In vitro and in vivo characterization of p-amino-phenethyl-m-trifluoromethylphenyl piperazine (PAPP), a novel serotonergic agonist with anthelmintic activity against Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis

The neurotransmitter serotonin (5-hydroxy tryptamine or 5HT) regulates key physiological processes in nematodes such as locomotion and feeding. PAPP (p-amino-phenethyl-m-trifluoromethylphenyl piperazine) is a known agonist of the 5-HT(1Hc) receptor of the barber pole worm, Haemonchus contortus. In this study, PAPP was highly active against L3-stage larvae of H. contortus and Trichostrongylus colubriformis in an in vitro larval migration assay, with EC50 values of 9.36 and 11.8 microM, respectively, that were comparable to levamisole (10.2 microM) and superior to pyrantel (55.39 microM). When administered orally or subcutaneously to nematode infected gerbils, PAPP provided >99% efficacy against H. contortus and >98% efficacy against Teladorsagia circumcincta at 100 mg/kg, comparable to levamisole at 10 mg/kg. Drug titration revealed significant activity down to 50 mg/kg against these two species. Spectrum was limited, however, with somewhat lower efficacy (83%) in T. colubriformis infected gerbils at 100 mg/kg. Oral delivery of hydrochloride, acetate and phosphate salts of PAPP to nematode infected gerbils did not result in an increase in either potency or spectrum. The finding that PAPP exhibits significant anthelmintic activity suggests that the nematode-specific serotonergic system is a viable target for future anthelmintic discovery.     

Biotransformation of flubendazole and selected model xenobiotics in Haemonchus contortus

Haemonchus contortus is one of the most pathogenic parasites of small ruminants (e.g., sheep and goat). The treatment of haemonchosis is complicated because of frequent resistance of H. contortus to common anthelmintics. The development of resistance can be facilitated by the action of drug metabolizing enzymes of parasites that can deactivate anthelmintics and thus protect parasites against the toxic effect of the drug. The aim of this project was to investigate the Phase I biotransformation of benzimidazole anthelmintic flubendazole in H. contortus and to determine the biotransformation of other model xenobiotics. For this purpose, in vitro (subcellular fractions of H. contortus homogenate) as well as ex vivo (live nematodes cultivated in flasks with medium) experiments were used. The results showed that cytosolic NADPH-dependent enzymes of H. contortus metabolize flubendazole via reduction of its carbonyl group. The apparent kinetic parameters of this reaction were determined (V'max=39.8+/-2.1 nM min(-1), K'm=1.5+/-0.3 microM). The reduction of flubendazole in H. contortus is stereospecific, the ratio of (-):(+) enantiomers of reduced flubendazole formed was 90:10. Reduced flubendazole was the only Phase I metabolite found. Effective reduction of other xenobiotics with carbonyl group (metyrapon, daunorubicin, and oracin) was also found. Significant activity of carbonyl-reducing enzymes may be important for H. contortus to survive the attacks of anthelmintics or other xenobiotics with carbonyl group.     

Anthelmintic activity of Croton zehntneri and Lippia sidoides essential oils

Because of the development of anthelmintic resistant populations, the search for new drugs is essential to maintain the productivity of small ruminants. The aim of this study was to evaluate the anthelmintic activity of Croton zehntneri and Lippia sidoides essential oils and their major constituents, anethole and thymol. The effects of these oils and their constituents were determined by in vitro assays with the eggs and larvae of the sheep gastrointestinal nematode Haemonchus contortus. The two essential oils were evaluated on intestinal nematodes of mice at 800 mg kg(-1) dose. In the last experiment, the mice were treated with larger doses of L. sidoides, 1200 and 1600 mg kg(-1). The essential oils and their constituents prevented more than 98% of the H. contortus eggs from hatching at a concentration of 1.25 mg ml(-1) and inhibited more than 90% of H. contortus larval development at a concentration of 10 mg ml(-1). At a concentration of 800 mg kg(-1), the two essential oils were 46.3% and 11.64% effective against Syphacia obvelata and Aspiculuris tetraptera. At 1200 and 1600 mg kg(-1), L. sidoides essential oil's efficacy on the mouse worm burden was 57.6% and 68.9%, respectively. The fact that L. sidoides essential oil was almost 70% effective against mouse intestinal nematodes indicates it should be evaluated against gastrointestinal nematodes of sheep and goats.     

Anthelmintic activity of Trianthema portulacastrum L. and Musa paradisiaca L. against gastrointestinal nematodes of sheep

Evaluation of anthelmintic effects of Trianthema (T.) portulacastrum L. (Aizoaceae) whole plant and Musa (M.) paradisiaca L. (Musaceae) leaves against prevalent gastrointestinal worms of sheep was done that may justify their traditional use in veterinary clinical medicine. In vitro anthelmintic activity of the crude aqueous methanolic extract (CAME) of both the plants was determined using mature female Haemonchus (H.) contortus and their eggs in adult motility assay (AMA) and egg hatch test (EHT), respectively. In vivo anthelmintic activity of crude powder (CP) and CAME in increasing doses (1.0-8.0 g kg(-1)) was determined in sheep naturally infected with mixed species of nematodes using fecal egg count reduction test (FECRT) and larval counts. The study design also included untreated as well as treated controls. Fecal egg count reduction and larval counts from coprocultures were performed pre- and post-treatments to assess the anthelmintic activity of the plants. CAME of T. portulacastrum and M. paradisiaca showed a strong in vitro anthelmintic activity and pronounced inhibitory effects on H. contortus egg hatching as observed through AMA and EHT, respectively. Both plants exhibited dose and time dependent anthelmintic effects on live worms as well as egg hatching. M. paradisiaca (LC(50)=2.13 μg mL(-1)) was found to be more potent than T. portulacastrum (LC(50)=2.41 μg mL(-1)) in EHT. However, in vivo, maximum reduction in eggs per gram (EPG) of faeces was recorded as 85.6% and 80.7% with CAME of T. portulacastrum and M. paradisiaca at 8.0 g kg(-1) on 15th day post-treatment, respectively as compared to that of Levamisole (7.5 mg kg(-1)) that caused 97.0% reduction in EPG. All the species of gastrointestinal nematodes (GINs), i.e. Haemonchus contortus, Trichostronglyus spp., Oesophagostomum columbianum and Trichuris ovis which were prevalent, found susceptible (P<0.01) to the different doses of CP and CAME of both plants. The data showed that both T. portulacastrum and M. paradisiaca possess strong anthelmintic activity in vitro and in vivo, thus, justifying their use in the traditional medicine system of Pakistan.     

Synergism of rotenone by piperonyl butoxide in Haemonchus contortus and Trichostrongylus colubriformis in vitro: potential for drug-synergism through inhibition of nematode oxidative detoxification pathways

The anthelmintic properties of rotenone and its activity in combination with the cytochrome P450 inhibitor piperonyl butoxide, were examined in in vitro assays with adults and larvae of Haemonchus contortus and larvae of Trichostrongylus colubriformis. Rotenone was toxic to larvae of both species, with LC(50) values in larval development assays of 0.54 and 0.64 microg/ml for H. contortus and T. colubriformis, respectively. The compound also caused complete cessation of movement in adult H. contortus after 72 h at a concentration of 20 microg/ml. Toxicity of rotenone towards the larvae of both species was increased in the presence of piperonyl butoxide (synergism ratios of 3-4-fold at the LC(50)) and the activity against adult H. contortus was also significantly enhanced following pre-treatment with piperonyl butoxide. This significant synergism suggests that these nematode species are able to utilize a cytochrome P450 enzyme system to detoxify rotenone and indicates that a role may exist for cytochrome P450 inhibitors to act as synergists for other anthelmintics which are susceptible to oxidative metabolism within the nematode.     

Anthelmintic resistance survey in New Zealand

The prevalence and level of thiabendazole resistance of sheep nematodes in the North Island of New Zealand was investigated by means of an in vitro egg-hatch technique; samples from sheep on 52 properties in six country areas were examined. Resistance of Haemonchus contortus and Trichostrongylus spp. was identified on the basis of egg hatch in 0.1 ppm thiabendazole. Evidence of resistance was obtained on 11(21.2%) of the properties. LD 50's and resistance ratios were calculated for the resistant nematode populations found.     

山西榆次区北郊绵羊胃肠道线虫感染调查及长刺似细颈线虫的描述

为初步了解山西榆次区放养绵羊消化道线虫的感染状况,采用蠕虫学剖检术对榆次区北郊农村的4只绵羊消化道线虫感染率和感染强度进行了初步研究。结果显示,榆次区北郊放养绵羊消化道线虫总感染率为100%（4/4）,共检出7种线虫,分别为：捻转血矛线虫感染率为100%,平均感染强度51条;环纹奥斯特线虫为100%,39条;羊仰口线虫为50%,5条;长刺似细颈线虫为100%,29条;哥伦比亚食道口线虫为50%,4条;绵羊毛尾线虫为100%,12条;绵羊夏伯特线虫为100%,81条。经t检验,真胃中捻转血矛线虫与环纹奥斯特线虫两虫种感染强度差异不显著;小肠中羊仰口线虫与长刺似细颈线虫和大肠中绵羊毛尾线虫与哥伦比亚食道口线虫、绵羊夏伯特线虫虫种感染强度差异显著。同时,对长刺似细颈线虫进行了形态再描述。     

Interactions between the predacious fungus Arthrobotrys oligospora and third-stage larvae of a series of animal-parasitic nematodes

Interactions between the predacious hyphomycete Arthrobotrys oligospora and third-stage larvae of nine animal-parasitic nematodes were tested in vitro. The trap-inducing capabilities of the ruminant trichostrongylus Cooperia oncophora, C. curticei, Haemonchus contortus and Ostertagia ostertagi and of equine cyathostomes were almost comparable to those of free-living soil nematodes, and significantly higher than those of the porcine Oesophagostomum dentatum and Oe. quadrispinulatum and of the murine Nematospiroides dubius. The trap-forming potential of Dictyocaulus viviparus was poor. All animal-parasitic nematodes were rapidly captured when fungal traps had been pre-induced in high numbers. The possible influence of predacious fungi on animal-parasitic nematode populations under natural conditions in the field is discussed.     

Milk and milk components reduce the motility of Ostertagia circumcincta larvae in vitro

AIM: To examine the effects in vitro of bovine milk and milk products and soymilk on the motility of sheathed and exsheathed L3 Ostertagia circumcincta (also known as Teladorsagia circumcincta) as a measure of larval viability and infectivity. METHODS: L3 were exsheathed in 0.2% sodium hypochlorite, resuspended in Hank's Balanced Salt Solution (HBSS) pH 7.4 and incubated with test solutions at 37 degrees C for up to 48 h. The motility of 50 larvae from each incubate was assessed at selected times using a McMaster slide. Larvae were considered immotile only if straight and not moving. Fresh bovine milk, homogenised milk (3.3% fat), low-fat milk (0.2% fat) and lamb milk replacer were diluted with HBSS pH 7.4 to concentrations from 1.6-100%, and incubated with exsheathed L3 for 1, 24 or 48 h. Bovine whey protein was tested in concentrations of 5-15% at pH 2.5-6.5, casein at 5 or 7.5%, and skim milk powder from 5-15% at pH 5.5 or 6.5, all for 2, 4 or 24 h. Soymilk was tested in concentrations of 1.6-100% for 1, 2, 24 or 48 h. HBSS was used as the control solution. Sheathed L3 were incubated in HBSS pH 7.4, 50% homogenised milk in HBSS, or 50% soymilk in HBSS. Each solution was incubated for 1,2, 24 or 48 h. RESULTS: The motility of exsheathed L3 was reduced by fresh bovine milk, homogenised milk, low-fat milk, lamb milk replacer, whey, casein and skim milk solutions, but not by soymilk. The mean percentage (and SE) immotile at 48 h were: fresh milk 38% (SE 20); homogenised milk 65% (SE 7); low-fat milk 57% (SE 5); lamb milk replacer 43% (SE 7); and soymilk 7% (SE 0.5). Larval immotility increased in whey protein solutions from 5-15%, from pH 2.5-6.5 and from 2 to 24 h (all p<0.001); in skim milk from 5-15% (p<0.001), and was greater at pH 6.5 than at pH 5.5 (p<0.001); in casein from 5-7.5% (p<0.001), but was no different at pH 5.5 and 6.5. The motility of sheathed L3 was reduced at 24 h (p=0.009) and 48 h (p<0.001) by 50% homogenised milk, but not by 50% soymilk or HBSS. CONCLUSIONS: Bovine milk proteins, or components associated with the proteins, reduced the motility of both sheathed and exsheathed L3 O. circumcincta. Soymilk had no effect on nematode motility. Lower larval motility may reduce worm establishment and be a contributing factor to the smaller burdens of gastrointestinal nematodes in milk-fed animals compared with animals after weaning.     

Detection and measurement of benzimidazole resistance alleles in Haemonchus contortus using real-time PCR with locked nucleic acid Taqman probes

Benzimidazole resistance is a common problem in parasitic nematodes of ruminants and early detection is vital if its spread is to be monitored and controlled. Real time PCR offers a fast and reliable method for rapid detection and measurement of resistance allele frequencies. In Haemonchus contortus a single nucleotide polymorphism at codon 200 of the beta-tubulin gene (TTC to TAC), causing a phenylalanine to tyrosine amino acid substitution, has been shown to be involved in many cases of resistance. Locked nucleic acid (LNA) Taqman probes have been used in this work to detect and measure the frequency of resistance alleles in individual and multiple H. contortus. Detection of resistant genotypes using LNA Taqman probes in individual H. contortus is simpler and more reliable than with previously described assays. Measurement of the frequency of resistant alleles in populations of H. contortus was achieved by using the cycle threshold (C(t)) values and a standard curve derived from populations with known allele frequencies. Results using the LNA probes on individual and multiple worms gave similar results to the allele specific PCR. The sensitivity of the LNA assay on multiple nematodes allowed reliable detection of > or = 10% resistance allele frequency. Using the final fluorescence method, it was possible to differentiate populations with approximately 0, 5 and 10% resistance allele frequencies.     

Prevalence of anthelmintic resistant nematodes in sheep in south-east England

The prevalence of anthelmintic resistant nematodes among 52 commercial flocks in south-east England was investigated by comparing the faecal egg counts of groups of lambs before, and seven days after, treatment with thiabendazole and levamisole. Evidence of thiabendazole resistance was found on seven farms. in each case Haemonchus contortus was the only species of nematode involved. In vitro egg hatch assays carried out for isolates from these farms gave ED50 estimates of 0.065 to 0.332 micrograms thiabendazole/ml compared with estimates of 0.027 to 0.031 micrograms thiabendazole/ml for a known susceptible strain of H contortus assayed at the same time. In a series of slaughter trials, there was a 17 to 85 per cent reduction, as compared with controls, in the mean worm burdens of groups of lambs infected with these isolates and killed seven days after treatment with thiabendazole, confirming their resistance to this anthelmintic.     

A high efficiency technique for the long-term preservation of infective nematode larvae.

Improvements are suggested for the existing long term techniques for the preservation of nematode larvae. Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus colubriformis and Cooperia curticei larvae exsheathed in sodium hypochlorite and then suspended in phosphate buffered saline (PBS pH 7.2) are cooled in the gas over liquid nitrogen at a cooling rate of -1 degree C min-1 down to -50 degrees C. Larvae are then stored in liquid nitrogen at -196 degrees C. After warming at 30 degrees C and reactivation at 20 degrees C for at least 12 h, their percent motility is maintained (approximately 85%) providing that no more than 3000 to 5000 larvae are suspended in 1.8 mL of PBS in cryotubes. Infectivity does not significantly decrease: 46% of larvae cooled for 2 or 6 mo develop to adult stages compared to 52% for larvae stored at 4 degrees C for 2 mo.     

Characterization of a galectin-like activity from the parasitic nematode, Haemonchus contortus, which modulates ovine eosinophil migration in vitro

The development of eosinophilia is a characteristic feature of helminth infection, although the exact nature of the interaction between eosinophils and parasites remains to be fully defined. Previously, it has been reported that Haemonchus contortus and other nematodes produce eosinophil-specific chemoattractants. This paper describes studies aimed at isolating and identifying the factor(s) responsible. Initial studies showed that soluble extracts of infective larvae (L3) of H. contortus provoked a chemokinetic, rather than chemotactic, response in ovine bone marrow eosinophils in vitro. This activity was inhibited by lactose to a markedly greater extent than sucrose suggesting a galectin-like identity. Lactose affinity chromatography of soluble H. contortus extracts resulted in the isolation a specific bound fraction which retained biological activity. SDS-PAGE gel electrophoresis indicated a single Coomassie-stained band at between 31 and 41kDa. Subsequent, mass spectrometric analysis confirmed that the bound fraction contained a mixture of nematode galectins. The results confirm that H. contortus larvae produce several galectin-like proteins, at least one of which demonstrates eosinophil chemokinetic activity in vitro. The possibility of the parasite-derived factor mimicking the mammalian galectin-9, a known eosinophil chemokine, is discussed.     

Comparing the sensitivity of two in vitro assays to evaluate the anthelmintic activity of tropical tannin rich plant extracts against Haemonchus contortus

The present trial aimed at comparing the sensitivity of two in vitro methods, i.e. the larval migration inhibition assay (LMIA) and the larval exsheathment inhibition assay (LEIA), to evaluate the anthelmintic (AH) properties of tannin-rich plant extracts against Haemonchus contortus infective larvae. The two assays were applied on the same batch of H. contortus infective larvae exposed to water/acetonic extracts obtained from four tropical plants with different tannin contents: Acacia gaumeri, Brosimum alicastrum, Havardia albicans and Leucaena leucocephala. Increasing concentrations (0, 75, 150, 300, 600, 1200 μg/ml PBS) of lyophilized extracts were used in both in vitro assays. A general lineal model test was used to determine the dose-effect in the LMIA or the difference in the percentage of exsheathed larvae between the respective control and treated groups. The LMIA showed a dose-dependent AH effect for H. albicans (P<0.001) and A. gaumeri (P<0.05), but not for L. leucocephala and B. alicastrum. In contrast, the exsheathment process was significantly affected by all doses of H. albicans and A. gaumeri extracts and a significant dose-dependent effect was found for B. alicastrum and L. leucocephala. Calculation of lethal dose (LD) was possible with LEIA using B. alicastrum and L. leucocephala but not with H. albicans and A. gaumeri as the lowest tested concentration was achieving more than 50% inhibition. Calculation of LD with the LMIA results was not feasible. These results suggest that tannin-rich plant extracts are more potent inhibitors of the exsheathment of H. contortus L(3) larvae than their motility. This information underlines the difference of sensitivity between methodological procedures to evaluate the AH properties of plant extracts on the same nematode stage.     

Anthelmintic efficacy of albendazole in cattle: comparison of critical and controlled tests.

Twelve calves were experimentally inoculated with 6 species of gastrointestinal nematodes and the liver fluke, Fasciola hepatica. Six calves were administered albendazole at 10 mg/kg of body weight, and the drug efficacy was determined by critical and controlled tests. Albendazole was only 74% effective against Haemonchus contortus (cambendazole-resistant strain), 99 to 100% effective against Ostertagia ostertagi, Trichostrongylus colubriformis, Cooperia oncophora, and Oesophagostomum radiatum, and 54% effective against the liver fluke. Except for H contortus, the critical test provided as accurate a measurement of drug activity against gastrointestinal nematodes as the controlled test provided.     

Comparative in vitro effects of closantel and selected β-ketoamide anthelmintics on a gastrointestinal nematode and vertebrate liver cells

PNU-87407 and PNU-88509, β-ketoamide anthelmintics that are structurally related to each other and to the salicylanilide anthelmintic closantel, exhibit different anthelmintic spectra and apparent toxicity in mammals. The basis for this differential pharmacology was examined in experiments that measured motility and adenosine triphosphate (ATP) levels in larval and adult stages of the gastrointestinal nematode, Haemonchus contortus , and in a vertebrate liver cell line and mitochondria. PNU-87407 and PNU-88509 both exhibited functional cross-resistance with closantel in larval migration assays using closantel-resistant and -sensitive isolates of H. contortus . Each compound reduced motility and ATP levels in cultured adult H. contortus in a concentration- and time-dependent manner; however, motility was reduced more rapidly by PNU-88509, and ATP levels were reduced by lower concentrations of closantel than the β-ketoamides. Tension recordings from segments of adult H. contortus showed that PNU-88509 induces spastic paralysis, while PNU-87407 and closantel induce flaccid paralysis of the somatic musculature. Marked differences in the actions of these compounds were also observed in the mammalian preparations. In Chang liver cells, ATP levels were reduced after 3 h exposures to 0.25 μ M PNU-87407, 1 μ M closantel or 10 μ M PNU-88509. Reductions in ATP caused by PNU-88509 were completely reversible, while the effects of closantel and PNU-87407 were irreversible. PNU-87407, closantel and PNU-88509 uncoupled oxidative phosphorylation in isolated rat liver mitochondria, inhibiting the respiratory control index (with glutamate or succinate as substrate) by 50% at concentrations of 0.14, 0.9 and 7.6 μ M , respectively.     

The effect of triflumuron (SIR8514) on the free-living stages of sheep nematodes

Studies both in vitro and in vivo showed that the insect growth regulator, triflumuron, exhibited potent larvacidal effects against the free-living stages of Trichostrongylus colubriformis. Effects were not as marked on the closely related nematodes, Haemonchus contortus and Ostertagia circumcincta. Nevertheless, these findings suggest that growth regulators may be used to develop novel methods of nematode control, and thus offer alternatives or adjuncts to conventional anthelmintic therapy and at the same time reduce the selection for anthelmintic resistance.     

Caenorhabditis elegans as a model to screen plant extracts and compounds as natural anthelmintics for veterinary use

The most challenging obstacles to testing products for their anthelmintic activity are: (1) establishing a suitable nematode in vitro assay that can evaluate potential product use against a parasitic nematode of interest and (2) preparation of extracts that can be redissolved in solvents that are miscible in the test medium and are at concentrations well tolerated by the nematode system used for screening. The use of parasitic nematodes as a screening system is hindered by the difficulty of keeping them alive for long periods outside their host and by the need to keep infected animals as sources of eggs or adults when needed. This method uses the free-living soil nematode Caenorhabditis elegans as a system to screen products for their potential anthelmintic effect against small ruminant gastrointestinal nematodes, including Haemonchus contortus. This modified method uses only liquid axenic medium, instead of agar plates inoculated with Escherichia coli, and two selective sieves to obtain adult nematodes. During screening, the use of either balanced salt solution (M-9) or distilled water resulted in averages of 99.7 (± 0.73)% and 96.36 (± 2.37)% motile adults, respectively. Adult worms tolerated DMSO, ethanol, methanol, and Tween 80 at 1% and 2%, while Labrasol (a bioenhancer with low toxicity to mammals) and Tween 20 were toxic to C. elegans at 1% and were avoided as solvents. The high availability, ease of culture, and rapid proliferation of C. elegans make it a useful screening system to test plant extracts and other phytochemical compounds to investigate their potential anthelmintic activity against parasitic nematodes.     

Haemonchus contortus resistance to ivermectin and netobimin in Brazilian sheep.

Suffolk, Texel, Hampshire Down and Ile de France sheep from the municipalities of Porto Amazonas, Piraquara and Araucaria in the State of Paraná, and Bagé in the State of Rio Grande do Sul were brought to Sobral, State of Ceará, to be used in a cross-breeding project. On arrival they had clinical signs of nematode parasitosis, and one Suffolk female died. The animals were treated orally with ivermectin (0.2 mg kg-1) and fifteen days later with netobimin (20.0 mg kg-1). Neither drug reduced the egg counts (measured in eggs per gram, EPG) significantly, and this suggested that the nematodes in the sheep were resistant to the anthelmintics used. Haemonchus contortus was the species involved. The egg counts were reduced after oral treatment with trichlorfon (100.0 mg kg-1). Haemonchus contortus larvae obtained from these animals before trichlorfon treatment and passaged through two nematode-free sheep were used in a further experiment. Twenty 6- to 9-month-old nematode-free lambs were infected with the H. contortus larvae (10,000 per animal) and after the infection was confirmed, were randomly divided into four groups of five animals. Group I was orally treated with ivermectin at 0.2 mg kg-1, Group II with oral netobimin at 20.0 mg kg-1, Group III with oral trichlorfon at 100.0 mg kg-1 and Group IV was a non-treated control. Egg counts and faecal cultures were taken before dosing on the day of treatment and seven days later when all animals were necropsied and the nematodes were collected from the abomasa and counted.(ABSTRACT TRUNCATED AT 250 WORDS)     

秀丽纤杆线虫在寄生性线虫抗原研究中的应用

秀丽纤杆线虫 (Caenorhabditis elegans)是一种模式线虫 ,目前广泛应用于寄生性线虫基因的功能研究 ,并且还被用于捻转血矛线虫等寄生性线虫疫苗侯选抗原基因的表达和耐药性产生机制方面的研究