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PubMed1992

Low-level infection with the nematode Nippostrongylus brasiliensis induces significant and sustained specific and non-specific IgE antibody responses in rats.

Specific and non-specific IgE antibody responses were studied in SD rats infected with between 5 and 2500 Nippostrongylus brasiliensis (NB) larvae. In rats with 2500 NB larvae, specific IgE antibody, measured by enzyme-linked immunosorbent assay (ELISA) using NB excretory/secretory substance as antigen, reached a peak at 4 weeks of infection and gradually declined. On the other hand, in rats infected with 10 or 100 NB larvae, specific IgE was induced at 4 weeks of infection and the level continued to rise until at least 8 weeks after infection. The level at 8 weeks was significantly higher in rats infected with 10 or 100 larvae than in rats infected with 2500 larvae. The results indicate that the low-level infection induced a much more sustained specific IgE response than that induced after heavy infection. However, the level of specific IgG was correlated with the dose of infection, and reached a plateau 6 weeks after infection. Total serum IgE increased significantly even in rats infected with five larvae, a dose which did not induce detectable specific IgE. The kinetics of the production of total IgE was different in rats with light and heavy infections. In rats infected with five or 10 larvae, total IgE increased slowly and reached a plateau 4 weeks after infection. On the other hand, rats infected with more than 500 larvae showed a remarkable rise in total IgE at 2 weeks of infection; this rise gradually declined thereafter. Six weeks after infection, total IgE levels were almost the same (2-3 micrograms/ml) in rats infected with 10-2500 NB larvae. These results show that low-level NB infection induces a significant and sustained specific and non-specific IgE response in rats.

Animals↗
PubMed2005

Intracranial haemorrhage associated with Angiostrongylus vasorum infection in three dogs.

This report describes three dogs with intracranial haemorrhage secondary to severe coagulation defects associated with Angiostrongylus vasorum infection. The initial case was diagnosed at necropsy, with two subsequent cases diagnosed antemortem and successfully treated. The dogs ranged in age from 14 months to four years and were presented for evaluation of a severe, subacute onset of suspected cerebral disease. Magnetic resonance imaging performed on all three dogs was suggestive of multiple areas of intraparenchymal brain haemorrhage. Coagulation assays showed a consumptive coagulopathy resembling chronic disseminated intravascular coagulation. Postmortem examination of the initial case confirmed the presence of multiple intracranial and extracranial haemorrhages. An unexpected finding was that of a marked multifocal nematode infection of the lungs with an associated vasculopathy. The parasites were confirmed to be A vasorum. In the two other dogs, faecal examination by Baermann technique confirmed A vasorum infection. Both dogs were treated with fenbendazole and one was additionally given a plasma transfusion. Repeated coagulation assays were normal within one week. Neurological examinations were normal for both dogs within six weeks. This case series indicates that A vasorum infection should be considered as a possible aetiology of intracranial haemorrhage in dogs.

Angiostrongylus↗
PubMed2004

Density-dependent effects on the survival and growth of the rodent stomach worm Protospirura muricola in laboratory mice.

The spirurid nematode, Protospirura muricola, is of intrinsic interest as a rodent model of gastric nematode infections. Since worm burdens can be very heavy in nature, density dependent processes may constrain parasite growth. Laboratory mice (BKW) were exposed to varying doses of infective larvae of P. muricola in the range 5 to 40 third-stage larvae (L3), in four separate experiments in which progressively higher doses were utilized. All mice were culled 60 days after infection and a total of 518 worms (226 male and 292 female worms) was recovered, measured and weighed. Overall survival was 58.9%, but survival declined significantly with increasing dose by approximately 21% (from 66% at 5 L3 per mouse to 52% at 40 L3 per mouse). The length and weight of worms correlated positively in both sexes. Total worm biomass increased linearly with increasing numbers of worms. However, whilst the length and weight of male worms declined with increasing worm burden (8.4 and 24.6% respectively), female worms were less affected, only length showing a significant reduction with increasing parasite burden (16.0%). Therefore, increasing worm burdens impeded growth of P. muricola, but reduction in length and weight were relatively small in relation to the overall size of this nematode. Increasing worm burdens were associated with loss of host weight and reduction in stomach weight and worm burdens in excess of 20 exerted a measurable cost to the host, which in the field, may be associated with loss of overall host fitness.

Animals↗
PubMed1992

Resistance of St. Croix lambs to Haemonchus contortus in experimentally and naturally acquired infections.

Parasitological and immunological parameters of experimental or naturally acquired infections with Haemonchus contortus were compared in St. Croix and Dorset lambs. In experimental infections, St. Croix lambs developed significantly greater levels of resistance to H. contortus, following primary exposure, as compared with Dorset lambs. This resistance was influenced both by age and by prior exposure to parasites. In grazing experiments on H. contortus-infected pasture, St. Croix lambs shed significantly fewer eggs as early as 5 weeks following initial exposure. Further, St. Croix lambs had more than 99% fewer worms in the abomasum at necropsy compared with age-matched Dorset lambs. Lymphoproliferative assays using peripheral blood mononuclear cells and antigen-specific serological tests demonstrated only minor differences in immune responsiveness between the two breeds despite the dramatic parasitological differences. Similarly, abomasal mucus from both breeds had elevated levels of parasite-specific antibodies and contained substances mediating larval paralysis. In contrast, St. Croix lambs which had become resistant to nematode infection had dramatically higher numbers of globule leukocytes in the abomasal mucosa compared with Dorset lambs.

Abomasum↗
PubMed1995

Effect of chemoprophylaxis with avermectins on the immune response to gastrointestinal nematodes in first-season grazing calves.

The influence of chemoprophylaxis on the immune response to gastrointestinal nematodes was evaluated in three groups of ten first-season grazing calves. Group C functioned as untreated controls, whereas Group L received two treatments, one at turn-out and one 8 weeks later, with doramectin (200 micrograms kg-1) and Group H three treatments, 3, 8, and 13 weeks post turn-out, with ivermectin (200 micrograms kg-1). At housing, five calves of each group were randomly selected for necropsied for worm counts. The remaining calves were challenged with 50,000 Ostertagi and 100,000 Cooperia oncophora and necropsied 4 weeks later. During the grazing season, Group C suffered from an outbreak of parasitic gastroenteritis which necessitated two anthelmintic treatments. In both treated groups no clinical symptoms were observed and growth rates were normal. Pepsinogen levels and antibody concentrations indicated a moderate and low gastrointestinal nematode infection in Group L and Group H, respectively. The Ostertagia and Cooperia worm populations present in the calves necropsied at housing were reduced in both treated groups in comparison with Group C. In the challenged calves, egg output was significantly higher in Group H than in Group L and Group C. Ostertagia and Cooperia worm burdens after challenge were high in Group H, moderate to low in Group L and low in Group C. This study indicates that highly suppressive prophylactic programmes, such as the ivermectin 3, 8 and 13 weeks schedule, can impair immune development against gastrointestinal nematodes during the first grazing season.

Animals↗
PubMed2006

The prevalence of intestinal parasites in dogs from Prague, rural areas, and shelters of the Czech Republic.

The prevalence of intestinal parasites was evaluated by examination of dog faecal samples in the Prague city centre, agricultural areas, and two shelters. The overall prevalence of parasites (i.e., protozoa and helminths, mentioned below) in Prague was 17.6%. Toxocara canis was the most common parasite, and was recovered from 6.2% of dogs, followed by Cystoisospora spp. (2.4%), Cryptosporidium spp. (1.4%), Trichuris sp. (1.1%), Taenia-type (1.0%), Giardia spp. (0.1%), Toxascaris sp. (0.9%), Dipylidium sp. (0.7%), Sarcocystis spp. (0.6%), Capillaria spp. (0.6%), Neospora/Hammondia spp. (0.5%), Ancylostoma sp. (0.4%), Uncinaria sp. (0.4%), and Spirocerca sp. (0.2%). The prevalence of infections with helminths and protozoans in two animal shelters in Prague was examined at the dog's admittance ir reception to the shelters and during housing. T. canis eggs (6.5%), Cystoisospora (4.4%), and Giardia (3.3%) cysts were the most prevalent. Significant increases in the prevalence of some parasites were found after a stay in the shelter. Giardia spp. showed an 11-fold increase in prevalence of dogs placed in the shelters for a longer time; Cryptosporidium spp. had a 7-fold increase, Capillaria spp. a 5-fold, Spirocerca sp., Neospora/Hammondia spp., and Cystoisospora spp. a 4-fold increase over dogs examined at the time of admittance to the shelter (p<0.01). Dog in rural areas were infected significantly more frequently (p<0.01) than those in Prague. In 540 faecal samples from rural areas, the overall prevalence of parasites (i.e., protozoa and helminths mentioned below) was 41.7%. The prevalence of T. canis was 13.7%, followed by Cystoisospora spp. (8.0%), Taenia spp. (3.5%), Sarcocystis spp. (3.0%), Giardia spp. (2.2%), Cryptosporidium spp. (2.0%), Trichuris sp. (1.7%), Toxascaris sp. (1.7%), Dipylidium sp. (1.3%), Neospora/Hammondia spp. (1.3%), Spirocerca sp. (1.1%), Uncinaria sp. (0.9%), Ancylostoma sp. (0.7%), and Capillaria spp. (0.6%). Examinations of dogs in urban and rural areas showed, with the exception of Trichuris sp. in Prague, a higher occurrence of nematode infection in autumn, notably T. canis (chi2>8.3, d.f.=3, p<0.04).

Animal Husbandry↗
PubMed1990

Is there a relationship between haemoglobin genotype and the innate resistance to experimental Haemonchus contortus infection in Merino lambs?

Responses to a single or repeated infection with 7000 infective larvae of Haemonchus contortus were studied in an experiment using a total of 106 3-month-old lambs with AA, AB or BB haemoglobin (Hb) genotypes. Results were assessed by faecal egg counts, adult worm counts, haematocrit values, haemoglobin concentrations, total serum protein and serum antibody IgG1 and IgA ELISA titres. None of these parameters showed a strong relationship to the Hb type. The prevalence of low responder (greater than 500 worms) and of high responder (less than 50 worms) animals in groups AA, AB and BB Hb types was 3.8 and 34.6, 20.6 and 35.2, 28.1 and 43.7%, respectively, suggesting that the responsiveness to nematode infection is under the control of gene(s) not closely linked with those determining the Hb genotype. Worm counts of a primary infection are more subject to variation than those of a secondary infection. There is a strong relationship between adult worm counts and faecal egg counts taken close to the time of slaughter. In living animals low and high responder discrimination can be based on individual faecal egg counts around 50 days after a secondary infection. Haematocrit values proved to be of little value in the low and high responder selection. In this regard neither Hb concentration nor total serum protein values are of practical significance. In 3-month-old lambs primary infection induced partial immunity which could prevent the establishment of a part of the secondary infection, irrespective of the presence or absence of the primary worm population. The development of immunity was not associated with an increase of serum IgG1 and IgA antibody levels. Specific antibody production was not influenced by Hb types. Mean antibody levels of low responder lambs showed no difference from those of high responders. Thus, serum IgG1 and IgA levels are of no predictive value in identifying lambs which are genetically resistant to Haemonchus infection.

Animals↗
PubMed2002

Effect of level of feed intake on the development of gastrointestinal parasitism in growing lambs.

A study was conducted to examine the role of nutrition in the development of gastrointestinal (GI) parasitism, performance and pathophysiology of parasitism in female lambs. Forty-four months old ewe lambs received for 6 weeks 0, 1500 or 7000 L(3) larvae of Teladorsagia circumcincta in two doses per week. The animals were given access to a pelleted diet to meet energy requirements for gaining weight close to their potential (H) or approximately 50% of it (L). The level of protein in the diet was 20-30% above requirements for both planes of nutrition. Measurements of body weight, serum pepsinogen concentration and faecal egg counts were taken at weekly intervals. All animals were slaughtered 2 weeks after the last larval dosing for estimation of worm count, carcass composition and reproductive tract development. Voluntary intake of infected animals decreased by approximately 10%. Both nutrition and infection influenced lamb performance and carcass composition. However, no direct effects on reproductive tract parameters due to the presence of infection were observed. The level of L(3) infection showed a significant effect not only on faecal egg counts and on worm burden, as it could be expected, but also on the proportion of females to males, which increased significantly with the level of infection. While the plane of nutrition did not show a significant effect on faecal egg counts or on worm burden, surprisingly, both female worm size and their fecundity decreased significantly with the level of nutrition. This response was accompanied by a significant increase in the concentration of circulating eosinophils suggesting that the immune response of lambs consuming high levels of energy was enhanced compared to that of lambs kept on a restricted diet. Results herein show that in young female lambs fed on adequate levels of protein, an improvement in energy supply does not only improve carcass characteristics but clearly enhances the development of resistance to GI nematodes infection. This may have decisive management implications for the control of parasitic infections in sustainable production systems.

Animals↗
PubMed2005

Cutting edge: the development of IL-4-producing B cells (B effector 2 cells) is controlled by IL-4, IL-4 receptor alpha, and Th2 cells.

Although IL-4-producing B cells (B effector 2 cells) are found following infection and immunization, the signals regulating IL-4 production by Be2 cells are unknown. We show that culturing naive B cells with Th2 cells induces up-regulation of IL-4 in the B cells with a concomitant down-regulation of T-bet, IL-12Rbeta2, and IFN-gamma. Up-regulation of IL-4 in the Be2 cells is dependent on both T cells and IL-4 as IL-4Ralpha-deficient B cells primed with Th2 cells did not transcribe IL-4, and B cells primed in the presence of IL-4-deficient Th2 cells produced IFN-gamma instead of IL-4. Likewise, the in vivo development of IL-4-expressing B cells in a nematode infection model was dependent on both T cells and IL-4Ralpha-mediated signals. Thus, the differentiation of naive B cells into IL-4-expressing Be2 cells is regulated by a combination of T cell-dependent signals and the cytokine environment and this process is critically dependent upon the IL-4/IL-4R signaling pathway.

Animals↗
PubMed2000

Evidence for a parasite-mediated inhibition of abomasal acid secretion in sheep infected with Ostertagia leptospicularis.

The acid secretory capacity of the abomasal mucosa was studied in sheep experimentally infected with Ostertagia leptospicularis. The acidity of the abomasal contents, permanently recorded by a pH probe located inside the abomasum, decreased markedly to mean levels between pH 5 and 6. Subcutaneous administration of histamine or carbachol successfully stimulated acid secretion (pH 3.4). The results indicate that the abomasal mucosa harboured a population of functional parietal cells which were also identified immunohistochemically (H(+)/K(+)-ATPase). Ultrastructural investigation before stimulation revealed that the majority of these cells was in a resting state. Despite high serum gastrin levels, the acid secretion was blocked either at the level of the parietal cell or the enterochromaffin-like cell by an unknown factor, possibly mediated by the parasites. This is the first report of a parietal cell dysfunction associated with a nematode infection in the abomasum. It is suggested that the parasites induce changes in their environment which favour their survival and/or increase their reproduction.

Abomasum↗
PubMed1990

Effects of size of Trichostrongylus colubriformis infections on histopathology of the mucosa along the whole small intestine in rabbits.

The influence of population size of Trichostrongylus colubriformis on the structures of the small intestine, especially with regard to the development and origin of an intestinal adaptive response, was examined in experimentally infected rabbits. The effects of low (500 L3) and high (50,000 L3) infection on histological (villous length, mucosa to serosa ratio, crypt surface) and biochemical (protein content, alkaline phosphatase and leucine aminopeptidase activities) aspects of the mucosa were assessed along the whole small intestine. The presence of a small number of worms induced only minor mucosal changes, indicating a regenerative response of the intestinal epithelium. The role of a local small population of T. colubriformis in the development of a previously described adaptive response appeared thus to be limited. On the other hand, the 50,000 L3 inoculum was associated with severe lesions of villi, marked crypt hyperplasia and with a major reduction of enzyme activities. The changes were found along the whole length of the small intestine. These results suggest that the generally recognized dose-dependent pathogenicity of the intestinal nematode infections could be ascribed to two different processes: firstly, a greater severity of the lesions; secondly, more extensive damage leading to the disappearance of any adaptive intestinal region.

Alkaline Phosphatase↗
PubMed2006

Roles of IL-18 in basophils and mast cells.

Basophils and mast cells are effecter cells in allergen/IgE-mediated immune responses. They induce type 1 immediate immune response in airway or other organ, resulting in bronchial asthma and other allergic diseases. However, they also play a critical role in host defense against infection with helminthes. Upon linkage of FcepsilonRI with a complex of allergen and IgE, basophils and mast cells release a large amount of Th2 cytokines and chemical mediators. Therefore these responses are "acquired allergic responses" and induce allergic diseases, such as bronchial asthma. However, basophils and mast cells derived from cultured bone marrow cells with IL-3 for 10 days express IL-18Ralpha chain and produce Th2 cytokines in response to the stimulation with IL-3 and IL-18 without FcepsilonRI cross-linkage. Furthermore, they produce Th2 cytokines upon stimulation with several TLR ligands, such as LPS. This finding may suggest the presence of allergen/IgE-independent allergic responses, which we would like to designate as "innate allergic response". However, in vivo treatment with IL-18 and IL-2 protects against gastrointestinal nematode infection by activating intestinal mucosal mast cells in STAT6-independent manner, suggesting the importance of innate allergic response against helminth infection. Here we discuss the functional role of IL-18-induced "innate allergic response" in disease and host defense.

Animals↗
PubMed1999

Changing surface antigen and carbohydrate patterns during the development of Oesophagostomum dentatum.

Living and fixed specimen of Oesophagostomum dentatum were labelled in situ with serum antibodies or a panel of biotin-labelled lectins. Specific binding of antibodies was observed in all parasitic stages--freshly exsheathed 3rd-stage larvae (L3), 3rd- and 4th-stage (L4) larvae cultured in vitro and L3 and L4 and adults isolated from pig intestines. The shedding of the stained layer by motile larvae was inhibited by levamisole-induced paralysis. Larvae cultured in vitro exposed serum-derived proteins on their surface which could be labelled with secondary antibody directed against the respective serum donor species. While freshly exsheathed larvae were recognized by O. dentatum-positive serum only, older larvae and adults cross-reacted with serum from pigs infected with O. quadrispinulatum, a closely related species. Lectin binding varied considerably between stages. While binding was not observed in pre-parasitic stages, Concanavalin A, Soybean Agglutinin, Wheat Germ Agglutinin, Ricinus communis Agglutinin and Peanut Agglutinin bound to developing larvae in varying degrees. Dolichos biflorus Agglutinin only bound to advanced (luminal) larval stages, while adults generally displayed only weak or partial lectin binding (except with Concanavalin A and Wheat Germ Agglutinin). Ulex europaeus Agglutinin only labelled larvae derived from cultures containing 10% pig serum. Cleavage of the carbohydrate residues by sodium periodate treatment resulted in reduction of antibody binding to cultured larvae, but not to freshly exsheathed L3. Concanavalin A, Soybean Agglutinin, and Peanut Agglutinin binding was also reduced by periodate treatment, while binding of Wheat Germ Agglutinin and Ricinus communis Agglutinin was inhibited only in early L3, but not in older stages. The different lectin labelling patterns are related to the different stages of the nematode--infective, invasive, histotropic, and luminal--and may serve as a mode of adaptation for the parasite against the host's immune attack by surface glycoprotein variation, together with antigen shedding (as demonstrated by labelling of motile larvae) and a possible acquisition of host molecules at the parasite's surface. Furthermore, a possible role of this developmental variation in surface carbohydrates in parasite-parasite interactions is discussed.

Animals↗
PubMed1982

Ostertagia ostertagi in calves: growth, nitrogen balance and digestibility studies conducted during winter feeding following different fenbendazole therapy programmes.

Observations of growth, nitrogen (N) balance and digestibility were made during the first winter housing period upon three groups of calves which had previously been naturally infected with Ostertagia ostertagi and which were left either untreated (A) or treated with fenbendazole on three occasions (B) or every two weeks during the entire grazing season (C). The diet given contained sufficient metabolisable energy but only about 60 per cent of the recommended crude protein to sustain a daily growth rate of 0.5 kg. Growth rates were only 50 per cent of that expected on a basis of metabolisable energy input with untreated calves A being poorest. Water intake and output was greatest in group A. There were no significant differences in digestibility between groups although group A had the lowest apparent crude protein digestibility. N balance was always lowest in group A and highest in group C but group B demonstrated a marked increase in N retention with time after housing. Differences in N retention were mainly accounted for by increased urinary N excretion. It is concluded that, under conditions of suboptimal protein intake, nematode infection in the growing calf can markedly affect production even after efficient anthelmintic treatment.

Animals↗
PubMed1997

Effects of infected insects on secondary invasion of steinernematid entomopathogenic nematodes.

Factors affecting 'invasion efficiency' of steinernematid entomopathogenic nematodes into hosts were elucidated. The phenomenon that only part (10-40%) of the nematode population invades the target host has been recorded in many studies. It has been mainly ascribed to differences in the ability of individual nematodes to infect. In the present study the effect of an infected host, the wax moth Galleria mellonella, on subsequent infection of the entomopathogenic nematodes Steinernema carpocapsae Mexican, S. riobravus and S. feltiae was evaluated. The invasion rate of the 3 nematode species to a non-infected host was reduced by 40-60% after pre-exposure to infected hosts. These nematodes regained their full invasion potential after they were rinsed with water. Invasion into insects which were previously injected with nematodes was significantly reduced by 60-80% 6-9 h after injection. The reduction in subsequent invasion due to the initial infection was nematode species specific. This phenomenon was also observed with other lepidopteran pests (Helicoverpa armigera and Spodoptera littoralis). The data indicate that the initial infection by entomopathogenic nematodes induced the release of a substance which reduced the subsequent invasion. The chemical and biological characteristics of this substance are currently under investigation.

Animals↗
PubMed2001

Resistance to macrocyclic lactone anthelmintics by Haemonchus contortus and Ostertagia circumcincta in sheep in New Zealand.

AIM: To establish the efficacy of oral formulations of ivermectin and moxidectin against naturally acquired abomasal nematode infections on a North Island sheep farm. METHODS: Two controlled slaughter trials were undertaken. In the first, 30 sheep on pasture were randomly allocated on the basis of faecal egg count to 1 of 3 groups, comprising an untreated control group and 2 treatment groups. One treatment group was given a single oral dose of ivermectin and the other a single oral dose of moxidectin, both at the manufacturer's recommended dose rates of 0.2 mg/kg liveweight. Six days after treatment, all animals were slaughtered and their abomasa recovered for worm counting. The second trial, which involved 47 animals, was essentially the same as the first except that, as well as involving the slaughter of 30 sheep from all 3 groups, 6 days after treatment, it also included a further 8 untreated control animals and 9 moxidectin treated animals which were slaughtered 27 days after treatment. RESULTS: At 6 days after treatment, moxidectin was highly effective against all 3 of the abomasal nematodes present. While ivermectin was similarly effective against Trichostrongylus axei 6 days after treatment, it was not effective against either Ostertagia circumcinta or Haemonchus contortus, against which average efficacies of only 63.6% and 61.6%, respectively, were recorded. At 27 days after treatment, moxidectin, was also highly effective against T. axei (97.3% reduction) but not against either H. contortus (71.4% reduction) or O. circumcinta (61.0% reduction). CONCLUSIONS: These results provide the first record of macrocyclic lactone resistance in H. contortus in sheep or in any other host in New Zealand, and the first case where such resistance has been exhibited in more than one parasite species at a time. Although the therapeutic efficacy of moxidectin was high against these resistant H. contortus and O. circumcincta strains, resistance to moxidectin was indicated by its diminished prophylactic activity against them. It is suggested that this reduction in the prophylactic activity of moxidectin is also likely to reduce its apparent current high therapeutic efficacy. CLINICAL RELEVANCE: As well as providing further evidence that it can no longer be automatically assumed that macrocylic lactone anthelmintics will be effective on sheep farms in this country, these findings also present a warning that increasingly complex parasite control options may have to be faced in the future.

Journal Article↗
PubMed2026

GmMYB29 activates Gm4CL3 to enhance soybean resistance to Heterodera glycines.

Soybean cyst nematode is a devastating soil-borne pathogen that severely limits soybean yield worldwide. To uncover downstream target genes of the resistance-associated transcription factor GmMYB29, we combined ChIP-seq and RNA-seq data from T3-generation GmMYB29-overexpressing soybean plants, alongside Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, to screen candidate genes carrying transcription factor binding peaks within the 2000 bp region upstream of transcription start sites (TSS). Four orthogonal molecular assays-yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), dual-luciferase reporter (LUC) system, and GUS histochemical staining-collectively confirmed the specific physical interaction between GmMYB29 and the promoter of Gm4CL3. We generated transgenic soybean hairy roots overexpressing Gm4CL3 (OX-Gm4CL3) and CRISPR-Cas9-mediated Gm4CL3 knockout lines (KO-Gm4CL3), with wild-type (WT) plants serving as controls. Inoculation assays using SCN 3 demonstrated that OX-Gm4CL3 roots displayed substantially improved SCN resistance, while KO-Gm4CL3 roots were hypersusceptible to nematode infection. Mechanistic investigations revealed that Gm4CL3 promotes lignin deposition in root tissues to block SCN penetration. Furthermore, GmMYB29 and Gm4CL3 act synergistically to activate lignin biosynthetic pathways and strengthen soybean resistance against SCN 3 (SCN Race 3, the dominant physiological race in Northeast China). In summary, this study functionally characterizes Gm4CL3 and defines a previously unreported GmMYB29-Gm4CL3 regulatory cascade that mediates plant defense against SCN. This module functions independent of classic SCN resistance loci rhg1/Rhg4, providing new genetic resources for SCN-resistant soybean molecular breeding.

Glycine max↗
PubMed1993

Antifilarial IgM versus IgG antibody determination in the diagnosis of Wuchereria bancrofti infection in Egyptians.

Circulating antifilarial IgM and IgG antibodies were assessed by indirect ELISA in 184 serum specimens from 80 patients with clinically and parasitologically diagnosed filarial infections (20 with acute filariasis 40 with chronic filariasis & 20 asymptomatic microfilaraemic subjects), 64 individuals with other parasitic infections, 20 parasitologically-free subjects from filariasis endemic areas and 20 normal healthy controls. A soluble surface membrane extract from Dirofilaria immitis worms was used as the antigen. Using a single serum dilution of 1:128 and optical densities (OD) at 492 nm, the respective cut off values for IgM and IgG were found to be 0.24 and 0.22. All healthy non-endemic controls were seronegative by IgM and IgG ELISAs. The highest antifilarial IgM OD492 values were obtained in 20 patients with acute filariasis (95% sensitivity), while the highest antifilarial IgG OD492 values were observed n 40 patients with chronic filariaisis (97.5% sensitivity). Asymptomatic microfilaraemic subjects gave IgM and IgG OD492 values which were significantly lower than those of other forms of clinical disease and endemic control subjects. The antifilarial IgM and IgG respective sensitivities in asymptomatic subjects were 75% and 70%. Endemic controls had positive antifilarial IgM (65%) and IgG (75%) levels. Of 64 subjects with other parasites only one with Ancylostoma duodenale had positive IgM level (98.4% specificity); while 9 patients with nematodal infections mainly had false positive antifilarial IgG antibody levels (85.9% specificity). These results suggest that measuring circulating antifilarial IgM antibody level may have some diagnostic advantage over measuring IgG antibody level for the detection of active filarial infection and consequently better management of the disease.

Acute Disease↗