Gastrointestinal nematode infection during pregnancy and lactation enhances spatial reference memory and reduces indicators of anxiety-like behaviour in uninfected adult female mouse offspring.

Maternal bacterial and viral infections that induce neuroinflammation in the developing brain are associated with impaired cognitive function and increased anxiety in the offspring. In contrast, maternal infection with the immunoregulatory murine gastrointestinal (GI) nematode, Heligmosomoides bakeri, appears to benefit neurodevelopment as juvenile 2- and 3-week-old male and female offspring had enhanced spatial memory, which may be due to a Th2/Treg biased neuroimmune environment. Here, the impact of maternal H. bakeri infection during pregnancy and lactation on the spatial and anxiety-like behaviours of adult, 3-month-old uninfected male and female offspring was explored for the first time. It was observed that adult female offspring of H. bakeri-infected dams had enhanced spatial reference memory and reduced anxiety-like behaviour compared to females of uninfected dams. These effects were not observed in adult male offspring. Thus, the positive influence of a maternal GI nematode infection on spatial memory of juvenile offspring persists in adult female offspring.

Model worms: knowledge gains and risks associated with the use of model species in parasitological research.

Model parasite species, whose entire life cycle can be completed in the laboratory and maintained for multiple generations, have played a fundamental role in our understanding of host­parasite interactions. Yet, keeping parasites in laboratory conditions may expose them to unnatural evolutionary pressures, and using laboratory cultures for research is therefore not without limitations. Using 2 widely-used model helminth species, the cestode Hymenolepis diminuta and the nematode Heligmosomoides polygyrus, I illustrate the caution needed when interpreting experimental results on model species. I first review more than 1200 experimental studies published on these species in the past 4 decades, to determine which research areas they have contributed to. This is followed by an examination of the institutional laboratory cultures that have provided the parasites used in these studies. Some of these have persisted for decades and accounted for a substantial proportion of published studies, whereas others have been short-lived. Using information provided by the curators of active cultures, I summarize data on their origins and maintenance conditions. Finally, I discuss how laboratory cultures may have been subject to the influence of evolutionary genetic processes, such as founder effects, genetic drift and inbreeding. I also address the possibility that serial passage through laboratory hosts across multiple generations has exerted artificial selection on several parasite traits, resulting in genetic and phenotypic divergence among laboratory cultures, and between these cultures and natural parasite populations. I conclude with recommendations for the continued usage of laboratory helminth cultures aimed at maximizing their important contribution to parasitological research.

Quantitative assessment of spicule length in Heligmosomoides spp. (Nematoda, Heligmosomidae): distinction between H. bakeri, H. polygyrus and H. glareoli.

Nematode spicules play a vital role in the reproductive activity of species that possess them. Our primary objective was to compare the lengths of spicules of the laboratory mouse (Mus musculus) ­ maintained isolate H. bakeri ­ with those of H. polygyrus from naturally infected wood mice (Apodemus sylvaticus). On a more limited scale, we also included H. glareoli from bank voles (Myodes glareolus), a species reputed to possess longer spicules than either of the 2 former species. In total, we measured 1264 spicules (H. bakeri, n = 614; H. polygyrus n = 582; and H. glareoli, n = 68). There was a highly significant difference between the spicule lengths of the Nottingham-maintained H. bakeri (mean = 0.518 mm) and H. polygyrus (0.598 mm) from 11 different localities across the British Isles. A comparison of the spicules of H. bakeri maintained in 4 different laboratories in 3 continents revealed a range in the mean values from 0.518 to 0.540 mm, while those of worms from Australian wild house mice were shorter (0.480 mm). Mean values for H. polygyrus from wood mice from the British Isles ranged from 0.564 to 0.635 mm, although isolates of this species from Norway had longer spicules (0.670 mm). In agreement with the literature, the spicules of H. glareoli were considerably longer (1.098 mm). Since spicules play a vital role in the reproduction of nematode species that possess them, the difference in spicule lengths between H. bakeri and H. polygyrus adds to the growing evidence that these 2 are quite distinct species and likely reproductively isolated.

Anti-Trichuris mucosal responses are maintained during H. bakeri co-infection despite impaired parasite expulsion.

In endemic regions concurrent infection with multiple gastrointestinal (GI) helminth species is more common than single species infection. However, the majority of model helminth infections focus on single species infections leading to a lack of understanding of how co-infection influences anti-parasite immune responses. Here, we use a model co-infection of Trichuris muris (Tm) and Heligmosomoides bakeri (Hb) to investigate the effect of Hb on anti-Tm immune responses. We observed a complete impairment of Tm expulsion in immune competent C57BL/6 mice when co-infected with Hb. This was coupled with reduced cellularity in the colonic mesenteric lymph node (cMLN) proximal to the caecum, however, cMLN cytokine responses and caecal mucosal immune responses in co-infected mice were not significantly different from mice infected with Tm alone. Interestingly, in immune-compromised mice, we found co-infection resulted in enhanced growth and fecundity of female Tm parasites. These data suggest that during helminth-helminth co-infection, immune-independent signals between species may promote survival and growth.

The development of spicules in Heligmosomoides bakeri (Nematoda, Heligmosomidae).

The spicules of male parasitic nematodes are key morphological features, which vary between species in shape and length and are used often for species identification. However, little is known about spicules and particularly if/how their length varies during growth. We first assessed the degree of variation in spicule length of male Heligmosomoides bakeri 21 days post infection (PI), and then in two follow-up experiments measured spicule lengths at half daily/daily intervals between days 6 and 14 PI. Mean spicule length in 21-day worms was 0.518 mm with a range of 94 µm, and variation between the two spicules of individual worms from 2 to 32 µm. Spicules were first detectable on day 6-6.5, after which their lengths increased until day 7 PI (mean = 0.61 and 0.59). This was followed by significant contraction, initially relatively quickly over the following 48 h and then more slowly over a longer period, stabilizing by days 10-14, with only minor further reduction in length. We conclude that the length of spicules varies significantly over the first few days after they have formed, and, consequently, the age of worms is an important factor for consideration when spicule lengths are measured for experimental/diagnostic or taxonomical purposes.

The effect of conventional preservatives on spicule length of Heligmosomoides bakeri (Nematoda, Heligmosomidae).

Nematode spicules vary in shape and size even between closely related species and, therefore, constitute key characters in nematode taxonomy for distinguishing between species. Spicules are seldom measured on fresh specimens, but rather at some time after extraction from culled hosts and after a period of preservation of the worms in chemical fixatives or by freezing. We carried out two experiments to assess the effects of freezing in Hanks' balanced salt solution, 70% or 80% ethanol and 10% formalin (both of the latter at room temperature and after storage at -80°C) on spicule length of Heligmosomoides bakeri at two time intervals after extraction from mice (Experiment 1, one and four weeks; Experiment 2, one and four months). In Experiment 1, no significant differences were detected, although there was some variation between treatments and over time. In Experiment 2, spicule length varied significantly between treatments and over time, the greatest shrinkage being in 80% ethanol and the least in 10% formalin. However, overall variation in spicule length was very limited, accounting for no more than 5.03% change in length over time and 4.95% between treatments at any of the periods of assessment. Therefore, while whole nematodes can shrivel and shrink in preservatives, making many measurements unreliable, our data indicated that spicule lengths are very little changed by preservation techniques over time, and so spicule length remains as a reliable taxonomic character.

Rapamycin exposure to host and to adult worms affects life history traits of Heligmosomoides bakeri.

Parasite life history can be affected by conditions of the host and of the external environment. Rapamycin, a known immunosuppressant of mammals, was fed to laboratory mice that were then infected with the Trichostrongylid nematode Heligmosomoides bakeri to determine if host rapamycin exposure would affect parasite survival, growth, and reproduction. In addition, adult worms from control fed mice were directly exposed to rapamycin to assess if rapamycin would affect worm viability and ex vivo reproduction. We found that host ingestion of rapamycin did not affect H. bakeri survival or growth for male or female worms, but female worms had increased reproduction both in vivo and when removed from the host and cultured ex vivo. After direct rapamycin exposure, motility of female worms was greater at low levels of rapamycin compared to high levels of rapamycin or high levels of DMSO (the vehicle used to solubilize rapamycin) in control media, but was similar to females in low levels of DMSO in control media. Male motility was not affected by the presence of rapamycin or DMSO in the media. Ex vivo egg deposition was higher when exposed to rapamycin than when cultured in control media that contained DMSO, regardless of DMSO dose. Overall, we conclude that host ingestion of rapamycin or direct exposure to rapamycin was generally favorable or neutral for parasite life history traits.

Globule Leukocytes and Other Mast Cells in the Mouse Intestine.

Only 2 major mast cell (MC) subtypes are commonly recognized in the mouse: the large connective tissue mast cells (CTMCs) and the mucosal mast cells (MMCs). Interepithelial mucosal inflammatory cells, most commonly identified as globule leukocytes (GLs), represent a third MC subtype in mice, which we term interepithelial mucosal mast cells (ieMMCs). This term clearly distinguishes ieMMCs from lamina proprial MMCs (lpMMCs) while clearly communicating their common MC lineage. Both lpMMCs and ieMMCs are rare in normal mouse intestinal mucosa, but increased numbers of ieMMCs are seen as part of type 2 immune responses to intestinal helminth infections and in food allergies. Interestingly, we found that increased ieMMCs were consistently associated with decreased mucosal inflammation and damage, suggesting that they might have a role in controlling helminth-induced immunopathology. We also found that ieMMC hyperplasia can develop in the absence of helminth infections, for example, in Treg-deficient mice, Arf null mice, some nude mice, and certain graft-vs-host responses. Since tuft cell hyperplasia plays a critical role in type 2 immune responses to intestinal helminths, we looked for (but did not find) any direct relationship between ieMMC and tuft cell numbers in the intestinal mucosa. Much remains to be learned about the differing functions of ieMMCs and lpMMCs in the intestinal mucosa, but an essential step in deciphering their roles in mucosal immune responses will be to apply immunohistochemistry methods to consistently and accurately identify them in tissue sections.

Anthelminthic properties of Methylene chloride-methanol (1:1) extracts of two Cameroonians medicinal plants on Heligmosomoides bakeri (Nematoda: Heligmosomatidea).

BACKGROUND: The resistance of some medico-veterinary parasite strains as well as the unavailability and toxicity of synthetic anthelminthics on humans, animals and the impacts of their residues in the environment have pushed scientists to turn to plants with anthelminthic properties. Hence, the aim of this work was to contribute to the fight against helminths of medical and veterinary importance in general, and also to clear the environment of their free living stages. METHODS: Fresh eggs of Heligmosomoides bakeri were obtained from the faeces of experimentally infected mice. L1 and L2 larval stages were obtained after 48 and 72 h of coproculture respectively. Methylene Chloride-Methanol (1:1) extracts of Annona senegalensis and Nauclea latifolia were diluted in DMSO or Tween 80 to prepare the following concentrations: 625, 1250, 2500, 3750 and 5000 µg/ml. The effects of extract solutions were evaluated on the embryonation of eggs, egg hatching and on L1 and L2 survival after 48, 10 and 24 h of incubation. Negative controls were 1.5% DMSO, 4% Tween 80 and a mixture of these solvents. The TLC was carried out and the profiles of secondary metabolites were made. RESULTS: Negative controls had no effect on the embryonation, eggs hatching and on larval mortality. However, it was found that, the extracts affected the free living stages of H. bakeri in a concentration-dependant manner. At the highest concentration (5000 µg/ml), the rate of inhibition of embryonation obtained were 20.80%, 38.15% and 84.83% for Methylene Chloride-Methanol of Annona senegalensis (MCM As), Nauclea latifolia (MCM Nl) extracts and mixture of Annona senegalensis and Nauclea latifolia (MCM As-Nl) extract respectively. For egg hatch, the inhibition rate was 16.10%, 46.24% and 87.07% for the above three extracts respectively at the same concentration of 5000 µg/ml. On L1 and L2 larval stages after 24 h of exposure to extracts, the mortality rates of 100%, 54.76% and 96.77% against 98%, 51.44% and 100% were obtained for MCM As, MCM Nl and MCM As-Nl respectively at the highest concentration. The Methylene Chloride-Methanol of A.senegalensis, N. latifolia extracts showed the presence of alkaloids except in N. latifolia extract, flavonoids, sterols, triterpens, tanins, polyphenols, anthraquinons, saponins and terpenoids. CONCLUSION: These findings suggest that, the mixture of the two plant extracts showed an additive (synergetic effect) ovicidal effect and a slight larval mortality on L1 as compared to the effect of MCM As extract alone. These effects were due to the presence ao secondary metabolites identifies in the plant extracts. Thus, they may be used as possible «disinfectants¼ for soil transmitted nematodes.

Protein deficiency and intestinal nematode infection in pregnant mice differentially impact fetal growth through specific stress hormones, growth factors, and cytokines.

BACKGROUND: Protein deficiency (PD) and intestinal nematode infections commonly co-occur during pregnancy and impair fetal growth, but the complex network of signals has not been explored. OBJECTIVE: Our objective was to assess those stress hormones, growth factors, and cytokines affected by maternal PD and nematode infection and associated with fetal growth. METHODS: Using a 2 × 2 factorial design, CD-1 mice, fed protein-sufficient (PS; 24%) or protein-deficient (PD; 6%) isoenergetic diets, were either uninfected or infected every 5 d with Heligmosomoides bakeri, beginning on gestational day (GD) 5. Biomarker concentrations were measured on GD 18 in maternal serum (m), fetal serum (f), and amniotic fluid (af) by using Luminex. RESULTS: Maternal PD lowered fetal body mass (PS/uninfected 1.25 ± 0.02 g, PS/infected 1.19 ± 0.02 g vs. PD/uninfected 1.11 ± 0.02 g, PD/infected 0.97 ± 0.02 g; P = 0.02), fetal lung (P = 0.005), and liver (P = 0.003) but not brain mass, whereas maternal infection lowered fetal length (PS/uninfected 2.28 ± 0.02 cm, PD/uninfected 2.27 ± 0.03 cm vs. PS/infected 2.21 ± 0.03 cm, PD/infected 2.11 ± 0.02 cm; P = 0.05) and kidney mass (P = 0.04). PD elevated stress hormones (m-adrenocortiotropic hormone, f-corticosterone, af-corticosterone) and reduced insulin-like growth factor 1 in all compartments (P ≤ 0.01), but these were unassociated with fetal mass or length. Fetal mass was positively associated with f-leptin (R(2) = 0.71, P = 0.0001) and negatively with fetal cytokines [tumor necrosis factor-α: R(2) = 0.62, P = 0.001; interleukin-4 (IL-4): R(2) = 0.63, P = 0.0004]. In contrast, maternal infection lowered f-prolactin (P = 0.02) that was positively associated with fetal length (R(2) = 0.43; P = 0.03); no other biomarker was affected by infection. Regression analyses showed associations between organ growth, cytokines, and growth factors: 1) thymus, spleen, heart, and brain with m-IL-10; 2) brain and kidney with f-vascular endothelial growth factor, af-monocyte chemotactic protein 1, af-interferon-γ, and af-eotaxin; and 3) liver and lung with f-leptin and af-corticosterone (all P ≤ 0.02). CONCLUSIONS: PD and nematode infection impaired fetal mass and linear growth, respectively. Fetal mass, length, and individual organ masses were regulated by different hormones, growth factors, and cytokines.

Host genetic influences on the anthelmintic efficacy of papaya-derived cysteine proteinases in mice.

Eight strains of mice, of contrasting genotypes, infected with Heligmosomoides bakeri were studied to determine whether the anthelmintic efficacy of papaya latex varied between inbred mouse strains and therefore whether there is an underlying genetic influence on the effectiveness of removing the intestinal nematode. Infected mice were treated with 330 nmol of crude papaya latex or with 240 nmol of papaya latex supernatant (PLS). Wide variation of response between different mouse strains was detected. Treatment was most effective in C3H (90·5-99·3% reduction in worm counts) and least effective in CD1 and BALB/c strains (36·0 and 40·5%, respectively). Cimetidine treatment did not improve anthelmintic efficacy of PLS in a poor drug responder mouse strain. Trypsin activity, pH and PLS activity did not differ significantly along the length of the gastro-intestinal (GI) tract between poor (BALB/c) and high (C3H) drug responder mouse strains. Our data indicate that there is a genetic component explaining between-mouse variation in the efficacy of a standard dose of PLS in removing worms, and therefore warrant some caution in developing this therapy for wider scale use in the livestock industry, and even in human medicine.

Aggregation of adult parasitic nematodes in sex-mixed groups analysed by transient anomalous diffusion formalism.

Intestinal parasitic worms are widespread throughout the world, causing chronic infections in humans and animals. However, very little is known about the locomotion of the worms in the host gut. We studied the movement of Heligmosomoides bakeri, naturally infecting mice, and used as an animal model for roundworm infections. We investigated the locomotion of H. bakeri in simplified environments mimicking key physical features of the intestinal lumen, i.e. medium viscosity and intestinal villi topology. We found that the motion sequence of these nematodes is non-periodic, but the migration could be described by transient anomalous diffusion. Aggregation as a result of biased, enhanced-diffusive locomotion of nematodes in sex-mixed groups was detected. This locomotion is probably stimulated by mating and reproduction, while single nematodes move randomly (diffusive). Natural physical obstacles such as high mucus-like viscosity or villi topology slowed down but did not entirely prevent nematode aggregation. Additionally, the mean displacement rate of nematodes in sex-mixed groups of 3.0 × 10-3 mm s-1 in a mucus-like medium is in good agreement with estimates of migration velocities of 10-4 to 10-3 mm s-1 in the gut. Our data indicate H. bakeri motion to be non-periodic and their migration random (diffusive-like), but triggerable by the presence of kin.

A gastrointestinal nematode in pregnant and lactating mice alters maternal and neonatal microbiomes.

The maternal microbiome is understood to be the principal source of the neonatal microbiome but the consequences of intestinal nematodes on pregnant and lactating mothers and implications for the neonatal microbiome are unknown. Using pregnant CD1 mice infected with Heligmosomoides bakeri, we investigated the microbiomes in maternal tissues (intestine, vagina, and milk) and in the neonatal stomach using MiSeq sequencing of bacterial 16S rRNA genes. Our first hypothesis was that maternal nematode infection altered the maternal intestinal, vaginal, and milk microbiomes and associated metabolic pathways. Maternal nematode infection was associated with increased beta-diversity and abundance of fermenting bacteria as well as Lactobacillus in the maternal caecum 2 days after parturition, together with down-regulated carbohydrate, amino acid and vitamin biosynthesis pathways. Maternal nematode infection did not alter the vaginal or milk microbiomes. Our second hypothesis was that maternal infection would shape colonization of the neonatal microbiome. Although the pup stomach microbiome was similar to that of the maternal vaginal microbiome, pups of infected dams had higher beta-diversity at day 2, and a dramatic expansion in the abundance of Lactobacillus between days 2 and 7 compared with pups nursing uninfected dams. Our third hypothesis that maternal nematode infection altered the composition of neonatal microbiomes was confirmed as we observed up-regulation of several putatively beneficial microbial pathways associated with synthesis of essential and branched-chain amino acids, vitamins, and short-chain fatty acids. We believe this is the first study to show that a nematode living in the maternal intestine is associated with altered composition and function of the neonatal microbiome.

Immunity to Soil-Transmitted Helminths: Evidence From the Field and Laboratory Models.

Infection with soil-transmitted helminths (STH) remains a major burden on global health and agriculture. Our understanding of the immunological mechanisms that govern whether an individual is resistant or susceptible to infection is derived primarily from model infections in rodents. Typically, experimental infections employ an artificially high, single bolus of parasites that leads to rapid expulsion of the primary infection and robust immunity to subsequent challenges. However, immunity in natura is generated slowly, and is only partially effective, with individuals in endemic areas retaining low-level infections throughout their lives. Therefore, there is a gap between traditional model STH systems and observations in the field. Here, we review the immune response to traditional model STH infections in the laboratory. We compare these data to studies of natural infection in humans and rodents in endemic areas, highlighting crucial differences between experimental and natural infection. We then detail the literature to date on the use of "trickle" infections to experimentally model the kinetics of natural infection.

Evaluation of the anthelminthic potential of Duranta erecta L. (Verbenaceae) fruits used in Nigerian ethnomedicine as a vermifuge.

ETHNOPHARMACOLOGICAL RELEVANCE: Duranta erecta L. fruits have been reported to have in vitro anthelminthic properties. People living in the tropical South-Eastern part of Nigeria use the plant in folk medicine for the treatment of malaria, abscesses and as a vermifuge. Although there are a few reports about its in vitro anthelminthic activity against different worm categories, scientific reports regarding its in vivo anthelminthic activity are limited. AIM OF THE STUDY: This study was designed with the aim of determining the potential of the plant as an anthelminthic and to verify the claims made by its local users. MATERIALS AND METHODS: Acute toxicity of the plant extract was determined using Lorke's method. Anthelminthic activity was investigated using adult male albino mice experimentally infected with Heligmosomoides bakeri infective L3. Graded ascending doses of the plant extract and Albendazole respectively were orally administered to the mice in the infected groups. Corprological and haematological parameters were recorded within the study period. Twenty-eight (28) days post-infection, all infected mice were humanely sacrificed and the Post-Mortem Adult Worm Burden (WB) was estimated and recorded. RESULTS: The results showed that the extract had an LD50 greater than 5000 mg/kg BW and therefore was not acutely toxic for oral use. It also showed that the plant extract was unable to eliminate the faecal egg output or adult worms in the gastrointestinal tract of infected animals even at the high doses used in the study. This was in contrast to Albendazole which significantly (p < .05) reduced faecal egg counts and worm burdens by 71% and 92% respectively in treated mice. Following infection, there was anaemia in all infected groups seen from results of erythrocytic parameters. Treatment with the plant extract, regardless of the dose, was unable to effectively reverse the effect of parasite infection on erythrocytic parameters. However, treatment with Albendazole positively reversed the anaemia, restoring the mice to pre-infection values by the end of the experiment. The results showed significant (p < .05) increase in WBC counts across all groups following infection with the parasite. Treatment with the plant extract and Albendazole respectively, significantly (p < .05) reduced the WBC counts to near pre-infection values in most treatment groups. CONCLUSION: As a result of the poor anthelminthic effects recorded in the study, it is therefore recommended that Duranta erecta L. fruits be explored for its other useful effects rather than as an anthelminthic.

Differential expression of genes in fetal brain as a consequence of maternal protein deficiency and nematode infection.

Maternal dietary protein deficiency and gastrointestinal nematode infection during early pregnancy have negative impacts on both maternal placental gene expression and fetal growth in the mouse. Here we used next-generation RNA sequencing to test our hypothesis that maternal protein deficiency and/or nematode infection also alter the expression of genes in the developing fetal brain. Outbred pregnant CD1 mice were used in a 2×2 design with two levels of dietary protein (24% versus 6%) and two levels of infection (repeated sham versus Heligmosomoides bakeri beginning at gestation day 5). Pregnant dams were euthanized on gestation day 18 to harvest the whole fetal brain. Four fetal brains from each treatment group were analyzed using RNA Hi-Seq sequencing and the differential expression of genes was determined by the edgeR package using NetworkAnalyst. In response to maternal H. bakeri infection, 96 genes (88 up-regulated and eight down-regulated) were differentially expressed in the fetal brain. Differentially expressed genes were involved in metabolic processes, developmental processes and the immune system according to the PANTHER classification system. Among the important biological functions identified, several up-regulated genes have known neurological functions including neuro-development (Gdf15, Ing4), neural differentiation (miRNA let-7), synaptic plasticity (via suppression of NF-κß), neuro-inflammation (S100A8, S100A9) and glucose metabolism (Tnnt1, Atf3). However, in response to maternal protein deficiency, brain-specific serine protease (Prss22) was the only up-regulated gene and only one gene (Dynlt1a) responded to the interaction of maternal nematode infection and protein deficiency. In conclusion, maternal exposure to GI nematode infection from day 5 to 18 of pregnancy may influence developmental programming of the fetal brain.

Response of outbred albino mice to concomitant Heligmosomoides bakeri, Plasmodium berghei and Trypanosoma brucei infections.

To investigate the response of mice to concomitant infections with Trypanosoma brucei (Tb), Plasmodium berghei (Pb) and Heligmosomoides bakeri (Hb) infections. Each group of 6 mice was either infected with Pb + Tb + Hb, Pb + Tb, Pb + Hb, Tb + Hb, Pb, Tb, Hb or remained as uninfected controls. Hb infected mice each received 200 infective larvae (L3) of Hb orally, Tb infected mice each received 2 × 10-6 organisms through the intraperitoneal route while Pb infected mice received 1 × 10-5 parasitized red blood cells through the intraperitoneal route. PCV, body weights (BW), faecal egg counts (FEC), Tb parasitaemia, Pb parasitaemia, clinical signs and worm burdens (WB) were determined. FEC were highest in Pb + Tb + Hb and least in Hb group and the difference was significant (P < 0.05). WB was significantly higher in mice with concurrent infections. PCV of infected mice was lower than that of uninfected controls and the difference was significant between Pb + Tb + Hb infected and uninfected controls. The difference in weight loss was significant between Pb + Tb + Hb infected and controls. Mortalities occurred in Pb + Tb + Hb, Tb + Hb and Pb + Hb infected mice. Mortalities and low PCV and low BW were indications that concomitant infections were more pathogenic to the mice than single infections, pathogenicity increasing with increasing number of parasite species involved.

Expression of growth-related genes in the mouse placenta is influenced by interactions between intestinal nematode (Heligmosomoides bakeri) infection and dietary protein deficiency.

Intestinal nematode infection and dietary protein deficiency are common during pregnancy and both have been shown to impair fetal growth in humans, livestock and laboratory animals. The placenta has been linked to fetal growth but its role in mediating the response to maternal infection and protein deficiency is not understood. We used microarrays to test the hypothesis that maternal intestinal nematode infection and protein deficiency alter the expression of placental genes related to fetal growth. Placentas were obtained on day 18 of pregnancy from CD-1 mice fed protein sufficient (24%) or protein deficiency (6%) isoenergetic diets and either uninfected or infected with Heligmosomoides bakeri. Gene expression was analysed using the Affymetrix GeneChip 2.0 ST mouse array (n=3/experimental group). Differentially expressed genes were identified using two-way ANOVA (P<0.02, fold-change >1.25) and pathway analyses were performed using DAVID software. Expression changes for selected genes were confirmed using qPCR. Heligmosomoides bakeri infection down-regulated 109 transcripts, including genes related to oxidative phosphorylation, and up-regulated 214 transcripts, including genes involved in ATP binding and hemopoiesis. Up-regulation of hemopoiesis genes may explain increased placental mass previously reported in H. bakeri-infected mice. Protein deficiency down-regulated 141 annotated transcripts, including genes involved in cell motility and endopeptidase activity, and up-regulated 131 annotated transcripts, including genes related to hemopoiesis. A statistical interaction was detected for 248 transcripts, including several genes with known functions in fetal growth. Notably, expression of the gene Irs1 (insulin receptor substrate) was lower in infected dams but only when they were fed a protein sufficient diet. Also, expression of several genes, including Igf1r (insulin-like growth factor-1 receptor) and Prl (prolactin) was up-regulated by infection in protein deficiency dams and down-regulated by protein deficiency in uninfected dams. Our results highlight that expression of placental genes involved in fetal growth is influenced by the interaction between protein deficiency and H. bakeri infection.

Tolerance and resistance to a nematode challenge are not always mutually exclusive.

The relationship between the manifestations of tolerance (a host's ability to reduce the impact of a given level of pathogens) and resistance (a host's ability to clear pathogens) has been assumed to be an antagonistic one. Here we tested the hypothesis that mice from strains more resistant to intestinal nematodes will experience reduced tolerance compared with less resistant mice. Three inbred strains of mice were used: C57BL/6 mice have been characterised as susceptible, whereas BALB/c and NIH mice have been characterised as resistant to Heligmosomoides bakeri infection. Mice of each strain were either parasitised with a single dose of 250 L3H. bakeri (n=10) in water or were sham-infected with water (n=10). Body weight, food intake and worm egg output were recorded regularly throughout the experiment. Forty-two days p.i. mice were euthanised and organ weights, eggs in colon and worm counts were determined. C57BL/6 mice showed significantly greater worm egg output (P<0.001), eggs in colon (P<0.05) and female worm fecundity (P<0.05) compared with NIH and BALB/c mice. Parasitised BALB/c mice grew more whilst parasitised C57BL/6 mice grew less than their sham-infected counterparts during the first 2 weeks post-challenge (P=0.05). Parasitism significantly increased liver, spleen, small intestine and caecum weights (P<0.001) but reduced carcass weight (P<0.01). Average daily weight gain and worm numbers were positively correlated in NIH mice (P=0.05); however, the relationship was reversed when carcass weight was used as a measure for tolerance. BALB/c mice did not appear to suffer from the consequences of parasitism, with carcass weight similar in all animals. Our hypothesis that strains more resistant to the H. bakeri infection are less tolerant compared with less resistant strains is rejected, as the two resistant strains showed variable tolerance. Thus, tolerance and resistance to an intestinal nematode infection are not always mutually exclusive.

Corprological and haematological parameters of albino mice (Mus musculus) concurrently infected with Heligmosomoides bakeri and Trypanosoma brucei.

The effect of concurrent infection with Trypanosoma brucei (T. brucei) and Heligmosomoides bakeri (H. bakeri) was investigated in this study. Thirty adult male albino mice were used for the study. The mice were divided into six groups of five mice each. Group 1 served as uninfected control, Groups 2 and 3 were infected with H. bakeri and T. brucei respectively, Group 4 received both T. brucei and H. bakeri on the same day, Group 5 was experimentally infected with H. bakeri three days after T. brucei infection, while Group 6 was infected with T. brucei three days after H. bakeri infection. Blood and faecal samples were collected and analyzed weekly to determine the faecal egg counts (FEC), packed cell volume (PCV) and level of parasitaemia (LP). Weekly body weights (BW) were also recorded. FEC and parasitaemia increased in all the infected groups during the study, but these were significantly (p<0.05) higher in the multiple-infection (groups 4, 5 and 6) than those with the single infection (groups 2 and 3). The same trend was also observed in the BW and PCV (p<0.05). The level of infection produced by single infection with T. brucei and H. bakeri respectively were similar (p<0.05). All treatment groups were significantly (p<0.05) different from the control group. From the results, it was concluded that concurrent helminth and protozoan parasite infections produced more deleterious effect on the host when compared with single infection with either parasite. However, the pathology produced by concurrent infection was more severe when the host was exposed to the protozoan parasite before the helminth parasite.