Culture of protozoan parasites

In vitro growth of Leishmania parasites from biopsy samples of suspected cutaneous and visceral leishmaniasis cases in Sri Lanka: An observational study

Sri Lanka reports a large focus of Leishmania donovani caused cutaneous leishmaniasis (CL). Subsequent emergence of visceral leishmaniasis (VL) was also reported recently. Expansion of the on-going disease outbreak and many complexities indicate urgent need to enhance early case detection methods. In vitro cultivation (IVC) of parasites causing visceral leishmaniasis (VL) is important for disease confirmation and to obtain sufficient quantities of parasites required in many scientific studies. IVC is carried out as a useful second line investigation for direct microscopy negative patients with CL in this setting. Along with the emergence of VL, current study was carried out to evaluate in vitro growth of local VL parasites and to identify their differences associated with in vitro growth characteristics. Routine parasitological diagnostic methods, i.e., light microscopy (LM), polymerase chain reaction (PCR) were used for confirmation of suspected cases. Lesion samples from 125 suspected CL cases and bone marrow or splenic aspirations from 125 suspected VL patients were used to inoculate IVCs. Media M199 (about 70 μl) supplemented with 15-20% of heat inactivated fetal bovine serum was used for initial culturing procedures in capillaries. Capillary cultures were monitored daily. Total of 44 different compositions/conditions were used for evaluating in vitro growth of VL causing parasite. Daily records on parasite counts, morphological appearance (size, shape, and wriggly movements) were maintained. In vitro transformation of Leishmania promastigotes to amastigotes and outcome of the attempts on recovery of live Leishmania from culture stabilates was also compared between CL and VL parasites. Proportion of cultures showing a transformation of promastigotes were 40/45 (88.9%) and 4/10 (40.0%) for CL and VL respectively. In the transformed cultures, parasites showing typical shape, size and movement patterns were less in VL (1/4, 25.0%) compared to CL (28/40, 70.0%). CL cultures showed a growth up to mass culturing level with mean duration of two weeks while it was about five weeks for VL cultures. Proportion of cultures that reached a parasite density of 1 × 106 cells/ml (proceeded to mass cultures) was significantly low in VL (4/10, 40%) as compared to CL (28/40, 70.0%). None of media compositions/conditions were successful for mass culturing of VL parasites while all of them were shown to be useful for growing CL strains. Also in vitro transformation to amastigote form and recovering of culture stabilates were not successful compared to CL. There were clear differences between in vitro growth of Leishmania parasites causing local CL and VL. Further studies are recommended for optimization of in vitro culturing of VL parasite which will be invaluable to enhance case detection in future.

Cultivation of Protozoa Parasites In Vitro: Growth Potential in Conventional Culture Media versus RPMI-PY Medium

The in vitro cultivation of Leishmania and Trypanosoma parasites plays an important role in the diagnosis and treatment of parasitic diseases. Although Evans’s modified Tobie and Novy–MacNeal–Nicolle media, for Leishmania spp. and Trypanosoma cruzi, respectively, are the two commonly used media for both isolation and maintenance of strains in vitro, their preparation is expensive and laborious and requires fresh rabbit blood from housed animals. The purpose of this study was to evaluate the in vitro growth of both parasites with an alternative monophasic, blood-free, easy, and affordable medium called RPMI-PY, which was previously demonstrated suitable for the in vitro growth of Leishmania infantum. The potential growth of different Leishmania species and Trypanosoma cruzi was evaluated in traditional culture media versus RPMI-PY medium, and we recorded the protozoa parasites’ morphology via orange acridine–ethidium bromide staining. The results of our study show that RPMI-PY medium can be used for Trypanosoma cruzi, Leishmania amazonensis, Leishmania major, and Leishmania tropica species since in all the species except Leishmania braziliensis, the exponential growth of the parasite was observed, in many cases higher than conventional media. The staining confirmed not only their growth during the 72 h investigation but also the optimal morphology and viability of the protozoa in the RPMI-PY medium.

The role of feeds in the transmission of chicken pathogens in Dodoma Urban District, Tanzania

Chicken production is an important economic activity in Tanzania. Indigenous chickens are kept in rural areas, while exotic breeds are kept in urban areas. Due to their high productivity, exotic breeds are becoming important sources of protein in fast-growing cities. Dodoma is one of the cities growing very fast in Tanzania. As a result, production of layers and broilers has increased dramatically. However, diseases remain the major challenge to chicken production despite the efforts of livestock officers to educate people on good management practices. This has made farmers think that feeds may be the source of pathogens. The study's objectives were thus to identify the major diseases affecting broiler and layer chickens in the Dodoma urban district, as well as the potential role of feeds in pathogen transmission to chickens. A household survey was conducted to identify common diseases affecting chickens in the study area. Thereafter, locally prepared feed samples were collected from twenty shops available in the district to determine the presence of Salmonella and Eimeria parasites. The presence of Eimeria parasites in the feeds was determined by raising day-old chicks in a sterile environment for 3 wk while feeding them the feed samples collected. Fecal samples from the chicks were analyzed for the presence of Eimeria parasites. Salmonella contamination of the feed samples was determined in the laboratory through the culture method. The study found that coccidiosis, Newcastle disease, fowl typhoid, infectious bursal disease, and colibacillosis are the main diseases affecting chickens in the district. After 3 wk of rearing, 3 out of 15 chicks developed coccidiosis. In addition, about 31.1% of the feed samples showed the presence of Salmonella spp. The prevalence of Salmonella was highest in limestone (53.3%), followed by fishmeal (26.7%), and maize bran (13.3%). It has been concluded that feeds are potential carriers of pathogens. To reduce economic losses and the continuous use of drugs in chicken production, health authorities should assess the microbial quality of poultry feeds.

Transcending Dimensions in Apicomplexan Research: from Two-Dimensional to Three-Dimensional In Vitro Cultures

Parasites belonging to the Apicomplexa phylum are among the most successful pathogens known in nature. They can infect a wide range of hosts, often remain undetected by the immune system, and cause acute and chronic illness. In this phylum, we can find parasites of human and veterinary health relevance, such as Toxoplasma, Plasmodium, Cryptosporidium, and Eimeria. There are still many unknowns about the biology of these pathogens due to the ethical and practical issues of performing research in their natural hosts. Animal models are often difficult or nonexistent, and as a result, there are apicomplexan life cycle stages that have not been studied. One recent alternative has been the use of three-dimensional (3D) systems such as organoids, 3D scaffolds with different matrices, microfluidic devices, organs-on-a-chip, and other tissue culture models. These 3D systems have facilitated and expanded the research of apicomplexans, allowing us to explore life stages that were previously out of reach and experimental procedures that were practically impossible to perform in animal models. Human- and animal-derived 3D systems can be obtained from different organs, allowing us to model host-pathogen interactions for diagnostic methods and vaccine development, drug testing, exploratory biology, and other applications. In this review, we summarize the most recent advances in the use of 3D systems applied to apicomplexans. We show the wide array of strategies that have been successfully used so far and apply them to explore other organisms that have been less studied.

An artificial host system enables the obligate parasite Cuscuta campestris to grow and reproduce in vitro

Cuscuta campestris is an obligate parasitic plant that requires a host to complete its life cycle. Parasite-host connections occur via a haustorium, a unique organ that acts as a bridge for the uptake of water, nutrients, and macromolecules. Research on Cuscuta is often complicated by host influences, but comparable systems for growing the parasite in the absence of a host do not exist. We developed an axenic method to grow C. campestris on an artificial host system (AHS). We evaluated the effects of nutrients and phytohormones on parasite haustoria development and growth. Haustorium morphology and gene expression were also characterized. The AHS consists of an inert, fibrous stick that mimics a host stem, wicking water and nutrients to the parasite. It enables C. campestris to exhibit a parasitic habit and develop through all stages of its life cycle, including production of new shoots and viable seeds. The phytohormones 1-naphthaleneacetic acid and 6-benzylaminopurine affect haustoria morphology and increase parasite fresh weight and biomass. Unigene expression in AHS haustoria reflects processes similar to those in haustoria on living host plants. The AHS is a methodological improvement for studying Cuscuta biology by avoiding specific host effects on the parasite and giving researchers full control of the parasite environment.

An artificial host system enables the obligate parasite Cuscuta campestris to grow and reproduce in vitro

Cuscuta campestris is an obligate parasitic plant that requires a host to complete its life cycle. Parasite-host connections occur via a haustorium, a unique organ that acts as a bridge for the uptake of water, nutrients, and macromolecules. Research on Cuscuta is often complicated by host influences, but comparable systems for growing the parasite in the absence of a host do not exist. We developed an axenic method to grow C. campestris on an artificial host system (AHS). We evaluated the effects of nutrients and phytohormones on parasite haustoria development and growth. Haustorium morphology and gene expression were also characterized. The AHS consists of an inert, fibrous stick that mimics a host stem, wicking water and nutrients to the parasite. It enables C. campestris to exhibit a parasitic habit and develop through all stages of its life cycle, including production of new shoots and viable seeds. The phytohormones 1-naphthaleneacetic acid and 6-benzylaminopurine affect haustoria morphology and increase parasite fresh weight and biomass. Unigene expression in AHS haustoria reflects processes similar to those in haustoria on living host plants. The AHS is a methodological improvement for studying Cuscuta biology by avoiding specific host effects on the parasite and giving researchers full control of the parasite environment.

Comparative evaluation of amniotic fluid as an alternative to fetal bovine serum in the maintenance of Leishmania major and Toxoplasma gondii

This study aimed to evaluate the efficacy of amniotic fluid (AF) as an alternative to fetal bovine serum (FBS) in the maintenance of Leishmania major promastigotes and Toxoplasma gondii tachyzoites. AF was collected by an obstetrician using sterile syringes during a cesarean section. The culture medium was supplemented with 5 different concentrations of FBS or AF including 2, 5, 10, 20, and 30%. These concentrations were used to maintain both mentioned parasites. L. major was maintained at temperatures 4 and 24 °C and examined once a week for 4 weeks, while T. gondii was maintained at temperatures 4, 24, and 37 °C and examined at hours 24, 48, 72, and 96. For L. major, at both 4 and 24 °C, we observed no significant difference between FBS and AF on day 7. However, on days 14, 21, and 28, the difference between FBS and AF was significant at both temperatures. For T. gondii, no significant difference was observed between FBS and AF at hour 24 and all temperatures. However, this difference was significant at hours 48, 72, and 96 and all temperatures. According to our results, although FBS had a greater efficacy than AF in the growth of L. major and the survival of T. gondii, the number of promastigotes increased over time in AF-containing medium and the number of tachyzoites reduced slowly with a mild slop. Therefore, AF can be a potential alternative to FBS.

Use of Oxford Nanopore MinION to generate full-length sequences of the Blastocystis small subunit (SSU) rRNA gene

Background

Blastocystis sp. is one of the most common enteric parasites of humans and animals worldwide. It is well recognized that this ubiquitous protist displays a remarkable degree of genetic diversity in the SSU rRNA gene, which is currently the main gene used for defining Blastocystis subtypes. Yet, full-length reference sequences of this gene are available for only 16 subtypes of Blastocystis in part because of the technical difficulties associated with obtaining these sequences from complex samples.

Methods

We have developed a method using Oxford Nanopore MinION long-read sequencing and universal eukaryotic primers to produce full-length (> 1800 bp) SSU rRNA gene sequences for Blastocystis. Seven Blastocystis specimens representing five subtypes (ST1, ST4, ST10, ST11, and ST14) obtained both from cultures and feces were used for validation.

Results

We demonstrate that this method can be used to produce highly accurate full-length sequences from both cultured and fecal DNA isolates. Full-length sequences were successfully obtained from all five subtypes including ST11 for which no full-length reference sequence currently exists and for an isolate that contained mixed ST10/ST14.

Conclusions

The suitability of the use of MinION long-read sequencing technology to successfully generate full-length Blastocystis SSU rRNA gene sequences was demonstrated. The ability to produce full-length SSU rRNA gene sequences is key in understanding the role of genetic diversity in important aspects of Blastocystis biology such as transmission, host specificity, and pathogenicity.

Liver infusion tryptose (LIT): the best choice for growth, viability, and infectivity of Leishmania infantum parasites

Leishmania spp. parasites have a complex biological cycle presenting basically two different morphological stages, the amastigote and promastigote forms. In vitro cultivation allows a more complete study of the biological aspects of these parasites, indicating better conditions for infection, immunoassay tests, drug evaluations, and vaccines. Thus, we evaluated the three most used culture media for Leishmania spp., Grace’s insect cell culture medium (Grace’s), liver infusion tryptose (LIT), and Schneider’s insect medium (Schneider’s), without supplementation or supplemented with fetal calf serum (FCS) and bovine serum albumin (Albumin) to evaluate the growth, viability, and infectivity of the L. infantum promastigotes. It was observed that promastigote forms have a better growth in LIT and Schneider’s with or without FCS when compared to that in Grace’s. The supplementation with albumin promoted greater viability of the parasites independent of the medium. For in vitro infection of J774.A1 macrophages using light microscopy and flow cytometry analyses, FCS-supplemented LIT and Grace’s promoted higher percentage of infected macrophages and parasite load compared with Schneider’s media. Taken together, our results demonstrated that the supplementation of LIT culture medium with FCS is the most suitable strategy to cultivate Leishmania infantum parasites enabling the maintenance of growth and infective parasites for research uses.

Opportunistic Oral Infections

An opportunistic infection (OI) is a disease of microbial cause or pathogenesis generally thought to occur in hosts with weakened immunity. Oral OIs are associated with many risk factors and pathogens. Causative organisms for oral OIs have unique modes of transmission. The clinical presentation of oral OIs is heterogeneous and diagnosis can be challenging. Therefore, laboratory identification of causative pathogens is useful for definitive diagnosis and targeted therapeutics, and can be achieved by biological, serologic, histologic, and/or molecular methods. Clinical risk assessment and history with review of systems, and accurate diagnosis, treatment, and follow-up, are essential.

Isolation of naturally infecting Leishmania infantum from canine samples in Novy-MacNeal-Nicolle medium prepared with defibrinated blood from different animal species

The most commonly used culture medium for the in vitro isolation of Leishmania spp. from canine biological samples is biphasic Novy-MacNeal-Nicolle (NNN) medium, whose solid phase is prepared using rabbit blood. Leishmania infantum parasites from natural infections are highly sensitive and demanding for growth in axenic conditions when firstly obtained from the dog's body. The objective of this study was to evaluate whether NNN medium (NNN-test) prepared with chicken blood (NNN-C), ox blood (NNN-O), horse blood (NNN-H) or sheep blood (NNN-S) was viable for the isolation of parasites from naturally infected dogs, in an endemic area for visceral leishmaniasis caused by L. infantum. Spleen aspirates from six dogs previously diagnosed as infected by parasitological methods were simultaneously inoculated in each NNN-test medium, including the conventional medium prepared with rabbit blood (NNN-R), and the cultures were examined for three weeks under optic microscopy. Spleen samples were also analyzed for parasite loads by quantitative PCR (qPCR). Cultures from three of the six dogs (50%) were positive in at least one of the NNN-test media: one sample presented the highest spleen parasite load by qPCR (1.19 × 10⁴ parasites/mL) and was positive in all test media; the second sample presented parasitic isolation in the first week of culture in all inoculated media, of which the NNN-C medium had the highest mean parasite count (NNN-C = 23.5 × 10⁴/mL vs. NNN-R = 3.25 × 10⁴/mL); the third sample was positive only in the NNN-S medium besides the conventional control NNN-R. Cultures from the three remaining dogs were negative in all NNN media, including the control and test media; of those three dogs, two presented the lowest spleen parasitic loads according to qPCR. Blood from chicken, ox, horse and sheep shown to be viable for the preparation of NNN culture medium for the primary isolation of L. infantum from samples of naturally infected dogs and can be considered as an alternative to rabbit blood when necessary.

Practical Guidance for Clinical Microbiology Laboratories: Laboratory Diagnosis of Parasites from the Gastrointestinal Tract

This Practical Guidance for Clinical Microbiology document on the laboratory diagnosis of parasites from the gastrointestinal tract provides practical information for the recovery and identification of relevant human parasites. The document is based on a comprehensive literature review and expert consensus on relevant diagnostic methods. However, it does not include didactic information on human parasite life cycles, organism morphology, clinical disease, pathogenesis, treatment, or epidemiology and prevention. As greater emphasis is placed on neglected tropical diseases, it becomes highly probable that patients with gastrointestinal parasitic infections will become more widely recognized in areas where parasites are endemic and not endemic. Generally, these methods are nonautomated and require extensive bench experience for accurate performance and interpretation.

Detection of viable but non-culturable legionella in hospital water network following monochloramine disinfection

BACKGROUND

Prevention of legionellosis remains a critical issue in healthcare settings where monochloramine (MC) disinfection was recently introduced as an alternative to chlorine dioxide in controlling Legionella spp. contamination of the hospital water network. Continuous treatments with low MC doses in some instances have induced a viable but non-culturable state (VBNC) of Legionella spp.

AIM

To investigate the occurrence of such dormant cells during a long period of continuous MC treatment.

METHODS

Between November 2010 and April 2015, 162 water and biofilm samples were collected and Legionella spp. isolated in accordance with standard procedures. In sampling sites where MC was <1.5mg/L, VBNC cells were investigated by ethidium monoazide bromide (EMA)-real-time polymerase chain reaction (qPCR) and 'resuscitation' test into Acanthamoeba polyphaga CCAP 1501/18. According to the Health Protection Agency protocol, free-living protozoa were researched in 60 five-litre water samples.

FINDINGS

In all, 136 out of 156 (87.2%) of the samples taken from sites previously positive for L. pneumophila ST269 were negative by culture, but only 47 (34.5%) negative by qPCR. Although no positive results were obtained by EMA-qPCR, four out of 22 samples associated with MC concentration of 1.3 ± 0.5mg/L showed VBNC legionella resuscitation. The presence of the amoeba A. polyphaga in the hospital water network was demonstrated.

CONCLUSION

Our study is the first report evidencing the emergence of VNBC legionella during a long period of continuous MC treatment of a hospital water network, highlighting the importance of keeping an appropriate and uninterrupted MC dosage to ensure the control of legionella colonization in hospital water supplies.

The first successful report of the in vitro life cycle of Chinese Leishmania: the in vitro conversion of Leishmania amastigotes has been raised to 94% by testing 216 culture medium compound

Chinese Leishmania isolate MHOM/CN/90/SC10H2 (L. H2), which was obtained from the spinal cords of patients from the Sichuan province of China, is an uncharacterized, pathogenic species closely related to Leishmania tarentolae. The in vitro transformation rate of L. H2 promastigotes into amastigotes has not been studied. This study is the first to successfully define the in vitro life cycle of L. H2 by investigating the percent conversion of L.H2 promastigotes to amastigotes in vitro under 216 different culture conditions. The highest proportion of L. H2 amastigotes observed (94%) was significantly higher than that previously reported. After conversion, the axenic amastigotes remained viable as verified by the levels of stage-specific genes (Gp46, A2 and β-tubulin) detected by RT-PCR. Meanwhile, morphological and protein characterizations of these axenic amastigotes were carried out in order to confirm the successful conversion. Specific antibodies were only able to detect 46 kDa, 52 kDa and 75 kDa proteins in samples isolated from axenic amastigotes. Afterward, these converted axenic amastigotes were transformed into the promastigote form by altering the culture condition. These converted axenic promastigotes still have the ability to infect macrophages, and their morphology changed back to the amastigote form following infection. These findings will assist further investigations into the biological characteristics of the host-parasite relationship and the process of pathogenesis.

Repertory of eukaryotes (eukaryome) in the human gastrointestinal tract: taxonomy and detection methods

Eukaryotes are an important component of the human gut, and their relationship with the human host varies from parasitic to commensal. Understanding the diversity of human intestinal eukaryotes has important significance for human health. In the past few decades, most of the multitudes of techniques that are involved in the diagnosis of the eukaryotic population in the human intestinal tract were confined to pathological and parasitological aspects that mainly rely on traditionally based methods. However, development of culture-independent molecular techniques comprised of direct DNA extraction from faeces followed by sequencing, offer new opportunities to estimate the occurrence of eukaryotes in the human gut by providing data on the entire eukaryotic community, particularly not-yet-cultured or fastidious organisms. Further broad surveys of the eukaryotic communities in the gut based on high throughput tools such as next generation sequencing might lead to uncovering the real diversity of these ubiquitous organisms in the human intestinal tract and discovering the unrecognized roles of these eukaryotes in modulating the host immune system and inducing changes in host gut physiology and ecosystem.

Systems analysis of host-parasite interactions

Parasitic diseases caused by protozoan pathogens lead to hundreds of thousands of deaths per year in addition to substantial suffering and socioeconomic decline for millions of people worldwide. The lack of effective vaccines coupled with the widespread emergence of drug‐resistant parasites necessitates that the research community take an active role in understanding host–parasite infection biology in order to develop improved therapeutics. Recent advances in next‐generation sequencing and the rapid development of publicly accessible genomic databases for many human pathogens have facilitated the application of systems biology to the study of host–parasite interactions. Over the past decade, these technologies have led to the discovery of many important biological processes governing parasitic disease. The integration and interpretation of high‐throughput ‐omic data will undoubtedly generate extraordinary insight into host–parasite interaction networks essential to navigate the intricacies of these complex systems. As systems analysis continues to build the foundation for our understanding of host–parasite biology, this will provide the framework necessary to drive drug discovery research forward and accelerate the development of new antiparasitic therapies. WIREs Syst Biol Med 2015, 7:381–400. doi: 10.1002/wsbm.1311

For further resources related to this article, please visit the WIREs website.

Novel culture medium for the axenic growth of Balamuthia mandrillaris

Until now, for axenic cultivation of Balamuthia mandrillaris, the BM-3 culture medium and the Modified Chang's special medium have been the only ones recommended, but they have some disadvantages, as both require many components and their preparations are laborious. Therefore, we developed a novel culture medium for B. mandrillaris axenic cultivation. Each one of the 11 components of BM-3 was combined with Cerva's medium as basal culture medium. Ten strains of B. mandrillaris including the reference strain CDC:V039 and 9 environmental isolates were used during trials. After testing all combinations, the basal medium complemented with 10× Hank's balanced salt solution was the only one that supported confluent growth of B. mandrillaris. Cell shape and motility of trophozoites were normal. This developed medium is as useful as BM-3 for axenization. The development of a cheaper and easy-to-prepare medium for B. mandrillaris opens the possibility of increasing its study.

Chemical biology approaches to designing defined carbohydrate vaccines

Carbohydrate antigens have shown promise as important targets for developing effective vaccines and pathogen detection strategies. Modifying purified microbial glycans through synthetic routes or completely synthesizing antigenic motifs are attractive options to advance carbohydrate vaccine development. However, limited knowledge on structure-property correlates hampers the discovery of immunoprotective carbohydrate epitopes. Recent advancements in tools for glycan modification, high-throughput screening of biological samples, and 3D structural analysis may facilitate antigen discovery process. This review focuses on advances that accelerate carbohydrate-based vaccine development and various technologies that are driving these efforts. Herein we provide a critical overview of approaches and resources available for rational design of better carbohydrate antigens. Structurally defined and fully synthetic oligosaccharides, designed based on molecular understanding of antigen-antibody interactions, offer a promising alternative for developing future carbohydrate vaccines.

Cultivation of parasites

Parasite cultivation techniques constitute a substantial segment of present-day study of parasites, especially of protozoa. Success in establishing in vitro and in vivo culture of parasites not only allows their physiology, behavior and metabolism to be studied dynamically, but also allows the nature of the antigenic molecules in the excretory and secretory products to be vigorously pursued and analyzed. The complex life-cycles of various parasites having different stages and host species requirements, particularly in the case of parasitic helminths, often make parasite cultivation an uphill assignment. Culturing of parasites depends on the combined expertise of all types of microbiological cultures. Different parasites require different cultivation conditions such as nutrients, temperature and even incubation conditions. Cultivation is an important method for diagnosis of many clinically important parasites, for example, Entamoeba histolytica, Trichomonas vaginalis, Leishmania spp., Strongyloides stercoralis and free-living amoebae. Many commercial systems like InPouch TV for T. vaginalis, microaerophilous stationary phase culture for Babesia bovis and Harada-Mori culture technique for larval-stage nematodes have been developed for the rapid diagnosis of the parasitic infections. Cultivation also has immense utility in the production of vaccines, testing vaccine efficacy, and antigen - production for obtaining serological reagents, detection of drug-resistance, screening of potential therapeutic agents and conducting epidemiological studies. Though in vitro cultivation techniques are used more often compared with in vivo techniques, the in vivo techniques are sometimes used for diagnosing some parasitic infections such as trypanosomiasis and toxoplasmosis. Parasite cultivation continues to be a challenging diagnostic option. This review provides an overview of intricacies of parasitic culture and update on popular methods used for cultivating parasites.

In vitro growth of the microsporidian Heterosporis saurida in the eel kidney EK-1 cell line

Heterosporis saurida is an intracellular microsporidian that infects lizardfish Saurida undosquamis. Although some attempts have been introduced to clarify microsporidian host-pathogen interactions, development of novel strategies to combat fish diseases is still needed. Here we present an in vitro cultivation model for fish microsporidia based on an eel kidney cell line (EK-1), which is susceptible to infection by H. saurida. Spores were isolated from infected lizardfish and used to inoculate EK-1 cells. H. saurida were propagated in the eel kidney EK-1 cell line and detected by immunofluorescence. Developmental stages of H. saurida were seen in EK-1 cells by transmission electron microscopy. Identity of the parasite was confirmed by partial sequencing of the 16S rDNA gene. Our cell culture model provides a valuable means to explore molecular and immunological events and will facilitate development of effective treatment strategies.

Functional genomics of Plasmodium falciparum using metabolic modelling and analysis

Plasmodium falciparum is an obligate intracellular parasite and the leading cause of severe malaria responsible for tremendous morbidity and mortality particularly in sub-Saharan Africa. Successful completion of the P. falciparum genome sequencing project in 2002 provided a comprehensive foundation for functional genomic studies on this pathogen in the following decade. Over this period, a large spectrum of experimental approaches has been deployed to improve and expand the scope of functionally annotated genes. Meanwhile, rapidly evolving methods of systems biology have also begun to contribute to a more global understanding of various aspects of the biology and pathogenesis of malaria. Herein we provide an overview on metabolic modelling, which has the capability to integrate information from functional genomics studies in P. falciparum and guide future malaria research efforts towards the identification of novel candidate drug targets.

Effect of human urine on cell cycle and infectivity of Leismania species promastigotes in vitro

In vitro cultivation of Leishmania parasites plays an important role in diagnosis and treatment of leishmaniasis and in vaccine and drug development studies. Conversely, long-term cultivation of Leishmania parasites usually results in decreased infectivity potential. Some studies reported a stimulatory effect of human urine in Leishmania promastigotes. However, there is no information about the effects of urine within culture on the infectivity of Leishmania parasites. Analysis of the effect of urine have showed that proliferation indexes were significantly increased in culture medium supplemented with human urine (L. tropica = 38.17 ± 5.12, L. donovani = 34.74 ± 5.6, L. major = 34.22 ± 4.66, and L. infantum 35.88 ± 6.40) than in controls. Infection indexes were 13 ± 1.7 for L. tropica, 55 ± 2.2 for L. infantum, 41 ± 3.14 for L. donovani, and 49 ± 3.26 for L. major. Our results showed that human urine increased the infectivity and proliferation of Leishmania parasites.

Milk of cow (Bos taurus), buffalo (Bubalus bubalis), and goat (Capra hircus): a better alternative than fetal bovine serum in media for primary isolation, in vitro cultivation, and maintenance of Leishmania donovani promastigotes

Tyndalized milk of goat, cow, and buffalo was found to be a potential substitute for fetal bovine serum (FBS) in the medium for the cultivation of Leishmania donovani promastigotes. The numbers (means) of promastigotes reached 2.6 x 10(7), 2.3 x 10(7), and 2.1 x 10(7)/ml, respectively, in the medium supplemented with 10% milk of goat, cow, and buffalo, in comparison to 1.9 x 10(7)/ml in the control with 10% FBS. In primary isolation, the milk-supplemented medium showed that 22 out of 26 samples were positive for promastigotes (84.6%) and the cells were maintained successfully during the observed period of 6 months.

Plasmodium yoelii: axenic development of the parasite mosquito stages

Study of the parasite mosquito stages of Plasmodium and its use in the production of sporozoite vaccines against malaria has been hampered by the technical difficulties of in vitro development. Here, we show the complete axenic development of the parasite mosquito stages of Plasmodium yoelii. While we demonstrate that matrigel is not required for parasite development, soluble factors produced and secreted by Drosophila melanogaster S2 cells appear to be crucial for the ookinete to oocyst transition. Parasites cultured axenically are both morphologically and biologically similar to mosquito-derived ookinetes, oocysts, and sporozoites. Axenically derived sporozoites were capable of producing an infection in mice as determined by RT-PCR; however, the parasitemia was significantly much less than that produced by mosquito-derived sporozoites. Our cell free system for development of the mosquito stages of P. yoelii provides a simplified approach to generate sporozoites that may be for biological assays and genetic manipulations.