Biomedical subjects

D D Heath

Publications and source records attributed to D D Heath.

At least 19 recordsLinked to original sources

PubMed2006

Characterisation and expression of an Hsp70 gene from Parastrongyloides trichosuri.

Parastrongyloides trichosuri is a nematode parasite of Australian brushtail possums that has an alternative free-living life cycle which can be readily maintained indefinitely in a laboratory setting. The ability to maintain this parasite in a free-living cycle and induce it to parasitism at the free-living L1 stage makes this an excellent model for the study of genes associated with parasitism. A 70kD protein from infective larvae of P. trichosuri that appears to be immunogenic in infected possums has been identified as a heat shock protein (Hsp)70 homologue. The complete gene for Pt-Hsp70 was cloned and sequenced. The protein encoded by the Pt-Hsp70 gene is the likely orthologue of the Caenorhabditis elegans protein, Hsp70A, also known as hsp-1. Reverse transcriptase-PCR data indicate that Pt-Hsp70 (designated Pt-hsp-1) is expressed at readily detectable levels in all developmental stages of both the parasitic and free-living P. trichosuri life cycles and the promoter is mildly inducible by heat shock. Bioinformatic analysis of expressed sequence tag databases indicates that C. eleganshsp-1 homologues, together with C. eleganshsp-3 homologues, are the predominant members of the Hsp70 superfamily that are normally expressed in parasitic stages of the Strongyloididae family. Promoter fusions to a beta-galactosidase coding sequence were prepared and introduced into wild type C. elegans to produce transgenic nematodes. Reporter gene expression was clearly present within embryonic cells and within intestinal cells of larval and adult stages. Thus, the expression of the Pt-hsp-1 promoter within P. trichosuri and transgenic C. elegans appears similar to the known expression of C. elegans hsp-1. This promoter should be of value in efforts to develop genetic manipulation tools for P. trichosuri.

Amino Acid Sequence↗

PubMed2006

Parastrongyloides trichosuri, a nematode parasite of mammals that is uniquely suited to genetic analysis.

Commonly studied nematode parasites have not proven amenable to simple genetic analyses and this has significantly reduced the available research options. We introduce here a nematode parasite of mammals, Parastrongyloides trichosuri, which has features uniquely suited for genetic analysis. This parasite has the capacity to undergo multiple reproductive cycles as a free-living worm and thereby amplify the numbers of its infective L3s in faeces. Culture conditions are presented that permit facile laboratory maintenance of this worm for >90 free-living life cycles (to date) without the need for re-entry into a permissive host. Even after long maintenance as a free-living worm, culture conditions can be manipulated to favour development of infective L3 worms, which remain able to successfully infect their marsupial hosts. The switch to infective L3 development is triggered by a secreted factor contained in culture medium conditioned by multiple generations of free-living worm culture. It is simple to perform single pair crosses with P. trichosuri to carry out Mendelian genetics in the laboratory and this has been done multiple times with sibling pairs to generate highly inbred lines. Lines of worms can readily be cryopreserved and recovered. Over 7000 expressed sequence tags have been produced from cDNAs at different life cycle stages and used to identify single nucleotide polymorphisms and microsatellites as genetic markers. Free-living worms live only a few days on average while the patency of parasitic infections can last for several months. Since we show this is not the result of re-infection, we conclude that parasitic worms have a lifespan capacity at least 20-30 times longer than their free-living counterparts. We discuss how it should be possible to exploit these unique features of P. trichosuri as a model for future studies that explore the genetic basis of longevity and parasitism.

Animals↗

PubMed2005

Infection of naïve, free-living brushtail possums (Trichosurus vulpecula) with the nematode parasite Parastrongyloides trichosuri and its subsequent spread.

Despite the importance of spatial processes in host-parasite interactions, parasite dispersal has been the subject of few experimental studies. Introduced marsupial common brushtail possums (Trichosurus vulpecula) are a major environmental and agricultural pest in New Zealand. Parastrongyloides trichosuri, an intestinal rhabdiasoid nematode parasite specific to possums, is being evaluated as a self-disseminating delivery system for engineered fertility control vaccines. This study addressed whether an artificial infection could be established in a naïve, free-living possum population, by measuring the post-release dynamics of possum-parasite interactions at the release site, and by following the spread of the parasite into surrounding possum populations. Infection was established efficiently by applying infective larvae to the skin of possums on a single occasion. All experimentally infected possums recaptured 3 weeks after infection had parasite eggs in their faeces. Over the subsequent 2.5 years, infection spread steadily over an area of about 6000 ha. Infection persisted at the original release site for the 3.5 years of the study and at a nearby site infected by natural spread for more than 3 years. Seasonal changes in faecal egg counts were similar at the two sites. The rapid establishment of the parasite and its spread provide additional support for its ongoing development as a vaccine delivery system.

Animals↗

PubMed2005

Invasion genetics of a freshwater mussel (Dreissena rostriformis bugensis) in eastern Europe: high gene flow and multiple introductions.

In recent years, the quagga mussel, Dreissena rostriformis bugensis, native to the Dnieper and Bug Limans of the northern Black Sea, has been dispersed by human activities across the basin, throughout much of the Volga River system, and to the Laurentian Great Lakes. We used six published microsatellite markers to survey populations throughout its native and introduced range to identify relationships among potential source populations and introduced ones. Mussels from 12 sites in Eurasia, including the central Caspian Sea and one in North America (Lake Erie), were sampled. Field surveys in the Volga River basin suggested that the species first colonized the middle reach of the river near Kubyshev Reservoir, and thereafter spread both upstream and downstream. Evidence of considerable gene flow among populations was observed and genetic diversity was consistent with a larger, metapopulation that has not experienced bottlenecks or founder effects. We propose that high gene flow, possibly due to multiple invasions, has facilitated establishment of quagga mussel populations in the Volga River system. The Caspian Sea population (D. rostriformis rostriformis (=distincta)) was genetically more distinct than other populations, a finding that may be related to habitat differences. The geographical pattern of genetic divergence is not characteristic of isolation-by-distance but, rather, of long-distance dispersal, most likely mediated by commercial ships' ballast water transfer.

Animals↗

PubMed2005

Hybridization dynamics between sympatric species of trout: loss of reproductive isolation.

Although reinforcement should enhance reproductive barriers in sympatric species, sympatric trout species do hybridize. Using mitochondrial and nuclear species markers, we investigated hybridization directionality, hybrid mating biases, and selection against hybrids in 13 sympatric cut-throat and rainbow trout populations on Vancouver Island, Canada. Approximately 50% of the genotyped fish were hybrid (F1 or higher-order) and populations ranged from very recent (all F1 hybrids) to extremely advanced higher-order hybridization. Overall, interbreeding was reciprocal, although some populations showed directional hybridization. Pronounced cytonuclear disequilibrium in post-F1 hybrids indicated a remarkable mating bias not previously reported, which is most likely because of behavioural reproductive preferences. Selection against hybrids was observed in only two populations, indicative of extrinsic selection. Two populations were 'hybrid swarms', with a complete loss of reproductive isolation. The complex hybridization dynamics in this system represent a valuable natural experiment of the genetic and evolutionary implications of recent and on-going interspecific hybridization.

Animals↗

PubMed2004

Sensitive genetic biomarkers for determining apoptosis in the brown bullhead (Ameiurus nebulosus).

Biomarkers are necessary for monitoring environmentally induced alterations at the molecular level in order to assess the impact of xenobiotic compounds on organism health. Apoptosis is a highly regulated cellular process that controls programmed cell death and is involved in tumor formation. Apoptosis thus may provide the basis for developing biomarkers for use in the field of ecotoxicology to monitor non-lethal levels of xenobiotic induced cellular stress and toxicity. This study shows that a brown bullhead (Ameiurus nebulosus) fibroblast cell line (BB-2) responds to known apoptotic inducers (staurosporine, cycloheximide, and tumor necrosis factor alpha (TNF-alpha)), as characterized by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP digoxigenin nick end-labelling (TUNEL). Furthermore, we characterized the apoptotic process using a series of newly identified bullhead genetic markers. Exposure to protein kinase C inhibitors altered the transcription of TF-cell apoptosis-related protein (TFAR)-15 and p23 with no effect on p53, inhibitor of apoptosis protein (IAP), or PNAS-2. Inhibition of protein synthesis caused a consistent reduction in the transcription of p53 and PNAS-2. This study demonstrates that our novel transcriptional markers are sensitive biomarkers for the study of the effects of xenobiotic chemicals on apoptosis in the brown bullhead.

Animals↗

PubMed2004

Genetic and morphological data supporting the hypothesis of adaptive radiation in the endemic fish of Lake Matano.

Adaptive radiation resulting from differential selection acting on functional features is believed to be an important source of biodiversity. In this study, morphometric measures and mitochondrial DNA are used to test for adaptive radiation within four fish genera (Glossogobius, Oryzias, Dermogenys and Telmatherina) endemic to an ancient island lake (Lake Matano, Sulawesi, Indonesia), using the framework proposed by Schluter (The Ecology of Adaptive Radiation, Oxford University Press, 2000). We demonstrate common ancestry and rapid divergence in one genus (Telmatherina) based on 560 bp of 16S sequence data. We found higher levels of variation in feeding-related traits (N = 8) for Telmatherina relative to the other genera, while no differences were found for sexual display traits (N = 8) or neutral morphological traits (N = 8). Telmatherina also had the highest number of distinct colouration patterns among the four genera. These data, combined with the very low productivity of the lake, are indicative of selection driving adaptive radiation. The morphometric divergence in the Telmatherina likely results from selection acting on feeding traits in this low productivity lake, leading to trophic specialization among closely related morphotypes. These results provide indirect but compelling data supporting the adaptive radiation of Telmatherina in this system.

Adaptation, Biological↗

PubMed2004

Immunity and vaccine control of Echinococcus granulosus infection in animal intermediate hosts.

Much progress has been made with characterisation of the EG95 vaccine which can be used to prevent hydatid infection in animal intermediate hosts of Echinococcus granulosus. The vaccine comprises a single recombinant oncosphere antigen and the adjuvant Quil A. It induces complement-fixing antibodies that kill the invading oncosphere early in an infection. In the majority of vaccinated animals, no hydatid cysts occur following a challenge infection. However, a small number of viable cysts may occur in some vaccinated animals. The vaccine has proved effective in vaccine trials carried out in sheep in New Zealand, Australia, Argentina, Chile and China as well as in goats and cattle. Investigations of the genetic diversity of the gene encoding EG95 have identified no unequivocal variation within the G1 strain parasites; however DNA sequence diversity within the EG95 family of genes has been found in G6/G7 parasites. GMP production scale-up of the vaccine has been undertaken in New Zealand and China and it is expected that the vaccine will be become available through these sources for implementation as part of hydatid control programs worldwide.

Animals↗

PubMed2003

Molecular and genetic characterisation of the host-protective oncosphere antigens of taeniid cestode parasites.

Highly effective recombinant vaccines have been developed against Taenia ovis infection in sheep, Taenia saginata infection in cattle, Taenia solium infection in pigs, Echinococcus granulosus and Echinococcus multilocularis infections in a variety of intermediate host species. These vaccines have been based on the identification and expression in Escherichia coli of antigens derived from the oncosphere life cycle stage, contained within the parasites' eggs. Investigation of the molecular aspects of these proteins and the genes encoding them have revealed a number of common features, including the presence of a predicted secretory signal sequence, and one or two copies of a fibronectin type III domain, each encoded by separate exons within the associated gene. Evidence has been obtained to confirm glycosylation of some of these antigens. Ongoing investigations will shed light on the biological roles played by the proteins within the parasites and the mechanism by which they make the parasites vulnerable to vaccine-induced immune responses.

Animals↗

PubMed2003

Construction of a recombinant orf virus that expresses an Echinococcus granulosus vaccine antigen from a novel genomic insertion site.

The potential of recombinant poxviruses as expression vectors has been extensively studied using Vaccinia virus but there has been only limited transfer of this technology to the Parapoxvirus genus. We detail here the construction of a recombinant Orf virus that expresses an antigenic peptide (EG95) of the causative agent of cystic hydatid disease, Echinococcus granulosus. Expression of this foreign antigen was regulated by a synthetic early/late poxvirus transcriptional promoter and levels of expression comparable to that achieved by a similar vaccinia virus recombinant were observed. The expression cassette was inserted into a unique orf virus gene (G1L) thereby confirming the non-essential nature of that gene and identifying a novel genomic insertion site. This recombinant will be a valuable tool with which to assess the potential of recombinant orf viruses to deliver vaccine antigens to sheep.

Animals↗

PubMed2003

Progress in control of hydatidosis using vaccination--a review of formulation and delivery of the vaccine and recommendations for practical use in control programmes.

A vaccine to protect sheep, goats, and bovines against hydatid disease caused by the cysts of Echinococcus granulosus is prepared as a recombinant fusion protein expressed in Escherichia coli. Solubilised inclusion bodies are injected, together with Quil A, subcutaneously on two occasions 1 month or more apart, and induce protection against infection which lasts for at least 12 months. A third injection given 6-12 months after the second injection induces a high and long-lasting protection against artificial or natural challenge infections. This review describes work carried out on the formulation, safety and efficacy of the vaccine under laboratory and field conditions, using artificial or natural challenges with E. granulosus eggs, followed by necropsy. Hydatid control programmes based on regular treatment of all dogs with the correct dose of a highly-efficient anthelmintic have sometimes not been successful in Continental environments. Access to dogs is difficult in summer because of the distances to summer pastures, and is often impossible in winter because of snow. A control program using strategic twice-yearly anthelmintic treatment of dogs is likely to be successful provided grazing animals are vaccinated as well. Vaccination as a control tool only requires the veterinarians to visit two times a year, and while the veterinarian is present, the dogs can be treated with anthelmintic for little additional cost. One visit should take place after the autumn kill of animals for winter consumption, and this is a good time to vaccinate animals born in the summer, and also all other animals while they are healthy and immunologically responsive. The other visit should take place in the spring, at which time animals born during winter can be vaccinated. Although a single immunization has been shown to induce a useful degree of protection, where possible it is best to give two initial injections, 1 month apart. If it is possible for veterinarians to stay in the field for 2 months in November/December and March/April, in order to give the two injections, a more rapid onset of full protective immunity will initially be achieved than if the injections are given 6 months apart. A large-scale safety and efficacy trial involving 50,000 and 100,000 lambs in Qinghai and Xinjiang Provinces of China has taken place. Results have confirmed safety and efficacy. In most countries, prevalence of infection increases with age. The vaccine has no effect on established cysts, and therefore, in order to prevent the biomass of Echinococcus spp. from increasing, it might be an effective strategy to begin a control programme by vaccinating all animals. Because many of the older stock will already be infected, they will remain a source of infection for dogs for the average lifetime of the stock. Dogs will still be able to be infected from the older stock, and will continue to infect humans. We advocate that a vaccination programme be accompanied by education about hydatid disease, and anthelmintic treatment of dogs in late autumn and early spring.

Animals↗

PubMed2003

Transmission dynamics and control options for Echinococcus granulosus.

Cystic echinococcosis, caused by the larval stage of Echinococcus granulosus, is a global public health problem. Whilst in a few localities, such as New Zealand, the parasite has been effectively controlled or even eradicated, in most endemic regions it remains a persistent problem. In some areas, such as the former Soviet Union, the disease incidence in humans has increased rapidly in recent years. It is important to have an understanding of the transmission dynamics, both between dogs and domestic livestock where the parasite maintains itself and from dogs to people. It is from this knowledge that effective control measures can be devised to reduce the prevalence of the parasite in animals and hence reduce the incidence of human disease. Mathematical models to describe the transmission of the parasite and the effects of different control strategies were first proposed over twenty years ago. Since then further information has been acquired, new technology has been developed and better computing technology has become available. In this review, we summarise these developments and put together a theoretical framework on the interpretation of surveillance information, how this affects transmission and how this information can be exploited to develop new intervention strategies for the control of the parasite. In particular, the parasite remains a persistent or re-emerging problem in countries of low economic output where resources for an intensive control programme, that has been successful in rich countries, are not available. By understanding of the transmission biology, including mathematical modelling, alternative and cost-effective means of control can be developed.

Animals↗

PubMed2003

Bimodal run distribution in a northern population of sockeye salmon (Oncorhynchus nerka): life history and genetic analysis on a temporal scale.

Life history variation and genetic differentiation were analysed in sockeye salmon in Klukshu River, Yukon Canada over 7 years (1994-2000). Sockeye salmon return to the Klukshu River in two distinct runs, with a small 'early run' in June-August, and a larger 'late run' in August-September. A maximum likelihood test for clusters indicated that the return frequency distribution was bimodal in all the years analysed. Life history differences (fork length, sex ratio, age at maturity, fresh- and saltwater residency times) were found between the early and late runs; however, inconsistent patterns suggest that environmental effects outweigh, or strongly interact with, genetic effects for the life history characters evaluated. Analysis of variation at eight microsatellite loci showed that the early and late runs are genetically differentiated in all years examined (exact test). FST estimates between runs within years were significantly greater than zero (range: 0.018-0.041) for all years except one (0.004). The genetic variance explained by early vs. late runs (2.27%) was twice the variance among years (1.16%) based on analysis of molecular variance. Our neighbour-joining tree showed early and late runs generally clustering separately, indicating higher gene flow among the early or late run fish across years relative to between-run gene flow. Two years did not fit the general clustering pattern; although the early and late runs in 1995 and 2000 were genetically differentiated, they clustered separately from the rest of the groups. We cannot offer a definitive explanation for these anomalies; however, an analysis of possible cryptic population structure in early and late runs indicated that at least a few fish strayed between the runs in each year, and the highest rate of mixing was in 1995 and 2000. Our data indicate that the runs are at least partially reproductively isolated as a result of temporal and/or spatial isolating mechanisms. Such reproductive isolation has important implications for conservation and management of the Klukshu sockeye salmon, and make them an evolutionarily interesting group because of parallels with incipient speciation.

Alleles↗

PubMed2002

Heritability and Y-chromosome influence in the jack male life history of chinook salmon (Oncorhynchus tshawytscha).

Jacking in chinook salmon (Oncorhynchus tshawytscha) is an alternative reproductive strategy in which males sexually mature at least 1 year before other members of their year class. We characterize the genetic component of this reproductive strategy using two approaches; hormonal phenotypic sex manipulation, and a half-sib breeding experiment. We 'masculinized' chinook salmon larvae with testosterone, reared them to first maturation, identified jacks and immature males based on phenotype, and genotyped all fish as male ('XY') or female ('XX') using PCR-based Y-chromosome markers. The XY males had a much higher incidence of jacking than the XX males (30.8% vs 9.9%). There was no difference in body weight, gonad weight, and plasma concentrations of testosterone and 17beta-estradiol between the two jack genotypes, although XY jacks did have a higher gonadosomatic index (GSI) than XX jacks. In the second experiment, we bred chinook salmon in two modified half-sib mating designs, and scored the number of jacks and immature fish at first maturation. Heritability of jacking was estimated using two ANOVA models: dams nested within sires, and sires nested within dams with one-half of the half-sib families common to the two models. The sire component of the additive genetic variance yielded a high heritability estimate and was significantly higher than the dam component (h(2)(sire) = 0.62 +/- 0.21; h(2)(dam) = -0.14 +/- 0.12). Our experiments both indicated a strong sex-linked component (Y-chromosome) to jacking in chinook salmon, although evidence for at least some autosomal contribution was also observed.

Analysis of Variance↗

PubMed2001

Genetic structure and relationships among steelhead trout (Oncorhynchus mykiss) populations in British Columbia.

Steelhead trout, Oncorhynchus mykiss (the anadromous form of rainbow trout), are declining over much of their range around the Pacific rim. We nondestructively collected tissue samples from 494 adult steelhead from eight tributaries and two mainstem river sites within three watersheds in northern British Columbia, Canada. We scored allele size for six highly polymorphic microsatellite DNA loci and provide primer sequences and polymerase chain reaction conditions for five of these loci for the first time. The populations were significantly genetically differentiated (theta = 0.039; 95% confidence = 0.030-0.053). AMOVA showed that most of the genetic variation was at the individual level (95.6%), although significant genetic variation existed at the tributary level (3.09%) and watershed level (1.31%). The calculated unbiased genetic distances were positively correlated with geographical distance within watersheds (P < 0.01; r(2)=0.35) indicating probable genetic equilibrium. Tributary populations in two of the watersheds were not as genetically divergent as would be expected given their large geographical separation. Cross-headwater transfers of fish within relatively recent history are the most likely explanation of this anomaly. Seven of the eight tributary populations fit a regression line of mean heterozygosity vs. rearing habitat area. The one anomalous population had a much lower heterozygosity than expected based on the linear regression, and may thus be the population of greatest conservation concern.

Alleles↗

PubMed2001

Anthelmintics for the control of nematode infections in the brushtail possum (Trichosurus vulpecula).

AIMS: To determine the efficacy of eprinomectin, doramectin and a combination of albendazole and levamisole in suppressing or eliminating nematode infections or faecal egg counts (FEC) in possums naturally or experimentally infected with Parastrongyloides trichosuri, Paraustrostrongylus trichosuri and Trichostrongylus colubriformis. METHODS: To establish an effective dose of eprinomectin, groups of naturally infected possums were treated with 0, 0.5, 2.5, 5.0 or 7.5 mg/kg liveweight (LW) eprinomectin pour-on (n=6 possums/group) and changes in FEC and nematode worm counts at necropsy determined, 18 days later. Efficacy of the 7.5 mg/kg dose was re-examined in a second group of naturally infected possums (n=12) by monitoring FEC weekly for 28 days post-treatment. Persistence of the anthelmintic effect of doramectin injection was tested using nematode-free possums treated with 0, 0.2, 0.4, 0.6 or 0.8 mg/kg LW (n=3 possums/ group), which were experimentally infected 14 days later with T. colubriformis, Paraustrostrongylus trichosuri and Parastrongyloides trichosuri infective larvae. Response to treatment was assessed by FEC and nematode worm counts at necropsy, 42 days posttreatment. Efficacy of a 1.0 mg/kg dose of doramectin was subsequently examined using naturally infected possums (n=11) by monitoring FEC weekly for 28 days post-treatment. To determine the efficacy of a levamisole-albendazole combination drench, possums with naturally acquired nematode infections (n=6) were treated orally with 37.5 mg/kg LW levamisole plus 23.75 mg/kg LW albendazole on 2 occasions, 7 days apart, and response to treatment was assessed by monitoring FEC for 57 days. RESULTS: Eprinomectin 7.5 mg/kg LW reduced Paraustrostrongylus trichosuri worm counts by 98 % (p<0.05). Doramectin 0.6 mg/kg LW reduced Parastrongyloides trichosuri and Trichostrongylus spp worm counts by 99% (p<0.05) and 0.8 mg/kg LW reduced Paraustrostrongylus trichosuri by 100% (p<0.05), in possums challenged with larvae 14 days after treatment. Treating possums with a levamisole-albendazole combination orally, twice, 7-days apart, reduced FEC by 99%. CONCLUSIONS: The doses of anthelmintics required to effectively control nematodes in possums were higher than those recommended for animals for which they are currently registered. Possums tolerate the high dose rates of anthelmintics used in this study without apparent adverse effects.

Journal Article↗

PubMed2000

Protection against hydatid disease induced with the EG95 vaccine is associated with conformational epitopes.

This paper describes attempts to map the location of host-protective epitopes of a recombinant vaccine antigen by assessing the ability of truncated regions of the antigen to elicit protective immune responses in sheep. Sheep were immunised with three truncated regions (EG95-1, EG95-2 and EG95-3) of the hydatid vaccine antigen, EG95. These regions overlapped each other and corresponded to amino acids 1-70 (EG95-1), 51-106 (EG95-2) and 89-153 (EG95-3) of the full length recombinant protein. Each region elicited antibody which reacted with the parent antigen, although these reactivities were a small proportion of the level of reactivity generated by immunisation with the full length antigen. Antisera raised against each of the truncated proteins reacted with the native parasite antigen. In vaccination and parasite challenge trials in sheep, none of the truncated regions elicited significant protection against challenge infection or antibody which was lethal to the parasite in vitro. Antibodies from sheep immunised with the combination of all three overlapping truncations elicited a comparatively low but significant level of lysis of the parasite in vitro. These antigens did not inhibit anti-EG95 antibody reactivity with EG95 nor did they inhibit in vitro oncosphere killing induced by anti-EG95 antibodies. These results indicate that the major part of the immune response induced by EG95 vaccination is directed against conformational epitopes and that the host-protective epitope(s) is/are conformational.

Amino Acid Sequence↗

PubMed2000

Vaccination against cysticercosis and hydatid disease.

Infections with the larval stages of taeniid cestode parasites cause substantial human morbidity as well as economic losses in domestic livestock species. Despite ongoing efforts around the world, few countries have been able substantially to reduce or eradicate these infections through the use of anthelmintics and lifestyle changes. Vaccines offer an additional potential tool to assist with the control of parasite transmission. Here, Marshall Lightowlers and colleagues review the substantial progress that has been made towards developing practical vaccines against hydatid disease in sheep and cysticercosis in sheep and cattle. Recombinant antigens have been used to induce more than 90% protection against challenge infections. Such success in animals encourages investigation of the potential use of vaccines in humans to prevent hydatid disease arising from infection with Echinococcus granulosus and cysticercosis from infection with Taenia solium.

Amino Acid Sequence↗