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Biomedical subjects

M Naciri

Publications and source records attributed to M Naciri.

53 records · Page 3Linked to original sources
PubMed1986

[Development of Eimeria tenella in a nonspecific host: the mouse].

The existence of extra-intestinal stages of a chick coccidium, Eimeria tenella, has been demonstrated in a non-specific host, the mouse. Between 1 and 14 days after inoculation the lungs and blood of mice were periodically infective for chicks. This is consistent with parasite development, rather than survival in the lungs and passage of free elements by the bloodstream. This type of development with extra-intestinal stages in a non-specific host has certain analogies with a related genus Toxoplasma. The type of development remains to be demonstrated.

Animals↗
PubMed1984

Influence of digestive microflora on parasite development and the pathogenic effect of Eimeria ovinoidalis in the axenic, gnotoxenic and conventional lamb.

The interaction between the digestive microflora and the development and pathogenic effect of Eimeria ovinoidalis was studied in lambs. All animals were reared and fed in the same conditions and were infected on the second day after birth with 150,000 sterilised oocysts. Two conventional lambs that had absorbed colostrum had haemorrhagic diarrhoea for several days and excreted 10(5) to 10(6) oocysts g-1 faeces. One lamb died. Similar results were recorded in two gnotoxenic lambs inoculated with 63 pure bacterial strains representative of the dominant digestive microflora and free of all pathogenic organisms. By contrast, no clinical signs and, in particular, no diarrhoea were observed in nine axenic lambs. OOcyst excretion in these only started on the 16th day, and the number of oocysts was between 10(2) and 10(3) g-1. The presence of digestive microflora is thus essential to the development of the parasite's pathogenic expression.

Animals↗
PubMed1983

Experimental study of some factors limiting 'competitive exclusion' of salmonella in chickens.

Some factors affecting the efficiency of competitive exclusion of Salmonella typhimurium var copenhagen in chicks were studied experimentally under gnotobiotic conditions. Axenic chickens were given dilute suspensions of adult faeces and exposed to the salmonellae. Prevention of colonisation of the gut by salmonellae ('competitive exclusion') was variable and depended possibly in part on the source of the adult faeces used to protect the chicks. Exclusion was also dose-dependent, a large inoculum of the salmonellae (10(7) viable organisms per animal) leading to colonisation in treated chicks. An inapparent carrier state was sometimes produced by lower doses of the salmonellae (10(2) viable organisms per animal), but bursts of excretion still appeared after inoculation of the salmonellae. In inapparent healthy carriers, the inoculation of a dose of Eimeria tenella oocysts that was known to produce subclinical caecal coccidiosis led to the shedding of large numbers of salmonellae for over two weeks, and the use of 'competitive exclusion' in poultry as a preventive measure for salmonella infections might thus be limited by the frequent occurrence of subclinical coccidiosis in the field.

Animals↗
PubMed1982

[Development of Eimeria tenella, agent of cecal coccidiosis in chickens, in non-specific hosts: existence of an infective exointestinal form].

The administration of various organs from Mice inoculated 1 to 7 days before with E. tenella oocysts induced caecal coccidiosis in Chicken. The most infective organs were the muscles and the intestine and to a lesser extent, the brain and the thymus. This demonstrates the existence of an exo-intestinal form of the parasite in a non specific host. This form is infective for the specific host.

Animals↗
PubMed1982

Evaluation of the effect of anticoccidial drugs on size of parasite population and its development in litters.

Evaluation of the number of oocysts present in liters and of their rate of sporulation is relatively easy in floor pens. We have observed that contamination varies considerably according to the anticoccidial drug present in feed. Despite a difference in effect on parasitic development, some identical performances were noted in all groups treated. Among the anticoccidial drugs studied, Monensin is the one which least reduces contamination of environment; Halofuginone is the one which reduces contamination the most.

Animals↗
PubMed1980

Evaluation of the efficacy of salinomycin in the control of coccidiosis in chicks.

Salinomycin (Coxistac) was tested for efficacy in broilers reared in floor pens at 60 and 80 ppm fed continuously from 1 to 56 days of age. One trial was conducted. Comparisons were made with unmedicated, infected and medicated, noninfected treatments (controls) in addition to infected treatments given either monensin at 100 ppm or halofuginone at 3 ppm continuously (days 1 to 56) in the feed. Coccidia exposure was obtained by infection via the feed. Salinomycin was highly efficacious at 60 ppm based upon improved performance, lesion score, hematocrit, and serum optical density compared with the unmedicated, infected group. Statistical analysis of main effects on weight gain, feed conversion ratio, hematocrit value, and serum optical density showed no significant differences between salinomycin, monensin, or halofuginone. The weight gain of birds given salinomycin at 80 ppm was depressed significantly (P less than .01) at 56 days as a result of decreased feed consumption.

Animals↗
PubMed1980

Method of evaluating the efficiency of anticoccidial drugs in floor-pen trials with multiple in-feed infection versus "seeding" model.

The evaluation of the efficacy of anticoccidials requires floor pen experiments. With the method of infection suggested, i.e., the ingestion of an infecting feed during 5 consecutive days, it is easier to check animal contamination than with the "seeder birds" method, and the anticoccidial has a dual action, it protects the animals and at the same time diminishes they environmental contamination. The presence of a non experimentally infected group, treated by an anticoccidial drug makes it possible to judge normal performances of the animals. In addition to lesion scorings, serum coloration and hematocrits are excellent criteria to evaluate the incidence of parasitism. An experimental work plan is suggested.

Animal Feed↗
PubMed1978

[Pathogenic study of turkey coccidiosis due to Eimeria adenoeides (author's transl)].

Male turkeys were infected with Eimeria adenoeides at approximately 15 or more days old. They received either a single inoculation or daily infections comprising a constant dose of oocytsts. The observed decrease in growth was largely due to a lower than normal intake of food. A comparison of single and multiple infections showed that the duration of the observed symptoms hardly differed in either case. Changes in certain blood parameters which occured during the course of the disease were similar to the changes seen in chickens with caecal coccidiosis. The persistence of these changes following repeated infections revealed the action of a parasite on digestive function which is not found in chickens infected with E. tenella. Modifications of the caecal bacterial flora were also observed (an increase in the populations of enterobacterial and anaerobes) during the course of the development of the parasitic disorder. Repeated infections prolonged the duration of this phenomenon. The similarity of those variations to those observed in the chicken with caecal coccidiosis suggests a fundamental role of some bacteria in the expression of the pathogenic potential of E. adenoeides.

Animal Feed↗
PubMedDate not supplied

Psychobiological consequences of two different weaning methods in sheep.

Weaning is associated with a break in the mother-infant contact. In sheep, under natural conditions, the rupture of the social bond is progressive. In contrast, weaning imposed by breeders may result in psychobiological disturbances. The aim of this experiment was to measure the behavioural, hormonal and immune consequences of two types of sudden weaning: total separation (TS) and partial separation (PS), in 42 Ile-de-France ewes and their 60 lambs. TS animals (lambs and ewes) vocalized less frequently and for a shorter period of time than did the PS animals. Neither the plasmatic cortisol level in lambs nor the humoral response of dams and young were modified by the two weaning methods. In contrast, the excretion of coccidial oocysts increased significantly after weaning in TS lambs only and the growth rate of TS females was lower than that of the other lambs. These results suggest that these methods of rupture of mother-young social contact have only limited negative consequences on both partners in sheep, contrary to primates and rodents.

Animals↗
PubMedDate not supplied

In vitro cultivation of Cryptosporidium parvum in the non-adherent human monocytic THP-1 cell line.

This study shows that the human monocytic cell line THP-1 supports the growth of C. parvum. Immunofluorescence controls showed that only scarce oocysts remained after infection and disappeared within the first 24 h of culture. A continuous asexual life cycle proceeded throughout the experiments, with at least 15-d cultures. This model provides a useful tool for studies on the biology of C. parvum in cells involved in its transport in immunocompromised host.

Animals↗
PubMedDate not supplied

Mechanisms of the Eimeria tenella growth inhibitory activity induced by concanavalin A and reticuloendotheliosis virus supernatants with interferon gamma activity in chicken macrophages and fibroblasts.

Pretreatment of chicken bone marrow macrophages and embryo fibroblasts with supernatants containing chicken interferon gamma (IFN-gamma) for 24 hr prior to inoculation inhibited intracellular Eimeria tenella replication, measured by [3H] uracil incorporation. The supernatants (Sns) were obtained from culture of lymphoblastoid cells transformed by a reticuloendotheliosis virus (REV) and chicken splenocytes stimulated with concanavalin A (Con A). The mechanisms of the E. tenella growth inhibitory activity induced by Sn REV and Sn Con A in chicken macrophages and fibroblasts were studied. Addition of oxygen scavengers (superoxide dismutase, D-mannitol, DABCO, benzoic acid, L-histidine hydrochloride) was able to overcome the inhibition of E. tenella replication after pretreatment with Sn REV or Sn Con A in macrophage cultures but not in fibroblast cultures. Nitric oxide (NO) synthesis was induced in macrophage culture treated with Sn REV or Sn Con A but not in fibroblast culture. Addition of NG monomethyl-L-arginine, an NO synthase inhibitor together with the supernatants was also able to overcome inhibition of E. tenella replication in macrophage culture. On the other hand, addition of L-tryptophan to Sn REV- or Sn Con A-treated fibroblasts was able to reverse the inhibitory effect on E. tenella replication. In conclusion, production of inorganic NO or toxic oxygen intermediates may be involved in the E. tenella growth inhibitory activity of chicken macrophages pretreated with supernatants containing an IFN-gamma activity, and cellular tryptophan depletion may be involved for chicken fibroblasts, thus matching the mechanisms of the IFN-gamma-induced growth inhibitory activity for protozoans in mammals.

Animals↗
PubMedDate not supplied

Renal Cryptosporidiosis (Cryptosporidium baileyi) in specific-pathogen-free chickens experimentally coinfected with Marek's disease virus.

Renal Cryptosporidiosis was experimentally induced during a study to investigate the pathogenicity of Cryptosporidium baileyi in specific-pathogen-free (SPF) chickens coinfected with Marek's disease virus (MDV). Cryptosporidium baileyi was administered orally at 4 days of age to chickens previously infected at hatching (day 0) with the HPRS 16 strain of oncogenic MDV. Three control groups received MDV at hatching, C. baileyi on day 4, or placebo consisting of distilled water. Renal cryptosporidiosis lesions were induced in the group coinfected with MDV and C. baileyi. The kidneys were markedly swollen and pale, with visible urate crystals in the ureters and surface tubules. Oocysts of C. baileyi were demonstrated in six of seven cases tested by a scoring method with modified Sheather's sugar solution on renal tissue scrapings and were confirmed in three cases by histologic examination of paraffin-embedded kidney sections. Histologic study also revealed subacute interstitial nephritis, acute ureteritis, and attachment of cryptosporidia on the epithelial cell surface of the ureters and collecting ducts, collecting tubules, and distal convoluted tubules. Various developmental stages of the parasite were present in the kidney sections. To our knowledge, this is the first report of experimentally induced renal cryptosporidiosis in SPF chickens coinfected with MDV.

Animals↗
PubMedDate not supplied

Interaction of Marek's disease virus and Cryptosporidium baileyi in experimentally infected chickens.

Histocompatible B13/B13 white specific-pathogen-free leghorn chickens were used to investigate the effect of coinfection with Cryptosporidium baileyi and the HPRS 16 strain of Marek's disease virus (MDV) in chickens and to assess the pathogenicity of C. baileyi when MDV is given before or after the parasite. Groups of chickens concurrently infected with C. baileyi orally inoculated at day (D)4 and MDV inoculated at hatching (C4M0 group) or at D8 (C4M8 group) were compared with relevant control groups inoculated with only C. baileyi at D4 (C4 group), only MDV at hatching (M0 group) or at D8 (M8 group), and an uninoculated control group (UC group). The chickens were kept in isolator units until the end of the experiment at D62. Our results showed a considerable synergistic effect in concurrently infected chickens and more severe consequences when chickens received MDV before C. baileyi infection. In fact, except for a slight transitory weakness, the chickens in C4 group remained free of overt clinical signs and there was no mortality. However, coinfection with both pathogens induced more lasting or permanent oocyst shedding. Severe clinical cryptosporidiosis with weakness, anorexia, depression, growth retardation, and chronic and severe respiratory disease causing death occurred in all chickens in the C4M0 group between D12 and D43 and in 67% of the chickens in the C4M8 group between D17 and D57. Eighty-two percent and 33%, respectively, died before the development of specific Marek's disease lesions. Mortality rates were 27% and 33% in the M0 and M8 groups, respectively. The presence of MDV enhanced the establishment of more lasting cryptosporidial infection in the respiratory tract, esophagus, crop, proventriculus, and kidneys (only in C4M0 group) as well as in bursa of Fabricius, ceca, and cloaca. Serologic analysis showed that chickens with chronic cryptosporidiosis in the C4M8 group had an increased level of C. baileyi-specific immunoglobulin A. Our results may explain some cases of mortality in chickens naturally infected with MDV and Cryptosporidium.

Animals↗
PubMedDate not supplied

Analysis of humoral immune response in chickens after inoculation with Cryptosporidium baileyi or Cryptosporidium parvum.

White leghorn chickens aged 14 days were orally inoculated with 1 x 10(6) oocysts of Cryptosporidium baileyi or C. parvum to compare the specific immune responses. Cross-reactions were evaluated using homologous or heterologous antigens in enzyme-linked immunosorbent assay (ELISA) and Western blot to determine the occurrence of an antigenic homology between these two species. Blood, bile, whole intestine, bursa of Fabricius, and feces were collected daily from the day of inoculation (day 0) to day 22 postinoculation (PI). Eight control chickens remained negative up to day 22 PI. Chickens inoculated with C. baileyi did not express clinical symptoms but shed oocysts from days 6 to 21 PI. Chickens inoculated with C. parvum exhibited no clinical signs, no oocysts in feces, and no developmental stages of the parasite. However, a specific immune response to both antigens appeared on day 9 PI. ELISA using homologous or heterologous antigens showed that anti-C. baileyi and anti-C. parvum antibodies in serum or bile were detectable using C. baileyi or C. parvum oocysts as antigen, but the intensity of the response was significantly higher when C. baileyi was used. Cross-reactions in immunoblot analysis confirmed ELISA results, revealing a greater number of bands using C. baileyi as antigen but showing that epitopes recognized on the protein with a molecular weight of 15,000-17,000 were different.

Animals↗
PubMedDate not supplied

Inhibition of Eimeria tenella development in vitro mediated by chicken macrophages and fibroblasts treated with chicken cell supernatants with IFN-gamma activity.

Pretreatment of chicken macrophages or fibroblasts with supernatants from concanavalin A-stimulated spleen cells or from the virus-transformed cell line reticuloendotheliovirus as source of interferon gamma (IFN-gamma) slows down subsequent sporozoite replication in the cells. To identify the presence of IFN-gamma, we combined four typical activities of IFN-gamma: inhibition of cytopathic effect of vesicular stomatitis virus on IFN-gamma-treated fibroblasts, cytostatic activity of IFN-gamma-activated macrophages, induction of major histocompatibility complex II antigen expression on IFN-gamma-activated fibroblasts and macrophages, and induction of nitrite production in macrophages. We have shown that chicken fibroblasts and macrophages possess a microbiostatic capacity once they are able to prevent the otherwise unchecked intracellular replication of Eimeria tenella following activation with culture supernatants identified as containing a strong IFN-gamma activity.

Animals↗