The impact of immunization with gentamicin-attenuated Leishmania infantum (H-line) on the immunophenotypic profile of popliteal lymph node (PLN) and peripheral blood mononuclear cells (PBMCs) of dogs was assessed by flow cytometry and immunohistochemistry. Compared with the dogs infected with L. infantum wild-type (Group WT), there was a significantly higher percentage of CD4+, CD44+ T cells and CD14+, MHC-II+ cells and a lower percentage of CD4+ CD25+ regulatory T cells in PLN of the immunized dogs with L. infantum H-line (Group H). The percentage of CD4+ and CD8+ T cells in PBMCs of immunized dogs was higher than that in dogs of Group WT. The CD4:CD8 ratio in PLN of dogs of Group H was significantly higher than that in dogs of Group WT. A significantly higher percentage of CD21+ B cells and a lower percentage of CD79b+ cells were found in PLN of the immunized dogs compared with dogs of Group WT. Immunohistochemical investigation showed no parasites in the PLN of immunized dogs whereas there were parasites in the PLN of 60% of dogs infected with L. infantum WT. In this study, the immunophenotypic profile of mononuclear cells of the immunized dogs correlates with cellular immunity.

Growth and propagation of fish-infecting microsporidians within cell culture has been more difficult to achieve than for insect- and human-infecting microsporidians. Fish microsporidia tend to elicit xenoma development rather than diffuse growth in vivo, and this process likely increases host specificity. We present evidence that the fish microsporidian, Loma salmonae, has the capacity to develop xenomas within a rainbow trout gill epithelial cell line (RTG-1). Spore numbers increased over a 4 weeks period within cell culture flasks. Xenoma-like structures were observed using phase contrast microscopy, and then confirmed using transmission electron microscopy. Optimization of the L. salmonae-RTG-1 cell model has important implications in elucidating the process of xenoma development induced by microsporidian parasites.

P. malariae was first used for therapy purposes at Horton in 1928.

Between 1928 and 1945, nine strains have been used. Most of these were from Africa, but some were from Holland, Roumania and South America. The strain from Holland was probably not indigenous to that country.

All transmission experiments carried out between 1928 and 1945 were with Anopheles maculipennis var. atroparvus. Nineteen separate batches of mosquitoes were fed on patients in whose blood parasites believed to be gametocytes were seen. In only six of these batches were any of the mosquitoes found to be infected and then with only scanty oocysts; sporozoites were never found. No patients were infected by the bites of any of these mosquitoes.

In 1947 a colony of A. stephensi (type) was established.

From 1948 to 1950, sixty-eight batches of A. stephensi were fed on patients in whose blood Plasmodium malariae parasites were present. Scanty gametocytes were found in some of these patients, and on occasion mosquitoes which fed on them became infected, but in others no infection occurred.

Other batches of mosquitoes did become infected after feeding on patients in whose blood no typical gametocytes were found even after a prolonged search. Out of sixty-eight batches of mosquitoes fed, infection was seen in twelve batches, in varying degree, but never with more than nine oocysts in an individual mosquito. Two consecutive human anopheline passages with laboratory-bred Anopheles mosquitoes (A. stephehsi type) and induced human carriers are reported.

Having at our disposal material from various sources obtained from the intestines of monitor lizards, it appeared useful to prepare drawings and descriptions of the less known species of parasites.

Taenia saginata cyst fluid proteins from 4, 8, 12 and 16-week-old cysticerci were analysed by a combination of direct I radio-isotope labelling, immunoprecipitation using a panel of sera from infected cattle infected with T. saginata and SDS–PAGE. Protein antigens of 12, 14, 16, 20 and 26 kDa were identified in all of the cyst fluids examined. These were immunogenic and were precipitated by serum taken from cattle from 8 weeks after infection onwards and were therefore considered to be of diagnostic potential. A 185 kDa protein antigen found only in the cyst fluid of 4-week-old cysticerci and a 43 kDa protein antigen first detected in cyst fluid from 8-week-old cysticerci were also identified but were considered to be of more limited diagnostic potential due to their restricted presence. An apparently non-immunogenic 67 kDa protein, found in all the cyst fluids examined, may have been host serum albumin.

1. The eggs of Thelastoma bulhõesi are shown to have a sticky outer coat of acid mucopolysaccharide.

2. The acid mucopolysaccharide is secreted by the lower uterus wall and by the vagina uterina.

3. A protein substance of unknown function has been observed in invaginations in the ovijector of T. bulhõesi.

4. This protein substance appears to be secreted by the lower part of the vagina uterina and passed along into the ovijector.

5. Possible functions of the mucopolysaccharide coat on the eggs, and of the protein substance in the ovijector, are discussed.

I wish to express my thanks to Dr P. Tate for many invaluable suggestions and for his constant encouragement during this investigation.

It is a common observation that in individual Ixodes ricinus L. ticks, size variations occur; such variation is reflected in the records of early workers (Wheler, 1899; Neumann, 1899: quoted by Nuttall, Warburton, Cooper & Robinson, 1911). The present paper attempts to examine the true specific importance of size variation by basing the study on measurements of the relatively inelastic scuta after the principle of using head capsule measurements for insectan larval instars.

1. A strain of Culex pipiens which is autogenous and stenogamic has been found at Hayling Island, England, and compared with British anautogenous strains.

2. Definite characteristics in adults of both sexes and in larvae have been found which separate the autogenous from the anautogenous British strains of C. pipiens.

3. The autogenous strain differs from the anautogenous strains in (a) the lighter colour of the thorax of the adults; (b) the greater average number of hairs on the ninth tergite of the adults; (c) the relative shortness of the male palps in comparison with the proboscis; (d) the larger average number of branches in each of the four siphonal tufts of the fourth instar larvae; (e) the lower siphonal index of the fourth instar larvae; and (f) the greater width of the egg relatively to its length.

When incubated in vitro for 24 h, intact eggs, chemically shelled eggs (obtained by treating intact eggs with NaOCl), activated larvae (eggs in which the outer shell and inner envelope were removed), and oncospheres (activated larvae treated with papain to remove the embryophore) absorb and metabolize radioactive glucose. Intact eggs, which are covered by the impermeable shell, absorb only small amounts of exogenous radioactive glucose, while chemically shelled eggs, activated larvae, and oncospheres absorb much larger amounts. Only very small amounts of the exogenous glucose are incorporated into the ethanol-precipitable carbohydrate fraction (which would include glycogen) by any of the preparations of eggs/larvae. However, the glucose is incorporated into higher molecular weight end-products that are liberated into the incubation medium. There is a temporal shift in the ability of activated larvae and oncospheres to metabolize exogenous glucose. Activated larvae and oncospheres absorb but do not metabolize glucose during the first 8 h post-activation. Between 8 and 16 h post-activation, however, virtually all of the absorbed glucose is metabolized into higher molecular weight end-products that are liberated into the incubation media. This temporal shift suggests that activation of oncospheres and cysticercoid morphogenesis are accompanied by distinct changes in carbohydrate metabolism.

Colour changes that occur during tanning of intact and punctured Globodera rostochiensis females and of isolated cuticle are described. Experiments with catechol and enzyme inhibitors show that the tanning enzyme, a phenoloxidase, is located in the cuticle, soluble in aqueous media and relatively abundant. Substrate for the enzyme is limited in the cuticle. Pseudocoelomic fluid of yellow females promoted tanning and contains either phenolic substrate(s) for the enzyme or part of a biochemical system responsible for release of the substrate. The substrate or biochemical system is thermolabile. Apparently, the tanning enzyme and its substrate(s) are partitioned in living females but the partitioning breaks down after death and the cuticle tans to form the cyst.

Of this Cestode I possess about a dozen adult specimens from one bird and nearly two dozen young specimens from another bird, preserved in the collection of the Wellcome Bureau and originally obtained, I believe, by Dr L. Sambon from the London Zoological Gardens. It is probably allied to, though certainly not identical with, the Ascometra vestita of Cholodkovsky (1912) obtained from the same host, viz. Houbara macqueeni. I have no information as to the locality from which the hosts were obtained in the present case. I shall describe the anatomy of this worm prior to discussing its systematic position.

The histone chaperone SET/TAF-Iβ is implicated in processes of chromatin remodelling and gene expression regulation. It has been associated with the control of developmental processes, but little is known about its function in helminth parasites. In Mesocestoides corti, a partial cDNA sequence related to SET/TAF-Iβ was isolated in a screening for genes differentially expressed in larvae (tetrathyridia) and adult worms. Here, the full-length coding sequence of the M. corti SET/TAF-Iβ gene was analysed and the encoded protein (McSET/TAF) was compared with orthologous sequences, showing that McSET/TAF can be regarded as a SET/TAF-Iβ family member, with a typical nucleosome-assembly protein (NAP) domain and an acidic tail. The expression patterns of the McSET/TAF gene and protein were investigated during the strobilation process by RT-qPCR, using a set of five reference genes, and by immunoblot and immunofluorescence, using monospecific polyclonal antibodies. A gradual increase in McSET/TAF transcripts and McSET/TAF protein was observed upon development induction by trypsin, demonstrating McSET/TAF differential expression during strobilation. These results provided the first evidence for the involvement of a protein from the NAP family of epigenetic effectors in the regulation of cestode development.

Diagnosis of loiasis and analysis of the specific immune response are limited by a paucity of parasite material. To circumvent this problem, a Loa loa antigen has been expressed in a prokaryote vector (pTrcHis). Immunization of Balb/c mice with this soluble recombinant protein produced a strong antibody response, with antibodies recognizing 2 major bands of 38 and 20 kDa in a native crude extract of Loa loa adult worms and microfilariae on Western blots. The target molecule was located mainly in the hypodermis and cuticle of the adult worm. Analysis of human IgG subclasses against this antigen by enzyme-linked immunosorbent assay (ELISA) showed IgG1, IgG2 and IgG3 but not IgG4 reactivity. IgG2 against this recombinant antigen was 100% specific for loiasis when tested against samples from European donor individuals. The same IgG2 antibodies showed 91% specificity for loiasis by comparison with Wuchereria bancrofti, Onchocerca volvulus, Mansonnella perstans and other helminth infections. Furthermore, the IgG2 antibody level correlated with the density of Loa loa microfilariae (r=0·400; P=0·02). This recombinant 15r3 molecule and specific IgG2 assay may be useful for monitoring control programmes.

The surface morphology of fixed ovarian balls from female Moniliformis dubius, aged 12, 18, 26, 28, 42, 77, 105 and 118 days, has been examined by means of scanning electron microscopy. The appearance of the surface has been found to be variable between ovarian balls from worms of the same and different ages. Some parts of the surface are seen to possess micro-projections, cavities and ridges while other parts have the appearance of an irregular meshwork of fibres. Various protruding features have been observed to extend from the surfaces of the ovarian balls taken from the inseminated female worms. In most cases, the surfaces of the protruding features differ in appearance from the surrounding surfaces of the ovarian balls. Some of these features have been assumed to represent growing zygotes and developing eggs covered by the supporting syncytium of the ovarian ball. Single or several thread-like structures have been observed in association with the surfaces of ovarian balls taken from the inseminated female worms. At present, the thread-like structures are believed to be portions of spermatozoa. By means of light microscopy, preliminary observations have been made on what is considered to be the division process of ovarian balls taken from uninseminated and inseminated worms varying in age from 7 to 98 days.

Five main types of harvest mite larvae have been found in Great Britain. These may be distinguished according to the following key:

(1) Galeal setae ciliated

Galeal setae not ciliated (2)

(2) Scutal setae duplicated

Scutal setae not duplicated (3)

(3) Humeral setae duplicated Humeral setae not duplicated (4)

(4) Eight setae in both the second and

the third rows of dorsal setae Normal type a

Six setae in both the second and

third rows of dorsal setae Normal type b

Eight setae in the second dorsal

row but only six in the third Normal type c

Type a and type b may be further divided into groups based on differences in scutal width and setal length. Nevertheless, scutal width, setal length and setal number are not correlated with each other. Were larvae to be separated into two species on the hypothesis that one of these characters (e.g. differences in setal number) is genetically determined, then the range of variation with respect to the other two characters (namely scutal width and setal length) would be the same for each species. Forms with duplicated humeral setae do not differ otherwise from the normal type. The ciliation of the galeal setae and the duplication of the scutal setae is not consistent and larvae of mixed or intermediate type are known. It seems to me that these morphological differences may not be genetically determined but are solely phenotypic (and in the case of setal number may be influenced by rainfall and temperature). This, together with the lack of points of distinction among nymphs and adults, suggests that there is only one British species which was first described as Acarus autumnalis (Shaw, 17 90). As no type is known to exist, a lectotype has been selected from British material and deposited in the British Museum.

The systematic position of this species is difficult to determine. Until larvae of known ancestry can be reared under controlled conditions the systematic significance of the variations described above must remain in doubt.

Nymphs and adults do not appear to differ greatly from those described by André (1930). The adult is recorded for the first time in England. The male genitalia are described.

Entamoeba histolytica is the protozoan parasite that causes human amoebiasis. It is one of the leading parasitic disease burdens in tropical regions and developing countries, with spread to developed countries through migrants from and travellers to endemic regions.

Understanding E. histolytica’s invasion mechanisms requires an understanding of how it interacts with external cell components and how it engulfs and kills cells (phagocytosis). Recent research suggests that optimal phagocytosis requires signalling events from the cell surface to the nucleus via the cytoplasm, and the induction of several factors that are transported to the plasma membrane. Current research in other protozoans suggests the presence of proteins with nuclear localization signals, nuclear export signals and Ran proteins; however, there is limited literature on their functionality and their functional similarity to higher eukaryotes.

Based on learnings from the development of antivirals, nuclear transport elements in E. histolytica may present viable, specific, therapeutic targets.

In this review, we aim to summarize our limited knowledge of the eukaryotic nuclear transport mechanisms that are conserved and may function in E. histolytica.