Cellular and humoral immune responses associated with protection in sheep vaccinated against Teladorsagia circumcincta.

Due to increased anthelmintic resistance, complementary methods to drugs are necessary to control gastrointestinal nematodes (GIN). Vaccines are an environmentally-friendly and promising option. In a previous study, a Teladorsagia circumcincta recombinant sub-unit vaccine was administered to two sheep breeds with different levels of resistance against GIN. In the susceptible Canaria Sheep (CS) breed, vaccinates harboured smaller worms with fewer eggs in utero than the control group. Here, we extend this work, by investigating the cellular and humoral immune responses of these two sheep breeds following vaccination and experimental infection with T. circumcincta. In the vaccinated CS group, negative associations between antigen-specific IgA, IgG2 and Globule Leukocytes (GLs) with several parasitological parameters were established as well as a higher CD4+/CD8+ ratio than in control CS animals, suggesting a key role in the protection induced by the vaccine. In the more resistant Canaria Hair Breed (CHB) sheep the vaccine did not significantly impact on the parasitological parameters studied and none of these humoral associations were observed in vaccinated CHB lambs, although CHB had higher proportions of CD4+ and CD8+ T cells within the abomasal lymph nodes, suggesting higher mucosal T cell activation. Each of the component proteins in the vaccine induced an increase in immunoglobulin levels in vaccinated groups of each breed. However, levels of immunoglobulins to only three of the antigens (Tci-MEP-1, Tci-SAA-1, Tci-ASP-1) were negatively correlated with parasitological parameters in the CS breed and they may be, at least partially, responsible for the protective effect of the vaccine in this breed. These data could be useful for improving the current vaccine prototype.

Vaccination against the brown stomach worm, Teladorsagia circumcincta, followed by parasite challenge, induces inconsistent modifications in gut microbiota composition of lambs.

BACKGROUND: Growing evidence points towards a role of gastrointestinal (GI) helminth parasites of ruminants in modifying the composition of the host gut flora, with likely repercussions on the pathophysiology of worm infection and disease, and on animal growth and productivity. However, a thorough understanding of the mechanisms governing helminth-microbiota interactions and of their impact on host health and welfare relies on reproducibility and replicability of findings. To this aim, in this study, we analysed quantitative and qualitative fluctuations in the faecal microbiota composition of lambs vaccinated against, and experimentally infected with, the parasitic GI nematode Teladorsagia circumcincta over the course of two separate trials performed over two consecutive years. METHODS: Two trials were conducted under similar experimental conditions in 2017 and 2018, respectively. In each trial, lambs were randomly assigned to one of the following experimental groups: (i) vaccinated/infected, (ii) unvaccinated/infected and (iii) unvaccinated/uninfected. Faecal samples collected from individual animals were subjected to DNA extraction followed by high-throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene and bioinformatics and biostatistical analyses of sequence data. RESULTS: Substantial differences in the populations of bacteria affected by immunisation against and infection by T. circumcincta were detected when comparing data from the two trials. Nevertheless, the abundance of Prevotella spp. was significantly linked to helminth infection in both trials. CONCLUSIONS: Despite the largely conflicting findings between the two trials, our data revealed that selected gut microbial populations are consistently affected by T. circumcincta infection and/or vaccination. Nevertheless, our study calls for caution when interpreting data generated from in vivo helminth-microbiome interaction studies that may be influenced by several intrinsic and extrinsic host-, parasite- and environment-related factors.

Purpureocillium lilacinum and Trichoderma virens for biological control of trichostrongylid parasites of sheep: an in vitro evaluation.

The study evaluated the ovicidal activity of enzymatic extracts of Purpureocillium lilacinum and Trichoderma virens against trichostrongylid eggs from sheep. Filtered extract (FE) and macerated crude extract (MCE) were prepared from fungal cultures in minimal broth. In the experiment, 100 trichostrongylid eggs, obtained from the feces of naturally infected sheep, were exposed to fungal extracts for 24 and 48 hours/25°C. In the control group, eggs were incubated in minimal broth. The number of L1 larvae was ascertained. Each treatment consisted of four repetitions and the experiment was repeated five times. It was observed that the effect of FE and MCE of P. lilacinum and T. virens on egg hatchability differed from that of the control group. MCE of T. virens and P. lilacinum showed higher ovicidal activity than FE over both periods and at 48 hours of exposure, respectively. From the percentage reductions in hatchability of the eggs, MCE was shown to be superior to FE for both fungi. This study demonstrated the ovicidal potential of these fungi against trichostrongylid eggs. However, further studies are needed in order to identify the molecules responsible for the ovicidal effects, and to evaluate the behavior of fungal extracts in biotic and abiotic interactions.

Purpureocillium lilacinum and Trichoderma virens for biological control of trichostrongylid parasites of sheep: an in vitro evaluation / Purpureocillium lilacinum e Trichoderma virens no controle biológico de tricostrongilídeos de ovinos: uma avaliação in vitro

Abstract The study evaluated the ovicidal activity of enzymatic extracts of Purpureocillium lilacinum and Trichoderma virens against trichostrongylid eggs from sheep. Filtered extract (FE) and macerated crude extract (MCE) were prepared from fungal cultures in minimal broth. In the experiment, 100 trichostrongylid eggs, obtained from the feces of naturally infected sheep, were exposed to fungal extracts for 24 and 48 hours/25°C. In the control group, eggs were incubated in minimal broth. The number of L1 larvae was ascertained. Each treatment consisted of four repetitions and the experiment was repeated five times. It was observed that the effect of FE and MCE of P. lilacinum and T. virens on egg hatchability differed from that of the control group. MCE of T. virens and P. lilacinum showed higher ovicidal activity than FE over both periods and at 48 hours of exposure, respectively. From the percentage reductions in hatchability of the eggs, MCE was shown to be superior to FE for both fungi. This study demonstrated the ovicidal potential of these fungi against trichostrongylid eggs. However, further studies are needed in order to identify the molecules responsible for the ovicidal effects, and to evaluate the behavior of fungal extracts in biotic and abiotic interactions.

Resumo O estudo avaliou a atividade ovicida de extratos enzimáticos de Purpureocillium lilacinum e Trichoderma virens sobre ovos de tricostrongilídeos de ovinos. Extrato filtrado (EF) e extrato macerado bruto (EMB) foram preparados a partir de culturas fúngicas em caldo mínimo. No ensaio experimental, 100 ovos de tricostrongilídeos, obtidos de fezes de ovinos naturalmente infectados, foram expostos durante 24 e 48 horas/25ºC aos extratos dos fungos. No grupo controle, os ovos foram incubados em caldo mínimo. O número de larvas L1 foi determinado. Cada tratamento consistiu em quatro repetições e o experimento foi repetido cinco vezes. Observou-se que o efeito ovicida do EF e EMB de P. lilacinum e T. virens diferiu do grupo controle. O EMB de T. virens e P. lilacinum evidenciou atividade ovicida superior ao EF em ambos os períodos avaliados e em 48 horas de exposição, respectivamente. O percentual de redução de eclodibilidade evidenciou que o EMB foi superior ao EF em ambos os fungos. Este estudo demonstra o potencial ovicida desses fungos sobre ovos de tricostrongilídeos. No entanto, estudos adicionais são necessários para identificar as moléculas responsáveis pelo efeito ovicida, bem como avaliar o comportamento dos extratos fúngicos em interações bióticas e abióticas.

Impacts of breed type and vaccination on Teladorsagia circumcincta infection in native sheep in Gran Canaria.

Vaccines and genetic resistance offer potential future alternatives to the exclusive use of anthelmintics to control gastrointestinal nematodes (GIN). Here, a Teladorsagia circumcincta prototype vaccine was administered to two sheep breeds which differ in their relative levels of resistance to infection with GIN. Vaccination of the more susceptible Canaria Sheep (CS) breed induced significant reductions in worm length and numbers of worm eggs in utero (EIU) when compared to control CS sheep. In the more resistant Canaria Hair Breed (CHB), although vaccination induced a reduction in all parasitological parameters analysed, differences between vaccinated and control sheep were not statistically significant. Such interactions between sheep breed and vaccination may allow better integrated control of GIN in future.

The rational simplification of a recombinant cocktail vaccine to control the parasitic nematode Teladorsagia circumcincta.

Using data from five independent vaccine trials, which employed a subunit cocktail vaccine containing eight recombinant proteins to protect sheep against Teladorsagia circumcincta, a strategy was developed to simplify antigen complexity of the vaccine. A meta-analysis of data from these five trials demonstrated statistically significant reductions in cumulative faecal egg count and worm burden in vaccinated sheep when compared with those which had received adjuvant only (P = 0.009 and P < 0.0001, respectively). Relationships between antigen-specific antibody levels, antibody avidity and parasitological parameters of efficacy were analysed for each of the eight proteins in these trials. Of these, the strongest correlations between percentage reduction in cumulative faecal egg count and avidity were obtained for the vaccine antigen T. circumcincta apyrase-1 (Tci-APY-1) in relation to either total antigen-specific IgG or IgG1 in sera (P = 0.019 and P = 0.030, respectively). In addition, IgG and IgA within the serum and abomasal mucus of control (parasite challenged) lambs strongly recognised Tci-APY-1 and T. circumcincta metalloproteinase-1 (Tci-MEP-1) but only weakly bound the other six antigens, indicating Tci-APY-1 and Tci-MEP-1 are most effectively recognised by the parasite-induced antibody response. On the basis of these findings, a two-protein vaccine comprising Tci-APY-1 and Tci-MEP-1 was tested in a direct comparison with the original eight-component vaccine. A further group was immunised with Tci-MEP-1 in combination with a mutated form of Tci-APY-1 (mTci-APY-1), which had no enzymatic activity. Across the trial, the mean faecal egg count levels of the eight-antigen recipients were lower than those of the adjuvant only control group (P = 0.013) and the mean FEC of the mTci-APY-1 and Tci-MEP-1 recipients was lower, although not statistically significantly, than that of the adjuvant-only control group (P = 0.093). Mean cumulative faecal egg count levels were reduced by 43% in lambs immunised with mTci-APY-1 plus Tci-MEP-1 compared with the controls (P = 0.079).

Effect of Gliricidia sepium leaves intake on larval establishment of Cooperia punctata in calves and bio-guided fractionation of bioactive molecules.

The aims of this study were: 1) to assess the anthelmintic effect of Gliricidia sepium on the establishment of C. punctata third-stage larvae (L3) in calves, and 2) to isolate and to elucidate an anti-exsheathment phytochemical from the plant offered during the trial. Twelve ¾ Holstein × Zebu calves were divided in two experimental groups: control (T1) and treatment (T2) (n = 6). After adaptation, each calf was infected with an oral dose of 400 C. punctata L3/Kg LW. Basal diet consisted of Digitaria decumbens hay (6.27% CP) and commercial concentrate (12% CP). In addition, during the experimental period T2 received fresh G. sepium leaves (26.88% CP) ad libitum. On day 9 post-infection, three calves per treatment were randomly selected for slaughter, and worm counts were performed. Larval establishment rates obtained were 13.44 ±â€¯0.13% and 3.1 ±â€¯1.42% for T1 and T2, respectively (P < .05). The reduction of larval establishment was 76.9%. The total length of worms recovered from the animals was also affected by the intake of G. sepium (P < .05). Phytochemicals present in G. sepium leaves offered to calves were isolated through silica gel columns and elucidated through Magnetic Nuclear Resonance (1H and 13C). Bio-guided isolation procedures lead to the elucidation of Oxytroside (Kaempferol 3-O-rhamnopyranosyl-(1 → 6)-ß-D-glucopyranoside-7-O-rhamnopyranoside), which fully inhibited the C. punctata exsheathment process (2400 µg mL-1). Gliricidia sepium represents an alternative to prevent severe C. punctata infections by reducing larval establishment in cattle.

Impact of chemical structure of flavanol monomers and condensed tannins on in vitro anthelmintic activity against bovine nematodes.

Plants containing condensed tannins (CT) may have potential to control gastrointestinal nematodes (GIN) of cattle. The aim was to investigate the anthelmintic activities of four flavan-3-ols, two galloyl derivatives and 14 purified CT fractions, and to define which structural features of CT determine the anti-parasitic effects against the main cattle nematodes. We used in vitro tests targeting L1 larvae (feeding inhibition assay) and adults (motility assay) of Ostertagia ostertagi and Cooperia oncophora. In the larval feeding inhibition assay, O. ostertagi L1 were significantly more susceptible to all CT fractions than C. oncophora L1. The mean degree of polymerization of CT (i.e. average size) was the most important structural parameter: large CT reduced larval feeding more than small CT. The flavan-3-ols of prodelphinidin (PD)-type tannins had a stronger negative influence on parasite activity than the stereochemistry, i.e. cis- vs trans-configurations, or the presence of a gallate group. In contrast, for C. oncophora high reductions in the motility of larvae and adult worms were strongly related with a higher percentage of PDs within the CT fractions while there was no effect of size. Overall, the size and the percentage of PDs within CT seemed to be the most important parameters that influence anti-parasitic activity.

Analysis of the protective immune response following intramuscular vaccination of calves against the intestinal parasite Cooperia oncophora.

Recently we reported the successful vaccination of calves against Cooperia oncophora with a double domain activation-associated secreted protein, purified from the excretory-secretory material of adult stage parasites. In an attempt to elucidate the immune mechanisms involved in protection, the humoral and cell-mediated immune responses following vaccination and infection were compared with non-vaccinated control animals. Antigen-specific IgG1, IgG2 and IgA levels were significantly increased in sera of vaccinated animals post vaccination, whereas no effect was observed for IgM. Antigen-specific intestinal IgG1 levels were significantly increased in the vaccinated animals, whereas no differences were observed for antigen-specific IgA, IgM and IgG2 levels. Upon re-stimulation in vitro with the vaccine antigen, a significant proliferation of both αß- and γδ-T cells, and B cells, collected from mesenteric lymph nodes, was only observed in vaccinated animals. RNA-seq analysis of intestinal tissue yielded a list of 67 genes that were differentially expressed in vaccinated animals following challenge infection, amongst which were several cell adhesion molecules, lectins and glycosyl transferases. A correlation analysis between all immunological and parasitological parameters indicated that intestinal anti-double domain activation-associated secreted protein IgG1 levels correlated negatively with cumulative faecal egg counts and positively with the proportion of L4s and L5s. The proportion of immature stages was also positively correlated with the proliferation of αß T cells. Worm length was negatively correlated with the transcript levels of several lectins and cell adhesion molecules. Overall, the results indicate that intramuscular administration of the vaccine resulted in an immune memory response particularly characterised by increased antigen-specific IgG1 levels in the intestinal mucosa.

Evidence for reversion towards anthelmintic susceptibility in Teladorsagia circumcincta in response to resistance management programmes.

Maintaining production and economic viability in the face of resistance to multiple anthelmintic actives is a challenge for farmers in many countries. In this situation, most farmers in New Zealand rely on the use of combination products, containing multiple actives with similar spectra of activity, in order to maintain control. However, there are concerns that use of combinations, once resistance has already developed to the individual actives, could rapidly lead to complete failure of all actives. This study followed seven farms, previously diagnosed with resistance to at least two classes of anthelmintic, which were implementing a tailored programme of 'best practice parasite management'. The aim was to ascertain whether the programmes, which included the almost exclusive use of combination anthelmintics, were able to prevent resistance from developing further. Strategies implemented on each farm varied, but had consistent underlying principles i.e. to avoid over-use of anthelmintics; to minimise parasite challenge to susceptible stock; to maintain refugia of susceptibility and to ensure that only effective anthelmintics were used. Annual faecal egg count reduction tests (FECRT) were undertaken in lambs on all farms to monitor anthelmintic efficacy over 5 years. The efficacy of albendazole, ivermectin and levamisole was calculated and the changes in efficacy against Teladorsagia circumcincta assessed. Overall, there was a significant improvement in the effectiveness of both levamisole and ivermectin against T. circumcincta, and a positive but non-significant trend in efficacy of albendazole, i.e. there was evidence for reversion towards susceptibility. Hence, the almost exclusive use of combination anthelmintics, integrated with other resistance management strategies, did not result in further resistance development despite all farms exhibiting resistance to multiple actives at the outset. What-is-more, the measured increases in anthelmintic efficacy suggests that adoption of best practice management strategies may extend the useful life of anthelmintics even after resistance has been diagnosed.

Isolation and Characterization of China Isolates of Duddingtonia flagrans, a Candidate of the Nematophagous Fungi for Biocontrol of Animal Parasitic Nematodes.

The nematophagous fungus Duddingtonia flagrans has been investigated as a biological agent for the control of gastrointestinal nematodes infecting domestic animals in other countries. However, D. flagrans has not been detected in China. In this study 1,135 samples were examined from 2012 to 2014; 4 D. flagrans isolates (SDH 035, SDH 091, SFH 089, SFG 170) were obtained from the feces of domestic animals and dung compost. The 4 isolates were then characterized morphologically. The SDH 035 strain was characterized by sequencing the ITS1-5.8S rDNA-ITS2 region. A BLAST search showed that the SDH 035 strain (GenBank KP257593) was 100% identical to Arthrobotrys flagrans (AF106520) and was identified as D. flagrans. The morphological plasticity of the isolated strain and the interaction of this strain with the nematode targets were observed by subjecting the infected trichostrongylide L3 to scanning electron microscopy. At 6 and 8 hr after trichostrongylide L(3) was added, hyphal ramifications were observed and L(3) were captured, respectively. Scanning electron micrographs were obtained at 0, 6, 12, 18, 24, 30, 36, 42, and 48 hr, where 0 is the time when trichostrongylide L(3) were first captured by the fungus. The details of the capture process by the fungus are also described. Chlamydospores were observed in the body of L(3) in the late stage of digestion. A sticky substance and bacteria could be observed in contact areas between predation structures and nematode cuticle.

Vaccination of calves against Cooperia oncophora with a double-domain activation-associated secreted protein reduces parasite egg output and pasture contamination.

With the increasing incidence of anthelmintic resistance worldwide, immunological control of worm infections through vaccination is often put forward as a rational and cost-effective alternative for anthelmintic drugs. In this study we report on the evaluation of a double-domain activation-associated secreted protein purified from the excretory-secretory material of the adult stage of the small intestinal parasite Cooperia oncophora as a vaccine antigen against this parasite. In a first experiment, calves were vaccinated three times i.m. with activation-associated secreted protein and Quil A adjuvant or with adjuvant alone, and subsequently challenged with a trickle infection of 25,000 infective larvae in total over 25 days. Vaccinated calves showed a significant reduction of 91% in their cumulative faecal egg counts and a significantly higher number of inhibited L4s present in their intestine compared with control animals. Furthermore, both female and male adult worms were significantly smaller in the vaccinated group than in the control group. In a second experiment, the vaccine antigen was further evaluated under field conditions. Calves were immunised as described above, followed by a natural challenge infection on pasture. Cooperia oncophora faecal egg counts in the vaccinated animals were reduced during the entire grazing period, resulting in a significant reduction in the cumulative faecal egg counts of 58.5%. Numbers of infective C. oncophora larvae were lower on plots grazed by vaccinated calves, with a reduction in mean pasture larval counts of 65% at housing. A significant reduction of 81.6% in total numbers of C. oncophora worms was shown in the vaccinated group compared with the control group. Taken together, the data highlight the protective capacity of the double-domain activation-associated secreted protein and the possibility of controlling C. oncophora infections through vaccination.

Proteomic analysis of Mecistocirrus digitatus and Haemonchus contortus intestinal protein extracts and subsequent efficacy testing in a vaccine trial.

BACKGROUND: Gastrointestinal nematode infections, such as Haemonchus contortus and Mecistocirrus digitatus, are ranked in the top twenty diseases affecting small-holder farmers' livestock, yet research into M. digitatus, which infects cattle and buffalo in Asia is limited. Intestine-derived native protein vaccines are effective against Haemonchus, yet the protective efficacy of intestine-derived M. digitatus proteins has yet to be determined. METHODOLOGY/PRINCIPAL FINDINGS: A simplified protein extraction protocol (A) is described and compared to an established method (B) for protein extraction from H. contortus. Proteomic analysis of the H. contortus and M. digitatus protein extracts identified putative vaccine antigens including aminopeptidases (H11), zinc metallopeptidases, glutamate dehydrogenase, and apical gut membrane polyproteins. A vaccine trial compared the ability of the M. digitatus extract and two different H. contortus extracts to protect sheep against H. contortus challenge. Both Haemonchus fractions (A and B) were highly effective, reducing cumulative Faecal Egg Counts (FEC) by 99.19% and 99.89% and total worm burdens by 87.28% and 93.64% respectively, compared to the unvaccinated controls. There was no effect on H. contortus worm burdens following vaccination with the M. digitatus extract and the 28.2% reduction in cumulative FEC was not statistically significant. However, FEC were consistently lower in the M. digitatus extract vaccinates compared to the un-vaccinated controls from 25 days post-infection. CONCLUSIONS/SIGNIFICANCE: Similar, antigenically cross-reactive proteins are found in H. contortus and M. digitatus; this is the first step towards developing a multivalent native vaccine against Haemonchus species and M. digitatus. The simplified protein extraction method could form the basis for a locally produced vaccine against H. contortus and, possibly M. digitatus, in regions where effective cold chains for vaccine distribution are limited. The application of such a vaccine in these regions would reduce the need for anthelmintic treatment and the resultant selection for anthelmintic resistant parasites.

Biological control of trichostrongyles in beef cattle by the nematophagous fungus Duddingtonia flagrans in tropical southeastern Brazil.

The efficacy of a fungal formulation based on the nematophagous fungus Duddingtonia flagrans was assessed in the control of cattle trichostrongyles. Twenty male Nellore calves, six-month-old, divided in two groups (fungus-treated and control without fungus) were fed on a pasture of Brachiaria decumbens naturally infected with larvae of bovine trichostrongyles. Animals of the treated group received doses of sodium alginate mycelial pellets orally (1 g/10 kg live weight, twice a week), for 12 months. Feces samples were collected for egg count (eggs per gram of feces-EPG) and coprocultures during 12 months. There was a significant reduction in EPG (56.7%) and infective larvae (L3) in coprocultures (60.5%) for animals of the treated group in relation to the control group at the end of the study. There was a significant reduction of L3 (64.5%) in herbage samples collected up to 0-20 cm from fecal pats and 73.2% in distant samples (20-40 cm) between the fungus-treated group and the control group. The treatment with sodium alginate pellets containing the nematode trapping fungus D. flagrans reduced trichostrongylid in tropical southeastern Brazil and could be an effective tool for biological control of this parasitic nematode in beef cattle.

Effectiveness of Asteraceae extracts on Trichostrongylidae eggs development in sheep.

Data on in vitro evaluation of extracts of three species of the Asteraceae family on the development of Trichostrongylidae eggs in sheep are presented. Egg hatchability was tested using herbal extracts prepared in a Soxhlet extractor, and using hydrolate prepared by means of hydrodistillation. The laboratory tests showed that the ethanol extract from flowers of the species Aster lanceolatus presented high activity against Trichostrongylidae eggs development in sheep, inhibiting larva formation by 91% within 48 hours, and maintaining similar rates after 72 hours.

Effectiveness of Asteraceae extracts on Trichostrongylidae eggs development in sheep / Eficácia de extratos da família Asteraceae no desenvolvimento dos ovos de Trichostrongilídeos de ovinos

Data on in vitro evaluation of extracts of three species of the Asteraceae family on the development of Trichostrongylidae eggs in sheep are presented. Egg hatchability was tested using herbal extracts prepared in a Soxhlet extractor, and using hydrolate prepared by means of hydrodistillation. The laboratory tests showed that the ethanol extract from flowers of the species Aster lanceolatus presented high activity against Trichostrongylidae eggs development in sheep, inhibiting larva formation by 91 percent within 48 hours, and maintaining similar rates after 72 hours.

Apresentam-se dados da avaliação in vitro de três espécies vegetais da família Asteraceae sobre o desenvolvimento dos ovos de Trichostrongilídeos de ovinos. Realizou-se o teste de eclodibilidade com extratos vegetais preparados por aparelho de Soxhlet e hidrolato preparado por hidrodestilação. Os testes laboratoriais evidenciaram que o extrato etanólico das flores da espécie Aster lanceolatus apresenta alta atividade sobre o desenvolvimento dos ovos de Trichostrongilídeos de ovinos, inibindo em 91 por cento a formação da larva em 48 horas, mantendo-se índices próximos em 72 horas.

Attempts to immunize sheep against Teladorsagia circumcincta using fourth-stage larval extracts.

A ConcanavilinA (ConA)-binding fraction of a detergent-soluble membrane extract from Teladorsagia circumcincta (formerly Ostertagia circumcincta) fourth-stage larvae was isolated, and two vaccine trials were conducted with this preparation in groups of 7 worm-free sheep. All groups were challenged with a total of 5000 T. circumcincta larvae from 1 week after the final immunization and protection assessed by comparing the egg and worm counts, and length of developing worms, of the immunized groups with their respective controls. Immunization with the ConA-binding antigen induced high-titre serum antibody responses in both trials. However, no significant reduction in either egg count or worm burdens was observed in the vaccinated groups in either trial. It was concluded that detergent-soluble, ConA-binding extracts prepared from T. circumcincta fourth-stage larvae did not contain significantly protective antigens, despite the fact that an extract prepared in a similar manner from Ostertagia ostertagi had previously significantly protected calves against homologous challenge.

Atividade in vitro do extrato hidroalcoólico de Lippia sidoides Cham sobre larvas de terceiro estádio de nematódeos gastrintestinais (família Trichostrongylidae) de caprinos / In vitro activity of the hydroalcoholic extract of Lippia sidoides Cham on buoyant larvae of third-stage gastrointestinal nematodes (family Trichostrongylidae) of goats

Avaliou-se in vitro a atividade larvicida do extrato hidroalcóolico de alecrim pimenta (Lippia sidoides Cham) sobre larvas de terceiro estádio de nematoides gastrintestinais de caprinos. Os resultados encontrados demonstraram que a concentração de 500 mg mL-1 apresentou atividade efetiva e com capacidade de ação de 95,89%, demonstrando desta forma a possibilidade do uso terapêutico anti-helmíntico para esse extrato.

The in vitro larvicidal activity of the hydroalcoholic extract of rosemary pepper (Lippia sidoides Cham) was evaluated on buoyant larvae of third-stage gastrointestinal gastrointestinal nematodes of goats. The results demonstrated that the concentration of 500 mg mL-1 presented effective activity, with a capacity of action of 95.89%, thus demonstrating the possibility of anthelmintic therapeutic use for this extract.

Long-acting moxidectin for the control of trichostrongylid infections of sheep in south-eastern Australia.

OBJECTIVE: To compare the effectiveness of a single long-acting injection of moxidectin, given in either summer or winter, with a two-summer ('standard') treatment strategy for controlling gastrointestinal nematodes in spring-lambing Merino ewes. DESIGN: A replicated study over 2 years in the high winter rainfall environment of western Victoria. METHODS: Measures of worm infection were worm egg counts of ewes and total worm counts of tracer lambs. Measures of production were body weight, proportion of pregnant ewes and number of weaned lambs. RESULTS: The egg counts of ewes given the standard strategy followed a characteristic pattern, rising to 300 to 600 eggs per gram before the second summer treatment in February. During this time, ewes given long-acting moxidectin in December had zero or negligible counts. There were no consistent differences between tracer worm counts or production measures for the two groups treated in summer, but when data from both years were pooled, the total egg output from December to May was significantly lower for ewes treated with long-acting moxidectin in December. Ewes not treated during summer had lower body weights, and higher worm egg counts and tracer worm counts, showing that this was not a suitable strategy at that time of the year. However, following treatment with long-acting moxidectin in winter, ewes had rapid compensatory weight gain and lower egg output than ewes treated in summer. CONCLUSION: A single injection of long-acting moxidectin in December is an effective treatment strategy for Merino ewes lambing in spring.