Conjoint Heligmosomoides polygyrus and Trypanosoma congolense infection in mice

The economic importance of gastro-intestinal nematodes and African trypanosome infections of farm animals in the tropics has been presented as the rationale for research into the aspects of these infections with the hope of devising control measures which will increase animal productivity. The scientific literature on the development, immunology and pathology of gastro-intestinal nematode and protozoan infections with particular reference to Heligmosomoides polygyrus and African trypanosomes and the effects of concurrent infections, with these classes of parasites, on the host has been reviewed.Experiments were conducted to develop a suitable laboratory model involving H. polygyrus and Trypanosoma congolense in female TO mice in order to study the effects of some factors such as the timing of conjoint infections, the role of immunity to the helminth infection in the face of conjoint challenge infection and the responses of the host as well as that of the parasites to conjoint infections.Infections with stabilated blood stream forms of T. congolense (TREU 1881) but not the infective metacyclics grown in vitro gave reproducible parasitological results which together with infections of 500 L3 of H. polygyrus in mice produced a suitable host-parasite system in which aspects of chronic gastrointestinal nematode and blood protozoan infections were studied.Except when T. congolense was superimposed on a 10-day old H. polygyrus infection, mice conjointly infected with T. congolense during a primary H. polygyrus infection were severely compromised, resulting in enhanced mortality. The synergistic pathogenic effects of dual infections in mice were particularly marked when T. congolense infection preceded infection with the nematode. T. congolense infection depressed the immune (cellular and humoral) responses which normally occur in mice after primary H. polygyrus infection. The protozoan infection either reduced or totally inhibited immunity against a challenge H. polygyrus infection. Possible mechanisms of this immunosuppression which include among others, the generation of suppressor macrophages and the inhibition of eosinophils, are discussed. These observations suggest that, conjoint infections with these parasites produce deleterious synergistic interactions which affect productivity and even cause further deaths.Although the protective responses against homologous challenge in mice immunized by abbreviation of H. polygyrus adult infection were completely lost as a result of concurrent infection with T. congolense, the stronger protection in those immunized by an abbreviated larval infection was merely reduced. These observations suggest that animals with a strong immunity to gastro-intestinal nematodes may largely overcome the suppressive influence of the trypanosome. It is suggested that enhanced resistance through abbreviation of primary nematode infection within the first one week of grazing an infected pasture at the beginning of the grazing season might combat problems of synergistic interactions during natural infections of nematodes and trypanosomes in ruminants

ACTIVITY OF CAMELLIA SINENSIS (GREEN TEA) AGAINST TROPHOZOITE AND CYSTIC FORMS OF ACANTHAMOEBA CASTELLANII IN VITRO

Acanthamoeba castellanii is a free-living unicellular protozoan, which causes acanthamoebiasis clinically seen as granulomatous amoebic encephalitis (GAE) of the brain and Acanthamoeba keratitis (AK) of the eyes. The conclusive effective treatment for these diseases is yet to be determined. This work focused on investigating the amoebicidal and cysticidal effect of Camellia sinensis by subjecting A. castellanii forms to serial concentrations of C. sinensis brews, solvent extract and their bioactive components. From the brew studies, serial concentrations of 25% - 100%(v/v) of C. sinensis brews exhibited a dose-dependent inhibition of trophozoite replication. A similar dose-dependent activity was observed with the exposure of A. castellanii to serial concentrations of 156.25µg/mL - 5000 µg/mL of C. sinensis solvent extract. Ultrastructural alterations in C. sinensis-treated A. castellanii was investigated with electron microscopy studies which revealed loss of cellular membrane integrity of trophozoites and destruction of cysts. These results were corroborated with light microscopy evaluations. Cytotoxicity analysis of C. sinensis against mammalian host cells revealed that C. sinensis exhibited low cytotoxic effects on primary corneal stromal cells and immortalizedhuman corneal epithelial cells (iHCE-2s), with high toxicity to Madin-Darby Canine Kidney cells (MDCKs). Evaluation of the C. sinensis chemical components revealed that epigallocatechin gallate (EGCG) and caffeine exhibited dose-dependent anti-acanthamoebic activity by inhibiting trophozoite replication within the concentrations of 3.125µM - 200µM, and also inhibited encystation alongside theobromine. Proteomic analysis of C. sinensis treated trophozoites showed inhibition of 14-3-3 protein sigma and Keratin type I cytoskeletal 10, while TPI, TrxRases and alpha-enolase inhibited trophozoites replication by inhibition protein and cellulose synthesis. These inhibitions were confirmed by the lack of amide I and II band peaks expression in the treated trophozoites by Fourier-transform infrared spectroscopy (FTIR) analysis. Taken together, these results demonstrated that C. sinensis possess antiacanthamoebic capability making it a potential novel compound which can be further investigated for anti-acanthamoebic drug production

ACTIVITY OF CAMELLIA SINENSIS (GREEN TEA) AGAINST TROPHOZOITE AND CYSTIC FORMS OF ACANTHAMOEBA CASTELLANII IN VITRO

Acanthamoeba castellanii is a free-living unicellular protozoan, which causes acanthamoebiasis clinically seen as granulomatous amoebic encephalitis (GAE) of the brain and Acanthamoeba keratitis (AK) of the eyes. The conclusive effective treatment for these diseases is yet to be determined. This work focused on investigating the amoebicidal and cysticidal effect of Camellia sinensis by subjecting A. castellanii forms to serial concentrations of C. sinensis brews, solvent extract and their bioactive components. From the brew studies, serial concentrations of 25% - 100%(v/v) of C. sinensis brews exhibited a dose-dependent inhibition of trophozoite replication. A similar dose-dependent activity was observed with the exposure of A. castellanii to serial concentrations of 156.25µg/mL - 5000 µg/mL of C. sinensis solvent extract. Ultrastructural alterations in C. sinensis-treated A. castellanii was investigated with electron microscopy studies which revealed loss of cellular membrane integrity of trophozoites and destruction of cysts. These results were corroborated with light microscopy evaluations. Cytotoxicity analysis of C. sinensis against mammalian host cells revealed that C. sinensis exhibited low cytotoxic effects on primary corneal stromal cells and immortalizedhuman corneal epithelial cells (iHCE-2s), with high toxicity to Madin-Darby Canine Kidney cells (MDCKs). Evaluation of the C. sinensis chemical components revealed that epigallocatechin gallate (EGCG) and caffeine exhibited dose-dependent anti-acanthamoebic activity by inhibiting trophozoite replication within the concentrations of 3.125µM - 200µM, and also inhibited encystation alongside theobromine. Proteomic analysis of C. sinensis treated trophozoites showed inhibition of 14-3-3 protein sigma and Keratin type I cytoskeletal 10, while TPI, TrxRases and alpha-enolase inhibited trophozoites replication by inhibition protein and cellulose synthesis. These inhibitions were confirmed by the lack of amide I and II band peaks expression in the treated trophozoites by Fourier-transform infrared spectroscopy (FTIR) analysis. Taken together, these results demonstrated that C. sinensis possess antiacanthamoebic capability making it a potential novel compound which can be further investigated for anti-acanthamoebic drug production

Effects of Trypanosoma brucei and Heligmosomoides bakeri infections on water consumption of lactating albino mice and the viability of their pre-weaned offspring

The effects of single and/or concurrent H. bakeri and T. brucei infections on water consumption of lactating and non-lactating mice were investigated. Pregnant mice were grouped into four (A, B, C and D) comprising of six animals per group. Groups A, B and C were either infected with H. bakeri or T. brucei alone or with both parasites together. Group D served as pregnant uninfected control while a different group (E) was used as non-pregnant and uninfected control. Packed cell volumes (PCV), faecal egg counts (FEC), worm burden and water consumption of the mice were determined. Mean live-weights of surviving offspring and their numbers were recorded. Infected animals had lower PCV compared to the controls. However, lactating mice infected with both parasites had the least PCV. Mortalities occurred in the dualinfected groups. Worm burden and FEC of mice with concurrent infections were significantly higher than that of the H. bakeri-only infected mice. Lactating mice consumed significantly more water than non-lactating mice . Uninfected and H. bakeri-only infected mice had heavier, healthy-looking and greater numbers of pups than their conjointly-infected counterparts that had fewer wrinkled-bodied pups with more early-mortalities following parturition. Drawing from these results, it is therefore necessary to promptly control diseases in pregnant and lactating animals and provide water adlibitum to lactating animals. Keywords: Water consumption, Lactating mice, Trypanosoma brucei, Heligmosomoides bakeri, concurrent infectio

In vitro activity of Camellia sinensis (green tea) against trophozoites and cysts of Acanthamoeba castellanii

© 2020 The Author(s) The effect of Camellia sinensis (green tea) on the growth of Acanthamoeba castellanii trophozoites was examined using a microplate based-Sulforhodamine B (SRB) assay. C. sinensis hot and cold brews at 75% and 100% concentrations significantly inhibited the growth of trophozoites. We also examined the structural alterations in C. sinensis-treated trophozoites using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). This analysis showed that C. sinensis compromised the cell membrane integrity and caused progressive destruction of trophozoites. C. sinensis also significantly inhibited the parasite's ability to form cysts in a dose-dependent manner and reduced the rate of excystation from cysts to trophozoites. C. sinensis exhibited low cytotoxic effects on primary corneal stromal cells. However, cytotoxicity was more pronounced in SV40-immortalized corneal epithelial cells. Chromatographic analysis showed that both hot and cold C. sinensis brews contained the same number and type of chemical compounds. This work demonstrated that C. sinensis has anti-acanthamoebic activity against trophozoite and cystic forms of A. castellanii. Further studies are warranted to identify the exact substances in C. sinensis that have the most potent anti-acanthamoebic effect

State of knowledge of research in the Guinean forests of West Africa region

© 2017 Elsevier Masson SAS. The Guinean forests of West Africa (GFWA) region is of highest conservation value in Africa and worldwide. The aims of this review are to systematically identify and collate studies focusing on the environment in the region. We found that, after Google Scholar search, in over 112,000 results for 17 disciplines, three countries (Nigeria, Cameroon and Togo) were subjected to much more investigations than the other countries. Guinea, Liberia, and Sierra Leone were the least studied countries, and overall there was a significant West to East increasing trend for all seven considered disciplines (Ecology, Zoology, Botany, Conservation biology, Pollution, Climate change and Ecological economy) in terms of number of results. Within 'Ecology' 'macroecology and biodiversity' was the most studied subdiscipline. Baseline taxonomic studies in 'Zoology' and 'Botany' received little interest, particularly in 2006-2016. For 'Conservation biology', studies focusing on 'protected areas' were more numerous than for any other subsector, followed by 'biodiversity surveys'. Our analysis revealed that there were significantly more studies focusing on forests than on mangrove areas. Our results pointed out that, there is an urgent need for more rigorous taxonomical and fine-scale distribution studies of organisms across the whole region, not only for the traditionally overlooked groups (e.g. invertebrates). It is also stressed that studies of macropatterns in conservation biology research for the region should be performed by more reliable data at the more local scale, given the misuse that has been done by general studies of these limited/biased data for inferring patterns. Long-term longitudinal studies on biodiversity patterns of important forest sites and population biology of selected populations are urgently needed, as these have been almost entirely neglected to date. Crucial issues are still to be solved: for instance, it remains fully unresolved whether wildlife can best be protected through the promotion of human economic development or through integral conservation of important biodiversity areas

Heligmosomoides bakeri: a model for exploring the biology and genetics of resistance to chronic gastrointestinal nematode infections

The intestinal nematode Heligmosomoides bakeri has undergone 2 name changes during the last 4 decades. Originally, the name conferred on the organism in the early 20th century was Nematospiroides dubius, but this was dropped in favour of Heligmosomoides polygyrus, and then more recently H. bakeri, to distinguish it from a closely related parasite commonly found in wood mice in Europe. H. bakeri typically causes long-lasting infections in mice and in this respect it has been an invaluable laboratory model of chronic intestinal nematode infections. Resistance to H. bakeri is a dominant trait and is controlled by genes both within and outside the MHC. More recently, a significant QTL has been identified on chromosome 1, although the identity of the underlying genes is not yet known. Other QTL for resistance traits and for the accompanying immune responses were also defined, indicating that resistance to H. bakeri is a highly polygenic phenomenon. Hence marker-assisted breeding programmes aiming to improve resistance to GI nematodes in breeds of domestic livestock will need to be highly selective, focussing on genes that confer the greatest proportion of overall genetic resistance, whilst leaving livestock well-equipped genetically to cope with other types of pathogens and preserving important production traits

The unique resistance and resilience of the Nigerian West African Dwarf goat to gastrointestinal nematode infections

<p>Abstract</p> <p>Background</p> <p>West African Dwarf (WAD) goats serve an important role in the rural village economy of West Africa, especially among small-holder livestock owners. They have been shown to be trypanotolerant and to resist infections with <it>Haemonchus contortus </it>more effectively than any other known breed of goat.</p> <p>Methods</p> <p>In this paper we review what is known about the origins of this goat breed, explain its economic importance in rural West Africa and review the current status of our knowledge about its ability to resist parasitic infections.</p> <p>Conclusions</p> <p>We suggest that its unique capacity to show both trypanotolerance and resistance to gastrointestinal (GI) nematode infections is immunologically based and genetically endowed, and that knowledge of the underlying genes could be exploited to improve the capacity of more productive wool and milk producing, but GI nematode susceptible, breeds of goats to resist infection, without recourse to anthelmintics. Either conventional breeding allowing introgression of resistance alleles into susceptible breeds, or transgenesis could be exploited for this purpose. Appropriate legal protection of the resistance alleles of WAD goats might provide a much needed source of revenue for the countries in West Africa where the WAD goats exist and where currently living standards among rural populations are among the lowest in the world.</p

Bushmeat consumption in large urban centres in West Africa

Bushmeat consumption in large Sub-Saharan African cities is perceived as a major threat to the conservation of many species because their considerable population sizes can generate a significant demand for bushmeat. The study of the effect of age, sex and geographic location in bushmeat eating in African cities may offer valuable insights on which population groups to target in behaviour change campaigns. Using 2,040 interviews in six West African cities from four countries, in forest and savannah settings, we analysed the differences between age and sex in people’s frequency of bushmeat consumption. Overall, we found similar patterns in all sampled cities. As many as 62.2 % males and 72.1% females replied that they ‘would not eat bushmeat at all’, though only 12.8% males and 8.8% females mentioned they regularly ate bushmeat. Younger generations of both sexes answered that they ‘would never eat bushmeat’ more often than older age groups, independently of their city of origin. These trends are encouraging though further research needs to be undertaken to find out whether bushmeat volumes consumed in cities are unsustainable and having a serious impact of prey populations