bluuebunny/crossref_metadata_2025 huggingface dataset:
Nematode parasites of Oceanica: VIII. Filariids of birds, with a new genus and four new species
Authors: Schmidt Gerald D. , Kuntz Robert E.
Published: June 2009

Filariids of birds of Taiwan, Palawan and Sabah are discussed. Oceanifilaria verrucosa gen. et. sp.nov. from woodpeckers is proposed in Dicheilonematinae. It differs from other genera in the subfamily in having asymmetrical caudal alae, in lacking sessile papillae between the alae and in possessing a band of cuticular bosses at the anterior end followed by a bare zone, the latter followed by irregular bosses over the rest of the body. Aprocta calliderma sp.nov. from a cuckoo differs from A. papillosa Chabaud, Anderson & Brygoo, 1959, in having an oesophagus about one-sixth as long. Parornithofilaria hepatica sp.nov. from a pigeon differs from P. lienalis (Orloff, 1947) Sonin, 1965, in having unequal spicules with the right 110–120 mm and the left 140–175 μm long. Parornithofilaria sonini sp.nov. from magpies differs from P. hepatica in spicule shape, tail length and distribution of caudal papillae. Other species reported and briefly discussed are: Hamato-spiculum quadridens (Molin, 1858) Boulenger, 1928, H. cylindricum (Zeder, 1803) Hartwich, 1954; Aprocta lepidogrammi (Tubangui & Masiluñgan, 1937) Anderson & Chabaud, 1958; A. cylindrica Linstow, 1883; Pseudaprocta decorata Li, 1933; P. gubernacularia Schikhobolova, 1930; P. sichoealinensis Oshmarin & Belous, 1951; Paraprocta brevicauda (Chandler, 1924) Maplestone, 1931; Paronchocerca tonkinensis (Chow, 1939) Lopez-Neyra, 1947; Diplotriaena corrugata Wehr, 1930; D. epsilon Johnston & Mawson, 1940; D. henryi Blanc, 1919; D. leiperi Anderson, 1959; D. ozouxi (Railliet & Henry, 1909) Henry & Ozoux, 1909; D. pungens (Schneider, 1866) Henry & Ozoux, 1909; and D. unguiculata (Rudolphi, 1819) Li, 1933.

We wish to acknowledge the field support by Dr D. S. Rabor, Department of Biology, Silliman University, Dumaguete City, Negros Oriental, Republic of the Philippines, and the technicians of the Parasitology Department of Naval Medical Research Unit No. 2 for general assistance in procurement and examination of hosts. Dr B. J. Myers assisted with initial handling of the specimens.
Demodex antechini sp.nov. (Acari, Demodicidae) parasitic on Antechinus stuartii (Marsupialia)
Authors: Nutting W. B. , Sweatman Gordon K.
Published: June 2009

The first marsupial demodicid, Demodex antechini, is described with notes on its life cycle, sexual dimorphism and pathology. This species is remarkably similar except for the marked sexual dimorphism, to demodicids of eutherian mammals. This suggests an early origin and a long evolutionary history of parallelism within the genus.

Our thanks to Patricia Woolley, Waite Agricultural Institute, Glen Osmond, Australia, for the specimens used in preparing this paper. We would also like to thank Clifford Desch for the photography and the drawings. The work reported here was supported in part by NSF Grant (GB-3516).
The development ofEchinococcus granulosuslarvae in laboratory animals
Authors: Heath D. D.
Published: June 2009

Rabbits and mice, but not sheep, guinea-pigs or rats, were suitable hosts for secondary echinococcosis using protoscoleces obtained from Australian sheep. The host specificity is tentatively related to the phylogenetic relationship between the donor host and receptor host.

The development rate of hydatid cysts in mice is described in terms of increase in fresh weight, dry weight, and maximum cyst diameter. Fertile cysts were found after 8 months when the water content of the cysts had increased to more than 95 %. The diameter of fertile cysts up to 14 months ranged from 6 to 30 mm. By 14 months, the average fresh weight of cysts was greater than the body weight of the mice.

This work was carried out during the tenure of an Australian Wool Board Senior Postgraduate Scholarship, and forms part of a thesis to be presented for the degree of Doctor of Philosophy of the Australian National University.

I wish to thank my supervisor, Professor J. D. Smyth, for guidance and criticism.
Modulation of the bacterial clearance activity of haemocytes from the freshwater mollusc, Lymnaea stagnalis, by the avian schistosome, Trichobilharzia ocellata
Authors: Núñez P. E. , Ademal C. M. , De Jong-Brink M.
Published: June 2009

The ability of haemocytes, from the haemolymph of the gastropod mollusc Lymnaea stagnalis, to recognize and eliminate the bacterium Aeromonas salmonicida was shown using an in vitro bacterial clearance assay. The assay employs a dye which is reduced by A. salmonicida in direct proportion to the number of viable bacteria resulting in a colour change which can be determined spectrophotometrically. Addition of cytochalasin B resulted in a marked decrease in bacterial clearance, implicating both intracellular and extracellular cytotoxicity of haemocytes. A comparison of haemocytes from uninfected snails and snails infected with the avian schistosome parasite Trichobilharzia ocellata showed that both juveniles and adults of L. stagnalis were susceptible to infection with T. ocellata. After exposure to the trematode for 1·5 h the haemocytes from these infected snails had an enhanced clearance capacity, whilst cells obtained from snails with 24–96 h infections showed decreased clearance of the bacteria, indicating suppression by the parasite. Haemocytes, as well as plasma, which was tested on haemocytes from uninfected snails, were used and hence a distinction was made between cell and humoralassociated effects. The results show that both cellular and humoral components of immunity were activated, then suppressed, following exposure to the parasite. Infection with T. ocellata seems to have a modulating effect on the bactericidal activity of the internal defence system of the snail host, L. stagnalis.
Genetic differences in the interactions of a microsporidian parasite and four clones of its cyclically parthenogenetic host
Authors: Ebert D.
Published: June 2009

Host–parasite interactions were studied for the microsporidiumPleistophora intestinalisand its host,Daphnia magna. Two host clones were established from the same population from which the parasites were taken (home-1 and 2), and two clones from two other ponds (neighbour and Munich clone). With increasing clutch number infected females from home-1 clone produced relatively smaller clutches than uninfected females. Age and body length at maturity were not affected by the infection, but body length of the sixth adult instar was reduced. In an experiment including all four host clones, the parasite reproduced well in the two home clones and in the neighbour clone, but poorly in the Munich clone. Juvenile growth and age at maturity was not affected in the two home clones, but for the neighbour and the Munich clone age was delayed by 2·2 days and 4·1 days, and juvenile growth reduced by 16 and 23%, respectively. Significant host-clone x parasite-treatment interactions were also found for size at maturity and clutch size. This pattern of host-parasite interactions suggests that there is no general positive relation between disease severity and parasite multiplication rate.
Schistosome extracts with heat shock factor activity revealed by the gel shift assay
Authors: Levy-Holtzman R. , Schechter I.
Published: June 2009

To understand the regulated expression of stage-specific genes of schistosomes, it is necessary to identify regulatory DNA elements and DNA-binding proteins that control the level of gene transcription. Here we describe the preparation of Schistosoma mansoni extracts with active transcription factors detected by the electrophoretic mobility shift assay (EMSA). We analysed the hsp70 system of S. mansoni because the promoters of the hsp70 gene contain two heat shock elements (HSE) that differ from the consensus sequence (CnnGAAnnTTCnnG) at one (HSEI) or three (HSEII) positions, and it is known that transcriptional activation of hsp70 genes is mediated by interaction of HSE with the heat shock factor (HSF). Analyses of parasite extracts from different developmental stages demonstrate the presence of putative HSF that correlates with the pattern of hsp70 mRNA expression (cercariae-, schistosomula+, adult worms+). Cercarial extracts did not show binding of 32P-labelled HSEI or HSEII. Extracts of schistosomula and of adult worms kept at 37 or 42 °C showed binding of HSEI but not HSEII. The specificity of HSEI-HSF complex formation was ascertained by inhibition experiments. The EMSA experiments and structural features of the hsp70 promoter indicate that HSEI is the major DNA element responsible for transcriptional activation of the hsp70 gene, while the HSEII may be a redundant sequence with minor (if any) regulatory function. The extracts reported here can be used to study transcriptional control of other schistosome genes.
Response of inbred mice to infection with a new isolate ofTrypanosoma musculi
Authors: Chiejina S. N. , Street J. , Wakelin D. , Behnke J. M.
Published: June 2009

A new isolate ofTrypanosoma musculihas been derived from organisms recovered fromMus spretuscaptured in Lisbon, Portugal. The time-course and profiles of infection with this isolate in inbred mice have been compared with those obtained with the existing Partinico II isolate. Infections with the Portuguese isolate are less intense, and controlled more quickly than those with the Partinico isolate. As with the latter, there are marked mouse strain-dependent influences on infection with the Portuguese isolate, but these strain-dependent characteristics differ considerably with each isolate. For example, NIH mice were the most susceptible to the Partinico II isolate, but virtually refractory to the Portuguese isolate. Mice exposed to infection with one isolate show complete immunity to both homologous and heterologous challenge infections. These striking interactions between host and parasite genotype are discussed in terms of immunological influences on infection.
Genetic structure and epidemiology ofAscarispopulations: patterns of host affiliation in Guatemala
Authors: Anderson T. J. C. , Romero-Abal M. E. , Jaenike J.
Published: June 2009

In Guatemalan villages people commonly rear pigs, and both hosts may be infected withAscaris. This study was designed to ask whether both humans and pigs are potential hosts in a single parasite transmission cycle in such villages, or alternatively, if there are two separate transmission cycles, one involving pigs and one involving human hosts. Parasites were collected from both host species from locations in the north and south of Guatemala. Allelic variation in the nuclear genome ofAscariswas measured using enzyme electrophoresis, while mitochondrial DNA (mtDNA) sequence variation was quantified using restriction mapping. Low levels of enzyme polymorphism were found inAscaris, but allele frequencies at two loci, mannose phosphate isomerase and esterase, suggest that there is little gene exchange between parasite populations from humans and pigs. MtDNA haplotypes fall into two distinct clusters which differ in sequence by 3–4%; the two clusters broadly correspond to worms collected from humans and those collected from pigs. However, some parasites collected from humans have mtDNA characteristic of the ‘pigAscaris’ haplotype cluster, while some parasites collected from pigs have mtDNA characteristic of the ’ haplotype cluster. These shared haplotypes are unlikely to represent contemporary cross-infection events. Patterns of phylogenetic similarity and geographical distribution of these haplotypes suggest, instead, that they are the result of two historical introgressions of mtDNA between the two host-associatedAscarispopulations. The results clearly demonstrate thatAscarisfrom humans and pigs are involved in separate transmission cycles in Guatemala.
Endotoxins and the pathogenesis ofTrypanosoma brucei bruceiinfection in mice
Authors: Alafiatayo R. A. , Crawley B. , Oppenheim B. A. , Pentreath V. W.
Published: June 2009

The involvement of endotoxins inTrypanosoma brucei bruceiinfection in CD-1 mice was investigated by theLimulusamoebocyte lysate (LAL) test. At 7 days post-infection mean serum endotoxin level was elevated by 2·5 times (36·4 pg/ml cf. control 14·25 pg/ml, P < 0·001) and a similar increase was maintained throughout the infection (survival 28–35 days). Purified disrupted parasites contained significant endotoxin activity (mean value 280 pg/mg protein). The mouse infections were also associated with progressive Gram-negative bacteraemia (present in 4 Out of 5 infected animals by day 28 p.i.). The increased endotoxin levels may be due to parasite products, the products of intercurrent bacterial infections, other unidentified sources (e.g. from the gut), or a combination of these. It is concluded that the raised endotoxins may be important contributive factors in the pathogenesis of experimental murine trypanosomiasis.
Dipstick dot ELISA for the detection of Taenia coproantigens in humans
Authors: Allan J. C. , Mencos F. , Garcia-Noval J. , Sarti E. , Flisser A. , Wang Y. , Liu D. , Craig P. S.
Published: June 2009

A dipstick dot ELISA for detection of Taenia-specific coproantigens was developed. The test was based on a sandwich ELISA using antibodies raised against adult Taenia solium. Antibodies were adsorbed to nitrocellulose paper previously adhered to acetate plastic to form dipsticks. Once blocked with 5% skimmed milk and dried the antibody-coated dipsticks were stable for several weeks at room temperature. Both micro and dot ELISA formats were genus specific although the dot ELISA was less sensitive than the micro ELISA based on the same antiserum. During field studies, in which the majority of samples were tested in rural villages soon after collection, 3728 samples were tested. All samples were also examined by microscopy using formol ether concentration and individuals questioned to determine whether they were aware of being infected. After the initial diagnostic work individuals were treated with taeniacidal drugs for worm recovery. Use of the coproantigen test significantly increased the number of cases diagnosed. Of the 41 cases diagnosed by the three diagnostic techniques combined 31 were detected by the dipstick assay making it the most sensitive technique employed. The specificity of the dipstick assay was 99·9% with a positive predictive value of 88·%. The combined diagnostic approach did not, however, diagnose all cases. The coproantigen test was fast and easy to use. Further improvements may make the dipstick test suitable for wide-scale use in field studies and diagnostic laboratories.
Observations on the pathogenicity and pathology of Ascaridia galli
Authors: Ikeme M. M.
Published: June 2009

The pathogenicity and pathology of Ascaridia galli infections of poultry were studied using repeated doses of varying numbers of eggs. No significant effect due to infection was seen on p.c.v. and Hb. values of infected chickens. Haemo concentration occurred parallel with sporadic diarrhoea, which follows high levels of repeated dosing. This phenomenon complicated the interpretation of blood protein values. A/G ratios were, however, worked out and analysed. No significant differences were noticed between the groups and it was concluded that under the levels of inoculation employed during the study there were no significant effects of A. galli infections on blood protein values as well as p.c.v. and Hb.values of infected chickens.

Symptomatic developments, macroscopic lesions and pathological changes of intestinal tissues due to infection were followed up in detail. They were most severe in chickens on the least nutritive diet and sustaining the highest levels of repeated doses. Pathogenicity of larval and adult parasites was described. The presence of large numbers of adult parasites was associated with intestinal obstruction in host. This was seen mostly in chickens on low nutrition and sustaining either low or high levels of repeated inoculation, and very rarely also in chickens under high plane of nutrition but sustaining repeated inoculation of small numbers of eggs. Cellular infiltration as a result of infection was found to be extremely rare.It was present as fibroblasts and only in association with dead larvae.

The author is indebted to the Department of Technical Cooperation, under whose Fellowship the study was carried out; the Department of Zoology, Edinburgh University, for facilities provided; the Ministry of Agriculture, Fisheries and Food; Lasswode Poultry Research Laboratories, for the free supply of chickens used here; Dr J. A. Campbell of Edinburgh University for his keen interest, encouragement and advice throughout this work; and finally to G. Obiwelozor for reproducing the photographs from the original manuscript.
Changes in adult Nippostrongylus brasiliensis during the development of immunity to this nematode in rats: 2. Total lipids and neutral lipids
Authors: Lee D. L.
Published: June 2009

The total lipids and the amount of neutral lipids of male and female N. brasiliensis, from 7-day and 15-day infections, have been studied quantitatively. There is an increase in total lipids from 10·9 ± 2 to 15·5 ± 2 % in females and an increase from 8·4 ± 1 to 14·6 ± 2 % in males. In both sexes there is a rise in cholesterol and trigylceride content and a fall in free fatty acid content. These changes are discussed with reference to the development of immunity of the host to this nematode.

I wish to thank Mrs B. Fisher, Mr A. W. Pearson and Mr N. Sykes for assistance during this work. These results form part of a programme of work supported by the A.R.C. while I was at the Molteno Institute, University of Cambridge, and continued at the Houghton Poultry Research Station. I wish to thank Dr P. Tate for accommodation at the Molteno Institute during the early part of this work.
Phenotypic analysis of the cellular responses in regional lymphoid organs of mice vaccinated againstSchistosoma mansoni
Authors: Constant S. L. , Mountford A. P. , Wilson R. A.
Published: June 2009

The cellular responses in regional lymphoid organs of C57B1/6 mice were examined, following protective immunization with 20 krad.-irradiated cercariae ofS. mansoni. Marked changes in total cell number were observed, with peak increases of 13·5-fold in the skin-draining (axillary) lymph nodes and 6·9-fold in the lung-draining (mediastinal) lymph nodes. In contrast, cellular responses were small in the spleen and undetectable in the brachial lymph nodes. The temporal pattern of responses was coincident with the kinetics of parasite migration, events in the mediastinal lymph node being apparent only after day 7. Phenotypic analysis of the cellular changes revealed an increase both in T lymphocytes and, to a greater extent, in B lymphocytes. The changes in Thyl+cells comprised an increase in both L3T4+and Lyt2+populations. A comparison of mice exposed to non-immunizing parasites (normal or 80 krad.-irradiated cercariae) with protected animals, revealed smaller and more transient cellular changes in the axillary lymph nodes of the former. We suggest that the successful immunization of mice with attenuated parasites depends upon the prolonged priming of lymphocytes within the lymph nodes draining the skin-exposure site and that the persistence of 20 krad.-irradiated parasites within these nodes provides the requisite stimulus.
Immunogenetic correlates of susceptibility to infection with Heligmosomoides polygyrus in outbred mice
Authors: Keymer A. E. , Tarlton A. B. , Hiorns R. W. , Lawrence C. E. , Pritchard D. I.
Published: June 2009

Outbred MF1 mice were characterized with respect to their susceptibility to infection with Heligmosomoides polygyrus (Nematoda) on the basis of faecal egg counts after 8 weeks of repeated infection (50 larvae/week). Selective breeding for resistance and susceptibility was carried out over 3 generations. The H-2 type of a sample of the mice was determined, and antigen recognition assessed on the basis of Western blots against adult and larval H. polygyrus homogenate. The selective breeding programme yielded very strong evidence for the heritability of susceptibility to infection. The results were consistent with a model of single gene control with resistance dominant over susceptibility. The presence of the H-2k haplotype was significantly associated with susceptibility, as was the recognition of a 17 kDa antigen in blots against both larval and adult worm homogenate. The proportion of mice phenotypically susceptible to infection, the proportion bearing the H-2k haplotype, and the proportion recognizing the 17 kDa antigen, were all approximately 0.25.
The laboratory maintenance of Diphyllobothrium dendriticum (Nitzsch, 1824)
Authors: Sharp G. J. E. , Secombes C. J. , Pike A. W.
Published: June 2009

A protocol for the routine laboratory maintenance of the life-cycle of Diphyllobothrium dendriticum, using herring gulls (Larus argentatus), Cyclops abyssorum and rainbow trout Oncorhynchus mykiss ( = Salmo gairdneri) as the definitive, first and second intermediate hosts respectively, is described.
A model of host–parasite relationships
Authors: Crofton H. D.
Published: June 2009

A model of host–parasite relationships is proposed and its properties examined.
Frequency distributions of parasites in a population of three-spined sticklebacks,Gasterosteus aculeatusL., with particular reference to the negative binomial distribution
Authors: Pennycuick Linda
Published: June 2009

All three species of parasites found in sticklebacks from Priddy had overdispersed distributions, similar in shape to host–parasite distributions described by other authors.

The distributions of bothEchinorhynchus clavulaandDiplostomum gasterosteiwere fitted closely by the negative binomial. The values ofkwere similar for both species, being always less than unity; theDiplostomumdistributions were more overdispersed and therefore had higher values ofp.

TheSchistocephalusdistributions were mostly described by the log normal, but the high percentage infection and relatively low overdispersion meant that the fit was often not close. There was also some truncation at the upper end.

The relationship between the parameters of the negative binomial (pandk) and the shape and parameters of the original distribution have been investigated, both theoretically and with respect to the distributions of the stickleback parasites.In generalpvaried as the overdispersion andkas the percentage infection.

The advantages of an overdispersed distribution to the host and parasite populations are discussed and related to the life cycles of the parasites.

I am most grateful to Dr H. D. Crofton for his help and encouragement during this study, and to the staff of the Computer Unit, University of Bristol for their assistance with programming problems. This work was supported by a Science Research Council research studentship and a NATO studentship.
Nippostrongylus brasiliensisin the rat: Failure to relate intestinal histamine and mast cell levels with worm expulsion
Authors: Keller R.
Published: June 2009

This paper describes experiments to determine whether intestinal tissue mast cells and/or intestinal histamine are involved in the second, expulsive step of worm elimination. In neonatal rats, intestinal tissue contains only very little histamine and mature mast cells are encountered only sporadically. From birth to the adult age, there was a gradual rise in both intestinal mast cells and histamine.

DuringNippostrongylus brasiliensisinfection in the adult rat, the concentration of histamine in the small intestine was clearly lower than in uninfected controls.Especially low histamine values were found to occur on days 6–12 of a primary infection in the region where the main worm burden was located. Similarly, the number of tissue mast cells present in the epithelium of the jejunum was decreased in the same region and during the same period of time. From the observation that the bulk of the parasites are expelled at a time when histamme and mast cell levels are low, it was concluded that mast cells and their constituents were not an essential factor in the second step of worm elimination

This work was supported by the Schweizerische Nationalfonds zur Förderung der wissenschaftlichen Forschung (Grant 5200.3). The skilful technical assistance of Miss I. Beeger, Miss R. Keist and Miss M. Iseli is gratefully acknowledged. I thank Mr H. Berchtold, Biostatistisches Zentrum der Universität Zürich, for the statistical evaluation of the data.
An investigation of the mechanism of infection by digenetic trematodes: the penetration of the miracidium ofFasciola hepaticainto its snail hostLymnaea truncatula
Authors: Wilson R. A. , Pullin P. , Denison Jean
Published: June 2009

The penetration barrier presented to the miracidium by the snail epithelium can be divided into three layers. The chemical composition and physical configuration of the outermost of these plays an important part in the initial attachment response of the miracidium. Attachment can be stimulated in the absence of the snail by pure chemicals in solution. However, the surface to which the miracidium attaches must have the correct physical configuration otherwise the miracidium is unable to form a stable attachment.

In vivo, the miracidial body begins to contract and relax following attachment to the snail. This coincides with the start of secretion by the apical gland and accessory gland cells. The snail's columnar epithelium is rapidly cytolysed so that 10 min after attachment the anterior of the miracidium has reached the underlying connective tissues.

As the miracidium penetrates the snail, its ciliated epithelial cells are shed in sequence from anterior to posterior. This shedding removes a protective barrier against osmosis which is probably the acid mucopolysaccharide present in the epithelial cells. The mechanism of shedding is not understood but involves the reversal of binding by the desmosomal mucosubstance which attaches the epithelial cells to surrounding intercellular ridges.

The miracidium metamorphoses into the sporocyst as it penetrates the snail, by forming a new body surface. The material for this is extruded from the vesiculated cells which lie beneath the musculature of the body wall. The process of surface formation coincides with cell shedding and moves backwards as cells are shed. At not more than 2·5 h after attachment the extruded cytoplasm forms a thin continuous layer over the surface of the organism. Contacts with underlying cells appear to have been broken and the cytoplasm is underlain by a thin fibrous basal lamella. In the first 24 h after penetration the surface of this syncytium becomes thrown into folds and metamorphosis into the sporocyst can be considered complete.
Interactions between malaria parasites infecting the same vertebrate host
Authors: Richie T. L.
Published: June 2009

Several species of malarial protozoans commonly parasitize the same host population and often the same individual host. This paper reviews the evidence for interactions among such host-sharing parasites. Field studies measuring the cross-sectional prevalence of malarial species often record fewer mixed infections than expected by chance, suggesting that one parasite has excluded another or suppressed its parasitaemia to undetectable levels. Prevalences may vary reciprocally between seasons, with one species increasing in prevalence while another decreases, despite parallel increases in the transmission rates of both, again suggesting suppression of one species by another. However, longitudinal studies of individual hosts indicate that malarial parasites may also favourably affect the host environment for each other, perhaps due to their depressive effect on the immune system: this is shown by the recrudescence of a latent malarial species immediately before or after the parasitic wave of another species. The suppression hypothesis is supported by data derived from the simultaneous inoculation of twoPlasmodiumspecies into laboratory animals; many studies have shown that one or both species are suppressed. This may be mediated by competition for host cells or nutrients, or by heterologous immunity. However, the suppressed species rebounds after the other species has abated, and may show a prolonged infection. Experimental evidence that one species can facilitate the recrudescence of another is minimal, but this may reflect the paucity of investigations of this phenomenon. Laboratory studies show only minor cross-resistance between host-sharing species, which is consistent with the hypothesis that their co-occurrence has led to antigenic divergence or that species showing strong heterologous resistance cannot co-exist in the same host population. Such complementarity occurs not only with the host immune response but also with many other life-history characteristics of host-sharing parasites, such as host cell preference. I conclude that malarial species have been important in each other's evolution, particularly in the tropics where multi-species complexes are common.
The treatment of experimental cutaneous leishmaniasis with liposome-entrapped Pentostam
Authors: New R. R. C. , Chance M. L. , Heath S.
Published: June 2009

Treatment of cutaneous leishmaniasis by antimonial compounds when administered by various routes to mice infected with Leishmania major or L. mexicana amazonensis is enhanced, relative to the free drug, by entrapment of these compounds within liposomes. The efficacy of the liposome treatment is dependent on the time and route of administration, and upon the phospholipid composition of the liposomes themselves. Drug-loaded liposomes administered intravenously (i.v.) are more effective at reducing the growth of a cutaneous lesion if they are administered after the nodule has begun to develop, rather than at the time of inoculation of the parasites. In contrast to the i.v. route, liposomes administered subcutaneously (s.c.) at the inoculation site are only effective if given at the time of infection.
Antigenic variation in cyclically transmittedTrypanosoma brucei. Variable antigen type composition of metacyclic trypanosome populations from the salivary glands ofGlossina morsitans
Authors: Hajduk S. L. , Cameron Cathy R. , Barry J. D. , Vickerman K.
Published: June 2009

Tsetse flies (Glossina morsitans) were fed on the blood of mice containing any one of 5 variable antigen types (VATs) ofTrypanosoma bruceiAnTAR 1 serodeme. The VATs of the metacyclic trypanosomes subsequently detected in the flies' saliva probes were investigated using monospecific antisera to AnTAR 1 VATs in indirect immunofluorescence and trypanolysis reactions; these sera included 3 raised against AnTats 1.6, 1.30 and 1.45, previously identified as components of the metacyclic population (M-VATs), and against the 5 VATs originally ingested by the flies. The percentage of metacyclics reacting with a particular M-VAT antiserum remained more or less constant (AnTat 1.6, 6·0–8·3%; AnTat 1.30, 13·7–18·2%; AnTat 1.45, 2·0–8·0%), regardless of the age of the fly or the ingested VAT. As these 3 VATs accounted for no more than 30% of the metacyclic population, the existence of at least one more VAT is envisaged. The ingested VAT could not be detected among the AnTAR 1 metacyclic trypanosomes.
Repetitive proteins from the flagellar cytoskeleton of African trypanosomes are diagnostically useful antigens
Authors: Imboden M. , Müller N. , Hemphill A. , Mattioli R. , Seebeck T.
Published: June 2009

Trypanosome infection of mammalian hosts leads, within days, to a strong early response against a small, distinct number of parasite proteins. One of these proteins is the variable surface glycoprotein (VSG). Most of the others are apparently non-variable, intracellular trypanosome proteins. Two of these antigens I2and I17are now characterized at the molecular level. Both exhibit a highly repetitive amino acid sequence organization, but they show no sequence similarity either to each other or to any other proteins known to date. Preliminary serological analyses indicate that both allow the early, sensitive and specific detection of infections with different species of trypanosomatids, making them interesting candidates for the development of diagnostic tools for trypanosomiasis detection.
Quantifying parameters in the transmission of Babesia microti by the tick Ixodes trianguliceps amongst voles (Clethrionomys glareolus)
Authors: Randolph S. E.
Published: June 2009

The estimation of two parameters in the transmission of Babesia microti by the tick Ixodes trianguliceps amongst small mammals, (1) the duration of infectivity in natural hosts and (2) the probability of transmission from an infected to a susceptible vole, is described. When B. microti was maintained by direct tick transmission, the probability of a complete cycle of transmission via the larval-nymphal and nymphal-adult transstadial routes was 1·0 and 0·71 respectively, but only if the larvae or nymphs had engorged, as distinct from feeding slowly, while the source parasitaemia exceeded 2 or 0·2% respectively, but had not yet passed the peak level. The duration of this condition for infectivity in voles infected by nymphal bites was only 1–4 days, whilst infections delivered by adult ticks barely reached the threshold level necessary for successful transmission. When syringe passage was introduced into the parasite maintenance schedule (a) the probability of transmission declined markedly and (b) the time-course of the parasitaemia was altered. If these parameter values are put into a simple model, together with field data on tick and host survival rates, it becomes apparent that additional factors, such as the highly aggregated distribution of ticks on their hosts, must account for the maintenance of B. microti at the levels seen in wild small mammal populations.
Feeding behaviour of tsetse flies (Glossina pallidipes Austen) on Trypanosoma-infected oxen in Kenya
Authors: Baylis M. , Mbwabi A. L.
Published: June 2009

An incomplete ring of electric nets was placed around oxen which were either uninfected, infected with Trypanosoma vivax, or infected with T. congolense. The numbers of fed and unfed Glossina pallidipes caught on the nets were used to estimate the attractiveness of the oxen to tsetse, and the feeding success of the tsetse on the oxen. Oxen infected with T. congolense attracted more G. pallidipes than the other groups of oxen. Taking into consideration daily variation in the abundance or activity of the flies, oxen infected with T. congolense were about 70% more attractive to G. pallidipes than were uninfected oxen or oxen infected with T. vivax. The latter two groups mostly attracted high numbers of G. pallidipes on days when the flies were especially abundant or active. The feeding success of G. pallidipes declined with increase in the rate at which oxen made anti-fly movements. Taking this movement rate into consideration, the feeding success of G. pallidipes on oxen infected with T. congolense was approximately 60% greater than on uninfected oxen or oxen infected with T. vivax. It is suggested that vasodilation induced by T. congolense may account for the difference in feeding success. The level of parasitaemia of T. congolense or T. vivax was not found to affect either the attractiveness of oxen or the feeding success on oxen. There was significant daily variation in the mean fat content of male G. pallidipes caught around the oxen but no effect of mean daily fat content on the proportion of males that fed. The mean haematin content of fed male G. pallidipes was positively correlated with the packed cell volume of the ox on which they fed.
Concomitant malaria (Plasmodium gallinaceum) and filaria (Brugia pahangi) infections in Aedes aegypti: effect on parasite development
Authors: Albuquerque C. M. R. , Ham P. J.
Published: June 2009

Mixed infections with malarial (Plasmodium gallinaceum) and filarial (Brugia pahangi) parasites were carried out in 8 trials with filaria susceptible (REFM) and filaria refractory (REP-RR) Aedes aegypti strains. A secondary infection with B. pahangi microfilariae (mff) by intrathoracic inoculation, reduced the development rate of a pre-existing P. gallinaceum infection. The level of reduction ranged from 9·5 to 49% in REFM and from 50 to 90% in REP-RR. An immune response against oocysts was seen as melanization in mosquitoes with a double infection in the strain refractory to B. pahangi (REP-RR) and a reduction in oocyst size in both mosquito strains. Melanization was not observed in mosquitoes infected only with P. gallinaceum. This may indicate that activation of the prophenoloxidase (PPO) cascade in response to mff in the haemolymph can also be addressed against oocysts in the midgut. No significant difference in the number of filarial parasites recovered was observed when comparing groups with a single or double infection. Retardation in development of filaria larvae was observed in mosquitoes with double infection (REFM strain), together with melanization and a higher rate of abnormal development. Nutritional deficiency caused by superinfection might also be responsible for the delay in filarial development and reduced oocyst size.
Inoculum size, incubation period and severity of malaria. Analysis of data from malaria therapy records
Authors: Glynn J. R. , Bradley D. J.
Published: June 2009

The size of the infecting inoculum may influence the severity of malaria, but evidence is scarce. Malaria therapy records provide a unique source of information on induced malaria in people. The therapy was given to large numbers of neurosyphilis patients and the malaria was left untreated as long as possible. Data from patients treated at the Horton Hospital, Epsom 1923–60 with a single strain of vivax malaria were analysed to assess the influence of inoculum size on severity of disease. Malaria was induced by mosquito bite, blood inoculation or direct sporozoite inoculation. The different measures of inoculum size were inversely correlated with pre-patent period, as expected. Overall, information was available on a total of 563 non-immune patients who were not treated during the first 5 days of patent parasitaemia. No strong or consistent relationships were found between measures of inoculum size and any of the measures of severity used: neither parasitaemia levels, nor peak fevers, nor number of paroxysms of fever. In the largest data set, longer pre-patent periods were associated with tertian fever, spontaneous recovery and less use of modifying treatment. Difficulties in interpreting the results are discussed, particularly with respect to misclassification of both exposure and outcome variables. While an inoculum size-severity relationship cannot be ruled out, a strong relationship is very unlikely.
Maltose utilization by extracellular hydrolysis followed by glucose transport in Trichomonas vaginalis
Authors: Kuile B. H. Ter , Müller M.
Published: June 2009

The amitochondriate parasitic protist Trichomonas vaginalis can utilize either glucose or maltose as carbon and energy source. The mechanisms of maltose utilization were explored with uptake experiments using radio-isotope labelled maltose in combination with the silicone-oil centrifugation technique and enzymatic assays measuring maltose hydrolysis. The uptake of maltose label became saturated after 2–3 h. The uptake of maltose as a function of the external maltose concentration was linear at low concentrations with no further increase at higher levels, kinetics characteristic of reactions obeying Michaelis–Menten kinetics preceded by a diffusion-limited step. Increased viscosity of the medium resulted in decreased maltose uptake, indicating an extracellular location of the diffusion-limited step. Most of the cellular α-glucosidase activity of T. vaginalis was detected on the cell surface, suggesting that maltose is hydrolysed to glucose outside the cell. Glucose interfered more with maltose uptake, and maltose less with glucose uptake, than would be expected if 1 mol of maltose were the equivalent of 2 mol of glucose. This pattern of interaction indicated that the interference occurs before the common metabolic pathway and even before the transport step, supporting the idea of extracellular maltose hydrolysis. We conclude that maltose is hydrolysed to glucose in the boundary layer of the cell, a process akin to membrane digestion in vertebrate enterocytes and on the teguments of helminths. The glucose formed is then transported by the glucose carrier of the organism.
Change of mate and mating competition between males of Schistosoma intercalation and S. mansoni
Authors: Tchuenté L. A. Tchuem , Southgate V. R. , Imbert-Establet D. , Jourdane J.
Published: June 2009

Previous studies on mating behaviour of Schistosoma intercalatum and S. mansoni, two human schistosomes which may overlap in parts of Africa, have shown that in mixed infections in mice there are no physiological barriers preventing heterospecific pairings. However, when choice is possible, matings occur preferentially between partners of the same species. In this paper, further experimental studies on mating behaviour of the two species were conducted. Sequential infections showed that heterospecific pairs of worms change partners to homospecific pairs when given the opportunity. The change of mate is a progressive process requiring up to, at least 8 weeks, and this phenomenon is due to the male worm seeking the appropriate female. S. mansoni males are better at pairing with females than S. intercalcatum males, and they will change partner to pair with homologous females in preference to heterologous females whenever given the opportunity. Moreover, in the absence of S. mansoni female worms, unpaired S. mansoni male worms pull away female S. intercalatum from male S. intercalatum. It appears from this study that S. mansoni males are much more competitive than S. intercalatum males at pairing with females, and this is a disadvantage for S. intercalatum in situations of sympatry.
Trypanosoma cruziexoantigen is a member of a 160 kDa gene family
Authors: Jazin E. E. , Bontempi E. J. , Sanchez D. O. , Åslund L. , Henriksson J. , Frasch A. C. C. , Pettersson U.
Published: June 2009

During the chronic stage of Chagas disease a 160 kDa antigen appears in the blood of patients and remains detectable many years after the onset of the disease. This antigen is secreted by the trypomastigote form of the parasite while it is undetectable in the epimastigote form. We report here that the chronic 160 kDa exoantigen is encoded by a gene family (CEA 160 family). We describe the cloning and partial nucleotide sequence of a gene (CEA 160–1) belonging to the CEA160 family. Comparison of the gene sequence with other sequences present in the databases revealed homologies with severalTrypanosoma cruzisurface antigens. Highest amino acid identity (59%) was with members of a family containing epitopes that mimic nervous tissues (Van Voorhiset al.1993). Another related group (18–22% amino acid identity) comprises proteins of 85 or 160 kDa sharing an amino acid motif that is conserved among bacterial neuraminidases (Foutset al.1991; Pollevicket al.1991; Kahnet al.1991; Takle & Cross, 1991; Francoet al.1993). The amino acid identities with the different antigens were not homogeneously distributed. Regions of higher identity (40–60%) were grouped in the central region of each protein.
Parasitic infection in malnourished school children: effects on behaviour and EEG
Authors: Levav M. , Mirsky A. F. , Schantz P. M. , Castro S. , Cruz M. E.
Published: June 2009

This paper describes a study of 194 children (aged 9–13) from a mountain village in Ecuador who were infected with one or more species of intestinal helminth or protozoan parasite. In addition to parasite load, the assessment consisted of a battery of psychological and neuropsychological tests, an EEG examination, measures of iodine level, presence of goitre and level of nutrition. We found that, in general, parasite infection, as measured at the baseline level, was not associated with cognitive impairment. The intensity of infection withA. lumbricoides, however, was correlated with the level of verbal ability and with inhibition-control aspects of cognitive behaviour. Multivariate analysis with level of nutrition, EEG status and parasite burden showed a consistent main effect of the degree of nutrition on neuropsychological performance, particularly the language, problem solving and inhibition-control dimensions.
Sequence, expression and localization of calmodulin-domain protein kinases inEimeria tenellaandEimeria maxima
Authors: Dunn P. P. J. , Bumstead J. M. , Tomley F. M.
Published: June 2009

We have isolated and sequenced cDNA clones fromEimeria tenellaandEimeria maximawhich encode proteins that share homology with a recently described family of calmodulin-domain protein kinases. The primary sequence data show that each of the protein kinases can be divided into 2 main functional domains – an amino-terminal catalytic domain typical of serine/threonine protein kinases and a carboxy-terminal domain homologous to calmodulin, which is capable of binding calcium ions at 4 ‘EF-hand’ motifs. Expression of theE. tenellacalmodulin-domain protein kinase (EtCDPK) increased towards the end of oocyst sporulation, as judged by Northern and Western blotting, and indirect immunofluorescent antibody labelling showed that within a few minutes of adding sporozoites to target host cells inin vitroculture EtCDPK was found to be specifically associated with a filament-like structure that converges at the apical end of the parasite. Once the parasite entered the host cell EtCDPK appeared to be left on the host cell membrane at the point of entry, indicating a brief yet specific role for this molecule in the invasion of host cells byE. tenella.
DNA synthesis in gametocytes of Plasmodium falciparum
Authors: Janse C. J. , Ponnudurai T. , Lensen A. H. W. , Meuwissen J. H. E. Th. , Ramesar J. , Van Der Ploeg M. , Overdulve J. P.
Published: June 2009

The DNA content of Plasmodium falciparum gametocytes during intra-erythrocytic development and during gametogenesis was established by cytophotometric methods. Intra-erythrocytic micro- and macrogametocytes (Stage I-Stage VB) contain about twice the amount of DNA of haploid sporozoites and ringstages, indicating that DNA is synthesized during transformation of ringforms into Stage I gametocytes. Microgametocytes, after activation at pH 8, rapidly duplicate their genome several times, while the DNA content of macrogametocytes remains constant during gametogenesis.
Observations on the implications of pathology induced by experimental schistosomiasis in baboons in evaluating the development of resistance to challenge infection
Authors: Sturrock R. F. , Cottrell B. J. , Lucas S. , Reid G. D. F. , Seitz H. M. , Wilson R. A.
Published: June 2009

Liver samples from 10Schistosomamansoni-infected baboons all yielded eggs but neither their egg counts nor duration of infection (< 226 weeks) correlated with the slightly elevated liver collagen levels or minimal histological fibrosis observed. Approximately 10% of inert 9 and 15 μm diameter microspheres injected into the mesenterio veins of 2 baboons with acute, challengeS. mansoniinfection reached their lungs (mainly 9 μm microspheres). Lung egg recoveries over 1000 were significantly less common among 175 baboons exposed once toS. monsoniinfections than among 56 baboons exposed more than once. Among 221S. mansoni-andS. haematobium-infected baboons, female worm, total tissue egg and lung egg recoveries were significantly correlated with each other but not with liver or (where available) spleen weights. Liver and spleen weights were strongly correlated with total body weight. Baboons did not develop significant liver fibrosis, even after prolonged schistosome infections. However, some liver ‘leakiness’ developed during acute primary and challenge infections, allowing small inert particles and eggs to pass to the lungs, but this ‘leakiness’ was not associated with resistance to challenge. In contrast to mice, such resistance in baboons cannot, therefore, be explained simply in terms of pathological changes due to previous infections.