human intestinal epithelial cells respond to Cryptosporidium parvum infection with increased prostaglandin H synthase 2 expression and prostaglandin E2 and F2alpha production.

Cryptosporidium parvum is an important cause of diarrhea in humans and several animal species. Prostaglandins play a central role in regulating intestinal fluid secretion in animal models of cryptosporidiosis, but their cellular sources and mechanisms of induction are unclear. Here, we show that C. parvum infection directly activates prostaglandin H synthase 2 expression and prostaglandin E2 and F2alpha production in human intestinal epithelial cells.

Animals↗
PubMed1997

Evaluation of decoquinate to treat experimental cryptosporidiosis in kids.

The purpose of this trial was to evaluate the effects of decoquinate at 2.5 mg/kg/day for 21 days to prevent an experimental cryptosporidiosis in kids. Twenty 1-day-old male kids (French Alpin), fed initially goat colostrum heated 1 h at 56 degrees C and fed twice daily with nonmedicated milk replacer, were assigned into 2 groups. Kids of both groups were orally inoculated with 10(6) Cryptosporidium parvum (D0 = inoculation day). Group A kids were kept as nonmedicated controls and group B kids were orally medicated with 2.5 mg/kg/day of decoquinate (Deccox L. Rhône Poulenc Animal Nutrition) for 21 days from D-3 to D17. The studied criteria were body weight gain, oocyst shedding and specific anti-C. parvum immune response. In group A, the inoculation was not followed by mortality; but only by diarrhea and high oocyst shedding. Decoquinate reduced the severity of cryptosporidiosis in group B kids. The treatment prevented episodes of diarrhea and weight gain decrease for the D0-D7 and D0-D14 disease periods but did not allow a better final weight gain. The oocyst shedding was decreased in number and in duration. This parasitic development has induced a specific anti-C. parvum immune response. This drug is well-tolerated by animals and may be recommended in the prevention of ruminant cryptosporidiosis, a disease which has very limited treatment options.

Animals↗
PubMed1997

Cryptosporidium parvum infection of human intestinal epithelial cells induces the polarized secretion of C-X-C chemokines.

Cryptosporidium parvum infects intestinal epithelial cells and does not invade deeper layers of the intestinal mucosa. Nonetheless, an inflammatory cell infiltrate that consists of neutrophils and mononuclear cells is often present in the lamina propria, which underlies the epithelium. This study investigated the host epithelial cell response to C. parvum by assessing in vitro and in vivo the expression and production of proinflammatory cytokines by intestinal epithelial cells after infection. The human colon epithelial cell lines HCT-8 and Caco-2 and human intestinal xenografts in SCID mice were infected with C. parvum. The expression and secretion of the C-X-C chemokines interleukin-8 (IL-8) and GROalpha were determined by reverse transcription-PCR analysis and enzyme-linked immunosorbent assay. Our results demonstrate that upregulated expression and secretion of IL-8 and GROalpha after C. parvum infection of intestinal epithelial cells first occurred 16 to 24 h after infection and increased over the ensuing 1 to 2 days. The kinetics of C-X-C chemokine production by C. parvum-infected epithelial cells contrast markedly with the rapid but transient expression of C-X-C chemokines by epithelial cells infected with invasive enteric bacteria. C-X-C chemokine secretion in C. parvum-infected epithelial cells occurred predominantly from the basolateral surface in polarized monolayers of Caco-2 cells grown in Transwell cultures, whereas cell lysis occurred at the apical surface. The basolateral secretion of IL-8 and GROalpha from C. parvum-infected epithelial cells suggests that C-X-C chemokines produced by those cells contribute to the mucosal inflammatory cell infiltrate in the underlying intestinal mucosa.

Animals↗
PubMed1997

Detection of Cryptosporidium parvum DNA in formed human feces by a sensitive PCR-based assay including uracil-N-glycosylase inactivation.

We developed a PCR-based method that can be used to identify Cryptosporidium parvum in human feces. Fecal oocysts were concentrated by centrifugation on a sodium chloride gradient and filtration on a nitrocellulose filter prior to DNA extraction and PCR amplification of a 452-bp C. parvum-specific DNA sequence with a protocol including dUTP and uracil-N-glycosylase. All samples obtained from naturally infected humans (n = 10), calves (n = 4), and goats (n = 2) were positive. A 100% detection rate was achieved with both formed and solid stools (n = 10) seeded with 1,000 C. parvum oocysts per g. Procedures based on stool concentration by a modified Ritchie method and subsequent oocyst identification by immunofluorescent labeling or acid-fast staining require concentrations of 50,000 to 500,000 oocysts per g to achieve a 100% detection rate with formed stools. The described PCR-based assay thus has a 50- to 500-fold increase in sensitivity compared to those of the methods commonly used to analyze formed feces.

Animals↗