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Actin is a globular multi-functional protein that forms microfilaments, and participates in many important cellular processes. Previous study found that Haemonchus contortus actin could be recognized by the serum of goats infected with the homology parasite. This indicated that H. contortus actin could be a potential candidate for vaccine. In this study, DNA vaccine encoding H. contortus actin was tested for protection against experimental H. contortus infections in goats. Fifteen goats were allocated into three trial groups. The animals of Actin group were vaccinated with the DNA vaccine on day 0 and 14, and challenged with 5000 infective H. contortus third stage larval (L3) on day 28. An unvaccinated positive control group was challenged with L3 at the same time. An unvaccinated negative control group was not challenged with L3. The results showed that DNA vaccine were transcribed at local injection sites and expressed in vivo post immunizations respectively. For goats in Actin vaccinated group, higher levels of serum IgG, serum IgA and mucosal IgA were produced, the percentages of CD4+ T lymphocytes, CD8+ T lymphocytes and B lymphocytes and the concentrations of TGF-β were increased significantly (P<0.05). Following L3 challenge, the mean eggs per gram feces (EPG) and worm burdens of Actin group were reduced by 34.4% and 33.1%, respectively. This study suggest that recombinant H. contortus Actin DNA vaccine induced partial immune response and has protective potential against goat haemonchosis.
Surface proteins of the nematode Haemonchus contortus were biochemically characterized and their antigenic properties were investigated. Living parasites were labelled with NHS-biotin. Next, extracts were made using cetyltrimethylammonium bromide (СТАВ), Tris buffered saline (TBS), sodium dodecyl sulphate (SDS) and 2-mercaptoethanol (BME) as solubilizing agents. The presence of glycoproteins in the extracts was examined by probing Western blots with the lectin Concanavalin A (Con A). The antigenic character of the surface proteins was studied by immunoblotting. Glycosylated polypeptides constituted the major part of the surface molecules of larvae, whereas the proportion of glycoproteins in adults is relatively smaller. Surface biotinylation of intact nematodes revealed that СТАВ-, TBS- and SDS-soluble proteins belong to the epicuticle of larvae. СТАВ- and TBS-soluble proteins are present in the surface of adult worms. Many surface proteins of H. contortus were recognized by hyperimmune sera. It was found that the majority of these antigens possess carbohydrate epitopes. However, antigens with nonsugar epitopes are also present in the epicuticle.
The large stomach worm, Haemonchus contortus is a highly pathogenic nematode parasite of sheep (Ovis aries) and goats (Capra hircus). It sucks blood and causes acute disease, anaemia and severe economic losses due to morbidity and mortality. This paper compares characteristics of surface cuticular ridges (synlophe) and morphometrics of total body length, cervical papillae, spicules, barbs, gubernaculum and vulvar flap morphology of H. contortus recovered in the two hosts from the States of Perak and Kelantan, Peninsular Malaysia. The morphological variation in H. contortus samples recovered from the two hosts in Kelantan was found to be higher than from Perak. A discriminant function, based on three measurements of the spicule, confirmed the identity of male worms in the two hosts as belonging to the same species H. contortus.
A study on the influence of gastrointestinal trichostrongyles on ram fertility was performed. Two groups of semen donor rams (Sarda breed) were utilized; one was experimentally infected with Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta and the other was used as a control group. In all animals, coprological, haematological and reproductive parameters were studied. The results suggest that the parasites had a limited effect with some changes in phosphorus, cholesterol and chlorine levels. In our experience the parasitic burden produced no significant change on ram fertility.
Faecal nematode egg counts and IgG activity to Haemonchus contortus were followed in naturally infected Polish Wrzosówka ewes. The egg counts were overdis- persed; most individuals had relatively low egg counts but a small proportion had high counts. Egg production followed a different pattern each grazing season. Larvae cultured from eggs in 1996 were predominantly H. contortus and Trichostrongylus spp. In 1997 the recoveries were largely Trichostrongylus spp. In 1998, larval recoveries were mainly Trichostrongylus spp. and Teladorsagia spp. There were no discernible patterns in the composition of the nematode population within each grazing season. Egg counts in different months were moderately repeatable, indicating that animals tended to maintain their rankings over time. The repeatabilities rose during the grazing season but declined with increasing intervals between sample dates. IgG activity against a somatic extract of adult H. contortus was higher than activity against a preparation from excretory/secretory antigens but the two responses were very strongly correlated. The repeatability of IgG activity at monthly intervals was higher than the repeatability of faecal egg counts. Animals with higher than average IgG activity had significantly lower than average egg counts but only in the last two years of the study. A combination of egg counts and antibody responses may be better at identifying resistant animals than either method used in isolation, but more research is necessary to determine why the association between antibody and egg counts varies in different years.
The association between faecal egg counts and serum IgG response against somatic (SAg) and two excretory/secretory antigens (ESAg-4h, ESAg-24h) obtained from adult Haemonchus contortus was monitored over one season in young Polish Wrzosówka ewes naturally infected with gastrointestinal nematodes. There was a considerable variation in faecal egg counts and in the proportion of larvae from each species recovered from faeces at different months. Very similar IgG responses against the three antigen preparations were observed; the differences among months were significant. The distribution of antibody among young ewes was unimodal and positively skewed. The repeatabilities of IgG responses against SAg and ESAg-24h were all positive and statistically significant, although repeatabilities against ESAg-4h were of border line significance. The correlation coefficients among IgG responses tended to increase in the second half of season. There was a significant association between increased IgG responses to somatic antigens and reduced faecal egg counts. The combination of antibody responses against different antigen preparations of H. contortus and faecal egg counts appear better at identifying resistant Polish Wrzosówka sheep than either method used in isolation.
In an experimental flock of Polish long-wool sheep (PL), rams and ewes were progressively replaced by Blackface (Bl) and Weisses Alpenschaf (WA) sheep. The ewes and their lambs were naturally infected with predominantly Teladorsagia circumincta and Haemonchus contortus nematode species. A survey was done from 1995 to 2000 by regular FECs. Significant fixed effects were: the timing of last anthelmintic treatment, month and year of sampling in ewes and lambs, plus the age (yearling or not) and the suckling effort for the ewes as well as the sex of the lambs. The breed effect was highly significant, PL ewes xcreted three times fewer eggs than Bl. Also PL and WA lambs possessed 1.5 fewer nematode eggs in their faeces than Bl ones. It is concluded that introduction of Bl and WA for breeding will require more careful control of nematode infection than the management of the local long-wool breed.
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