Society For Parasitology Research Articles

Antiparasite activity of sea-anemone cytolysins onGiardia duodenalis and specific targeting withanti-Giardia antibodies

The killing activity of sea-anemone cytolysins on Giardia duodenalis wasinvestigated. Three different toxins, sticholysin I and II from Stichodactyla helianthus (St I and St II) and equinatoxin II from Actinia equina (EqtII) were all found to beactive in an acute test, with a C 50 in the nanomolar range (St I, 0.5 nM; St II, 1.6 nM; and EqtII, 0.8 nM). A method to target the cytolysin activity more specifically towards theparasite cells by using anti- Giardia antibodies was then investigated. Parasite cells weresensitised with a primary murine monoclonal or polyclonal antibody followed by a biotinylatedsecondary anti-mouse-IgG monoclonal antibody. Subsequently, avidin and a biotinylated EqtIImutant were added, either in two separate steps or as a pre-formed conjugate. When themonoclonal antibody was used, the C 50 of biotinylated EqtII was 1.3 nM withsensitised cells and 5 nM with non-sensitised cells, indicating a four-fold enhancement of activitywith the cell treatment. Treatment with the polyclonal antibody was somehow more effective thanwith the monoclonal antibody in an acute test. This indicates that sea-anemone cytolysins canefficiently kill Giardia cells, and that it is possible to improve, to a certain extent, theanti-parasite specificity of these toxins with anti- Giardia antibodies. However, thefeasibility of this approach in vivo remains to be demonstrated. © 1999 Australian Society forParasitology

Trypanosomiasis and Leishmaniasis: Between the Idea and the Reality of Control

The International Symposium on Trypanosomiasis and Leishmaniasis, organized by the British Society for Parasitology and the University Victor Segalen, Bordeaux 2, France, was held at Le Palatium, Arcachon, France 18–21 April, 1998.

Workshop on irradiated larval vaccines

The development of anthelmintic resistance in gastrointestinal parasites of sheep and goats has meant that there is an urgent need for non-chemical control of these parasites. In order to investigate a potential alternative method of control, a workshop on irradiated larval vaccines (ILV) was held in conjunction with the Second International Conference on Novel Approaches to the Control of Helminth Parasites of Livestock. The objectives of the workshop were to: (1) Review knowledge of irradiated helminth vaccines through the presentation of invited and contributed papers. (2) Identify opportunities for an ILV and in which host/parasite/production systems. (3) Determine what are the gaps in knowledge required to produce and apply an ILV. The workshop concluded that ILVs could be useful as research tools in the further definition of immune responses to parasites and in stimulating the immune response in young sheep and goats to facilitate the estimating of heritability of faecal egg counts. Although the workshop identified some problems associated with a live attenuated vaccine, an ILV could be a useful control measure in the production systems identified by the workshop. Before an ILV could be used on farms, additional research is required into the period of protection afforded by an ILV especially under field conditions. The efficacy of an ILV could be improved by interaction between host genotype and nutritional status and is deserving of further investigation. 1998 Australian Society for Parasitology. Published by Elsevier Science Ltd.

Birds and their Parasites: Victims of Infection or Fashion?

Vilnius, Lithuania June 1998

Production of monoclonal antibodies against target schistosomal antigen secreted in the urine of Schistosoma mansoni-infected patients

This study was undertaken to develop an immunodiagnostic test of active human schistosomiasis mansoni using a monoclonal antibody which targets urinary schistosomal antigen. Polyclonal antisera raised in rabbits against the processed urine of Schistosoma mansoni-infected patients showed very high and significant reactivity with ES product of ova compared with other different S. mansoni antigens. The monoclonal antibody (4.23) was reactive with repetitive epitopes of S. mansoni soluble egg antigen and ES product of ova with molecular mass range of 65–23 kDa and 80–23 kDa, respectively. It recognised different stages of the parasite life-cycle, with no cross reaction with Fasciola or hydatid antigen. MAbs were characterised by isotyping, immunoelectrophoresis, SDS–PAGE and the enzyme-linked immunoelectrotransfer blot technique, ELISA, and their recognition of carbohydrate or protein antigenic epitopes by periodate oxidation and trichloroacetic acid treatment of the antigen. It was used for detection of circulating schistosomal antigen in an antigen capture antibody sandwich ELISA on sera and urines of 58 S. mansoni-infected patients, 17 S. haematobium-infected patients, 15 parasite-free negative healthy controls and sera from 13 schistosomiasis-free patients harbouring Fasciola or hydatid infections. The percentage sensitivity of the assay in the serum of S. mansoni-infected patients was 98.4% and in urine 94.8%. A positive correlation was found between the number of faecal S. mansoni eggs and the circulating antigen, both in serum and in urine. Antigen circulating in urine correlated with that in the sera of S. mansoni patients. These data provide a sensitive and non-invasive method almost comparable with the use of sera for immunodiagnosis of schistosomiasis and an indirect way to reflect the intensity of infection. Australian Society for Parasitology.

Intracellular alkalinisation in Vero cells parasitised by Trypanosoma cruzi

We studied the intracellular pH of Vero cells parasitised by Trypanosoma cruzi, using different methods: fluorimetric measurement after labelling the cells with the pH-sensitive intracellular fluorescent dye 2′,7′,-bis- (2-carboxyethyl)-5- (and-6)-carboxyfluorescein, acetoxymethyl ester; flow cytometry; and image analysis after staining the cells with neutral-red vital stain. The results show that the intracellular pH of the parasitised cells rose in comparison with that of the uninfected control cells. A study of the population of parasitised cells made by flow cytometry allowed us to subdivide the cells from the infected cultures into two populations according to their pH as obtained by fluorimetric measurements. Image analysis showed that the cell cytoplasm was more alkaline in the vicinity of the sites containing parasites. Treatment of the parasitised cells with amiloride, ouabain, or with 4,4′-diisothiocyano-2,2′-stilbene disulphate consistently lowered the pH values of the parasitised cells, but not sufficiently to return to the values of the non-parasitised control cells. When the control cells were subject to similar treatments with the inhibitors, only amiloride acidified the cytoplasm to any extent. The basification undergone by the parasitised cells was independent of the transport systems and may be a consequence of the release of NH + 4 by the intracellular amastigotes. © 1998 Australian Society for Parasitology.

Invited review Recent studies on the reproductive biology of the schistosomes and their relevance to speciation in the Digenea

The members of the family Schistosomatidae, dioecious Digenea, are discussed with regard to their distribution, intermediate and definitive host parasite relationships. The biological species concept is considered together with the di.culties of its application to Schistosoma spp. and the Digenea. The correlation between pairing of adult schistosomes, physical and sexual development and the maintenance of reproductive potential is emphasised. Development of the female reproductive system does not depend upon species-specific pairing. In some combinations, e.g., Schistosoma haematobium:Schistosoma intercalatum and Schistosoma bovis:Schistosoma curassoni, a specific mate choice system apparently does not exist, whereas it does in other combinations, e.g., Schistosoma mansoni\\Schistosoma intercalatum. In mixed infections change of mate may occur and when the opportunity arises heterospecific pairs of worms will change partners to conspecific pairs. Interspecific pairing in adult schistosomes will lead to either hybridisation or parthenogenesis. Yet the majority of schistosomes that inhabit the same definitive host maintain their genetic identity: specific mate recognition, site selection within the host and heterologous immunity have been suggested as isolating mechanisms. Experimental intraspecific crosses have enabled evaluation of the degree to which some populations separated and became reproductively isolated through pre-mating isolating mechanisms, indicative of incipient spec- iation, e.g., the Lower Guinea and Zaire strains of S. intercalatum. The occurrence and significance of parthenogenesis in schistosomes and other species of Digenea are discussed. The consequences of interspecific mating interactions in schistosomes with regard to parasite epidemiology, interspecific competition and genetic heterogeneity are debated. Geographical isolation and host specificity represent important pre-zygotic isolating mechanisms. It is suggested that site selection within the host and heterologous immunity may both reduce interspecific genetic interchange when digenean parasites utilise the same definitive host. ©1998 Australian Society for Parasitology. Published by Elsevier Science Ltd.

A comparison of three different dihydroartemisinin formulations for the treatment of acute uncomplicated falciparum malaria in Thailand

We compared the safety and efficacy of three formulations of dihydroartemisinin for the treatment of acute uncom- plicated falciparum malaria in patients who received a total dose of 600 mg dihydroartemisinin over 5 days. The first group was treated by dihydroartemisinin produced and formulated in the People’s Republic of China, the second group was treated by dihydroartemisinin produced in Vietnam but formulated by the Government Pharmaceutical Organization of Thailand and the third group was treated by dihydroartemisinin produced and formulated by the Government Pharmaceutical Organization of Thailand. All patients were admitted to hospital to evaluate safety and e.cacy for a total of 28 days. By the third day of treatment, most patients were blood-smear negative for parasites and none had serious adverse effects. Minor symptoms such as nausea, dizziness and headache were similar in the three groups and disappeared after 3 days of treatment. One-hundred and thirty-three patients completed the 28-day follow- up period. The cure rates of groups I, II and III were 80%, 85% and 92%, respectively (P 0.02). There were no significant differences in fever clearance or parasite clearance among the three groups. We conclude that the three formulations of dihydroartemisinin produced and formulated in different countries were safe and effective in treating uncomplicated falciparum malaria acquired in Thailand. © 1998 Australian Society for Parasitology. Published by Elsevier Science Ltd.

Phylogeny of benign Theileria species from cattle in Thailand, China and the U.S.A. based on the major piroplasm surface protein and small subunit ribosomal RNA genes

The major piroplasm surface protein and small subunit ribosomal RNA genes of benign Theileria species isolated from cattle in China, Thailand and the U.S.A. were amplified by polymerase chain reaction, cloned and sequenced. The major piroplasm surface protein genes of these three isolates were more than 89% identical at amino-acid level. Several deletions in the gene from the Thai isolate led to considerable structural change through frame shifts of the major piroplasm surface protein. Phylogenetic analyses based on both of the major piroplasm surface protein and small subunit ribosomal RNA genes suggest that there may be a second cosmopolitan benign Theileria species infecting cattle in addition to the Theileria sergenti\\buffeli\\orientalis complex.© 1998 Australian Society for Parasitology. Published by Elsevier Science Ltd.

Mosquitoes and Monsoon

Hyderabad, India August 1997

Ligula intestinalis: interactions with the pituitary-gonadal axis of its fish host

I was delighted to be able to join with so many friends and colleagues, in writing this short paper to mark the retirement of Donald Lee. There are many outstanding milestones in Donald's career. However, I thought that I could perhaps draw special attention to his long and distinguished association with the British Society for Parasitology (BSP), and the journal, Parasitology. He was President of the BSP between 1978 and 1980 and, in recognition of his service to the Society and contributions to the discipline of parasitology, was elected an Honorary Member in 1980. Donald has also had a long association with Parasitology, as a member of the Editorial Board and as a frequent contributor. His first paper in the journal was published in 1958; it described the occurrence of Syngamus sp. in a fieldfare (Turdus pilaris) that had been accidentally killed. At the time of writing, his most recent publication, but I suspect not his last, was a biochemical study on proteins produced by Nippostrongylus brasiliensis, Nematodims battus and Ascaridia galli (Foster & Lee, 1996). Of course, Donald has published in many other journals and authored several books. However, if one considers only those papers published in Parasitology, they provide a record of intellectual vigour and curiosity that has remained undiminished throughout his career.

The Last Fifty Years of Western Medicine in Korea: Korean Society for Parasitology

The Last Fifty Years of Western Medicine in Korea: Korean Society for Parasitology

Differences in the life cycles of two species of reptile tick: Implications for species distributions

INTRODUCTION I am delighted to be the 1993 recipient of the John Frederick Adrian Sprent Prize. I wish to thank the Australian Society for Parasitology for making such an award possible. In accepting this honour I wish to acknowledge Associate Prof. C. Michael Bull and Dr Ross H. Andrews for their guidance during my postgraduate study at Flinders University of South Australia. My lecture, which is based on part of my Ph.D. thesis, is entitled “Differences in the life cycles of two species of reptile tick: implications for species distributions”.

Presidential address: The changing face of parasitology in New Zealand

WELL here we are-Auckland, New Zealand, 1992, the fourth joint meeting with the Australian Society for Parasitology and the twenty-first meeting of the New (f) Zealand Society for Parasitology. In the 20 years since the inaugural meeting was held at Victoria University in Wellington we have grown from a foundation membership of 44 to the present membership of 106. We are still a very small society when compared with (g) the 59 affiliated scientific bodies of the Royal Society of New Zealand. In the 1990 annual report of the Royal Society we were the eighth smallest society based on membership numbers. (h) During the past 20 years we have accomplished much:

Australian Society for Parasitology Presidential Address: Echinococcus and Giardia: Variation on a theme

INTRODUCTION organisms, this could result in a disjointed collection WHEN Professor Sprent reiterated his interest in of research findings, particularly in view of the time publishing the Presidential Addresses of the constraints of this address. However, I hope my title Australian Society for Parasitology, I was only too allays any fears and conveys the fact that I intend to pleased to continue a tradition established in the early focus on a common theme with respect to both days of the Society over 20 years ago. The practice of organisms. publishing the Presidential Addresses was revived by Although Echinococcus and Giardia are phyloProfessor Bryant in 1983 (Bryant, 1983) and followed genetically and biologically quite distinct, apart from shortly afterwards by Dr Howell (Howell, 1985). I sharing the small intestine as their predilection site, should like to take advantage of this unique avenue of they both have one very important characteristic in publication to give an overview and my interpretation common: pronounced variability, particularly at the of some of the research I have been involved with on intraspecific level. However, with both organisms, it Echinococcus and Giardia. With two such disparate has been very difficult to reconcile whether observed variation in characters such as host occurrence, de* Annual Scientific Meeting, Fremantle, Western velopment, infectivity, virulence, response to drugs, Australia, 9-l 1 August 1990. etc. reflect genetic differences or are environmentally or

The Bancroft-Mackerras medal of the Australian society for parasitology: 1990 Award to Ian G. Wright

The Bancroft-Mackerras medal of the Australian society for parasitology: 1990 Award to Ian G. Wright

Acknowledgements

The British Society for Parasitology gratefully acknowledges financial support for this meeting from the following organisations:

The Current Pathobiology and Chemotherapy of Clonorchiasis. By Rim Han-Jong. 141 pages. Korean Society for Parasitology, Seoul National University, Seoul.

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Larval Migration of Strongyloides ratti with Reference to Esophagus Length

Since Abe (1964, Japanese Journal of Parasitology 13: 317) reported the existence of a cranial migration route for Strongyloides ratti larvae, many abstracts on this subject (not followed by complete papers) have been presented at annual meetings of the Japanese Society of Parasitology. Recently, Tada et al. (1979, Japanese Journal of Parasitology 28: 219-227) suggested migration via the smooth subcutis from the infection site to the head. Further, Hattori (1981, Japanese Journal of Parasitology 30: 597-607) described a cranial-paranasal migration route of S. ratti in rats-from the skin subcutaneously to the subarachnoidal space and then to the paranasal cavity, finally reaching the intestine without lung involvement. Mimori et al. (1982, Japanese Journal of Parasitology 31: 361-368) also supported the cranial migration pathway. To confirm the migration route reported by Hattori (1981, loc. cit.), we recovered larvae from tissues of rats at 12-hr intervals after infection, and traced the migration route to the intestine using a modified criterion or Esophagus Index of the larvae.

Parasites and Human Disease

The fourteen papers in this excellent book were presented at an international symposium organized by the Linnean Society of London and the British Society for Parasitology, held at Keele University 12–13 July 1984. The papers examine various aspects of host genetics, parasite genetics, population genetics, theoretical ecology and experimental and field epidemiology. Hostparasite systems range from bacteria and phage to humans and helminth infections.The papers are generally very well written, with clearly stated hypotheses and a minimum of jargon. Some of parasitologists' dearest assumptions are examined: that host susceptibility to infection may be a genetically determined, qualitative response (i.e., susceptible or resistant); that parasites may act as agents of selection upon their hosts; that parasites evolve to become commensals. Articles that are directly applicable to the epidemiology of human pathogens are by Rollinson and Southgate on genetic variability of schistosome and snail populations; by Tait on protein variation in parasitic protozoa; by Luzzatto, Usanga and Modiano on genetic resistance of humans to Plasmodium falciparum; and by Anderson and Crombie on age-intensity and age-prevalence profiles of Schistosoma mansoni infections in snails and mice.