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This study determined the immunoglobulin (A and G) activity against gastrointestinal nematodes (GIN) and also the hematological parameters in four beef-calf breeds naturally infected in a tropical region of Mexico. Thirty-six infected calves were used to determine the fecal nematode egg counts (FEC), the IgA and IgG activity in serum and saliva, the packed cell volume (PCV), the plasmatic protein (PP) and the differential leukocyte counts. These parameters were measured for a five-month period. ELISA assay was performed using adult worm crude antigen (AWCA) from Haemonchus contortus, Trichostrongylus colubriformis, Mecistocirrus digitatus and Cooperia punctata. The variables were analyzed using a fixed model according to the breed group. The FEC records (means ± standard deviation) for the different breeds were: Brangus (122±115), Charolais (391±507), Guzerat (294±326) and Brown Swiss (413±395). No statistical differences (P>0.05) were found among breeds. Cooperia and Haemonchus were the main identified genera in the coprocultures. Differences in hematological parameters were observed among breeds (P<0.01); Guzerat showed the highest PCV (42.6±4.7%). The lowest leukocyte counts were observed in the Charolais breed (9.2±2.4 × 109cells L-1). Differences between Guzerat and Charolais were only detected in eosinophils, neutrophils and lymphocytes. Increased activity of IgA was observed against M. digitatus (21% OD) compared with the response against C. punctata in serum samples (13% OD). The lowest IgA activity in serum and saliva was found in Guzerat calves. Charolais and Brown Swiss showed the highest IgA activity in serum and the highest value in saliva was found in Brangus.

The aim of this study was to characterize the biochemical composition of two main IB-16 Bacillus thuringiensisproteins and to determine their toxicity on the blood-feeder nematode, Haemonchus contortus. The soluble toxin of IB-16 strain of B. thuringiensisproduces 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 vitroassays were carried out using H. contortushistiotropic larvae (L4) 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. thuringiensispurified fractions of 70 and 25?kDa showed lethal activity of 67.1 and 17.3 of toxicity on H. contortusL4, respectively.

The initial infection process of nematode-trapping fungi is based on an interaction between the trapping structure of the fungus and the surface of the nematode cuticle. A bioassay was designed to investigate the predatory response of several isolates of nematode-trapping fungi against 3 mutants of Caenorhabditis elegans (AT6, AT10 and CL261), which have been reported to differ in the reaction of their cuticle to antibodies and lectins. The bioassay was also applied to infective larvae of animal (Haemonchus contortus, Teladorsagia (Ostertagia) circumcincta and Trichostrongylus axei) and plant (Meloidogyne spp.) parasitic nematodes. Differences in trapping ability were most marked in the first 24 h, and were density dependent. Although the isolate of Arthrobotrys responded very rapidly in the first 24 h, Duddingtonia flagrans was generally the most effective isolate and Monacrosporium responded relatively poorly throughout all experiments. All the fungi tested trapped the srf mutants of C. elegans more efficiently than the wild type, and there were differences between the different srf mutants of C. elegans. Differences in trapping ability were also observed between different isolates of D. flagrans; similarly, differences in trapping behaviour were observed not only amongst the different species of plant-parasitic nematodes, but also between the sheathed and exsheathed larvae of the animal-parasitic nematodes.

The effect of hydroalcoholic extracts of fruits and leaves from Caesalpinia coriariaon the egg hatching inhibition of Haemonchus contortusand Haemonchus placeiwas evaluated. The tested concentrations were 25.0, 12.5, 6.2, 3.1, and 1.5 mg/mL; likewise, a 4% methanol solution and albendazole were used as negative and positive controls, respectively. The results were analyzed under a 2 × 2 × 6 factorial arrangement of treatments under a completely randomized design, and for the mean comparison, Tukey's test was used. The mean (LC50) and maximum (LC90) lethal concentrations were estimated with Probit analysis of SAS. The hydroalcoholic leaf extract as well as the fruit extract had ovicidal activity (Table 030; P< 0.05), inhibiting hatching in around 100% with the concentration of 25.0 mg/mL. The fruit extract had better egg hatching inhibition (P< 0.001) in H. contortusand H. placeithan the leaf extract. The LC50for the fruit extract were 1.63 and 3.91 mg/mL and for the leaf were 3.98 and 11.68 mg/mL for H. contortusand H. placei, respectively. The main compounds contained in both extracts were tannins, flavonoids, gallic acid, and ethyl gallate. It is concluded that the hydroalcoholic extracts from mature fruits and leaves of C. coriariahave the ability of inhibit the egg hatching of H. contortusand H. placei.

Arthrobotrys musiformisis a nematophagous fungus with potential for the biological control of Haemonchus contortuslarvae. This study aimed to identify and demonstrate the proteolytic activity of extracellular products from A musiformiscultured in a liquid medium against H contortusinfective larvae. A musiformiswas cultured on a solid medium and further grown in a liquid medium, which was then processed through ion exchange and hydrophobic interaction chromatography. The proteolytic activity of the purified fraction was assayed with either gelatin or bovine serum albumin as substrate. Optimum proteolytic activity was observed at pH 8 and a temperature of 37°C. Results obtained with specific inhibitors suggest the enzyme belongs to the serine-dependent protease family. The purified fraction concentrate from A musiformiswas tested against H contortusinfective larvae. A time-dependent effect was observed with 77 per cent immobility after 48 hours incubation, with alteration of the sheath. It is concluded that Amusiformisis a potential candidate for biological control because of its resistant structures and also because of its excretion of extracellular products such as proteases. The present study contributes to the identification of one of the in vitro mechanisms of action of Amusiformis, namely the extracellular production of proteases against H contortusinfective larvae. More investigations should be undertaken into how these products could be used to decrease the nematode population in sheep flocks under field conditions, thereby improving animal health while simultaneously diminishing the human and environmental impact of chemical-based drugs.