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-ß 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.

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-ß 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-ß 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-ß 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-ß 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-ß and FCεR1A genes are important modulators of GI nematode infections of Pelibuey lambs.

The nematophagous fungus Duddingtonia flagrans reduces the gastrointestinal parasitic nematode larvae population in faeces of orally treated calves maintained under tropical conditions-Dose/response assessment.

This research assessed the dose/response to Duddingtonia flagrans chlamydospores (Df-C) administered to calves naturally infected with gastrointestinal nematodes (GINs), and its effect in reducing the infective larvae (L3) population in faeces in a farm in the Mexican tropics. Forty zebu calves, between 6 and 12 months of age, were randomly distributed into four groups of 10 calves. One control and three groups treated with different oral doses of Df-C based on their body weight (BW) were established as follows: group 1 (control); group 2, 0.250 × 106Df-C per kg/BW; group 3, 0.5 × 106Df-C per kg/BW and group 4, 1 × 106Df-C per kg/BW. The fungal doses were administered daily for 10 days. Every group was confined to individual pens, and they received a nutritional regime based on Buffel grass, concentrated supplement and water ad libitum. Every third day, starting one week before treatments, faeces were taken from the rectum of each animal to determine the number of eggs per g of faeces (epg) through the McMaster technique. Four coprocultures of 20 g each from each individual faecal sample were prepared and incubated for 14 days. The efficacy of the treatments was based on the mean of the GIN L3 recovered from coprocultures of the different groups. Data were analysed using a completely randomized design through an ANOVA analysis, followed by a Duncan multiple range test. The efficacy of treatments was expressed as the larval reduction rate. High variation in the epg in the different groups along the experiment was recorded. The reduction in the GIN L3 population was observed from the 4 to 11 day post-treatment in the three assessed doses. Results in group 2 (lowest fungal dose), showed 88.5, 57.6, 55.9 and 30% (58% overall reductions) in the GIN L3 in the faeces of animals 4, 7, 9 and 11 days post-treatment, respectively. In group 3 (medium fungal dose), 95.8, 80.4, 63.4 and 52.7% GIN L3 reductions (73% overall reduction) were recorded, respectively. At the highest Df-C dose used (1 × 106 per kg/BW), the results were 88.9, 78.0, 59.3 and 67.3% (73.5% overall reduction), respectively (p < 0.05). The species of identified nematodes through L3 morphometric and molecular taxonomy were Cooperia spp. and H. contortus. From the three Df-C assessed doses, the medium dose (0.5 × 106Df-C per kg/BW) was sufficient to substantially reduce the GIN L3 in zebu calves maintained under conditions in the Mexican tropics.

Phenotype characterization of Pelibuey native lambs resistant to Haemonchus contortus.

Specific phenotypic traits of the blood-feeder nematode Haemonchus contortus were characterized on Pelibuey native, cross-breed sheep in a tropical region of Mexico with background of anthelmintic problems. Data were collected on 4-month-old lambs (n= 63) and analyzed weekly in three stages: stage 1 (S1, not infected (0-3 weeks)); S2, first infection with 350 H. contortus infective larvae (L(3)) per kg of body weight by oral route (3-10 weeks); and S3, second infection with 175 H. contortus L(3) per kg of body weight by oral route (10-18 weeks). Once infection took place, sheep grazed in a free-nematode experimental paddock, and hemoncosis-related traits, such as the number of eggs per gram of feces (epg), packed cell volume (%pvc), and eosinophils (%eo), were measured each week. Results were analyzed on specific traits and stages using SAS statistics. Statistical differences of the main phenotypic traits (P < 0.05) were observed throughout S2 on Pelibuey high (hr) and low (lr) responders, respectively: epg mean, 475 +/- 340.5 and 1439 +/- 243.6; %pvc mean, 31 +/- 0.3 and 27 +/- 0.2; and %eo mean, 2.5 +/- 0.3 and 1.99 +/- 0.2. In addition, lr and hr sheep grazed for 3 months on an area infected with Haemonchus, Cooperia, and Strongyloides, and the hr sheep showed a low number of epg after being exposed to multiple infections, so that no further treatment was required. These results showed that the selection of animals resistant to nematodes can be an alternative method of control against anthelmintic resistance problems in order to improve animal health and avoid a negative environmental impact.