This study was undertaken to assess whether glycolipid antigens (particularly gangliosides) are associated with Pneumocystis carinii obtained from human lungs. Gangliosides were extracted, purified in high performance thin-layer chromatography and stained with resorcinol. Two resorcinol-positive bands, co-migrating with GM1 and GD1a were demonstrated, suggesting the existence of ganglioside molecules on P. carinii. No resorcinol-positive bands were revealed in the pulmonary control tissue. In addition, an antiserum obtained from rabbits immunized with P. carinii antigen reacted with gangliosides GM1, and GD1a, as revealed by a dot immunobinding assay. This reactivity was inhibited by first incubating the antiserum with ganglioside micelles. Furthermore, anti-glycosphingolipid antibodies (aGM1) reacted with the bands of 200 and 55 kDa of P. carinii antigen. These results suggest that ganglioside antigens expressed on P. carinii can trigger specific immune responses.

1. Cephenomyia auribarbis Mg., a tachino-oestrid parasite of the red deer (Cervus elaphus L.), is distributed throughout the deer forests of Scotland. The adult is found on the wing during June and July.

2. The larva normally occurs attached to the walls of the nasal passages and pharynx, where it remains for 10 or 11 months. At maturity it drops to the ground and pupates beneath the surface. The adult emerges in 3–4 weeks.

3. In January, 1931, a larva of the early third instar was recovered from a stag shot at Blair Atholl, Perthshire. It was found in fat in the pelvic region and not in the nostril or pharynx as might have been expected.

4. It is suggested that the larva may have been swallowed by the host and bored its way through the wall of the gut into the peritoneal cavity, whence it had wandered to the pelvic region; or else that a first-stage larva had been accidentally deposited by a female on the hide and had bored through the body wall to the peritoneal cavity.

5. The adult female and the early third-stage larva are described and illustrated.

6. A comparison is made between the cephalo-pharyngeal apparatus of Cephenomyia auribarbis, Cephalomyia ovis, and Gastrophilus intestinalis. It is noted that the basilar sclerite of the first two species is provided with an accessory lateral appendage on each side. A greater surface is thus furnished for the attachment of the large depressor muscles of the buccal hooks. The larva thus securely holds its ground in the nasal cavities and pharynx, where the risks of summary ejection are always present. In G. intestinalis the accessory appendage is absent. The chances of the larva of this species losing its hold on the gastric mucous membrane of the host are very slight.

Many workers must have asked themselves whether a malaria parasite of bird or mammal has any harmful effect on the mosquito in whose body it grows and multiplies so remarkably; but though various opinions have been expressed, I cannot discover that any conclusive answer to this question has been given.

A cDNA library constructed from 3 day post-infective L3 of the filarial nematode Brugia pahangi was screened by differential hybridization with cDNA probes prepared from different life-cycle stages. Five cDNA clones hybridizing selectively to the mosquito-derived L3 probe were isolated and characterized. Northern blot analysis of 4 of the clones confirmed that each was most highly expressed in the mosquito-derived L3. The expression of each mRNAduring parasite development in the mosquito vector was investigated using RT–PCR, and all were shown to be abundant in the immature L3. Four of the 5 cDNAs cloned coded for structural proteins: 2 cuticular collagens, and the muscle proteins tropomyosin and troponin. Further studies on troponin using an antiserum raised to the recombinant protein demonstrated that the protein, unlike the mRNA, was present in all life-cycle stages examined, while immunogold labelling demonstrated that it was localized to the muscle blocks.

We identified 2 novel genes encoding different 2-Cys peroxiredoxins (PRxs), designated CsPRx2 and CsPRx3, in Clonorchis sinensis, which invades the human hepatobiliary tracts. The CsPRx2 gene expression was temporally increased along with the parasite's development and its protein product was detected in almost all parts of adult worms including subtegument, as well as excretory-secretory products. Conversely, CsPRx3 expression was temporally maintained at a basal level and largely restricted within interior parts of various tissues/organs. The recombinant forms of CsPRx proteins exhibited reducing activity against various hydroperoxides in the presence of either thioredoxin or glutathione (GSH) as a reducing equivalent, although they preferred H2O2 and GSH as a catalytic substrate and electron donor, respectively. A steady-state kinetic study demonstrated that the CsPRx proteins followed a saturable, Michaelis-Menten-type equation with the catalytic efficiencies (kcat/Km) ranging from 103 to 104 M−1 s−1, somewhat lower than those for other PRxs studied (104–105 M−1 s−1). The expression patterns and histological distributions specific to CsPRx2 and CsPRx3 might suggest different physiological functions of the antioxidant enzymes in protecting the worms against oxidative damage.

The morphology and life history of a new species of insect-parasitic nematode, Neoplectana leucaniae are described. This nematode, which may be cultured on a veal pulp medium, was used in a number of experiments against larvae and adults of New Zealand Melolonthinae, and was found capable of parasitizing all test hosts used. Lack of persistence of the nematode in soil makes it unsuitable for use in the biological control of soil-inhabiting pest insects.

The cellular and syncytial components of the mature uterine bell of the palaeacanthocephalan, Polymorphus minutus are described, and compared with previous accounts of the histology of uterine bells. Each uterine bell always contains 17 separately distinguishable nuclei. This situation provides a good illustration of the phenomenon of organ eutely, common in Acanthocephala. The luminal spaces of the bell are described and their relevance to the translocation of eggs discussed.

I should like to thank Dr D. W. T. Crompton for his help and encouragement during the course of this work and Dr P. Tate for the provision of facilities. The work was carried out during the tenure of an S.R.C. Research Studentship.

A fourfold enhancement of resistance to diamino-diphenylsulphone has been produced over a period of 15 months in strain A of P. gallinaceum by subjecting the strain, maintained in a state of patent infection, to increasing doses of the drug.

The DDS-resistant strain was cross-resistant to the minimum effective dose of sulphadiazine and slightly resistant to twice this dose, but it showed only a slight enhancement of resistance to pyrimethamine and proguanil.

The antimalarial action of DDS was antagonized by p–A.B. in the ratio of 100 to 1. DDS, in the minimum effective dose, was antagonized completely by folic acid if given in equal doses, but not by smaller doses of the antagonist; the antagonism was not competitive.

The relationship of cross-resistance between p–A.B.-inhibited sulphonamides and proguanil and pyrimethamine is discussed.

In the eastern Mediterranean, the copepod Lepeophtheirus thompsoni Baird, 1850, has been reported to infest turbot, brill and flounder. By combining several methods, including enzyme electrophoresis, we show that this species is found only in turbot. By contrast, brill and flounder are infested by a species of Lepeophtheirus that corresponds to no other species reported in the literature. We propose that the species be designated as L. europaensis and we describe the characteristics of the gravid female. This study was extended to the Atlantic populations of flatfishes and includes an investigation of L. pectoralis (Muller, 1776), which infects flounder in the North Sea; we also confirmed the presence of L. thompsoni (Baird, 1850) over the whole geographic range of turbot. Lastly, we discuss the specificity and distribution of these species along the European coasts.

The series of articles that follow in this volume deals with specific aspects of how parasites might influence nutrient utilization by their human hosts. To put these aspects of parasitic disease in context, this contribution is intended to provide an overview of human nutritional needs and to introduce concepts of how nutritional consequences of parasitic infection might be viewed. Although parasitic diseases are often considered to be those caused by protozoa and helminths, the principles considered here can be applied to any infectious agent, including bacteria and viruses.

During the two years preceding the outbreak of war, Dr Hindle was engaged in researches on the biology of lice. Soon after the war began he joined the army, leaving his notes with me. He has now been in France for over a year and is serving as Captain in the Royal Engineers. An abstract of his work has been set up in type for many months for publication by the Local Government Board but his contribution has been withheld unavoidably through a desire that it should be supplemented by further work which has since been conducted in the Quick Laboratory.

Nematodes of the genus Heterorhabditis are insect parasites that are widely used as biological control agents. When conditions are unfavourable for reproduction in H. bacteriophora, a long-lived, non-feeding, survival and dispersal stage, the dauer juvenile (DJ), is formed. This DJ stage is also adapted for host finding and infection. When it infects a suitable host, the DJ recovers and resumes growth and development. We describe a series of methods for improved detection of recovery in H. bacteriophora. We also describe some of the physiological changes that occur immediately after the onset of recovery in these nematodes as revealed using fluorescent nucleic acid binding SYTO dyes. Although recovery could be monitored using morphological changes, we found that observation of the uptake of fluorescent latex microspheres by recovering nematodes was a far more sensitive and efficient means of detecting recovery. SYTO dyes were also found to be useful indicators of recovery, binding to the pharyngeal glands and genital primordia as little as 3 h after the onset of recovery. The use of SYTO dyes also indicated that the pharyngeal glands produce large quantities of RNA following the onset of recovery, implying that these structures may produce proteins important in the infection and/or feeding process of H. bacteriophora.

Seasonal occurrence of metazoan ectoparasites is described for the first time in marine European flounder, Platichthys flesus (L.). The parasitofauna, in this study monitored during 1 year, was found to be similar to that previously recorded for flounder. Moreover, specimens of Caligus sp. Müller, 1785 and Lepeophtheirus pectoralis (Copepoda: Caligidae), Acanthochondria cornuta (Copepoda: Chondracanthidae), Holobomolochus confusus (Copepoda: Bomolochidae) and Nerocila orbignyi (Isopoda: Cymothoidae), and also, a praniza larva (Isopoda: Gnathiidae), were isolated. From these, L. pectoralis and A. cornuta were the dominant parasites in all samples of flounder, while Caligus sp., H. confusus, N. orbignyi and the gnathiid praniza seemed to infect the flounder only occasionally. As far as the seasonality of infections is concerned, it differed considerably from that described for estuarine environments. Indeed, both prevalence and abundance of L. pectoralis and A. cornuta reached significant peaks in the summer, whereas the literature identifies the autumn as the season of maximum infection on estuarine flounder. Thus, the former period seems more favourable for the occurrence of epizooties of L. pectoralis and A. cornuta in flounder culturing systems running on seawater and operated in the studied or similar environments.

An immunodominant antigen in Trypanosoma congolense-infected cattle is a 69 kDa protein which is conserved among species and developmental stages of African trypanosomes. Immunoscreening of a cDNA expression library identified a 2·35 kbp clone which contains a complete open reading frame encoding a protein of 653 amino acids with a predicted molecular mass of 71 kDa. Protein sequence analyses revealed 45–65% identity with hsp70s from a broad range of organisms, the highest homology being with the mammalian BiP (immunoglobulin heavy chain binding protein). The 69 kDa trypanosome protein shares with other BiP-related molecules two characteristics that are associated with their localization in the endoplasmic reticulum and their function as chaperonins, i.e. a hydrophobic N-terminal signal sequence and a conserved C-terminal tetrapeptide (X)DEL. Divergence between the 69 kDa antigen and other BiP-homologues occurs in the C-terminal region. This may be responsible for the high immunogenicity of the trypanosome protein. The gene for the 69 kDa antigen appears to be present as a cluster of several copies which are not organized in tandem repeats. It is expressed in all developmental stages of T. congolense, but the specific mRNA levels are higher in metacyclics than in other stages.

The present studies on infections with Leishmania (Viannia) braziliensis in rhesus macaques were made to characterize the evolution of different parasite strains and the immune responses they elicited in this experimental host. A standardized inoculum of promastigotes was injected intradermally either above the eyelid or on the forearm of each monkey. Sixteen infected monkeys developed longstanding infections which lasted until the end of the observation period (33 months). The time required for lesion development was very variable, not only for the isolates showing molecular differences but also for individual animals in groups infected with the same parasite strain. The inocula produced lesions of variable severity, ranging from localized cutaneous leishmaniasis (CL) with a tendency to spontaneous healing to non-healing disease. One infected animal developed persistent metastatic skin and mucosal lesions. Anti-Leishmania antibodies and parasite-specific T-cell responses were induced by the experimental infections. As the granulomatous inflammatory response found at the lesions in L. (V.) braziliensis-infected M. mulatta was similar to that in patients with CL, this primate model could be useful for studying the pathophysiology and immunoregulatory events associated with disease evolution, as well as for the evaluation of new drugs or candidate vaccines.

A cotylocercous cercaria occurring in the marine snail, Astraea americana, at Tortugas, Florida, was found to encyst in small fish as second intermediate hosts.

Fish experimentally infested with the cysts were fed to the gray snapper, Neomaenis griseus, and adult worms developed in the intestine and pyloric caeca which were identified as Hamacreadium mutabile Linton, 1910, a member of the sub-family Allocreadiinae.

A general relationship of the cotylocercous cercariae to the family Allocreadiidae is discussed.

Antigenic variation of the intestinal protozoan parasite Giardia lamblia is caused by an exchange of the parasite's variant surface protein (VSP) coat. Many investigations on antigenic variation were performed with G. lamblia clone GS/M-83-H7 which produces surface antigen VSP H7. To generate novel information on giardial vsp gene transcription, vsp RNA levels were assessed by quantitative reverse transcription-(RT)-PCR in both axenic VSP H7-type trophozoites and subvariants obtained after negative selection of GS/M-83-H7 trophozoites by treatment with a cytotoxic, VSP H7-specific monoclonal antibody. Our investigation was not restricted to the assessment of the sense vsp transcript levels but also included an approach aimed at the detection of complementary antisense vsp transcripts within the two trophozoite populations. We found that sense vsp H7 RNA predominated in VSP H7-type trophozoites while sense RNA from only one (vsp IVg) of 8 subvariant vsp genes totally analysed predominated in subvariant-type trophozoites. Interestingly, the two trophozoite populations exhibited a similar relative distribution regarding the vsp H7 and vsp IVg antisense RNA molecules. An analogous sense versus antisense RNA pattern was also observed when the transcripts of gene cwp 1 (encoding cyst wall protein 1) were investigated. Here, both types of RNA molecules only appeared after cwp 1 had been induced through in vitro encystation of the parasite. These findings for the first time demonstrated that giardial antisense RNA production did not occur in a constitutive manner but was directly linked to complementary sense RNA production after activation of the respective gene systems.

The descriptions which have been given by travellers leave no doubt that land-leeches can cause considerable annoyance, and that the protective garments and substances that were applied by them to the skin and clothing were unsatisfactory. It was thought that other and more elaborate clothing would not supply the answer, as they would be hot and uncomfortable to wear. Accordingly, a search was made for an efficient repellent. Altogether seventy-eight substances were examined, and of these hydroxycitronellal was the most powerful but expensive and not readily obtainable. Di-methyl phthalate was efficient and the most generally useful. As di-methyl phthalate is a liquid which easily escapes from containers, creams incorporating the substance were evolved. Formulae for these creams are given.

1. Recent studies by Gerichter have demonstrated that I have erred in referring the skrjabingylin lungworms to the family Trichostrongylidae.

2. On the basis of his data and a re-evaluation of my theories of metastrongylid evolution it is suggested that the Skrjabingylinae (except Dictyocaulus) are close to the Filaroidinae and that quite possibly the position of the vulva in the former is the consequence of a secondary shift from opening just anterior to the anus to opening in the mid-region of the body; the ‘trichostrongylid’ configuration of the ovejectoral apparatus would thus be convergent.

3. The genus Dictyocaulus is removed from the Skrjabingylinae and left in a subfamily Dictyocaulinae in the family Metastrongylidae, although its trichostrongylid affinities are very suggestive. If trichostrongylid, this genus is considered to exhibit convergence with the metastrongylids and not to represent an evolutionary link between the two families.

4. The nature of metastrongylid life cycles is discussed, and the compatibility of known data with the evolutionary scheme proposed for the family is pointed out. It is evident that in metastrongylids symbiotizing marine littoral and pelagic hosts (Pinnipedia and Odontoceti) larval development must rely upon new intermediate host groups if the basic pattern has been retained from ancestors in terrestrial hosts.

5. The possible importance of histological studies and of investigations on chromosome number and structure for a further understanding of the evolution of the suborder Strongylina is pointed out.

6. A revised scheme for the evolution of the Metastrongylidae is presented as Fig. 1. The family Metastrongylidae now includes six subfamilies: Metastrongylinae, Filaroidinae, Skrjabingylinae, Pseudaliinae, Protostrongylinae, and Dictyocaulinae. The basic premises previously expressed (Dougherty, 1949b) on the evolution of the family are retained in the amended scheme.

A comparative isoenzyme study between a natural population of Echinostoma caproni and 2 strains of E. caproni and E. togoensis, maintained for a long time in the laboratory led to the following conclusions. (1) The natural E. caproni population showed polymorphism of associated PGM and GPI genotypes. Some zymograms were identical to those of experimental strains. Allelic frequencies show that the natural population is panmictic according to the Hardy-Weinberg equilibrium. (2) The laboratory strains were monomorphic, and interbreeding produced double-heterozygous F1 progeny, identical to those of the natural population.