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Conrad NL, Zorzi VSG, Pinheiro NB, Borchard JL, de Moura MQ, Leite FPL. Dynamics of ex vivo cytokine transcription during experimental Toxocara canis infection in Balb/c mice. REVISTA BRASILEIRA DE PARASITOLOGIA VETERINARIA = BRAZILIAN JOURNAL OF VETERINARY PARASITOLOGY : ORGAO OFICIAL DO COLEGIO BRASILEIRO DE PARASITOLOGIA VETERINARIA 2024; 33:e014223. [PMID: 38511816 PMCID: PMC10954251 DOI: 10.1590/s1984-29612024017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 02/09/2024] [Indexed: 03/22/2024]
Abstract
The cytokine microenvironment is crucial in generating and polarizing the immune response. A means of monitoring this environment would be of great value for better understanding Toxocara canis immune modulation. The aim of this study was to analyze the dynamics of cytokine transcription ex vivo, during early (24-48 hours) and late (15-30 days) times post-infection, in the mesenteric lymph nodes, spleen and intestinal mucosa of Balb/c mice experimentally infected with T. canis larvae. Mice in the treated group were infected with 100 third-stage larvae (L3), whereas mice in the control group were not infected. Analyses were performed at different times: 24-48 hours post-infection (HPI), 15-30 days post-infection (DPI). IL4, IL10, IL12 and Ym1 mRNA transcriptions were analyzed through qPCR. This study showed cytokine transcription mediated by migrating larvae in the mesenteric lymph nodes and spleen at 24-48 HPI, whereas cytokine transcription in the intestinal mucosa was observed only at late times (15-30 DPI). These results suggest that the T. canis larvae migration during infection might play a role in cytokine dynamics. Since the cytokine microenvironment is crucial in modulating immune response, knowledge of cytokine dynamics during T. canis infections pave the way to better understand its interaction with the host.
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Affiliation(s)
- Neida Lucia Conrad
- Programa de Pós-graduação em Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas - UFPel, Pelotas, RS, Brasil
| | - Vitória Sequeira Gonçalves Zorzi
- Programa de Pós-graduação em Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas - UFPel, Pelotas, RS, Brasil
| | - Natália Berne Pinheiro
- Programa de Pós-graduação em Microbiologia e Parasitologia, Instituto de Biologia, Universidade Federal de Pelotas - UFPel, Pelotas, RS, Brasil
| | - Jéssica Lopes Borchard
- Programa de Pós-graduação em Microbiologia e Parasitologia, Instituto de Biologia, Universidade Federal de Pelotas - UFPel, Pelotas, RS, Brasil
| | - Micaele Quintana de Moura
- Programa de Pós-graduação em Microbiologia e Parasitologia, Instituto de Biologia, Universidade Federal de Pelotas - UFPel, Pelotas, RS, Brasil
| | - Fábio Pereira Leivas Leite
- Programa de Pós-graduação em Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas - UFPel, Pelotas, RS, Brasil
- Programa de Pós-graduação em Microbiologia e Parasitologia, Instituto de Biologia, Universidade Federal de Pelotas - UFPel, Pelotas, RS, Brasil
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De Seram EL, Uehlinger FD, de Queiroz C, Redman EM, Campbell JR, Nooyen D, Morisetti A, Pollock CM, Ekanayake S, Penner GB, Gilleard JS. Integration of ITS-2 rDNA nemabiome metabarcoding with Fecal Egg Count Reduction Testing (FECRT) reveals ivermectin resistance in multiple gastrointestinal nematode species, including hypobiotic Ostertagia ostertagi, in western Canadian beef cattle. Int J Parasitol Drugs Drug Resist 2023; 22:27-35. [PMID: 37119733 PMCID: PMC10165142 DOI: 10.1016/j.ijpddr.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 04/19/2023] [Accepted: 04/20/2023] [Indexed: 05/01/2023]
Abstract
A large-scale Fecal Egg Count Reduction Test (FECRT) was integrated with ITS-2 rDNA nemabiome metabarcoding to investigate anthelmintic resistance in gastrointestinal nematode (GIN) parasites in western Canadian beef cattle. The study was designed to detect anthelmintic resistance with the low fecal egg counts that typically occur in cattle in northern temperate regions. Two hundred and thirty-four auction market-derived, fall-weaned steer calves coming off pasture were randomized into three groups in feedlot pens: an untreated control group, an injectable ivermectin treatment group, and an injectable ivermectin/oral fenbendazole combination treatment group. Each group was divided into six replicate pens with 13 calves per pen. Individual fecal samples were taken pre-treatment, day 14 post-treatment, and at monthly intervals for six months for strongyle egg counting and metabarcoding. Ivermectin treatment resulted in an 82.4% mean strongyle-type fecal egg count reduction (95% CI 67.8-90.4) at 14 days post-treatment, while the combination treatment was 100% effective, confirming the existence of ivermectin-resistant GIN. Nemabiome metabarcoding of third-stage larvae from coprocultures revealed an increase in the relative abundance of Cooperia oncophora, Cooperia punctata, and Haemonchus placei at 14 days post-ivermectin treatment indicating ivermectin resistance in adult worms. In contrast, Ostertagia ostertagi third-stage larvae were almost completely absent from day 14 coprocultures, indicating that adult worms of this species were not ivermectin resistant. However, there was a recrudescence of O. ostertagi third stage larvae in coprocultures at three to six months post-ivermectin treatment, which indicated ivermectin resistance in hypobiotic larvae. The calves were recruited from the auction market and, therefore, derived from multiple sources in western Canada, suggesting that ivermectin-resistant parasites, including hypobiotic O. ostertagi larvae, are likely widespread in western Canadian beef herds. This work demonstrates the value of integrating ITS-2 rDNA metabarcoding with the FECRT to enhance anthelmintic resistance detection and provide GIN species- and stage-specific information.
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Affiliation(s)
- Eranga L. De Seram
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5B4, Canada
- Department of Farm Animal Production and Health, Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - Fabienne D. Uehlinger
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5B4, Canada
| | - Camila de Queiroz
- Faculty of Veterinary Medicine, Host-Parasite Interactions (HPI) Program, University of Calgary, Calgary, AB, T2N 4Z6, Canada
- Department of Pathobiology, School of Veterinary Medicine, Saint George's University, West Indies, Grenada
| | - Elizabeth M. Redman
- Faculty of Veterinary Medicine, Host-Parasite Interactions (HPI) Program, University of Calgary, Calgary, AB, T2N 4Z6, Canada
| | - John R. Campbell
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5B4, Canada
| | - Drue Nooyen
- Faculty of Veterinary Medicine, Host-Parasite Interactions (HPI) Program, University of Calgary, Calgary, AB, T2N 4Z6, Canada
| | - Arianna Morisetti
- Faculty of Veterinary Medicine, Host-Parasite Interactions (HPI) Program, University of Calgary, Calgary, AB, T2N 4Z6, Canada
| | | | - Samantha Ekanayake
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5B4, Canada
| | - Gregory B. Penner
- Department of Animal and Poultry Science, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada
| | - John S. Gilleard
- Faculty of Veterinary Medicine, Host-Parasite Interactions (HPI) Program, University of Calgary, Calgary, AB, T2N 4Z6, Canada
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Strydom T, Lavan RP, Torres S, Heaney K. The Economic Impact of Parasitism from Nematodes, Trematodes and Ticks on Beef Cattle Production. Animals (Basel) 2023; 13:1599. [PMID: 37238028 PMCID: PMC10215612 DOI: 10.3390/ani13101599] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/01/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Global human population growth requires the consumption of more meat such as beef to meet human needs for protein intake. Cattle parasites are a constant and serious threat to the development of the beef cattle industry. Studies have shown that parasites not only reduce the performance of beef cattle, but also negatively affect the profitability of beef agriculture and have many other impacts, including contributing to the production of greenhouse gases. In addition, some zoonotic parasitic diseases may also threaten human health. Therefore, ongoing cattle parasite research is crucial for continual parasite control and the development of the beef cattle industry. Parasitism challenges profitable beef production by reducing feed efficiency, immune function, reproductive efficiency, liveweight, milk yield, calf yield and carcass weight, and leads to liver condemnations and disease transmission. Globally, beef cattle producers incur billions (US$) in losses due to parasitism annually, with gastrointestinal nematodes (GIN) and cattle ticks causing the greatest economic impact. The enormity of losses justifies parasitic control measures to protect profits and improve animal welfare. Geographical differences in production environment, management practices, climate, cattle age and genotype, parasite epidemiology and susceptibility to chemotherapies necessitate control methods customized for each farm. Appropriate use of anthelmintics, endectocides and acaricides have widely been shown to result in net positive return on investment. Implementing strategic parasite control measures, with thorough knowledge of parasite risk, prevalence, parasiticide resistance profiles and prices can result in positive economic returns for beef cattle farmers in all sectors.
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Affiliation(s)
- Tom Strydom
- MSD Animal Health, 20 Spartan Road, Isando, Kempton Park 1619, South Africa;
| | - Robert P. Lavan
- Merck & Co., Inc., 126 E. Lincoln Avenue, Rahway, NJ 07065, USA
| | - Siddhartha Torres
- Merck Animal Health, 2 Giralda Farms, Madison, NJ 07940, USA; (S.T.); (K.H.)
| | - Kathleen Heaney
- Merck Animal Health, 2 Giralda Farms, Madison, NJ 07940, USA; (S.T.); (K.H.)
- Heaney Veterinary Consulting, 303 Fletcher Lake Avenue, Bradley Beach, NJ 07720, USA
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Borchard JL, Conrad NL, Pinto NB, Moura MQD, Berne MEA, Leite FPL. Acute and chronic immunomodulatory response mechanisms against Toxocara canis larvae infection in mice. REVISTA BRASILEIRA DE PARASITOLOGIA VETERINÁRIA 2022. [DOI: 10.1590/s1984-29612022056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract The objective of this work was to evaluate the early and late immunological modulation of an experimental infection of T. canis larvae in mice. Mice were infected with 100 infective larvae and euthanized at different period: 24, 48 hours post infection (HPI), 15- and 30 days post infection (DPI). The humoral response was evaluated by indirect ELISA. Quantitative RT–PCR (qPCR) was used to quantify the mRNA transcription of cytokines IL4, IL10, IL12 and Ym1 in the early and late infection periods. Infection with T. canis was able to generate specific total IgG at 15- and 30- DPI. Analyzing the IgG isotype revealed a significant differentiation for IgG1 compared with IgG2a, IgG2b and IgG3, characterizing a Th-2 response. Evaluating the gene transcription at the early phase of infection, higher transcription levels of IL10, IL4 and Ym1 and a downregulation of IL12 were observed. By the late phase, increased transcription levels of IL4, Ym1 and IL12 were observed, and downregulation of IL-10 transcription was observed. The data obtained suggest that during experimental infection with T. canis, the participation of the IL4, IL10, IL12 cytokines and Ym1 can play an important role in T. canis immunomodulation.
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Tuo W, Zarlenga D, Bakshi M, Vinyard B. Repeated, drug-truncated infections with Ostertagia ostertagi elicit strong humoral and cell-mediated immune responses and confer partial protection in cattle. Vet Parasitol 2021; 296:109510. [PMID: 34217073 DOI: 10.1016/j.vetpar.2021.109510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 06/23/2021] [Accepted: 06/24/2021] [Indexed: 10/21/2022]
Abstract
Bovine ostertagiasis causes significant production losses to the cattle industry. Protective immunity induced by natural infection is slow to develop and anthelmintic resistance is rapidly developing. There is a need to advance alternatives for control of gastrointestinal nematode parasites. The present study investigated the effects of repeated, drug-truncated infections (rDTI) on development of protective immunity and attenuation of a challenge infection by O. ostertagi. Helminth-free calves were randomly assigned to either a rDTI or a control group (n = 5). The rDTI group received daily oral infections of 5000 Ostertagia L3 for 5 consecutive days, then were drug-treated on 14 and 15 days post infection (dpi), to attenuate O. ostertagi at the late fourth larval (L4) through young adult stages. DTI was repeated 3 weeks after the drug treatment. A total of 5 DTIs were administered to the DTI-treated animals. Non-DTI-treated, control animals received tap water as infection control. All animals were drug-treated at the same time. Animals were challenge-infected 4 weeks following the final round of rDTI. The results show that eggs per gram of feces (EPG) in the rDTI group were significantly reduced (P < 0.05) from 21 to 39 dpi, with an overall reduction in cumulative EPG. The control group exhibited reduced (P = 0.0564) average weight gains when compared to those of the rDTI group during weeks 4-5 post infection, a period coinciding with peak EPG output of control animals. Antigen-specific IgG, IgE and IgA responses were detected after the 2nd DTI, and stronger antibody recall responses were elicited by challenge infection. High levels of antigen-specific peripheral blood mononuclear cell (PBMC)/T cell proliferation to whole worm and excretory-secretory (ES) antigens were detected in rDTI-treated animals. These data indicate that partial protective immunity against ostertagiasis, involving cell-mediated and humoral responses, can be attained by rDTI which allowed for maximal antigen exposure from staggered parasitic developmental stages. The data suggest that rDTI can be used as a model to study host-parasite interactions and identify parasite antigens responsible for eliciting host protective immune responses.
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Affiliation(s)
- Wenbin Tuo
- Animal Parasitic Diseases Lab, USDA/ARS, Beltsville, MD 20705, USA.
| | - Dante Zarlenga
- Animal Parasitic Diseases Lab, USDA/ARS, Beltsville, MD 20705, USA
| | - Mariam Bakshi
- Animal Parasitic Diseases Lab, USDA/ARS, Beltsville, MD 20705, USA
| | - Bryan Vinyard
- Statistics Group, Northeast Area Office of the Director, USDA/ARS, Beltsville, MD 20705, USA
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6
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Johnson J, Kasimanickam VR, Kastelic JP, Kasimanickam RK. Reduced gastrointestinal worm burden following long term parasite control improves body condition and fertility in beef cows. Vet Parasitol 2020; 287:109259. [PMID: 33035775 DOI: 10.1016/j.vetpar.2020.109259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 09/26/2020] [Accepted: 09/27/2020] [Indexed: 01/10/2023]
Abstract
The objective of this study was to compare effects of gastrointestinal parasite control over a long vs short term (PC-LT vs. PC-ST) on fecal parasite load, body condition and pregnancy in beef cows. On Day 0, fecal samples were collected from Angus cross cows (n = 1462) and they were assigned a body condition score (BCS: 1, emaciated; 9, Obese) and randomly divided into two groups (within location) to receive extended-release eprinomectin [PC-LT; n = 749; 50 mg/50 kg body weight (BW)] or pour-on ivermectin (PC-ST; n = 713; 25 mg/50 kg BW). All cows were synchronized with CO-Synch + CIDR [100 μg GnRH + progesterone vaginal insert (CIDR) application on Day 20, CIDR removal +25 mg PGF2a on Day 27, and artificial insemination +100 μg GnRH on Day 30 (66 h after CIDR removal)] protocol, artificially inseminated (AI; Day 30) and on Day 44, exposed to breeding bulls (1:40 bull to cow ratio) for the remainder of the 85 day breeding season. On Day 90, a second fecal sample was collected from all cows and the cows were examined to determine pregnancy/AI (P/AI). All cows were assigned a BCS on Day 180 and re-examined to determine pregnancy/breeding season (P/BS). Worm egg count per gram of feces (FEG) was determined by McMaster method. There were no differences (P > 0.1) between PC-LT and PC-ST groups on Day 0 for FEG (46.9 ± 13.1 vs 42.6 ± 15.2, respectively; mean ± SEM) or BCS (5.95 ± 0.12 vs 6.00 ± 0.20). The mean FEG (PC-LT, 12.3 ± 4.7 vs. PC-ST, 131.3 ± 10.9) on Day 90 and BCS (PC-LT, 6.04 ± 0.07 vs. PC-ST, 5.79 ± 0.13) on Day 180 differed (P < 0.05) between the two groups. Mean P/AI [PC-LT, 62.9 %; (471/749) vs PC-ST, 57.4 %; (409/713)] and P/BS [PC-LT, 92.9 % (696/749) vs PC-ST, 90.0 (642/713)] also differed (P < 0.05). Lower FEG at Day 90 resulted in moderate to good body condition at Day 180 and cows with moderate to good body condition at Day 180 had higher P/BS. In conclusion, lower worm burden with long-term parasite control reduced FEG and improved BCS, P/AI and P/BS.
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Affiliation(s)
- Jerimyah Johnson
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
| | - Vanmathy R Kasimanickam
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
| | - John P Kastelic
- Department of Production Animal Health, University of Calgary, Faculty of Veterinary Medicine, Calgary, AB, Canada.
| | - Ramanathan K Kasimanickam
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
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Claerebout E, Geldhof P. Helminth Vaccines in Ruminants: From Development to Application. Vet Clin North Am Food Anim Pract 2020; 36:159-171. [PMID: 32029181 PMCID: PMC7125739 DOI: 10.1016/j.cvfa.2019.10.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Edwin Claerebout
- Faculty of Veterinary Medicine, Laboratory of Parasitology, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium.
| | - Peter Geldhof
- Faculty of Veterinary Medicine, Laboratory of Parasitology, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium
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Navarre CB. Epidemiology and Control of Gastrointestinal Nematodes of Cattle in Southern Climates. Vet Clin North Am Food Anim Pract 2020; 36:45-57. [PMID: 32029188 DOI: 10.1016/j.cvfa.2019.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Control of gastrointestinal nematodes (GIN) can have both economic and health benefits for cattle operations in the southern United States. In the past several decades, GIN control has relied almost exclusively on the use of anthelmintics. With the increase in anthelmintic resistance new strategies must be developed. Anthelmintic use should be minimized by integrating grazing management and a good herd health program into GIN control programs. This takes knowledge of GIN biology and epidemiology in the region (climate and weather) combined with specific information from the ranch.
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Affiliation(s)
- Christine B Navarre
- School of Animal Sciences, Louisiana State University Agricultural Center, Louisiana State University, 111 Dalrymple Building, 110 LSU Union Square, Baton Rouge, LA 70803-0106, USA.
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9
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Characterization of IL-10-producing neutrophils in cattle infected with Ostertagia ostertagi. Sci Rep 2019; 9:20292. [PMID: 31889109 PMCID: PMC6937330 DOI: 10.1038/s41598-019-56824-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 12/17/2019] [Indexed: 02/07/2023] Open
Abstract
IL-10 is a master regulator of immune responses, but its cellular source and function in cattle during the initial phase of immune priming have not been well established. Despite a massive B cell response in the abomasal draining lymph nodes in Ostertagia ostertagi (OO)-infected cattle, protective immunity is slow to develop, and partial protection requires years of repeated exposure. In addressing this problem, our initial hypothesis was that B cells produce IL-10 that downregulates the host protective immune response. However, our results showed that neutrophils made up the majority of IL-10-producing cells in circulation and in secondary lymphoid tissues, particularly the spleen (80%). Conversely, IL-10-producing B cells were rare. In addition, approximately 10% to 20% of the neutrophils in the blood and spleen expressed MHC II and were IL-10 negative, suggesting that neutrophils could also participate in antigen presentation. In vitro investigation of bovine neutrophils revealed that exposure thereof to OO extract increased IL-10 and MHC II expression in these cells in a dose-dependent manner, consistent with IL-10+/MHC II+ neutrophils detected in cattle shortly after experimental OO infection. Co-culture of untreated neutrophils with anti-CD3 antibody (Ab)-stimulated CD4+ T cells led to enhanced T cell activation; also, IL-10 depletion with neutralizing Ab enhanced the stimulatory function of neutrophils. OO extract depressed neutrophil stimulation of CD4+ T cells in the presence of IL-10-neutralizing Ab, suggesting that OO utilizes both IL-10-dependent and independent mechanisms to manipulate the bovine immune response. Finally, contact and viability were required for T cell-stimulatory neutrophil function. This report, to the best of our knowledge, is the first to demonstrate that neutrophil-derived IL-10 is directly involved in T cell regulation in cattle. Our data suggest that neutrophils and neutrophil-derived IL-10 are co-opted by nematode parasites and other pathogens to attenuate host immune responses and facilitate pathogen survival.
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Scott H, Gilleard JS, Jelinski M, Barkema HW, Redman EM, Avramenko RW, Luby C, Kelton DF, Bauman CA, Keefe G, Dubuc J, Uehlinger FD. Prevalence, fecal egg counts, and species identification of gastrointestinal nematodes in replacement dairy heifers in Canada. J Dairy Sci 2019; 102:8251-8263. [PMID: 31326168 DOI: 10.3168/jds.2018-16115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 05/17/2019] [Indexed: 11/19/2022]
Abstract
Information is scarce regarding the epidemiology of gastrointestinal nematodes in Canadian dairy heifers. The objectives of this study were to estimate the prevalence and fecal egg counts of gastrointestinal nematodes in dairy heifers, and using a novel deep-amplicon sequencing approach, to identify the predominant gastrointestinal nematode species in Canadian dairy replacement heifers. Fresh environmental fecal samples (n = 2,369) were collected from replacement heifers on 306 dairy farms across western Canada, Ontario, Québec, and Atlantic Canada. Eggs per gram of feces (EPG) were determined using a modified Wisconsin double-centrifugation sugar flotation technique. Predominant nematode species at the farm level were identified by deep-amplicon nemabiome sequencing of the internal transcribed spacer-2 rDNA locus of nematode third-stage larvae. Generalized estimating equations were used to estimate predicted parasite prevalence and mean EPG in all heifers and by province, allowing for clustering within herds. Individual heifer egg counts ranged from 0 to 141 EPG (median: 0 EPG; interquartile range: 0 to 71 EPG). Gastrointestinal nematodes were detected in 20.9% (95% confidence interval: 17.2 to 24.6%) of heifers, and the predicted mean strongylid EPG accounting for clustering on farms was 1.1 (95% confidence interval: 0.6 to 1.6). The predominant parasite species were Cooperia oncophora and Ostertagia ostertagi. This is the first study in Canada to use a combination of deep-amplicon nemabiome sequencing and a traditional egg count method to describe the epidemiology of gastrointestinal nematodes in dairy heifers.
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Affiliation(s)
- H Scott
- Western College of Veterinary Medicine, Department of Large Animal Clinical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, Canada, S7N 5B4
| | - J S Gilleard
- Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
| | - M Jelinski
- Western College of Veterinary Medicine, Department of Large Animal Clinical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, Canada, S7N 5B4
| | - H W Barkema
- Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
| | - E M Redman
- Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
| | - R W Avramenko
- Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, AB, Canada, T2N 4N1
| | - C Luby
- Western College of Veterinary Medicine, Department of Large Animal Clinical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, Canada, S7N 5B4
| | - D F Kelton
- Ontario Veterinary College, University of Guelph, 28 College Ave. W, Guelph, ON, Canada, N1G 2W1
| | - C A Bauman
- Ontario Veterinary College, University of Guelph, 28 College Ave. W, Guelph, ON, Canada, N1G 2W1
| | - G Keefe
- Atlantic Veterinary College, University of Prince Edward Island, 50 University Ave., Charlottetown, PE, Canada, C1A 4P3
| | - J Dubuc
- Faculté de Médecine Vétérinaire, Université de Montréal, 3200 rue Sicotte, Saint-Hyacinthe, QC, Canada, J2S 2M2
| | - F D Uehlinger
- Western College of Veterinary Medicine, Department of Large Animal Clinical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK, Canada, S7N 5B4.
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11
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Mendez J, Sun D, Tuo W, Xiao Z. Bovine neutrophils form extracellular traps in response to the gastrointestinal parasite Ostertagia ostertagi. Sci Rep 2018; 8:17598. [PMID: 30514873 PMCID: PMC6279769 DOI: 10.1038/s41598-018-36070-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 11/15/2018] [Indexed: 12/15/2022] Open
Abstract
Ostertagia ostertagi (OO) is a widespread parasite that causes chronic infection in cattle and leads to annual losses of billions of dollars in the cattle industry. It remains unclear why cattle are unable to mount an effective immune response despite a large influx of immune cells to the infected abomasal mucosa and draining lymph nodes. Neutrophils, the immune system’s first responders, have the capacity to release neutrophil extracellular traps (NETs) to contain various pathogens, including some parasites. In the present study, the mechanisms by which O. ostertagi influences bovine NET formation were investigated. O. ostertagi larval soluble extract (OO extract) was able to induce typical NETs by purified neutrophils in vitro, confirmed by co-localization of extracellular DNA with typical NET-associated proteins histone and neutrophil elastase (NE). Consistent with existing literature, inhibition assays demonstrated that these OO extract-induced NETs were dependent upon the enzymes NADPH oxidase and myeloperoxidase (MPO). Live OO stage 4 larvae (L4) stimulated neutrophils to form NETs similar to those induced by OO extract. Bovine neutrophils also released NETs in response to Caenorhabditis elegans, a free-living soil nematode, suggesting that bovine NET production may be a conserved mechanism against a broad range of nematodes. This is the first report demonstrating O. ostertagi-induced NET formation by bovine neutrophils, a potentially underappreciated mechanism in the early immune response against nematode infections.
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Affiliation(s)
- Jonatan Mendez
- Department of Avian and Animal Sciences, University of Maryland, College Park, MD, 20742, USA
| | - Donglei Sun
- Department of Veterinary Medicine, University of Maryland, College Park, MD, 20742, USA
| | - Wenbin Tuo
- Animal Parasitic Diseases Laboratory, USDA/ARS, Beltsville, MD, 20705, USA.
| | - Zhengguo Xiao
- Department of Avian and Animal Sciences, University of Maryland, College Park, MD, 20742, USA.
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12
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Immunity to gastrointestinal nematodes in ruminants: effector cell mechanisms and cytokines. J Parasit Dis 2018; 42:471-482. [PMID: 30538343 DOI: 10.1007/s12639-018-1023-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 08/02/2018] [Indexed: 12/18/2022] Open
Abstract
Gastrointestinal nematodes (GINs) of ruminants are prevalent and have major economic impacts worldwide. The insight studies of immune responses triggered against GINs are of great concern to understand interaction between host's immune system and parasite. T-helper 2 cytokines drive the effector cell mechanisms which include eosinophils and mast cells. The immune responses are controlled by Th2 secreted interleukins (IL); IL3, IL-4, IL-5, IL-9, IL-10 and IL-13. B-Cell immune response is incorporated in defense mechanisms developed against GINs specially immunoglobulins (Ig); IgA, IgE and IgG. The immune resistance of the infected host is presented by failure of larval establishment or hypobiosis, low worm burden and decreased female fecundity. The host-parasite interaction is a complex series that affected by host's genetic constitution, nutrition, age and physiological status. The GINs have different immune evasion mechanisms to improve their survival within the host. Also, management of the host influences GINs parasitism. Thus, the aim of this review is to highlight the hallmarks of immune responses that endorse GINs parasitism. The insights studies of the triggered immune responses developed against GINs will improve the appropriate protective immune strategy.
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Bellet C, Green M, Bradley A, Kaler J. Short- and long-term association between individual levels of milk antibody against Ostertagia ostertagi and first-lactation heifer’s production performances. Vet Parasitol 2018; 256:1-8. [DOI: 10.1016/j.vetpar.2018.04.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 04/09/2018] [Accepted: 04/14/2018] [Indexed: 10/17/2022]
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14
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Hu XL, Liu G, Wei YT, Wang YH, Zhang TX, Yang S, Hu DF, Liu SQ. Regional and seasonal effects on the gastrointestinal parasitism of captive forest musk deer. Acta Trop 2018; 177:1-8. [PMID: 28963064 DOI: 10.1016/j.actatropica.2017.09.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 09/07/2017] [Accepted: 09/25/2017] [Indexed: 11/27/2022]
Abstract
Parasite infections can cause adverse effects on health, survival and welfare of forest musk deer. However, few studies have quantified the parasite infection status and evaluated the parasite temporal dynamics and differences between breeding centers for captive forest musk deer. The purpose of this study was to assess seasonal and regional effects on the parasite prevalence, shedding capacity, diversity, aggregation and infracommunity to establish baseline data on captive forest musk deer. The McMaster technique was applied to count parasite eggs or oocysts in 990 fecal samples collected at three breeding centers located in Qinling Mountains and Tibetan Plateau during spring, summer, and winter. Five gastrointestinal parasite groups were found in musk deer, and Eimeria spp. were dominant (mean oocysts per gram=1273.7±256.3). A positive correlation between Eimeria spp. and Strongyloides spp. (r=0.336, p<0.001) based on shedding capacity data was found, as well as a negative correlation between Eimeria spp. and Moniezia spp. (r=-0.375, p=0.003). Both seasonal and regional differences in diversity, prevalence, shedding capacity, aggregation and infracommunity were observed for five parasite groups. The low level of aggregation and high shedding capacity of Eimeria spp. and Strongyloides spp. might reflect the contaminated environment, and indicate that host-parasite relationships are unstable. The high degree of aggregation of Trichuris spp., Ascaris spp., and Moniezia spp. also suggests that some individual hosts had less ability to resist pathogens and greater transmission potential than others. These conclusions suggest that a focus on disease control strategies could improve the health of forest musk deer in captivity.
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Charlier J, Thamsborg SM, Bartley DJ, Skuce PJ, Kenyon F, Geurden T, Hoste H, Williams AR, Sotiraki S, Höglund J, Chartier C, Geldhof P, van Dijk J, Rinaldi L, Morgan ER, von Samson-Himmelstjerna G, Vercruysse J, Claerebout E. Mind the gaps in research on the control of gastrointestinal nematodes of farmed ruminants and pigs. Transbound Emerg Dis 2017; 65 Suppl 1:217-234. [PMID: 29124904 DOI: 10.1111/tbed.12707] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Indexed: 12/31/2022]
Abstract
Gastrointestinal (GI) nematode control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health and welfare. In this synthetic review, we identify key research priorities for GI nematode control in farmed ruminants and pigs, to support the development of roadmaps and strategic research agendas by governments, industry and policymakers. These priorities were derived from the DISCONTOOLS gap analysis for nematodes and follow-up discussions within the recently formed Livestock Helminth Research Alliance (LiHRA). In the face of ongoing spread of anthelmintic resistance (AR), we are increasingly faced with a failure of existing control methods against GI nematodes. Effective vaccines against GI nematodes are generally not available, and anthelmintic treatment will therefore remain a cornerstone for their effective control. At the same time, consumers and producers are increasingly concerned with environmental issues associated with chemical parasite control. To address current challenges in GI nematode control, it is crucial to deepen our insights into diverse aspects of epidemiology, AR, host immune mechanisms and the socio-psychological aspects of nematode control. This will enhance the development, and subsequent uptake, of the new diagnostics, vaccines, pharma-/nutraceuticals, control methods and decision support tools required to respond to the spread of AR and the shifting epidemiology of GI nematodes in response to climatic, land-use and farm husbandry changes. More emphasis needs to be placed on the upfront evaluation of the economic value of these innovations as well as the socio-psychological aspects to prioritize research and facilitate uptake of innovations in practice. Finally, targeted regulatory guidance is needed to create an innovation-supportive environment for industries and to accelerate the access to market of new control tools.
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Affiliation(s)
- J Charlier
- Kreavet, Kruibeke, Belgium.,Avia-GIS, Zoersel, Belgium
| | - S M Thamsborg
- Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg C, Denmark
| | | | - P J Skuce
- Moredun Research Institute, Edinburgh, UK
| | - F Kenyon
- Moredun Research Institute, Edinburgh, UK
| | | | - H Hoste
- UMR IHAP 1225, INRA, ENVT, Université de Toulouse, Toulouse, France
| | - A R Williams
- Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg C, Denmark
| | - S Sotiraki
- VetResInst, HAO-DEMETER, Thessaloniki, Greece
| | - J Höglund
- BVF, Section for Parasitology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | | | - P Geldhof
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - J van Dijk
- Institute of Infection and Global Health, University of Liverpool, Neston, Cheshire, UK
| | - L Rinaldi
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Napoli, Italy
| | - E R Morgan
- Institute for Global Food Security, Queen's University Belfast, Belfast, UK.,School of Veterinary Science, University of Bristol, North Somerset, UK
| | | | - J Vercruysse
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - E Claerebout
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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16
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Tuo W, Li L, Lv Y, Carrillo J, Brown D, Davis WC, Song J, Zarlenga D, Xiao Z. Abomasal mucosal immune responses of cattle with limited or continuous exposure to pasture-borne gastrointestinal nematode parasite infection. Vet Parasitol 2016; 229:118-125. [DOI: 10.1016/j.vetpar.2016.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 09/26/2016] [Accepted: 10/01/2016] [Indexed: 12/29/2022]
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17
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PEÑA-ESPINOZA MIGUEL, THAMSBORG STIGM, DESRUES OLIVIER, HANSEN TINAVA, ENEMARK HEIDIL. Anthelmintic effects of forage chicory (Cichorium intybus) against gastrointestinal nematode parasites in experimentally infected cattle. Parasitology 2016; 143:1279-93. [PMID: 27173405 PMCID: PMC4988272 DOI: 10.1017/s0031182016000706] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 03/23/2016] [Accepted: 03/29/2016] [Indexed: 12/11/2022]
Abstract
Two experiments studied the effects of dietary chicory against gastrointestinal nematodes in cattle. In Experiment (Exp.) 1, stabled calves were fed chicory silage (CHI1; n = 9) or ryegrass/clover hay (CTL1; n = 6) with balanced protein/energy intakes between groups. After 16 days, all calves received 10 000 Ostertagia ostertagi and 66 000 Cooperia oncophora third-stage larvae (L3) [day (D) 0 post-infection (p.i.)]. In Exp. 2, calves were assigned to pure chicory (CHI2; n=10) or ryegrass/clover (CTL2; n = 10) pastures. After 7 days, animals received 20 000 O. ostertagi L3/calf (D0 p.i.) and were moved regularly preventing pasture-borne infections. Due to poor regrowth of the chicory pasture, CHI2 was supplemented with chicory silage. At D40 p.i. (Exp. 1) and D35 p.i. (Exp. 2) calves were slaughtered for worm recovery. In Exp.1, fecal egg counts (FEC) were similar between groups. However, O. ostertagi counts were significantly reduced in CHI1 by 60% (geometric mean; P < 0·01), whereas C. oncophora burdens were unaffected (P = 0·12). In Exp. 2, FEC were markedly lowered in CHI2 from D22 p.i onwards (P < 0·01). Ostertagia ostertagi adult burdens were significantly reduced in CHI2 by 66% (P < 0·001). Sesquiterpene lactones were identified only in chicory (fresh/silage). Chicory shows promise as an anti-Ostertagia feed for cattle and further studies should investigate its on-farm use.
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Affiliation(s)
- MIGUEL PEÑA-ESPINOZA
- Section for Bacteriology, Pathology and
Parasitology, National Veterinary Institute,
Technical University of Denmark, Bülowsvej
27, 1870 Frederiksberg C, Denmark
| | - STIG M. THAMSBORG
- Section for Parasitology and Aquatic
Diseases, Department of Veterinary Disease Biology,
Faculty of Health and Medical Sciences, University of
Copenhagen, Dyrlægevej 100, 1870
Frederiksberg C, Denmark
| | - OLIVIER DESRUES
- Section for Parasitology and Aquatic
Diseases, Department of Veterinary Disease Biology,
Faculty of Health and Medical Sciences, University of
Copenhagen, Dyrlægevej 100, 1870
Frederiksberg C, Denmark
| | - TINA V. A. HANSEN
- Section for Parasitology and Aquatic
Diseases, Department of Veterinary Disease Biology,
Faculty of Health and Medical Sciences, University of
Copenhagen, Dyrlægevej 100, 1870
Frederiksberg C, Denmark
| | - HEIDI L. ENEMARK
- Section for Bacteriology, Pathology and
Parasitology, National Veterinary Institute,
Technical University of Denmark, Bülowsvej
27, 1870 Frederiksberg C, Denmark
- Norwegian Veterinary Institute,
Section for Parasitology, PO Box 750
Sentrum, N-0106, Norway
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18
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Bellet C, Green M, Vickers M, Forbes A, Berry E, Kaler J. Ostertagia spp ., rumen fluke and liver fluke single- and poly-infections in cattle: An abattoir study of prevalence and production impacts in England and Wales. Prev Vet Med 2016; 132:98-106. [DOI: 10.1016/j.prevetmed.2016.08.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 08/24/2016] [Accepted: 08/29/2016] [Indexed: 11/26/2022]
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19
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Splice variants and regulatory networks associated with host resistance to the intestinal worm Cooperia oncophora in cattle. Vet Parasitol 2015; 211:241-50. [PMID: 26025321 DOI: 10.1016/j.vetpar.2015.05.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/27/2015] [Accepted: 05/09/2015] [Indexed: 11/21/2022]
Abstract
To elucidate the molecular mechanism of host resistance, we characterized the jejunal transcriptome of Angus cattle selected for parasite resistance for over 20 years in response to infection caused by the intestinal worm Cooperia oncophora. The transcript abundance of 56 genes, such as that of mucin 12 (MUC12) and intestinal alkaline phosphatase (ALPI), was significantly higher in resistant cattle. Novel splicing variants, exon skipping events, and gene fusion events, were also detected. An algorithm for the reconstruction of accurate cellular networks (ARACNE) was used to infer de novo regulatory molecular networks in the interactome between the parasite and host. Under a combined cutoff of an error tolerance (ϵ = 0.10) and a stringent P-value threshold of mutual information (1.0 × 10(-5)), a total of 229,100 direct interactions controlled by 20,288 hub genes were identified. Among these hub genes, 7651 genes had ≥ 100 direct neighbors while the top 9778 hub genes controlled more than 50% of total direct interactions. Three lysozyme genes (LYZ1, LYZ2, and LYZ3), which are co-located in bovine chromosome 5 in tandem and are strongly upregulated in resistant cattle, shared a common regulatory network of 55 genes. These ancient antimicrobials were likely involved in regulating host-parasite interactions by affecting host gut microbiome. Notably, ALPI, known as a gut mucosal defense factor, controlled a molecular network consisting 410 genes, including 14 transcription factors (TF) and 10 genes that were significantly regulated in resistant cattle. Several large regulatory networks were controlled by TF, such as STAT6, SREBF1, and ELF4. Gene ontology (GO) processes significantly enriched in the regulatory network controlled by STAT6 included lipid metabolism. Our findings provide insights into the immune regulation of host-parasite interactions and the molecular mechanisms of host resistance in cattle.
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20
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Anthelmintic resistance in cattle nematodes in the US. Vet Parasitol 2014; 204:3-11. [DOI: 10.1016/j.vetpar.2014.03.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 03/05/2014] [Accepted: 03/10/2014] [Indexed: 11/20/2022]
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21
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McNeilly TN, Rocchi M, Bartley Y, Brown JK, Frew D, Longhi C, McLean L, McIntyre J, Nisbet AJ, Wattegedera S, Huntley JF, Matthews JB. Suppression of ovine lymphocyte activation by Teladorsagia circumcincta larval excretory-secretory products. Vet Res 2013; 44:70. [PMID: 23964850 PMCID: PMC3848371 DOI: 10.1186/1297-9716-44-70] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 07/29/2013] [Indexed: 11/20/2022] Open
Abstract
Teladorsagia circumcincta is an important pathogenic nematode of sheep. It has been demonstrated previously that stimulation of murine T lymphocytes with excretory-secretory (ES) products derived from fourth stage larvae of T. circumcincta (Tci-L4-ES) results in de novo expression of Foxp3, a transcription factor intimately involved in regulatory T cell function. In the current study, Foxp3+ T cell responses in the abomasum and the effects of Tci-L4-ES on ovine peripheral blood mononuclear cells (PBMC) following T. circumcincta infection were investigated. T. circumcincta infection resulted in a significant increase in numbers of abomasal Foxp3+ T cells, but not an increase in the proportion of T cells expressing Foxp3. Unlike in mice, Tci-L4-ES was incapable of inducing T cell Foxp3 expression but instead suppressed mitogen-induced and antigen-specific activation and proliferation of ovine PBMC in vitro. This effect was heat labile, suggesting that it is mediated by protein(s). Suppression was associated with up-regulation of interleukin-10 (IL-10) mRNA, and specific monoclonal antibody neutralisation of IL-10 resulted in a 50% reduction in suppression, indicating involvement of the IL-10 signaling pathway. Suppression was significantly reduced in PBMC isolated from T. circumcincta infected vs. helminth-naïve lambs, and this reduction in suppression was associated with an increase in Tci-L4-ES antigen-specific T cells within the PBMC. In conclusion, we have identified a mechanism by which T. circumcincta may modulate the host adaptive immune response, potentially assisting survival of the parasite within the host. However, the impact of Tci-L4-ES-mediated lymphocyte suppression during T. circumcincta infection remains to be determined.
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Affiliation(s)
- Tom N McNeilly
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik EH26 0PZ, UK.
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22
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Current drug targets for helminthic diseases. Parasitol Res 2013; 112:1819-31. [PMID: 23529336 DOI: 10.1007/s00436-013-3383-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/05/2013] [Indexed: 01/08/2023]
Abstract
More than 2 billion people are infected with helminth parasites across the globe. The burgeoning drug resistance against current anthelmintics in parasitic worms of humans and livestock requires urgent attention to tackle these recalcitrant worms. This review focuses on the advancements made in the area of helminth drug target discovery especially from the last few couple of decades. It highlights various approaches made in this field and enlists the potential drug targets currently being pursued to target economically important helminth species both from human as well as livestock to combat disease pathology of schistosomiasis, onchocerciasis, lymphatic filariasis, and other important macroparasitic diseases. Research in the helminths study is trending to identify potential and druggable targets through genomic, proteomic, biochemical, biophysical, in vitro experiments, and in vivo experiments in animal models. The availability of major helminths genome sequences and the subsequent availability of genome-scale functional datasets through in silico search and prioritization are expected to guide the experimental work necessary for target-based drug discovery. Organized and documented list of drug targets from various helminths of economic importance have been systematically covered in this review for further exploring their use and applications, which can give physicians and veterinarians effective drugs in hand to enable them control worm infections.
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23
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Areskog M, von Samson-Himmelstjerna G, Alvinerie M, Sutra JF, Höglund J. Dexamethasone treatment interferes with the pharmacokinetics of ivermectin in young cattle. Vet Parasitol 2012; 190:482-8. [PMID: 22959189 DOI: 10.1016/j.vetpar.2012.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 07/06/2012] [Accepted: 07/12/2012] [Indexed: 12/29/2022]
Abstract
An experiment was carried out to study the possible interaction between dexamethasone (DXM) treatment and the efficacy of ivermectin (IVM) treatment in young cattle. Two groups, each of seven calves, were experimentally inoculated with an equal mixture containing 15,000 third stage larvae of Cooperia oncophora and Ostertagia ostertagi each, and with no history of being resistant to any anthelmintics. However, in this study C. oncophora was unexpectedly classified as IVM-resistant according to the outcome from the faecal egg count reduction test (FECRT). Blood parameters and faecal egg counts (FEC) were monitored from 0 to 35 days post infection (d.p.i.). The calves in one group received intramuscular injections of short and long-term acting DXM at 22 and 24 d.p.i., respectively. The other group remained as a control. Three days post patency (24 d.p.i.) both groups were injected subcutaneously with IVM (Merial) at the recommended dose (0.2mg/kg). A significant difference (p<0.001) in FEC patterns was observed between groups. Although both groups still excreted eggs (100-200 eggs per gram faeces) 11 days post anthelmintic treatment, the control group had a significantly higher reduction between 23 and 35 d.p.i. (p=0.025). After 35 days, four animals per group were euthanized, and worms in the gastrointestinal tract were counted. No O. ostertagi were found in the abomasums, but low to high numbers (800-6200) of C. oncophora remained in the small intestines in both groups. Overall, these findings indicated that there was an interaction between the efficacy of IVM and DXM treatment. As significantly lower plasma levels of IVM were observed in the DXM group, we conclude that the impaired efficacy of ivermectin was most likely due to the altered pharmacokinetics.
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Affiliation(s)
- Marlene Areskog
- Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, SE-751 89 Uppsala, Sweden.
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24
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Li RW, Choudhary RK, Capuco AV, Urban JF. Exploring the host transcriptome for mechanisms underlying protective immunity and resistance to nematode infections in ruminants. Vet Parasitol 2012; 190:1-11. [PMID: 22819588 DOI: 10.1016/j.vetpar.2012.06.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 06/08/2012] [Accepted: 06/15/2012] [Indexed: 12/11/2022]
Abstract
Nematode infections in ruminants are a major impediment to the profitable production of meat and dairy products, especially for small farms. Gastrointestinal parasitism not only negatively impacts weight gain and milk yield, but is also a major cause of mortality in small ruminants. The current parasite control strategy involves heavy use of anthelmintics that has resulted in the emergence of drug-resistant parasite strains. This, in addition to increasing consumer demand for animal products that are free of drug residues has stimulated development of alternative strategies, including selective breeding of parasite resistant ruminants. The development of protective immunity and manifestations of resistance to nematode infections relies upon the precise expression of the host genome that is often confounded by mechanisms simultaneously required to control multiple nematode species as well as ecto- and protozoan parasites, and microbial and viral pathogens. Understanding the molecular mechanisms underlying these processes represents a key step toward development of effective new parasite control strategies. Recent progress in characterizing the transcriptome of both hosts and parasites, utilizing high-throughput microarrays and RNA-seq technology, has led to the recognition of unique interactions and the identification of genes and biological pathways involved in the response to parasitism. Innovative use of the knowledge gained by these technologies should provide a basis for enhancing innate immunity while limiting the polarization of acquired immunity can negatively affect optimal responses to co-infection. Strategies for parasite control that use diet and vaccine/adjuvant combination could be evaluated by monitoring the host transcriptome for induction of appropriate mechanisms for imparting parasite resistance. Knowledge of different mechanisms of host immunity and the critical regulation of parasite development, physiology, and virulence can also selectively identify targets for parasite control. Comparative transcriptome analysis, in concert with genome-wide association (GWS) studies to identify quantitative trait loci (QTLs) affecting host resistance, represents a promising molecular technology to evaluate integrated control strategies that involve breed and environmental factors that contribute to parasite resistance and improved performance. Tailoring these factors to control parasitism without severely affecting production qualities, management efficiencies, and responses to pathogenic co-infection will remain a challenge. This review summarizes recent progress and limitations of understanding regulatory genetic networks and biological pathways that affect host resistance and susceptibility to nematode infection in ruminants.
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Affiliation(s)
- Robert W Li
- USDA-ARS, Bovine Functional Genomics Laboratory, Beltsville, MD, USA.
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25
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RINALDI M, GELDHOF P. Immunologically based control strategies for ostertagiosis in cattle: where do we stand? Parasite Immunol 2012; 34:254-64. [DOI: 10.1111/j.1365-3024.2011.01313.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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26
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Li RW, Rinaldi M, Capuco AV. Characterization of the abomasal transcriptome for mechanisms of resistance to gastrointestinal nematodes in cattle. Vet Res 2011; 42:114. [PMID: 22129081 PMCID: PMC3260172 DOI: 10.1186/1297-9716-42-114] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 11/30/2011] [Indexed: 11/10/2022] Open
Abstract
The response of the abomasal transcriptome to gastrointestinal parasites was evaluated in parasite-susceptible and parasite-resistant Angus cattle using RNA-seq at a depth of 23.7 million sequences per sample. These cattle displayed distinctly separate resistance phenotypes as assessed by fecal egg counts. Approximately 65.3% of the 23,632 bovine genes were expressed in the fundic abomasum. Of these, 13,758 genes were expressed in all samples tested and likely represent core components of the bovine abomasal transcriptome. The gene (BT14427) with the most abundant transcript, accounting for 10.4% of sequences in the transcriptome, is located on chromosome 29 and has unknown functions. Additionally, PIGR (1.6%), Complement C3 (0.7%), and Immunoglobulin J chain (0.5%) were among the most abundant transcripts in the transcriptome. Among the 203 genes impacted, 64 were significantly over-expressed in resistant animals at a stringent cutoff (FDR < 5%). Among the 94 224 splice junctions identified, 133 were uniquely present: 90 were observed only in resistant animals, and 43 were present only in susceptible animals. Gene Ontology (GO) enrichment of the genes under study uncovered an association with lipid metabolism, which was confirmed by an independent pathway analysis. Several pathways, such as FXR/RXR activation, LXR/RXR activation, LPS/IL-1 mediated inhibition of RXR function, and arachidonic acid metabolism, were impacted in resistant animals, which are potentially involved in the development of parasite resistance in cattle. Our results provide insights into the development of host immunity to gastrointestinal nematode infection and will facilitate understanding of mechanism underlying host resistance.
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Affiliation(s)
- Robert W Li
- Bovine Functional Genomics Laboratory, Animal and Natural Resources Institute, USDA-ARS, Beltsville, MD 20705, USA.
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27
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Shakya K, Miller J, Lomax L, Burnett D. Evaluation of immune response to artificial infections of Haemonchus contortus in Gulf Coast Native compared with Suffolk lambs. Vet Parasitol 2011; 181:239-47. [DOI: 10.1016/j.vetpar.2011.03.051] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 03/04/2011] [Accepted: 03/29/2011] [Indexed: 11/29/2022]
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28
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Rinaldi M, Dreesen L, Hoorens PR, Li RW, Claerebout E, Goddeeris B, Vercruysse J, Van Den Broek W, Geldhof P. Infection with the gastrointestinal nematode Ostertagia ostertagi in cattle affects mucus biosynthesis in the abomasum. Vet Res 2011; 42:61. [PMID: 21569362 PMCID: PMC3102617 DOI: 10.1186/1297-9716-42-61] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 05/11/2011] [Indexed: 12/22/2022] Open
Abstract
The mucus layer in the gastrointestinal (GI) tract is considered to be the first line of defense to the external environment. Alteration in mucus components has been reported to occur during intestinal nematode infection in ruminants, but the role of mucus in response to abomasal parasites remains largely unclear. The aim of the current study was to analyze the effects of an Ostertagia ostertagi infection on the abomasal mucus biosynthesis in cattle. Increased gene expression of MUC1, MUC6 and MUC20 was observed, while MUC5AC did not change during infection. Qualitative changes of mucins, related to sugar composition, were also observed. AB-PAS and HID-AB stainings highlighted a decrease in neutral and an increase in acidic mucins, throughout the infection. Several genes involved in mucin core structure synthesis, branching and oligomerization, such as GCNT3, GCNT4, A4GNT and protein disulphide isomerases were found to be upregulated. Increase in mucin fucosylation was observed using the lectin UEA-I and through the evaluation of fucosyltransferases gene expression levels. Finally, transcription levels of 2 trefoil factors, TFF1 and TFF3, which are co-expressed with mucins in the GI tract, were also found to be significantly upregulated in infected animals. Although the alterations in mucus biosynthesis started early during infection, the biggest effects were found when adult worms were present on the surface of the abomasal mucosa and are likely caused by the alterations in mucosal cell populations, characterized by hyperplasia of mucus secreting cells.
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Affiliation(s)
- Manuela Rinaldi
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Leentje Dreesen
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Prisca R Hoorens
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Robert W Li
- Bovine Functional Genomics Laboratory, Animal and Natural Resources Institute, USDA-ARS, 10300 Baltimore Avenue, Beltsville, MD 20705, USA
| | - Edwin Claerebout
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Bruno Goddeeris
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
- Department of Biosystems, Faculty of Bioscience Engineering, K.U. Leuven, Kasteelpark Arenberg 30, 3001 Leuven, Belgium
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Wim Van Den Broek
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Peter Geldhof
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
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Ibelli A, Nakata L, Andréo R, Coutinho L, Oliveira M, Amarante A, Furlong J, Zaros L, Regitano L. mRNA profile of Nellore calves after primary infection with Haemonchus placei. Vet Parasitol 2011; 176:195-200. [DOI: 10.1016/j.vetpar.2010.11.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 11/10/2010] [Accepted: 11/10/2010] [Indexed: 10/18/2022]
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Knight JS, Baird DB, Hein WR, Pernthaner A. The gastrointestinal nematode Trichostrongylus colubriformis down-regulates immune gene expression in migratory cells in afferent lymph. BMC Immunol 2010; 11:51. [PMID: 20950493 PMCID: PMC2970587 DOI: 10.1186/1471-2172-11-51] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 10/17/2010] [Indexed: 01/03/2023] Open
Abstract
Background Gastrointestinal nematode (GIN) infections are the predominant cause of economic losses in sheep. Infections are controlled almost exclusively by the use of anthelmintics which has lead to the selection of drug resistant nematode strains. An alternative control approach would be the induction of protective immunity to these parasites. This study exploits an ovine microarray biased towards immune genes, an artificially induced immunity model and the use of pseudo-afferent lymphatic cannulation to sample immune cells draining from the intestine, to investigate possible mechanisms involved in the development of immunity. Results During the development of immunity to, and a subsequent challenge infection with Trichostrongylus colubriformis, the transcript levels of 2603 genes of cells trafficking in afferent intestinal lymph were significantly modulated (P < 0.05). Of these, 188 genes were modulated more than 1.3-fold and involved in immune function. Overall, there was a clear trend for down-regulation of many genes involved in immune functions including antigen presentation, caveolar-mediated endocytosis and protein ubiquitination. The transcript levels of TNF receptor associated factor 5 (TRAF5), hemopexin (HPX), cysteine dioxygenase (CDO1), the major histocompatability complex Class II protein (HLA-DMA), interleukin-18 binding protein (IL-18BP), ephrin A1 (EFNA1) and selenoprotein S (SELS) were modulated to the greatest degree. Conclusions This report describes gene expression profiles of afferent lymph cells in sheep developing immunity to nematode infection. Results presented show a global down-regulation of the expression of immune genes which may be reflective of the natural temporal response to nematode infections in livestock.
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Affiliation(s)
- Jacqueline S Knight
- AgResearch Ltd., Hopkirk Research Institute, Grasslands Research Centre, Palmerston North 4442, New Zealand.
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31
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Li RW, Hou Y, Li C, Gasbarre LC. Localized complement activation in the development of protective immunity against Ostertagia ostertagi infections in cattle. Vet Parasitol 2010; 174:247-56. [PMID: 20884121 DOI: 10.1016/j.vetpar.2010.08.037] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 07/27/2010] [Accepted: 08/24/2010] [Indexed: 12/18/2022]
Abstract
The abomasal nematode Ostertagia ostertagi is a major causal agent contributing to production inefficiencies in the cattle industry in temperate regions of the world. Protective immunity to infections develops very slowly and resistance to reinfection manifests only after prolonged exposure. Mechanisms underlying the development of protective immunity remain largely unexplored. Immune animals, which have significantly reduced worm burdens, were developed after multiple drug-attenuated experimental infections and were compared to a primary infected group and their respective uninfected controls. In this study, transcriptomic analysis identified three signaling pathways significantly impacted during both primary and repeat infections, the complement system, leukocyte extravasation and acute phase responses. Increased mRNA levels of complement components C3, factor B (CFB) and factor I (CFI) in the abomasal mucosa of the infected cattle were confirmed using quantitative PCR while Western blot analysis established the presence of elevated levels of activated C3 proteins in the mucosa. One of the initiators of local complement activation could be related to secretory IgA and IgM because infections significantly up-regulated expression of J chain (IGJ), as well as polymeric Ig receptor (PIGR) and an IgM-specific receptor (FAIM3), suggesting sustained increases in both synthesis and transepithelial transport of IgA and IgM during the infection. The elevated levels of pro-inflammatory cytokines, such as IL-4 and IL-1β, during infection may be involved in gene regulation of complement components. Our results suggest enhanced tissue repair and mucin secretion in immune animals may also contribute to protective immunity. These results are the first evidence that local complement activation may be involved in the development of long-term protective immunity and provide a novel mechanistic insight into resistance against O. ostertagi in cattle.
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Affiliation(s)
- Robert W Li
- Bovine Functional Genomics Laboratory, Animal and Natural Resources Institute, United States Department of Agriculture, Beltsville, MD 20705, USA.
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32
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Gasbarre LC, Smith LL, Hoberg E, Pilitt PA. Further characterization of a cattle nematode population with demonstrated resistance to current anthelmintics. Vet Parasitol 2009; 166:275-80. [DOI: 10.1016/j.vetpar.2009.08.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 08/13/2009] [Accepted: 08/15/2009] [Indexed: 10/20/2022]
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33
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Demographic crash associated with high parasite load in an experimental roe deer (Capreolus capreolus) population. EUR J WILDLIFE RES 2009. [DOI: 10.1007/s10344-009-0298-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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34
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Araujo RN, Padilha T, Zarlenga D, Sonstegard T, Connor EE, Van Tassel C, Lima WS, Nascimento E, Gasbarre LC. Use of a candidate gene array to delineate gene expression patterns in cattle selected for resistance or susceptibility to intestinal nematodes. Vet Parasitol 2008; 162:106-15. [PMID: 19375862 DOI: 10.1016/j.vetpar.2008.12.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 12/12/2008] [Accepted: 12/15/2008] [Indexed: 12/12/2022]
Abstract
In the present study, we use microarray technology to investigate the expression patterns of 381 genes with known association to host immune responses. Hybridization targets were derived from previously characterized bovine cDNAs. A total of 576 reporters (473 sequence-validated cDNAs and 77 controls) were spotted onto glass slides in two sets of four replicates. Two color, comparative hybridizations across both mesenteric lymph node (MLN) and small intestine mucosa (SIM) RNA samples were done between animals with previously demonstrated phenotypic differences based on natural exposure to gastrointestinal (GI) nematodes over a 6-month exposure period. A total of 138 significant hybridization differences were detected by mixed model analysis of variance. A subset of these significant differences was validated by quantitative, real-time RT-PCR to assay transcript levels for 18 genes. These results confirmed that in the SIM, susceptible animals showed significantly higher levels in the genes encoding IGHG1, CD3E, ACTB, IRF1, CCL5 and C3, while in the MLN of resistant animals, higher levels of expression were confirmed for PTPRC, CD1D and ITGA4. Combined, the results indicate that immune responses against GI nematode infections involve multiple response pathways. Higher levels of expression for IgE receptor, integrins, complement, monocyte/macrophage and tissue factors are related to resistance. In contrast, higher levels of expression for immunoglobulin chains and TCRs are related to susceptibility. Identification of these genes provides a framework to better understand the genetic variation underlying parasite resistance.
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Affiliation(s)
- Ricardo N Araujo
- USDA, ARS, Bovine Functional Genomics Laboratory, Beltsville, MD, USA
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35
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Li RW, Sonstegard TS, Van Tassell CP, Gasbarre LC. Local inflammation as a possible mechanism of resistance to gastrointestinal nematodes in Angus heifers. Vet Parasitol 2007; 145:100-7. [PMID: 17182188 DOI: 10.1016/j.vetpar.2006.11.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Revised: 11/17/2006] [Accepted: 11/21/2006] [Indexed: 12/31/2022]
Abstract
Understanding mechanisms of resistance to gastrointestinal nematodes is important in developing effective and sustainable control programs. A resource population of Angus cattle consisting of approximately 600 animals with complete pedigree records has been developed. The majority of these animals were completely characterized for their resistance to natural challenge by gastrointestinal nematodes. As the first step towards understanding the molecular basis of disease resistance, we investigated expression profiles of 17 cytokines, cytokine receptors, and chemokines using real-time RT-PCR in animals demonstrating resistance or susceptibility to pasture challenge. The animals exposed to natural infection for approximately 6 months were treated to remove existing parasites and then experimentally challenged with both Ostertagia ostertagi and Cooperia oncophora. The mRNA expression profiles of these genes in abomasal and mesenteric lymph nodes (ALN, MLN), fundic and pyloric abomasa (FA, PA), and small intestine (SI) were compared between resistant and susceptible animals. Resistant heifers exhibited elevated expression of inflammatory cytokines such as TNFalpha, IL-1beta, and MIP-1alpha in fundic and pyloric abomasa 7 days post infection. Expression levels of IL-10, polymeric immunoglobullin receptor gene (PIGR), and WSX-1 were also 2.7-19.9-folds higher in resistant than susceptible heifers in these tissues. No difference in expression of CXCL6, CXCL10, IFN-gamma, IL-2, IL-4, IL-6, IL-8, IL-12 p40, IL-13, IL-15 and IL-18 was observed between the two groups. The expression of MIP-1alpha, IL-6, and IL-10 was also elevated in small intestines in resistant animals. In contrast, little difference in expression of these genes was detected between resistant and susceptible groups in the draining lymph nodes. These data indicate that resistant animals can better maintain inflammatory responses at the site of infection, suggesting a possible novel mechanism of resistance.
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Affiliation(s)
- Robert W Li
- Bovine Functional Genomics Laboratory, USDA-ARS, Beltsville, MD 20705, USA.
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36
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Infectious and Parasitic Diseases of the Alimentary Tract. JUBB, KENNEDY & PALMER'S PATHOLOGY OF DOMESTIC ANIMALS 2007. [PMCID: PMC7155580 DOI: 10.1016/b978-070202823-6.50096-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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37
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Stromberg BE, Gasbarre LC. Gastrointestinal Nematode Control Programs with an Emphasis on Cattle. Vet Clin North Am Food Anim Pract 2006; 22:543-65. [PMID: 17071352 DOI: 10.1016/j.cvfa.2006.08.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Control strategies for nematode parasites rely on knowledge of the relationships between the parasites and their hosts. Specifically, these programs are based on identifying crucial points of interaction in the environment provided by the host, including genetics and the immune response, and critical periods in the physical environment in which the eggs and larval stages must develop. When these targets are identified and the interactions understood, cost-effective sustainable programs can be developed using currently available antiparasitic compounds. Resistance to the major classes of anthelmintic compounds requires consideration of new approaches, such as immunity or genetics of the host. Additionally, the efficacy of these compounds can be expanded with combined or concomitant use. Increased study of the use of novel approaches, including fungi, elements such as copper, and plant products, has also occurred. This article explores each of these areas to allow readers to appreciate how various approaches may be developed and incorporated into an effective parasite control program.
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Affiliation(s)
- Bert E Stromberg
- Veterinary and Biomedical Sciences Department, College of Veterinary Medicine, University of Minnesota, 1971 Commonwealth Avenue, St. Paul, MN 55108, USA.
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38
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Hagberg M, Wattrang E, Niskanen R, Tråvén M, Höglund J, Lundén A. Mononuclear cell subsets in bronchoalveolar lavage fluid during Dictyocaulus viviparus infection of calves: a potential role for gamma/delta TCR-expressing cells in airway immune responses? Parasite Immunol 2005; 27:151-61. [PMID: 15987338 DOI: 10.1111/j.1365-3024.2005.00757.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mononuclear cell populations in the lungs of calves infected with Dictyocaulus viviparus were studied during primary infection and reinfection in order to identify cells involved in development of protective immunity to parasitic bronchitis. Three groups of calves were either inoculated with 500 third-stage larvae at both weeks 0 and 10 (n = 6), inoculated only at week 10 (n = 6), or remained uninfected (n = 3). The animals were monitored weekly by collection of bronchoalveolar lavage fluid (BALF), blood and faeces. Among mononuclear BALF-cell populations, the gamma/delta TCR-expressing cells showed a pronounced transient increase in proportion as well as in relative cell size 2 weeks post primary infection, whereas CD4-, CD8-, Ig- and CD14-expressing cells showed no significant differences related to the infection. The increase in gamma/delta TCR-expressing cells coincided with significantly increased proportions of eosinophils and recovery of adult worms in BALF. After reinfection, gamma/delta TCR-expressing cells increased again, but not until week 3 post inoculation, whereas eosinophils were increased by week 2 and reached higher levels than after primary infection. After reinfection, establishment of D. viviparus was less successful than after primary infection. In conclusion, these results indicate a role for gamma/delta TCR-expressing lymphocytes in the pathogenesis of D. viviparus infection.
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Affiliation(s)
- M Hagberg
- Department of Parasitology (SWEPAR), National Veterinary Institute and Swedish University of Agricultural Sciences, Uppsala, Sweden.
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39
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Pernthaner A, Cole SA, Morrison L, Hein WR. Increased expression of interleukin-5 (IL-5), IL-13, and tumor necrosis factor alpha genes in intestinal lymph cells of sheep selected for enhanced resistance to nematodes during infection with Trichostrongylus colubriformis. Infect Immun 2005; 73:2175-83. [PMID: 15784560 PMCID: PMC1087415 DOI: 10.1128/iai.73.4.2175-2183.2005] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cytokine gene expression in cells migrating in afferent and efferent intestinal lymph was monitored for extended time periods in individual sheep experimentally infected with the nematode Trichostrongylus colubriformis. Animals from stable selection lines with increased levels of either genetic resistance (R) or susceptibility (S) to nematode infection were used. Genes for interleukin-5 (IL-5), IL-13, and tumor necrosis factor alpha (TNF-alpha), but not for IL-4, IL-10, or gamma interferon (IFN-gamma), were consistently expressed at higher levels in both afferent and efferent lymph cells of R sheep than in S sheep. However, only minor differences were observed in the surface phenotypes and antigenic and mitogenic responsiveness of cells in intestinal lymph between animals from the two selection lines. The IL-4 and IL-10 genes were expressed at higher levels in afferent lymph cells than in efferent lymph cells throughout the course of the nematode infection in animals of both genotypes, while the proinflammatory TNF-alpha gene was relatively highly expressed in both lymph types. These relationships notwithstanding, expression of the IL-10 and TNF-alpha genes declined significantly in afferent lymph cells but not in efferent lymph cells during infection. Collectively, the results showed that R-line sheep developed a strong polarization toward a Th2-type cytokine profile in immune cells migrating in lymph from sites where the immune response to nematodes was initiated, although the IFN-gamma gene was also expressed at moderate levels. Genes or alleles that predispose an animal to develop this type of response appear to have segregated with the R selection line and may contribute to the increased resistance of these animals.
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Affiliation(s)
- Anton Pernthaner
- AgResearch Limited, Wallaceville Animal Research Center, P.O. Box 40063, Ward St., Upper Hutt, New Zealand.
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40
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Caro MR, Buendía AJ, Ortega N, Gallego MC, Martínez CM, Cuello F, Ruiz-Ybañez MR, Erb KJ, Salinas J. Influence of the Th2 immune response established by Nippostrongylus brasiliensis infection on the protection offered by different vaccines against Chlamydophila abortus infection. Vet Res Commun 2005; 29 Suppl 1:51-9. [PMID: 15943065 DOI: 10.1007/s11259-005-0836-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Chlamydophila abortus is the aetiological agent of enzootic abortion in small ruminants in which it infects the placenta to cause abortion during the last trimester of gestation. In a mouse model, a Th1 immune response involving IFN-gamma production and CD8+ T cells is necessary for the infection to be resolved. The authors previously demonstrated that infection with Nippostrongylus brasiliensis, a rodent gastrointestinal nematode extensively used in experimental models to induce Th2 responses, alters the specific immune response against C. abortus infection, increasing bacterial multiplication in liver and reducing specific IFN-gamma production. The aim of the present work was to clarify whether a Th2 immune response has any influence on the success of vaccination using both inactivated and attenuated vaccines. The results showed that the Th2 response established prior to vaccination did not influence the induction of protection offered by the vaccines. However, the effectiveness of this protective response can be altered, depending on the adjuvant employed in the inactivated vaccines, when the Th2 response is established after vaccination, just before challenge with C. abortus.
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Affiliation(s)
- M R Caro
- Department of Animal Health, Veterinary School of University of Murcia, Spain
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41
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Gómez-Muñoz MT, Canals-Caballero A, Almeria S, Pasquali P, Zarlenga DS, Gasbarre LC. Inhibition of bovine T lymphocyte responses by extracts of the stomach worm Ostertagia ostertagi. Vet Parasitol 2004; 120:199-214. [PMID: 15041095 DOI: 10.1016/j.vetpar.2004.01.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2003] [Accepted: 01/14/2004] [Indexed: 11/17/2022]
Abstract
Lowered immune responses during bovine ostertagiosis have been reported in both in vivo and in vitro assay systems. In the present study we have employed three different life cycle stages of the nematode Ostertagia ostertagi to determine if products of this economically important parasite inhibit in vitro proliferation of Con A-stimulated cells from uninfected animals. We have demonstrated an inhibitory effect upon the growth of Con A-stimulated lymphocytes after addition of fourth stage larval (L4) soluble extract (L4SE) to the cultures. In contrast, extracts from the third stage larvae (L3) had little or no inhibitory activity. The suppressive products were also shown to be secreted by the late L4. The suppressive activity is reversible if the L4 products are removed from culture. There is no immediate effect on proliferating cells and the L4SE must be in culture for 24-48 h before suppression is observable. The L4SE caused slight but not statistically significant decreases in the percentage of T cells and increases in B cell percentages in cultures when compared with cultures stimulated with Con A alone. No changes were seen in percentage of cells positive for markers for CD4, CD8, gammadelta T cells, or monocytes/macrophages as a consequence of the addition of L4SE. In contrast, there was a strong and significant reduction in the expression of the IL-2 receptors in cells cultured in the presence of the worm extract. There was no evidence of either necrosis or apoptosis resulting from the presence of L4 products in culture. The expression of messenger RNA for interleukin-2, -4, -13, tumor necrosis factor-alpha (TNF-alpha), and gamma-interferon (gamma-IFN) was decreased when L4SE was included in cultures of Con A-stimulated cells compared to cultures stimulated with Con A only. In contrast, messenger RNA expression of transforming growth factor-beta (TGF-beta) and interleukin-10 (IL-10) was increased in cells growing in the presence of L4 products. The potential role of these cytokines during ostertagiosis is discussed.
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Affiliation(s)
- M T Gómez-Muñoz
- Departamento de Atención Sanitaria, Salud Pública y Sanidad Animal, Facultad de Ciencias Experimentales y de la Salud, Universidad Cardenal Herrera-CEU, Valencia, Spain.
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42
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Vercauteren I, Geldhof P, Vercruysse J, Peelaers I, van den Broeck W, Gevaert K, Claerebout E. Vaccination with an Ostertagia ostertagi polyprotein allergen protects calves against homologous challenge infection. Infect Immun 2004; 72:2995-3001. [PMID: 15102812 PMCID: PMC387912 DOI: 10.1128/iai.72.5.2995-3001.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
As an alternative to antihelminthic drugs, we are exploiting vaccination to control infections with the abomasal nematode Ostertagia ostertagi in cattle. Our focus for vaccine targets is excretory-secretory (ES) products of this parasite. One of the most abundant antigens in larval and adult Ostertagia ES products is a protein homologous to nematode polyprotein allergens. We found that the Ostertagia polyprotein allergen (OPA) is encoded by a single-copy gene. OPA comprises three or more repeated units, and only the 15-kDa subunits are found in ES products. The native antigen is localized in the intestinal cells of third-stage larvae and in the hypodermis and cuticle of fourth-stage larvae and adult parasites. Vaccination of cattle with native OPA (nOPA) in combination with QuilA resulted in protection against Ostertagia challenge infections. The geometric mean cumulative fecal egg counts in the nOPA-vaccinated animals were reduced by 60% compared to the counts in the control group during the 2-month course of the experiment. Both male and female adult worms in nOPA-vaccinated animals were significantly shorter than the worms in the control animals. In the abomasal mucus of vaccinated animals the nOPA-specific immunoglobulin G1 (IgG1) and IgG2 levels were significantly elevated compared to the levels in the control animals. Reductions in the Ostertagia egg output and the length of the adult parasites were significantly correlated with IgG1 levels. IgG2 titers were only negatively associated with adult worm length. Protected animals showed no accumulation of effector cells (mast cells, globular leukocytes, and eosinophils) in the mucosa. In contrast to the native antigen, recombinant OPA expressed in Escherichia coli did not stimulate any protection.
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Affiliation(s)
- Isabel Vercauteren
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Ghent, Belgium.
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43
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Claerebout E, Knox DP, Vercruysse J. Current research and future prospects in the development of vaccines against gastrointestinal nematodes in cattle. Expert Rev Vaccines 2003; 2:147-57. [PMID: 12901605 DOI: 10.1586/14760584.2.1.147] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Vaccination is being considered as the most feasible alternative for anthelmintic drugs to control gastrointestinal nematode infections in cattle. However, despite the identification of several candidate protective antigens, no vaccines against gastrointestinal nematode parasites are currently available. The main problems that hamper the development of nematode vaccines in ruminants are that vaccination with recombinant nematode proteins produced in bacterial or eukaryotic expression systems did not induce a protective immune response and no suitable antigen delivery system is available for presentation of protective worm antigens to the bovine mucosal immune system. The present review will focus on recent advances and remaining obstacles in vaccine development against gastrointestinal nematodes in cattle, in particular against the abomasal parasite Ostertagia ostertagi.
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Affiliation(s)
- Edwin Claerebout
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
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44
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Buendía A, Fallon PG, Del Rio L, Ortega N, Caro MR, Gallego MC, Salinas J. Previous infection with the nematode Nippostrongylus brasiliensis alters the immune specific response against Chlamydophila abortus infection. Microb Pathog 2002; 33:7-15. [PMID: 12127795 DOI: 10.1006/mpat.2002.0507] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An experimental mouse model to analyze the interaction between the immune responses elicited following infection with Nippostrongylus brasiliensis and Chlamydophila abortus has been established. Mice infected with C. abortus 7 days after N. brasiliensis showed an increased bacterial multiplication in spleen and liver compared to bacteria-alone infected mice. However the morbidity of these mice, expressed as weight loss, was significantly lower. Analysis of the immune responses elicited showed that spleen from co-infected mice had reduced IFN-gamma production in response to C. abortus antigen. The bias towards a type 2 response in co-infected mice was confirmed by an increase in the production of IL-4 and in the lower ratio IgG2a/IgG1. In pregnant mice co-infection caused a delay in the time of abortion and an increased systemic susceptibility to C. abortus infection.
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Affiliation(s)
- Antonio Buendía
- Departamento de Histología y Anatomía Patológica, Universidad de Murcia, Campus de Espinardo, 30100, Murcia, Spain
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Kooyman FNJ, Yatsuda AP, Ploeger HW, Eysker M. Serum immunoglobulin E response in calves infected with the lungworm Dictyocaulus viviparus and its correlation with protection. Parasite Immunol 2002; 24:47-56. [PMID: 11856446 DOI: 10.1046/j.0141-9838.2001.00436.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Protection of a primary Dictyocaulus viviparus infection was measured against a homologueous challenge infection in two independent experiments and this was correlated with serum immunoglobulin IgE responses. A primary infection of 30 third stage larvae (L3) of D. viviparus on day 0 protects calves for 70% against a challenge infection of 2000 L3 on day 35 compared to calves with no primary infection. The variation in post mortem worm counts within this group (n = 6) was very large with mean worm counts of 145 (range 3-446) lungworms. Parasite specific IgA, IgE, IgG1 and IgG2 and total IgE levels in serum were measured by ELISA. Parasite specific IgA, IgG1 and IgG2 were elevated after infection, but correlation with protection was only found with IgG1 levels on day 42 and with IgG2 levels on day 70. IgE was measured in a sandwich ELISA using antisheep IgE that cross-reacts with cattle IgE. No parasite specific IgE could be detected. However, total serum IgE was elevated after infection and total serum IgE levels before and on the day of challenge correlated with protection (P < 0.05). Total serum IgE also correlates with peripheral eosinophil counts between days 14 and 28 after primary infection. Western blots with three different parasite antigen preparations, L1, excretory/secretory products and crude worm adult antigens, were used to detect parasite specific IgE in sera depleted of IgG and IgM. These depleted sera from protected calves contained parasite specific IgE, while sera from nonprotected calves were negative. A band of approximately 100 kDa was recognized in all three antigens. In a second experiment, primary doses of 30, 60, 120, 240, 480 and 960 L3 of D. viviparus were used and necropsy was 11 days after challenge. This experiment confirmed the correlation between protection and total IgE levels before and on the day of challenge. The rapid and strong IgE responses in protected animals after such a low infection might be caused by the specific characteristics of the lungworm antigens or by the somatic migration of the worm and might be involved in the rapid development of protection against lungworm reinfections in cattle.
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Affiliation(s)
- F N J Kooyman
- Department of Parasitology and Tropical Veterinary Medicine, Institute of Infectious Diseases and Immunology, University Utrecht, Utrecht, The Netherlands.
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Abstract
The natural genetic variability of the ruminant immune system provides a feasible means to control gastrointestinal (GI) parasite infection without anthelmintics. However, the paradigm of traditional selection has not been effectively applied to the moderately heritable traits of parasite resistance (h approximately equal to 0.3) due to the difficulty and expense of gathering accurate phenotypes in a commercial production setting. These characteristics make host traits related to GI nematode infection ideal candidates for genomics-based research. To initiate explanation of important allelic differences, economic trait loci (ETL) are being identified and mapped using a resource population of Angus cattle segregating for GI nematode resistance and susceptibility to the two most common nematode parasites of US cattle, Ostertagia ostertagi and Cooperia oncophora. The population is composed of five generations of half-sib progeny with complete phenotypic records produced from controlled infections. To detect the genomic locations of the three distinct phenotypic traits being expressed (innately immune, acquired immune, and immunologically non-responsive), genotypes have been generated for DNA markers (N=199) spaced at regular intervals (approximately 20cm intervals) throughout the entire genome (3000cm). Although initial ETL detection may be limited by half-sib family size, the unique structure of this population provides additional statistical power for refining map position of potential ETL. After allele frequency and contribution to phenotype are determined in this population, marker tests associated with ETL most beneficial for controlling parasite infection can be accurately used for selection. Comparative map and functional genomic information from humans and other species of biomedical importance will be utilized in further investigations to elucidate the genes underlying ETL.
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Affiliation(s)
- T S Sonstegard
- Gene Evaluation and Mapping Laboratory, Animal and Natural Resources Institute, USDA-ARS Beltsville Area, Building 200, Room 2A, BARC-East, Beltsville, MD 20705-1350, USA
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Edmonds JD, Horohov DW, Chapmat MR, Pourciau SS, Antoku K, Snedden K, Klei TR. Altered immune responses to a heterologous protein in ponies with heavy gastrointestinal parasite burdens. Equine Vet J 2001; 33:658-63. [PMID: 11770986 DOI: 10.2746/042516401776249282] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study was performed to test the hypothesis that immunity to heterologous vaccination would improve when the parasites were removed. It was also expected that parasitised ponies would exhibit a biased Th2 cytokine response to KLH immunisation. Helminth parasites are common in horses even in the era of highly effective broad-spectrum antiparasiticides. These parasites have been shown to alter the outcome to heterologous immunisation in a number of host species. The effect of gastrointestinal parasites on heterologous vaccination has not been addressed in equids. In the current study, humoral, lymphoproliferative, and cytokine responses to a single i.m. injection of keyhole limpet haemocyanin (KLH) were compared between groups of ponies with high, medium or low gastrointestinal parasite burdens. Antibody levels determined by ELISA showed that animals with low levels of parasites had a trend toward increased KLH specific total immunoglobulin, IgG(T) and IgA compared to heavily parasitised ponies. Medium and heavily parasitised ponies demonstrated a trend toward reduced lymphoproliferative response to KLH that was not restored after the addition of interleukin-2 (Il-2). Cells from these ponies also produced significantly lower levels of IL-4 compared to lightly parasitised ponies. These data indicate that heavily parasitised ponies have uniformly decreased cellular and humoral immune responses to soluble protein immunisation. The mechanisms involved may have potential deleterious effects on standard vaccine protocols of parasitised equines.
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Affiliation(s)
- J D Edmonds
- Department of Pathobiological Science, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803, USA
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Agneessens J, Claerebout E, Vercruysse J. Development of a copro-antigen capture ELISA for detecting Ostertagia ostertagi infections in cattle. Vet Parasitol 2001; 97:227-38. [PMID: 11390075 DOI: 10.1016/s0304-4017(01)00398-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study reports on the development of a copro-antigen capture ELISA for detecting Ostertagia ostertagi infections in cattle. The ELISA was based on polyclonal rabbit antibodies, which recognize O. ostertagi excretory/secretory antigens (ES). ES antigens are released by the metabolic active stages of the parasite in the abomasum, and passed in the faeces of the host. The detection limit of pure ES material was 30 ng ml(-1) in sample buffer and 125 ng ml(-1) in faecal extract. The test was evaluated using a follow up from six artificially infected calves. Elevated levels of Ostertagia coproantigens could be measured from 21 days after infection, indicating that only the presence of adult parasites can be detected. To evaluate the capacity of the assay to measure levels of infection, three groups of cattle were tested: 38 artificially infected calves, 17 naturally infected first grazing season calves and 16 naturally infected adult dairy cows. Optical densities were significantly correlated to the worm burdens of the animals and the ELISA had an overall sensitivity of 91% and a specificity of 45%. The test gave negative readings for faeces of animals carrying patent mono-infections with Cooperia oncophora.
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Affiliation(s)
- J Agneessens
- Department of Parasitology, Faculty of Veterinary Medicine, Salisburylaan 133, B-9820, Merelbeke, Belgium.
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Onah DN, Nawa Y. Mucosal immunity against parasitic gastrointestinal nematodes. THE KOREAN JOURNAL OF PARASITOLOGY 2000; 38:209-36. [PMID: 11138315 PMCID: PMC2721204 DOI: 10.3347/kjp.2000.38.4.209] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The last two decades witnessed significant advances in the efforts of immunoparasitologists to elucidate the nature and role of the host mucosal defence mechanisms against intestinal nematode parasites. Aided by recent advances in basic immunology and biotechnology with the concomitant development of well defined laboratory models of infection, immunoparasitologists have more precisely analyzed and defined the different immune effector mechanisms during the infection; resulting in great improvement in our current knowledge and understanding of protective immunity against gastrointestinal (GI) nematode parasites. Much of this current understanding comes from experimental studies in laboratory rodents, which have been used as models of livestock and human GI nematode infections. These rodent studies, which have concentrated on Heligmosomoides polygyrus, Nippostrongylus brasiliensis, Strongyloides ratti/S. venezuelensis, Trichinella spiralis and Trichuris muris infections in mice and rats, have helped in defining the types of T cell responses that regulate effector mechanisms and the effector mechanisms responsible for worm expulsion. In addition, these studies bear indications that traditionally accepted mechanisms of resistance such as eosinophilia and IgE responses may not play as important roles in protection as were previously conceived. In this review, we shall, from these rodent studies, attempt an overview of the mucosal and other effector responses against intestinal nematode parasites beginning with the indices of immune protection as a model of the protective immune responses that may occur in animals and man.
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Affiliation(s)
- D N Onah
- Department of Parasitology, Miyazaki Medical College, Kiyotake, Miyazaki 889-1692, Japan
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Abstract
Defining the characteristics of immunity and immune responses to equine cyathostome infections is clearly important to advancing our understanding of the development of these nematodes within the host, the clinical conditions attributed to them, and in developing more rational and novel strategies for their control. Nonetheless, little is currently known on this topic. Current data based on field observations, worm burdens and fecal egg counts suggest that horses acquire a resistance to cyathostome infection with age. This response is slow to develop and incomplete in that most horses regardless of age harbor significant populations of these nematodes. More convincing evidence has been obtained from experimental infections which indicate that mature horses previously exposed to infection are resistant to re-infection and this resistance is directed at all stages of the parasite life cycle. Further, some immunity against the developing stages within the mucosa appears to require less exposure and occurs in younger animals. Some non-specific events which induce expulsion of all species of lumenal dwelling nematodes also appear to take place post-infection with L3. Antibodies have been detected in limited studies against somatic extracts of adult worms. Not surprisingly, titers of these antibodies do not correlate resistance to re-infection. Serendipitous observations have, however, associated a greater expression of the gene for IL-4 with the spontaneous expulsion of lumenal parasites. The development of a usable model is required to further advance our knowledge in this area.
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Affiliation(s)
- T R Klei
- Department of Veterinary Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State University, Baton Rouge 70803, USA
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