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ABSTRACT: Live vaccines containing attenuated parasite strains are increasingly used to control chicken coccidiosis. In this paper antibody responses elicited by infections with wild-type and attenuated strains of Eimeria tenella and Eimeria necatrix were characterized by immunoblotting and ELISA with homologous and heterologous antisera. Few differences between antisera from birds infected with wild and attenuated strains of E. tenella were evident in immunoblots conducted with merozoite antigen preparations from both E. tenella strains, however the reactivity of sera raised in birds infected with the wild-type strain was noticeably more intense. In ELISAs conducted with merozoite antigen preparations, antisera from birds infected with the wild-type strains of E. tenella and E. necatrix consistently produced a significantly higher (P<0.05) antibody response than antisera from birds infected with the attenuated strains. Likewise, avidity ELISAs conducted with the E. tenella strains demonstrated that antibodies in birds infected with the wild-type strain were of significantly higher avidity (P<0.05) than antibodies in birds infected with the attenuated strain. The differences in the antibody responses are probably due to changes in the attenuated strain as a result of selection for precocious development and the less severe tissue damage and inflammation of the intestine resulting from infection with the attenuated strain.
Veterinary Parasitology 10/2010; 175(1-2):47-51. · 2.58 Impact Factor
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ABSTRACT: In Australia, macropodids are common intermediate hosts for the cestode Echinococcus granulosus, and sylvatic transmission is maintained via wild dogs. The parasite causes mortality in a number of macropodid species and the sylvatic cycle provides a source of infection to domestic livestock and humans. We determined the efficacy of the hydatid vaccine, EG95 in the tammar wallaby, Macropus eugenii, challenging either 1 or 9 months post-vaccination. EG95 provides similar protection to that seen in sheep (96-100%). Control tammars were significantly more likely to become infected (odds ratio 29.44; CI 4.13, 209.97; P=0.001) and to develop more cysts (count ratio 26.69; CI 5.83, 122.19; P<0.001). The vaccination may be beneficial if administered pre-release in captive breeding programmes for endangered macropodids. Further work to develop oral delivery methods may enable vaccine administration of wild animals and thereby a reduction in sylvatic transmission.
Parasitology 02/2009; 136(4):461-8. · 2.96 Impact Factor
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ABSTRACT: The application of attenuated vaccines for the prevention of chicken coccidiosis has increased exponentially in recent years. In Eimeria infections, protective immunity is thought to rely on a strong cell mediated response with antibodies supposedly playing a minor role. However, under certain conditions antibodies seem to be significant in protection. Furthermore, antibodies could be useful for monitoring natural exposure of flocks to Eimeria spp. and for monitoring the infectivity of live vaccines. Our objective was to investigate the chicken antibody response to the different parasite life cycle stages following infection with an attenuated strain of Eimeria tenella. Western blotting analysis of parasite antigens prepared from the lining of caeca infected with the attenuated strain of E. tenella revealed two dominant antigens of 32 and 34 kDa, apparently associated with trophozoites and merozoites that were present at high concentrations between 84 and 132 h post-infection. When cryosections of caeca infected with E. tenella were probed with IgY purified from immune birds the most intense reaction was observed with the asexual stages. Western blotting analysis of proteins of purified sporozoites and third generation merozoites and absorption of stage-specific antibodies from sera suggested that a large proportion of antigens is shared by the two stages. The time-courses of the antibody response to sporozoite and merozoite antigens were similar but varied depending on the inoculation regime and the degree of oocyst recirculation.
Veterinary Parasitology 08/2008; 154(3-4):193-204. · 2.58 Impact Factor
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ABSTRACT: Infection of small macropodids with the larval stage of Echinococcus granulosus can cause fatalities as well as significant pulmonary impairment and other adverse sequelae. The brush-tailed rock-wallaby (Petrogale penicillata) is a small macropodid listed as vulnerable on the IUCN's Red List of Threatened Species. This study used radiographic techniques to determine the prevalence and severity of pulmonary hydatid infection and growth rates of hydatid cysts in a wild population of this macropodid. The overall prevalence was 15.3% (9/59 animals) with 20.0% (8/40 animals) of adults infected. During the study period, the death of at least 1 infected animal was directly attributed to pulmonary hydatidosis. Rapid cyst growth occurred in some animals (up to 43% increase in cyst volume in 3 months). Cyst volume reduced lung capacity by up to 17%. Secondary pulmonary changes were uncommon but, in 1 animal, resulted in reduction in lung capacity by approximately 50%. Infection was associated with a higher blood urea concentration, but no significant differences in other blood variables were detected. These results indicate that hydatid infection may be a significant risk to threatened populations of small macropodids and should be addressed in conservation management plans for these animals.
Parasitology 06/2008; 135(6):715-23. · 2.96 Impact Factor
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ABSTRACT: The aim of this study was to develop and validate an ELISA for detecting chicken antibodies to Eimeria tenella. An initial comparison of merozoite and sporozoite antigen preparations revealed few differences in their ability to monitor the onset, kinetics and magnitude of the antibody response suggesting that both antigens would be equally useful for development of an ELISA. Furthermore the cross-reactivity of these antigens with sera from birds infected with chicken Eimeria species was similar. The merozoite antigen was selected for further evaluation because it was easier to prepare. Discrimination between sera from birds experimentally infected with E. tenella and birds maintained in an Eimeria-free isolation facility was excellent. In sera collected from free-range layers and commercial broilers there also appeared to be clear discrimination between infected and uninfected birds. The ELISA should prove useful for monitoring infectivity in vaccination programmes in layer and breeder flocks and for assessing the effectiveness of biosecurity measures in broiler flocks.
Veterinary Parasitology 01/2008; 150(4):306-13. · 2.58 Impact Factor
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ABSTRACT: Immunoglobulin Y is different from most of the other immunoglobulins because it does not bind protein A or protein G. Thiophilic gel chromatography has been successfully used to purify IgY from chicken egg yolk, but the technology has not previously been used to purify IgY from serum. In this research note, we describe the optimization of T-gel chromatography for purification of IgY from serum. Data are provided on the recovery and purity of IgY obtained using potassium sulfate buffers of different concentrations. Decreasing the strength of potassium sulfate buffer from 0.5 to 0.3 M did not alter the amount of IgY recovered but increased the purity. Using 0.3 M potassium sulphate, we recovered approximately 63.7% of the serum Ig as almost pure IgY.
Poultry Science 10/2007; 86(9):1910-4. · 1.73 Impact Factor
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ABSTRACT: Abstract Extract A 15-year-old pony mare developed firm irregular bony swellings on all four legs. These were most severe around the carpal and fetlock joints of the forelegs, restricting both flexion and extension. Over about 6 months the horse had periodic bouts of coughing. She showed moderate weight loss and a depressed demeanour.
New Zealand veterinary journal 01/1995; 43(3):123. · 0.89 Impact Factor
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ABSTRACT: Anthelmintic resistance is widespread among cyathostomins infecting horses. The ability to identify the level of an individual horse’s immunity to cyathostomins might facilitate the development of novel approaches to worm control in this host. Horses on nine properties in south east Queensland were recruited for a study to test the hypothesis that certain individuals consistently contribute disproportionately to pasture contamination with these parasites. Faecal samples from approximately 56 horses were collected monthly for 12 months. As the FEC data were heavily skewed to the right and contained a high proportion of zero counts (48.5%), a zero-inflated negative binomial model was used to assess the associations between explanatory variables and FEC. Various explanatory variables (Table 1) were fitted separately in a univariable model in both the negative binomial and logistic parts of the model. Selected variables were progressively included in a multivariable model and retained in the final model when the likelihood ratio test returned a p-value < 0.05. 95% confidence intervals (CI) were calculated using the Huber/White estimate of variance to account for clustering by horse. All analyses were undertaken Stata Version 10 (StataCorp, College Station, TX, USA, 2007). The count and odds ratios for the final model are shown in Table 1. Treatment with an anthelmintic in the previous month and two months previously, breed and season all remained in the logistic part of the final model, whereas anthelminthic treatment 2 months previously, sex and breed all remained in the negative binomial component.
