Analysis of P-gp genes relative expression associated to ivermectin resistance in Haemonchus contortus larval stages from in vitro cultures (L3 and xL3) and from gerbils (Meriones unguiculatus) (L4) as models of study

The aim of the study was to compare the relative gene expression of Haemonchus contortus P-glycoprotein genes (Hco-pgp) between fourth (L4), infective (L3), and transitory infective (xL3) larval stages as laboratory models to study ivermectin (IVM) resistance. The H. contortus resistant to IVM (IVMr) and susceptible to IVM (IVMs) strains were used to develop xL3in vitro culture and to infect Meriones unguiculatus (gerbils) to collect L4 stages. Morphometric differences were evaluated from 25 individuals of H. contortus from each strain. Relative gene expression from xL3 and L4 was determined between comparison of IVMr stages and from IVMr vs IVMs stages. Seven Hco-pgp genes (1, 2, 3, 4, 9, 10, and 16) were analysed by RT-qPCR using L3 stage as control group, per strain, and GAPDH and β-tubulin as constitutive genes. Morphological changes were confirmed between xL3 and L4 developing oral shape, oesophagus, and intestinal tube. In addition, the body length and width showed statistical differences (p < 0.05). The Hco-pgp1, 2, 3, and 4 genes (p < 0.05) were upregulated from 7.1- to 463.82-fold changes between IVMr stages, and Hco-pgp9 (13.12-fold) and Hco-pgp10 (13.56-fold) genes showed differences between L4 and xL3, respectively. The comparative study between IVMr vs IVMs strains associated to xL3 and L4 displayed significant upregulation for most of the Hco-pgp genes among 4.89-188.71 fold-change. In conclusion, these results suggest the use of H. contortus xL3 and L4 as suitable laboratory models to study IVMr associated with Hco-pgp genes to contribute to the understanding of anthelmintic resistance.

Phytochemical profile and nematicidal activity of a hydroalcoholic extract from Cazahuate flowers (Ipomoea pauciflora M. Martens & Galeotti) against Haemonchus contortus infective larvae

Haemonchus contortus (Hc) is a hematophagous parasite affecting the health and productivity of flocks. The administration of chemical anthelmintic drugs (AH) is the common method of deworming; however, generates resistance in the parasites to AH and it is a public health risk due to drug residues in milk, meat and sub-products. Natural compounds from plants are explored to diminish this parasitosis, improving their health and productivity, without the negative effects of AH. Ipomoea genus is a group of climbing plants belonging to the Convulvulaceae family possessing perennial leaves and tuberous roots. Medicinal properties has been attributed to this plant including nutritional agents, emetics, diuretics, diaphoretics, purgatives and pesticides. The objective of this study was assessing the in vitro nematocidal activity of a hydroalcoholic extract (HA-E) obtained from Ipomoea pauciflora (Cazahuate) flowers against Hc infective larvae (L3) and to identify its phytochemical profile (PhC-P). The assay was carried out using microtiter plates (MTP). Four HA-E concentrations were assessed and Ivermectin and distilled water were used as positive and negative control groups, respectively. Approximately 100 Hc L3 were deposited in each well (n=12) and incubated at 25-35°C for 7 days. Data were analyzed using ANOVA and a General Linear Model (GLM) followed by Tukey test (P<0.05). The treatments showing a concentration-dependent effect (CDE) were analyzed to identify their 50% and 90% lethal concentrations (CL50, 90) via a Probit Analysis. The highest mortality was observed at 50 mg/mL (82.64 ± 0.71%) and the lowest at 6.25 mg/mL (56.46 ± 2.49%), showing a CDE with increasing mortality from 6.25 to 50 mg/mL. The PhC-P revealed the presence of alkaloids, coumarins, flavonoids, tannins and triterpenes/ sterols. A HA-E from flowers of I. pauciflora will be considered to assess its potential use in the control of haemonchosis in small ruminants.

Cell death induction by mycelium extracts from Pleurotus spp. on cervical cancer cell lines

Mushrooms have health benefits, including anti-tumoral properties. We evaluated the cytotoxic and cell death induction effects of water-soluble extracts of Pleurotus ostreatus and Pleurotus eryngii mycelium in the cervical cancer cell lines HeLa (HVP18⁺) and SiHa (HVP16⁺) as well as the non-tumoral cell line HaCaT. Both Pleurotus extracts presented similar protein patterns from 190 to 10 kDa and displayed protease activity on a gelatine substrate. The mycelium extracts of both Pleurotus strains induced a dose-dependent cytotoxic effect on HPV⁺ cells IC₅₀ 65 µg), whereas HaCaT cells were less susceptible (IC₅₀ 90 µg). The cytotoxic effect at the IC₅₀ concentration was not associated with apoptosis, the activation of Caspases-3/7 was not significantive; only P. eryngii induced a moderate (1.2-fold) increase in SiHa cells. Pleurotus extracts induced autophagy, mainly in SiHa cells (4.3-fold). Neither extracts induced changes in p53 protein expression, suggesting that the cytotoxic effect could be due to p53-independent pathways.

An Artemisia cina n-hexane extract reduces the Haemonchus contortus and Teladorsagia circumcincta fecal egg count in naturally infected periparturient goats

The objective of this study was to evaluate an n-hexane extract of Artemisia cina (Acn-h) as a natural anthelmintic treatment for periparturient goats naturally infected with the nematodes Haemonchus contortus and Teladorsagia circumcincta. A total of 200 periparturient Alpine and Nubian goats were used. Deworming criteria were based on the following parameters: fecal egg account (epg), ocular mucosa color (OMC), and body condition (BC). A previous analysis using coprocultures of the flock revealed the presence of H. contortus (80%) and T. circumcincta (20%). The Acn-h contained two new compounds identified by mass spectrometry data as isoguaiacin and norisoguaiacin at 284.14 and 315 m/z. The lethal effects of Acn-h at 0.5, 1, 2, and 4 mg/mL on H. contortus adult stages were 31.6, 66.5, 81.3, and 86.9%, respectively (p < 0.05), showing similar efficacy at 2 and 4 mg/mL with albendazole (positive control group). Then, two experimental groups, with 100 goats in peripartum in each, were distributed randomly and treated at day 0 as follows: group 1 = 4 mg/kg of Acn-h as single oral dose, and group 2 = control group, treated with water (as a placebo). The epg, OMC, and BC parameters were recorded at 0 (periparturient period), 7 (birth period), and 23 (postpartum) days and analyzed using a completely randomized design with Duncan's test for comparison of means and analysis of variance. The following epg reductions were recorded in the Acn-h-treated group as follows: 20.1 ± 34.4 and 31.7 ± 38.2% at days 7 and 23 compared to the control group. During the whole experiment, no significant differences in OMC or BC were observed in relation to the control group, excepting at day 23 (p < 0.05) for BC in the group treated with A. cina. Thus, Acn-h can be a useful natural alternative tool for the control of the nematodes H. contortus and T. circumcincta in periparturient goat flocks.

Analysis of the immunomodulatory activity of excreted and secreted products from Haemonchus placei transition infective larvae (xL3)

The excretory/secretory (E/S) products released by infective transitory larvae (xL₃) of Haemonchus placei have an important biological function in stimulating immune mechanisms during the invasive process. Our objective was to analyse the modulatory activity of 15 and 70 kDa E/S products from H. placei xL₃. Both E/S products were collected from xL₃in vitro cultures at 24 and 72 h. Proteins were confirmed by SDS-PAGE, and the corresponding spots were elicited by gel isoelectrofocusing (IEF) and characterised by mass spectrometry. Additionally, flow cytometry of CD4⁺/γδ⁺ T cells and immune gene expression were performed by proliferation assays using each E/S product to stimulate lymphocyte and peripheral blood mononuclear cells (PBMCs) from non-infected calves. The IEF results displayed two spots of 7.0 and 5.7 pI for the 15 and 70 kDa products, respectively. Additionally, 29 and 17 peptides from the 15 and 70 kDa E/S products, respectively, were identified with the hypothetical neurotransmitter and enzymatic functions necessary for larval development. The relative expression displayed upregulation of IL4, 5, 6, 8, 10, 13, IFNγ, and FCεR1A genes (from 2.0- to 17.6-fold, p < 0.05) stimulated by the 15 and 70 kDa proteins, indicating specific genes against haemonchosis. Although the percentage of median florescence intensity (MFI%) of CD4⁺/γδ⁺ T cells did not change for both E/S products compared to the negative control and concanavalin-A stimulated cells as the positive control (p > 0.05), the 15-kDa protein reduced the levels of both T cells, and the 70-kDa proteins increased the γδ⁺ cells slightly. Additionally, there was increased PBMCs proliferation by the 70 kDa proteins (p < 0.05), denoting the biological role of other immune cells. The 15 and 70 kDa protein E/S products from H. placei xL₃ showed modulation of the immune response, and although more studies are required, they indicate important functions in the host/parasite interaction.

Haemonchus contortus infection induces a variable immune response in resistant and susceptible Pelibuey sheep

The immune response and phenotypic characteristics of Pelibuey lambs were analysed after the induction of a Haemonchus contortus trickle infection. Male lambs (n = 29; 20 kg live weight) were infected with 100 H. contortus infective larvae per kg of live weight on day 3, 5 and 7 of the experiment. The number of eggs per gram (epg), seven haematological parameters and the immunoglobulin A (IgA) level were analysed for 56 experimental days. In addition, histopathological samples from the fundic abomasal region and the relative expression of 10 immune-related genes from 15 infected and three non-infected lambs were analysed at day 0 and 49 of the experiment. The epg count and some haematological parameters (leucocytes, red blood cells, haemoglobin and total protein) with statistically significant differences (P < 0.01) were used to identify nine resistant and 20 susceptible lambs (1166 ± 1071 and 3171 ± 1463 epg, respectively). Moreover, acute infiltration of immune cells and parasitic granuloma formation were observed in susceptible lambs; the resistant group had moderate inflammatory cell infiltration. With respect to relative gene expression, resistant lambs showed upregulation (P < 0.001) of 10 genes, from 2.2 to 15.99 fold. Moreover, there was a strong indirect correlation (P < 0.05) between the epg count and interleukin 5 (IL5) gene expression. By contrast, there was an average 0.34 fold downregulation in nine of the immune-related genes (P ≤ 0.05) in susceptible lambs (the only exception was Fc fragment of IgE receptor Ia [FCER1A] upregulation). In addition, there was a direct correlation (P ≤ 0.05) between the epg count and the expression of IL8, which encodes an inflammatory chemokine. In conclusion, this study showed differential IL5 and IL8 gene expression during haemonchosis in resistant and susceptible Pelibuey lambs, respectively, together with a variable immune response based on histopathological and haematological parameters.

The immune gene expression induced by Cooperia punctata in naturally infected calves with resistance and susceptible phenotype traits

The analysis of the immune gene expression was performed in Zebu × Holstein calves with resistant and susceptible phenotypes naturally infected with Cooperia punctata. Fourteen calves of 4 months old were grazed for 11 weeks under a tropical climate. The parasitic infection showed an average epg value of 1055 ± 1155 and an IgG optical density of 0.814 ± 0.0.037 with statistic differences among the different weeks (p < 0.05), and a pcv value of 24 ± 2.0 % (p > 0.05). High variation in epg value was observed, between 7 ± 7.14 and 4657 ± 1886, and, based on these differences; the infected hosts were classified as five resistant calves with epg ≤ 200 and nine susceptible calves with epg ≥ 300. Moreover, IgG levels displayed statistical differences between resistance and susceptible calves to C. punctata infection. The immune gene expression was analysed in three resistant and susceptible calves, respectively. Nine cytokine genes and the FCεR1A receptor were analysed at the 3rd and 11th weeks post-infection. In the first period upregulation was found, from 2.19- to 9.45-fold, (p < 0.05) for IL-2, -5, - 6, -10, TGF-β and FCεR1A in the resistant group; the expression was decreased at the 11th week with low level of IgG. In contrast, downregulation for susceptible calves was found for nine immune genes and upregulation for INF-γ in both periods together with increased IgG levels. In conclusion, immune gene expression was regulated at the begging infection of C. punctata in resistant grazing calves. In contrast, suppression of important genes was involved in calves susceptible to C. punctata.

In Vitro and In Vivo Nematicide Effect of Extract Fractions of Pleurotus djamor Against Haemonchus contortus

Sheep haemonchosis is a disease that causes anemia, diarrhea, weight loss, low production, and even death of young animals. This represents a negative economic impact on the livestock sector. For decades, chemicals have been used to control this parasitic disease; however, cases of anthelmintic resistance have increased around the world. For this reason, the search for control alternatives is necessary. Several studies have shown that edible mushrooms of Pleurotus genus have different medicinal properties, including nematicidal activity. In this study, the chromatographic fractionation of the hydroalcoholic extract of fruiting bodies Pleurotus djamor was carried out to identify and isolate the metabolites responsible for nematicidal activity. From the fractionation of the extract, the fraction PdR2 and the subfraction PdB were obtained, which were evaluated against Haemonchus contortus under in vitro conditions. The nematicidal effect of the fraction PdB in gerbils infected artificially with H. contortus was evaluated. Finally, the analysis of the PdB fraction by gas chromatography-mass spectrometry and nuclear magnetic resonance was carried out. The results showed that the PdB had 100% of egg hatching inhibition from 5 mg/mL. Regarding larvicidal activity, it presented >97.2% from 24 h to 20 mg/mL. The in vivo evaluation of the PdB fraction showed a reduction of H. contortus larvae of 92.56%. The compounds present in this fraction were the mixture of allitol and an unidentified terpene in a ratio of 9:1. The PdB fraction is a potential alternative for the control of H. contortus, where allitol and a terpene could be responsible for nematicidal activity.

Immune response related to Pelibuey sheep naturally infected with gastrointestinal nematodes in a tropical region of Mexico

We analysed the immune response involved in sheep naturally infected with gastrointestinal (GI) nematodes. Fifteen Pelibuey lambs were grazed in paddocks contaminated with GI nematodes for 13 weeks. To assess the infection, the number of eggs per gram (epg) and the percentage of packed cell volume (pcv) were evaluated. Blood and abomasal tissue samples were collected at week 8 post-infection to analyse the expression levels of IL-4, IL-5, IL-6, IL-8, IL-13, TGF-β and FCεR1A genes. The nematode Haemonchus contortus was the main species identified. In addition, two groups of lambs were classified based on the x ± SE of epg and pcv values: G-1, with 151 ± 28 and 29 ± 0.33%, respectively, and G-2, with 475 ± 59.5 and 26 ± 0.38%, respectively. For G-1, upregulation of IL-4, IL-8, IL-13, TGF-β and FCεR1A genes from 2.42- to 14.99-fold was observed in blood and abomasal tissue samples (p > .05), and IL-5, IL-8 and TGF-β genes had significant gene expression levels in blood (p < .05). For G-2, moderate gene expression levels, ranging from 1.22- to 3.45-fold, were observed in abomasal tissue (p > .05), and the IL-5 gene presented significant gene expression in blood (p < .05). Strong positively correlated values (r) between pcv and IL-4, IL-8 and TGF-β genes were observed in G-1. In contrast, significant negative correlations between epg and IL-4, IL-5 and FCεR1A genes indicate acute infection for G-2. Our results suggest that IL-4, IL-5, IL-13, TGF-β and FCεR1A genes are important modulators of GI nematode infections of Pelibuey lambs.

Molecular mechanisms of cell death induced in glioblastoma by experimental and antineoplastic drugs: New and old drugs induce apoptosis in glioblastoma

Glioblastoma multiforme (GBM) is one of the most aggressive astrocytic tumors; it is resistant to most chemotherapeutic agents currently available and is associated with a poor patient survival. Thus, the development of new anticancer compounds is urgently required. Herein, we studied the molecular mechanisms of cell death induced by the experimental drugs resveratrol and MG132 or the antineoplastic drugs cisplatin and etoposide on a human GBM cell line (D54) and on primary cultured mouse astrocytes (PCMAs). Caspases, Bcl-2, inhibitors of apoptosis proteins (IAP) family members, and p53 were identified as potential molecular targets for these drugs. All drugs had a cytotoxic effect on D54 cells and PCMAs, with a similar inhibitory concentration (IC₅₀) after 24 h. However, MG132 and cisplatin were more effective to induce apoptosis and autophagy than resveratrol and etoposide. Cell death by apoptosis involved the activation of caspases-3/7, -8, and -9, increased lysosomal permeability, LC3 lipidation, poly-(ADP-ribose) polymerase (PARP)-1 fragmentation, and a differential expression of genes related with apoptosis and autophagy like Mcl-1, Survivin, Noxa, LC3, and Beclin. In addition, apoptosis activation was partially dependent on p53 activation. Since experimental and antineoplastic drugs yielded similar results, further work is required to justify their use in clinical protocols.

Immune response in Blackbelly lambs to Haemonchus contortus and Trichostrongylus colubriformis mixed infection in a hot and humid climate

The main objective was to determine the immune response of Blackbelly lambs infected with Haemonchus contortus, Trichostrongylus colubriformis, or both species. In the first stage, an experimental challenge was performed with 200 infective larvae (L3)/kg body weight (BW) of H. contortus (Hct, n = 8). Additionally, eight animals were infected with 500 L3/kg BW of T. colubriformis (Tcl), eight lambs with the mixed infection at the same dose (HctTcl), and lambs without infection were the control group. In the second infection, the same lambs were reinfected with high doses: 400 L3/kg BW of Hct and 900 L3/kg BW of Tcl. The third stage consisted of a natural reinfection in grazing. Faecal samples were taken to determine the faecal egg count (FEC) of gastrointestinal nematodes (GINs). IgA was determined in serum and saliva by an indirect Enzyme-Linked Immuno Sorbent Assay (ELISA). The haematological parameters were recorded. With the first challenge, it was not possible to promote an immune response, whereas in the second infection, FEC were higher than 1000 eggs per gram of faeces (EPG) in infected animals. During the third stage, FECs were higher in lambs infected with Tcl. Eosinophils (EOS) did not show differences in the first and second stages, but during grazing the infected lambs had higher counts than the control group (P andlt; 0.05). IgA activity values showed the same trend, and lambs infected with HctTcl had a higher response (33% of the positive standard) than groups mono-infected (16.5% and 22.6%, respectively).

Influence of the physiological stage of Blackbelly sheep on immunological behaviour against gastrointestinal nematodes

The influence of the physiological stage of a Blackbelly flock against natural infection by gastrointestinal parasitic nematodes (GIN) was investigated. Data on serum and saliva IgA levels and peripheral cellular immune response were recorded in 51 sheep for 6 months. The flock was divided based on their physiological stage as follows: a) pregnant ewes, b) lactating ewes, c) non-pregnant ewes, d) pre-weaning lambs, e) growing lambs and f) replacement sheep. Additionally, sheep were classified based on the parasite infection as stabled or grazing management system as follows: g) non-infected stabled sheep, h) infected and stabled sheep and i) infected grazing sheep. Faeces and blood samples were collected every fifteen days. The percentage of packed cell volume (PCV), plasma protein, (PP) and leucocyte differential counts (LDC) were recorded. Likewise, serum and saliva IgA levels were measured by the indirect ELISA technique. The number of GIN eggs excreted per g of faeces (EPG) was also determined using the McMaster technique. Data were analysed using the SAS program to identify fixed effect of physiological stages, infection time and interactions. Results showed high EPG values in stabled lactating ewes (2764) and in growing lambs (2950-4550 EPG). Pregnant ewes had higher PCV values (27%) than lactating ewes (23.5%). Infected lambs showed low PCV values (28.5%) and high PP values (5.9 g/dL) compared with non-infected lambs (31% PCV and 5.6 g/dL PP). The two most abundant GIN species identified were Haemonchus contortus (91%) and Trichostrongylus colubriformis (81%). Pregnant and non-pregnant ewes showed 29% and <20% of IgA values, respectively. High EPG, low IgA and eosinophils counts were observed until 180 days of age in infected lambs. In conclusion, the group of infected lactating ewes and lambs showed susceptibility to GIN than the other groups, including the pregnant ewes.

Caffeoyl and coumaroyl derivatives from Acacia cochliacantha exhibit ovicidal activity against Haemonchus contortus

ETHNOPHARMACOLOGY RELEVANCE

Acacia cochliacantha is a small tree whose foliage is traditionally used in Mexico for treatment of kidney pain, gastrointestinal illnesses and to kill intestinal parasites. In recent decades, the study of vegetal extracts has offered other possible alternatives for the control of Haemonchus contortus. Considering that this nematode affects dramatically the health and productivity of small ruminants, the aim of this study was to identify the anthelmintic compounds from A. cochliacantha hydro-alcoholic extract (HA-E) through an ovicidal test.

MATERIAL AND METHODS

In vitro egg hatch assay was conducted to determinate the anthelmintic effects of a HA-E (60g). Liquid-liquid ethyl acetate/water extraction gave two fractions (EtOAc-F, 1.92g; Aq-F; 58.1g). The less polar compounds from ethyl acetate fraction were extracted by addition of dichloromethane offering a precipitate phase (Mt-F, 1.25g) and a soluble mixture (DCMt-F 1.15g). All fractions were evaluated for ovicidal activity obtaining the egg hatching inhibition (EHI, 0.07-25mg/mL). Ivermectin (0.5mg/mL) was used as a reference drug (positive control), and distilled water, 2.5% DMSO and 2% methanol were used as negative controls. The isolated compounds from the most active fractions were subjected to spectroscopic (¹H NMR) Spectrometric (MS) and UV HPLC analysis in order to identify the bioactive compounds.

RESULTS

The less polar treatments (AcOEt-F, DCMt-F, DCMt-P) showed the highest ovicidal activities (98-100% EHI; at 0.62-1.56mg/mL) and the major compounds found in these fractions were identified as caffeoyl and coumaroyl derivatives, including caffeic acid (1), p-coumaric acid (2), ferulic acid (3), methyl caffeate (4), methyl-p-coumarate (5), methyl ferulate (6) and quercetin. In case of the less active fractions (Aq-F, Mt-F) were constituted principally by glycosylated flavonoids.

CONCLUSION

These results show that caffeoyl and coumaroyl derivatives from Acacia cochliacantha leaves had promising anthelmintic activity against Haemonchus contortus. This leguminous may offer an alternative source for the control of gastrointestinal nematodes of small ruminants.

Biochemical characterization of two purified proteins of the IB-16 Bacillus thuringiensis strains and their toxicity against the sheep nematode Haemonchus contortus in vitro

The aim of this study was to characterize the biochemical composition of two main IB-16 Bacillus thuringiensis proteins and to determine their toxicity on the blood-feeder nematode, Haemonchus contortus. The soluble toxin of IB-16 strain of B. thuringiensis produces five main bands of proteins, the chemical composition of which might play an important role on the lethal activity. Two bands of proteins around 25 and 70 kDa were chosen and purified by HPLC using a hydrogel column and sephadex-beads G-50. Biochemical analysis was carried out to determine enzyme and carbohydrate moieties on purified fractions of the 25 and 70 kDa proteins. In addition, in vitro assays were carried out using H. contortus histiotropic larvae (L(4)) and the purified fractions. Biochemical results showed only enzyme activity in the purified fraction of the 25 kDa protein using gelatine as the substrate. In contrast, carbohydrate moieties were only observed in the purified fraction of the 70 kDa protein. Moreover, IB-16 B. thuringiensis purified fractions of 70 and 25 kDa showed lethal activity of 67.1% and 17.3% of toxicity on H. contortus L(4), respectively.

The predatory capability of three nematophagous fungi in the control of Haemonchus contortus infective larvae in ovine faeces

The effect of oral administration of three different nematode-trapping fungi, in aqueous suspension containing either Dactylaria sp. or Arthrobotrys oligospora conidia or Duddingtonia flagrans chlamydospores, on the number of Haemonchus contortus infective larvae in sheep faeces, was evaluated. The three selected species of fungi produce three-dimensional adhesive nets in the presence of nematodes. Sixteen Creole sheep were divided into four groups of four animals each. Groups 1 and 2 were orally drenched with a suspension containing 2x10(7) conidia of either A. oligospora or Dactylaria sp. Group 3, received a similar treatment, with D. flagrans chlamydospores, instead of conidia, being administered, at the same dose. Group 4 acted as control, without any fungi. Faecal samples were collected directly from the rectum of each sheep and faecal cultures were prepared and incubated at 15 and 21 days. Larvae were recovered from faecal cultures and counted. The highest reduction of the nematode population occurred in the D. flagrans group, reaching reductions of 96.3% and 91.4% in individual samplings in plates incubated for 15 and 21 days, respectively. Arthrobotrys oligospora showed moderate reductions in the faecal larval population, ranging between 25-64% at 15 days incubation. In general, Dactylaria sp., was less efficient in its trapping ability. Despite the inconsistent results with Dactylaria sp., reduction percentages of 73.4% and 80.7% were recorded in individual samplings during the first and second days, in plates incubated for 15 days. Duddingtonia flagrans, was shown to be a potential biological control agent of H. contortus infective larvae.

Cryopreservation of infective larvae of Haemonchus contortus

Three freeze protectants were evaluated to preserve H. contortus infective larvae. Freezing solutions used: A) saline solution phosphate buffer pH 7.2 (PBS); B) 10% DMSO (dimethyl sulphoxide); C) 10% glycerol. Fifty thousand infective larvae were put into each of 10 vials per freeze protectant and then stored into liquid nitrogen. Results were based on the motility of the larvae under a light microscope at 30, 90, 180, and 360 days of freezing. Ten vials of each freeze protectant were removed from the liquid nitrogen at these times and immediately were put on water at 37 C during a minute. Motility percentages obtained were as follows: PBS: 36%, 20%, 7% and 39%; DMSO,: 87%, 69%, 46% and 85%; glycerol: 67%, 62%, 29% and 55%; at 30, 90, 180 and 360 days respectively. Inoculation of infectiva larvae from DMSO and glycerol to calves was successful after 28 days. DMSO was a better freeze preserver for H. contortus.

A new method for serodiagnosis of sheep fascioliasis using helminth excretory-secretory products

The diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA) for antibodies to Fasciola hepatica was evaluated using adult fluke excretory-secretory products as antigen. The sensitivity and specificity of the test were compared with those of the indirect hemagglutination (IHA) technique. The results of the DIG-ELISA showed that the reaction zone diameters obtained with 42 sera from sheep with natural or experimental exposure to F. hepatica were significantly greater than those obtained with 85 sera from ovines infected with other parasites. Both sensitivity and specificity were 100% in the DIG-ELISA, whereas the sensitivity was 68.2% and the specificity was 100% in the IHA. The data suggest that the DIG-ELISA is a valuable serodiagnostic test for sheep fascioliasis.