Both neonatal and C57BL/6 gamma interferon (IFN-␥) 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-␥ leads to a protective immunity is yet poorly understood. In order to investigate the effect of IFN-␥ 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-␥ 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-␥, the adult knockout mice up-regulated the mRNA levels of inflammatory cytokines, such as IL-1, IL-6, and granulocyte-macrophage colony-stimulating factor, in the mucosa, but not tumor necrosis factor alpha (TNF-␣), whereas all these cytokines were upregulated in the infected neonatal mice. Further experiments indicated that injections of TNF-␣ 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-␣ may participate in the control of parasite development.Cryptosporidium parvum is an obligate intracellular protozoan parasite that infects intestinal epithelial cells of humans and various other mammals. C. parvum causes protracted diarrhea in young and immunodeficient individuals and can lead to death for AIDS patients. Cryptosporidiosis is frequent in young farm animals and has economic and environmental consequences. In immunocompetent hosts, the disease is self-limited, suggesting a major role for host defense factors in controlling the infection.Most of the studies of experimental cryptosporidiosis have been performed with rodents whose immune systems were impaired, e.g., neonatal mice (14,25,35), rats immunosuppressed with dexamethasone (27), or congenitally mutated nude (21, 23) and SCID mice (17,34). More recent studies have used mice with targeted mutations for the genes of major histocompatibility complex class II (1), CD40, CD40L (7), or gamma interferon (IFN-␥) (33, 38). The key role of IFN-␥ in resistance to C. parvum infection initially demonstrated with antibody depletion was confirmed more recently with IFN-␥ knockout mice (GKO) (6,33,34). However, the mechanisms whereby IFN-␥ intervenes in the clearance of C. parvum are still not well understood. Some possibilities, not mutually exclusive, include a direct toxic effect of IFN-␥ on the parasite or the infected cells or the induction of other cytokines that can be toxic for the pa...
The recent cloning of chicken genes coding for interleukins, chemokines, and other proteins involved in immune regulation and inflammation allowed us to analyze their expression during infection with Eimeria. The expression levels of different genes in jejunal and cecal RNA extracts isolated from uninfected chickens and chickens infected with Eimeria maxima or E. tenella were measured using a precise quantitative reverse transcription-PCR technique. Seven days after E. tenella infection, expression of the proinflammatory cytokine interleukin-1 (IL-1) mRNA was increased 80-fold. Among the chemokines analyzed, the CC chemokines K203 (200-fold) and macrophage inflammatory factor 1 (MIP-1) (80-fold) were strongly upregulated in the infected ceca, but the CXC chemokines IL-8 and K60 were not. However, the CXC chemokines were expressed at very high levels in uninfected cecal extracts. The levels of gamma interferon (IFN-␥) (300-fold), inducible nitric oxide synthase (iNOS) (200-fold), and myelomonocytic growth factor (MGF) (50-fold) were also highly upregulated during infection with E. tenella, whereas cyclooxygenase 2 showed a more modest (13-fold) increase. The genes upregulated during E. tenella infection were generally also upregulated during E. maxima infection but at a lower magnitude except for those encoding MIP-1 and MGF. For these two cytokines, no significant change in expression levels was observed after E. maxima infection. CD3؉ intraepithelial lymphocytes may participate in the IFN-␥ upregulation observed after infection, since both recruitment and upregulation of the IFN-␥ mRNA level were observed in the infected jejunal mucosa. Moreover, in the chicken macrophage cell line HD-11, CC chemokines, MGF, IL-1, and iNOS were inducible by IFN-␥, suggesting that macrophages may be one of the cell populations involved in the upregulation of these cytokines observed in vivo during infection with Eimeria.Chicken coccidiosis is caused by intracellular protozoan parasites belonging to seven species of Eimeria. These parasites invade and reside in the lining of the intestine or ceca. Parasite development causes diarrhea, morbidity, and mortality, and the impact of coccidiosis on the industry has serious economic consequences. Thus far, chemoprophylaxis has controlled the disease but has been complicated by the emergence of drug resistance. Infection by Eimeria promotes antibody and cellmediated immune responses. However, cellular immunity mediated by various cell populations, including T lymphocytes, NK cells, and macrophages, plays a major role in disease resistance (27). There is increasing evidence of CD4 ϩ and intraepithelial lymphocyte (IEL) involvement during a primary infection, while T-cell receptor ␣-and -chain-positive CD8 ϩ IEL play a key role in secondary infection (25). The development of a vaccine has been hampered by the lack of understanding of the various components of the host immune system involved in protective immunity.The low level of homology between chicken genes and their mammalian co...
Cryptosporidium parvum is a protozoan parasite that infects intestinal epithelial cells and induces inflam-In the absence of IFN-␥, the chemokine response was altered for IP-10, MIG, i-TAC, RANTES, and MIP-1 mRNAs, while the three ELR C-X-C chemokine mRNAs studied (lipopolysaccharide-induced C-X-C chemokine, MIP-2␣, and KC mRNAs) were strongly overexpressed. These results are consistent with the neutrophil recruitment observed in the lamina propria of GKO mice at day 9 postinfection but are not consistent with the hypothesis that these cells play an important role in the resolution of the infection. On the contrary, the altered response of chemokines responsible for the recruitment of macrophages and T cells in GKO mice suggests that these two populations may be critical in the development of a protective immune response.
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.
The chemoprophylactic effects of halofuginone lactate were tested against calf experimental cryptosporidiosis. Twenty 2-day-old calves, divided into four groups, were orally inoculated with 1 x 10(6) oocysts of Cryptosporidium parvum. The infected control group was unmedicated whereas the three other groups were medicated with the drug at 30, 60 and 120 micrograms kg-1 day-1, respectively, for 7 days, from Day (D) 2 to D8 post-inoculation (D 0 was inoculation day). The calves were weighed twice weekly and disease development and drug efficacy were assessed daily from D0 to D30 from consistency of feces, shedding of oocysts and mortality. Experimental C. parvum infection caused a severe clinical disease with profuse watery diarrhea, high oocyst shedding and mortality (3 out of 5) in the unmedicated group. The results clearly demonstrated the efficacy of halofuginone lactate in reducing the severity of clinical cryptosporidiosis. This efficacy was dose-dependent. The lowest dose (30 micrograms kg-1 day-1) was not able to prevent clinical disease and mortality (3 out of 5). No clinical signs were observed with the 60 and 120 micrograms kg-1 day-1 doses, but the animals shed oocysts after drug withdrawal. This shedding was more delayed the higher the dose of drug administered, but the delayed shedding had no effect on the growth of the animals.
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 GRO␣ were determined by reverse transcription-PCR analysis and enzyme-linked immunosorbent assay. Our results demonstrate that upregulated expression and secretion of IL-8 and GRO␣ 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 GRO␣ 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. Cryptosporidium parvum is a common cause of diarrhea in humans and animals (5). Infection most commonly involves the small intestine and is usually self-limited, and the diarrhea which accompanies infection is transient in immunocompetent hosts (6). However, in immunocompromised individuals (e.g., patients with AIDS), diarrhea persists and frequently the infection and pathological changes are more widespread, possibly involving the biliary tract, pancreas, stomach, esophagus, and respiratory tract as well as the small intestine (3, 12, 19, 35). In the intestine, C. parvum resides in epithelial cells (31). The life cycle of C. parvum in the intestinal mucosa includes several stages (14). When oocysts are ingested, sporozoites excyst and rapidly infect host epithelial cells. C. parvum establishes itself intracellularly but extracytoplasmically in a parasitophorous vacuole beneath the apical membrane of the epithelial cell. After asexual multiplications in epithelial cells over the ensuing 16 to 48 h, type I and II merozoites are released and infect new epithelial cells. Type II merozoites differentiate into microgamonts and macrogamonts and initiate sexual reproduction between 3 and 5 days postinfection (p.i.). After macrogametes are fertilized by microgametes, they develop into oocysts, which sporulate in situ.
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.
Fecal and serum anti-Cryptosporidium parvum immunoglobulin A (IgA), IgM, and IgG were monitored by an enzyme-linked immunosorbent assay after experimental and natural infection of calves with C. parvum. Although all experimentally infected calves showed high levels of colostral antibodies in the feces, they acquired C. parnum infection. Three of five animals died. Calves which acquired natural infection showed only diarrhea. Levels of colostral coproantibodies dropped quickly. Experimental infection was followed by a rise in local anti-C. parvum IgM levels from day 5 postinfection (p.i.). IgM peaked at day 14 p.i. and then disappeared quickly. Anti-C. parvum IgA levels rose between days 7 and 14 p.i. and decreased slowly. Rising levels of coproantibodies coincided with falling oocyst output. Fecal anti-C. parvum IgG levels rose slightly during oocyst output, and IgG disappeared 3 weeks p.i. Similar kinetics were established in naturally infected calves. Although fecal anti-C. parvum IgA levels declined slowly, reinfections were established 5, 7, and 14 weeks after the primary contact. Serum anti-C. parvum IgG levels rose during maximal oocyst excretion, whereas serum anti-C. parvum IgA levels peaked later than did local IgA levels. Challenge reinfection of naturally infected calves at day 112 was not followed by clinical signs or oocyst output or by a secondary antibody response. Sequential Western immunoblotting with fecal extracts revealed up to 32 different parasite antigens. Convalescent-phase sera recognized up to 23 antigens. Fecal IgA reacted intensely with antigens with relative molecular weights (Mr) of approximately 11,000 and 15,000. These antigens were not recognized by convalescent-phase serum IgG. Both local IgA and serum IgG also showed strong reactions with 23,000and 44,000-M, antigens and with several antigens of between 66,200 and 200,000 Mr. Most bands remained detectable for at least 16 weeks p.i. Cryptosporidium parvum is a parasite distributed worldwide. It causes diarrhea and sometimes mortality in a broad range of mammals. In calves, the economic impact of cryptosporidiosis is considerable and comparable to that of rotavirus infection (23). C. parvum has been identified as the second most common infectious agent in outbreaks of diarrhea (1, 16). C. parvum is non-host specific and can easily be transmitted from one species to another. Infected calves and
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.