The mRNA Vaccine Technology Era and the Future Control of Parasitic Infections.

Despite intensive long-term efforts, with very few exceptions, the development of effective vaccines against parasitic infections has presented considerable challenges, given the complexity of parasite life cycles, the interplay between parasites and their hosts, and their capacity to escape the host immune system and to regulate host immune responses. For many parasitic diseases, conventional vaccine platforms have generally proven ill suited, considering the complex manufacturing processes involved and the costs they incur, the inability to posttranslationally modify cloned target antigens, and the absence of long-lasting protective immunity induced by these antigens. An effective antiparasite vaccine platform is required to assess the effectiveness of novel vaccine candidates at high throughput. By exploiting the approach that has recently been used successfully to produce highly protective COVID mRNA vaccines, we anticipate a new wave of research to advance the use of mRNA vaccines to prevent parasitic infections in the near future. This article considers the characteristics that are required to develop a potent antiparasite vaccine and provides a conceptual foundation to promote the development of parasite mRNA-based vaccines. We review the recent advances and challenges encountered in developing antiparasite vaccines and evaluate the potential of developing mRNA vaccines against parasites, including those causing diseases such as malaria and schistosomiasis, against which vaccines are currently suboptimal or not yet available.

Chromosome-level genome of Schistosoma haematobium underpins genome-wide explorations of molecular variation.

Urogenital schistosomiasis is caused by the blood fluke Schistosoma haematobium and is one of the most neglected tropical diseases worldwide, afflicting > 100 million people. It is characterised by granulomata, fibrosis and calcification in urogenital tissues, and can lead to increased susceptibility to HIV/AIDS and squamous cell carcinoma of the bladder. To complement available treatment programs and break the transmission of disease, sound knowledge and understanding of the biology and ecology of S. haematobium is required. Hybridisation/introgression events and molecular variation among members of the S. haematobium-group might effect important biological and/or disease traits as well as the morbidity of disease and the effectiveness of control programs including mass drug administration. Here we report the first chromosome-contiguous genome for a well-defined laboratory line of this blood fluke. An exploration of this genome using transcriptomic data for all key developmental stages allowed us to refine gene models (including non-coding elements) and annotations, discover 'new' genes and transcription profiles for these stages, likely linked to development and/or pathogenesis. Molecular variation within S. haematobium among some geographical locations in Africa revealed unique genomic 'signatures' that matched species other than S. haematobium, indicating the occurrence of introgression events. The present reference genome (designated Shae.V3) and the findings from this study solidly underpin future functional genomic and molecular investigations of S. haematobium and accelerate systematic, large-scale population genomics investigations, with a focus on improved and sustained control of urogenital schistosomiasis.

Potential of the CRISPR-Cas system for improved parasite diagnosis: CRISPR-Cas mediated diagnosis in parasitic infections: CRISPR-Cas mediated diagnosis in parasitic infections.

CRISPR-Cas technology accelerates development of fast, accurate, and portable diagnostic tools, typified by recent applications in COVID-19 diagnosis. Parasitic helminths cause devastating diseases afflicting 1.5 billion people globally, representing a significant public health and economic burden, especially in developing countries. Currently available diagnostic tests for worm infection are neither sufficiently sensitive nor field-friendly for use in low-endemic or resource-poor settings, leading to underestimation of true prevalence rates. Mass drug administration programs are unsustainable long-term, and diagnostic tools - required to be rapid, specific, sensitive, cost-effective, and user-friendly without specialized equipment and expertise - are urgently needed for rapid mapping of helminthic diseases and monitoring control programs. We describe the key features of the CRISPR-Cas12/13 system and emphasise its potential for the development of effective tools for the diagnosis of parasitic and other neglected tropical diseases (NTDs), a key recommendation of the NTDs 2021-2030 roadmap released by the World Health Organization.

Lentiviral Transduction-based CRISPR/Cas9 Editing of Schistosoma mansoni Acetylcholinesterase.

Background: Recent studies on CRISPR/Cas9-mediated gene editing in Schistosoma mansoni have shed new light on the study and control of this parasitic helminth. However, the gene editing efficiency in this parasite is modest. Methods: To improve the efficiency of CRISPR/Cas9 genome editing in schistosomes, we used lentivirus, which has been effectively used for gene editing in mammalian cells, to deliver plasmid DNA encoding Cas9 nuclease, a sgRNA targeting acetylcholinesterase (SmAChE) and a mCherry fluorescence marker into schistosomes. Results: MCherry fluorescence was observed in transduced eggs, schistosomula, and adult worms, indicating that the CRISPR components had been delivered into these parasite stages by lentivirus. In addition, clearly changed phenotypes were observed in SmAChE-edited parasites, including decreased SmAChE activity, reduced hatching ability of edited eggs, and altered behavior of miracidia hatched from edited eggs. Next-generation sequencing analysis demonstrated that the lentiviral transduction-based CRISPR/Cas9 gene modifications in SmAChE-edited schistosomes were homology-directed repair predominant but with much lower efficiency than that obtained using electroporation (data previously published by our laboratory) for the delivery of CRISPR components. Conclusion: Taken together, electroporation is more efficient than lentiviral transduction in the delivery of CRISPR/Cas9 into schistosomes for programmed genome editing. The exploration of tactics for enhancing CRISPR/Cas9 gene editing provides the basis for the future improvement of programmed genome editing in S. mansoni.

CRISPR/Cas9: A new tool for the study and control of helminth parasites.

Recent reports of CRISPR/Cas9 genome editing in parasitic helminths open up new avenues for research on these dangerous pathogens. However, the complex morphology and life cycles inherent to these parasites present obstacles for the efficient application of CRISPR/Cas9-targeted mutagenesis. This is especially true with the trematode flukes where only modest levels of gene mutation efficiency have been achieved. Current major challenges in the application of CRISPR/Cas9 for study of parasitic worms thus lie in enhancing gene mutation efficiency and overcoming issues involved in host passage so that mutated parasites survive. Strategies developed for CRISPR/Cas9 studies on Caenorhabditis elegans, protozoa and mammalian cells, including novel delivery methods, the choice of selectable markers, and refining mutation precision represent novel tactics whereby these impediments can be overcome. Furthermore, employing CRISPR/Cas9-mediated gene drive to interfere with vector transmission represents a novel approach for the control of parasitic worms that is worthy of further exploration.

Membrane Technology for Rapid Point-of-Care Diagnostics for Parasitic Neglected Tropical Diseases.

Parasitic neglected tropical diseases (NTDs) affect over one billion people worldwide, with individuals from communities in low-socioeconomic areas being most at risk and suffering the most. Disease management programs are hindered by the lack of infrastructure and resources for clinical sample collection, storage, and transport and a dearth of sensitive diagnostic methods that are inexpensive as well as accurate. Many diagnostic tests and tools have been developed for the parasitic NTDs, but the collection and storage of clinical samples for molecular and immunological diagnosis can be expensive due to storage, transport, and reagent costs, making these procedures untenable in most areas of endemicity. The application of membrane technology, which involves the use of specific membranes for either sample collection and storage or diagnostic procedures, can streamline this process, allowing for long-term sample storage at room temperature. Membrane technology can be used in serology-based diagnostic assays and for nucleic acid purification prior to molecular analysis. This facilitates the development of relatively simple and rapid procedures, although some of these methods, mainly due to costs, lack accessibility in low-socioeconomic regions of endemicity. New immunological procedures and nucleic acid storage, purification, and diagnostics protocols that are simple, rapid, accurate, and cost-effective must be developed as countries progress control efforts toward the elimination of the parasitic NTDs.

Novel Hepatic Schistosomula Antigens as Promising Targets for Immunodiagnosis and Immunoprotection of Schistosomiasis japonica.

BACKGROUND: Antigens of migrating schistosomula are promising candidates as schistosomiasis vaccine targets, since immune attack on hepatic schistosomula would interrupt the parasites life cycle and reduce egg burden on the host. METHODS: In this study, we report a collection of Schistosoma japonicum schistosomula proteins (SjScPs) that are highly expressed in hepatic schistosomula. The expression characteristics, antigenicity and immune protection of these proteins were studied by western blot, ELISA, immunofluorescence and challenge assays. RESULTS: We found that several of these SjScPs were highly antigenic and could effectively stimulate humoral immune responses in both human and other mammalian hosts. In particular, SjScP25, SjScP37, SjScP41, SjScP80, and SjScP88 showed high potential as biomarkers for schistosomiasis immunodiagnosis. Furthermore, we demonstrated that immunization with several of the recombinant SjScPs were able to protect mice from S japonicum challenge infection, with SjScP25 generating the most protective results. CONCLUSIONS: Our work represents a group of novel schistosome immunogens, which may be promising schistosomiasis japonica diagnosis and vaccine candidates.

CRISPR/Cas9-mediated genome editing of Schistosoma mansoni acetylcholinesterase.

CRISPR/Cas9-mediated genome editing shows cogent potential for the genetic modification of helminth parasites. We report successful gene knock-in (KI) into the genome of the egg of Schistosoma mansoni by combining CRISPR/Cas9 with single-stranded oligodeoxynucleotides (ssODNs). We edited the acetylcholinesterase (AChE) gene of S. mansoni targeting two guide RNAs (gRNAs), X5 and X7, located on exon 5 and exon 7 of Smp_154600, respectively. Eggs recovered from livers of experimentally infected mice were transfected by electroporation with a CRISPR/Cas9-vector encoding gRNA X5 or X7 combining with/ without a ssODN donor. Next generation sequencing analysis of reads of amplicon libraries spanning targeted regions revealed that the major modifications induced by CRISPR/Cas9 in the eggs were generated by homology directed repair (HDR). Furthermore, soluble egg antigen from AChE-edited eggs exhibited markedly reduced AChE activity, indicative that programed Cas9 cleavage mutated the AChE gene. Following injection of AChE-edited schistosome eggs into the tail veins of mice, an significantly enhanced Th2 response involving IL-4, -5, -10, and-13 was detected in lung cells and splenocytes in mice injected with X5-KI eggs in comparison to control mice injected with unmutated eggs. A Th2-predominant response, with increased levels of IL-4, -13, and GATA3, also was induced by X5 KI eggs in small intestine-draining mesenteric lymph node cells when the gene-edited eggs were introduced into the subserosa of the ileum of the mice. These findings confirmed the potential and the utility of CRISPR/Cas9-mediated genome editing for functional genomics in schistosomes.

Neglected tropical diseases in Australia: a narrative review.

•Neglected tropical diseases (NTDs) represent a threat to the health, wellbeing and economic prosperity of billions of people worldwide, often causing serious disease or death. •Commonly considered diseases of low and middle-income nations, the presence of NTDs in high income countries such as Australia is often overlooked. •Seven of the 20 recognised NTDs are endemic in Australia: scabies, soil-transmitted helminths and strongyloidiasis, echinococcosis, Buruli ulcer, leprosy, trachoma, and snakebite envenoming. •Dengue, while not currently endemic, poses a risk of establishment in Australia. There are occasional outbreaks of dengue fever, with local transmission, due to introductions in travellers from endemic regions. •Similarly, the risk of introduction of other NTDs from neighbouring countries is a concern. Many NTDs are only seen in Australia in individuals travelling from endemic areas, but they need to be recognised in health settings as the potential consequences of infection can be severe. •In this review, we consider the status of NTDs in Australia, explore the risk of introducing and contracting these infections, and emphasise the negative impact they have on the health of Australians, especially Aboriginal and Torres Strait Islander peoples.

Schistosomiasis in the People's Republic of China - down but not out.

Schistosomiasis has been subjected to extensive control efforts in the People's Republic of China (China) which aims to eliminate the disease by 2030. We describe baseline results of a longitudinal cohort study undertaken in the Dongting and Poyang lakes areas of central China designed to determine the prevalence of Schistosoma japonicum in humans, animals (goats and bovines) and Oncomelania snails utilizing molecular diagnostics procedures. Data from the Chinese National Schistosomiasis Control Programme (CNSCP) were compared with the molecular results obtained.Sixteen villages from Hunan and Jiangxi provinces were surveyed; animals were only found in Hunan. The prevalence of schistosomiasis in humans was 1.8% in Jiangxi and 8.0% in Hunan determined by real-time polymerase chain reaction (PCR), while 18.3% of animals were positive by digital droplet PCR. The CNSCP data indicated that all villages harboured S. japonicum-infected individuals, detected serologically by indirect haemagglutination assay (IHA), but very few, if any, of these were subsequently positive by Kato-Katz (KK).Based on the outcome of the IHA and KK results, the CNSCP incorporates targeted human praziquantel chemotherapy but this approach can miss some infections as evidenced by the results reported here. Sensitive molecular diagnostics can play a key role in the elimination of schistosomiasis in China and inform control measures allowing for a more systematic approach to treatment.

Vaccines for Human Schistosomiasis: Recent Progress, New Developments and Future Prospects.

Schistosomiasis, caused by human trematode blood flukes (schistosomes), remains one of the most prevalent and serious of the neglected tropical parasitic diseases. Currently, treatment of schistosomiasis relies solely on a single drug, the anthelmintic praziquantel, and with increased usage in mass drug administration control programs for the disease, the specter of drug resistance developing is a constant threat. Vaccination is recognized as one of the most sustainable options for the control of any pathogen, but despite the discovery and reporting of numerous potentially promising schistosome vaccine antigens, to date, no schistosomiasis vaccine for human or animal deployment is available. This is despite the fact that Science ranked such an intervention as one of the top 10 vaccines that need to be urgently developed to improve public health globally. This review summarizes current progress of schistosomiasis vaccines under clinical development and advocates the urgent need for the establishment of a revolutionary and effective anti-schistosome vaccine pipeline utilizing cutting-edge technologies (including developing mRNA vaccines and exploiting CRISPR-based technologies) to provide novel insight into future vaccine discovery, design, manufacture and deployment.

Bioinformatic comparison of Kunitz protease inhibitors in Echinococcus granulosus sensu stricto and E. multilocularis and the genes expressed in different developmental stages of E. granulosus s.s.

BACKGROUND: Cystic and alveolar echinococcosis caused by the tapeworms Echinococcus granulosus sensu stricto (s.s.) and E. multilocularis, respectively, are important zoonotic diseases. Protease inhibitors are crucial for the survival of both Echinococcus spp. Kunitz-type inhibitors play a regulatory role in the control of protease activity. In this study,we identified Kunitz-type domain protease inhibitors(KDPIs) present in the genomes of these two tapeworms and analyzed the gene sequences using computational, structural bioinformatics and phylogenetic approaches to evaluate the evolutionary relationships of these genes. Hi-seq transcriptome analysis showed that E. granulosus s.s. KDPIs were differentially expressed in the different developmental stages. We validated some of the genes expressed in adult worm, protoscolex and cyst germinal membrane of E. granulosus s.s. and E. multilocularis by quantitative PCR. RESULTS: A total of 19 genes from E. multilocularis and 23 genes from E. granulosus s.s. were predicted to be KDPIs with the most containing a single Kunitz-domain. A maximum likelihood method phylogenetic tree indicated that the E. granulosus s.s. and E. multilocularis Kunitz domain peptides were divided into three branches containing 9 clusters. The ratio of positively charged residues and neutral residues are different between E. multilocularis and E. granulosus s.s. KDPIs. We also found that E. multilocularis had higher percentage of sequences containing signal peptides (17/19, 89.47%) than that of E. granulosus s.s. (14/23, 60.87%). Transcript analysis showed all the E. granulosus s.s. KDPI genes were expressed differentially in four developmental stages of the worm. Transcription analysis showed that 9 KDPIs (including EG_07244,EGR_08716 and EGR_10096) were highly upregulated in adult worm, and 2 KDPIs (EG_09268 and EG_09490) were highly expressed in the cyst germinal membrane. Quantitative gene expression analysis(qPCR) of four genes confirmed the expression of these genes. EGR_08716 and its homologous gene (EmuJ_001137000) were highly and specifically expressed in adult worms of the two worms. CONCLUSIONS: A total 19 and 23 KDPIs were identified in the genomes of E. multilocularis and E. granulosus s.s. , respectively. The differential expression of these KDPIs in different stages may indicate their different roles in the different hosts. The difference in characterization of KDPIs may be associated with the different pathology of metacestode stage of these two parasites.

Whole-genome sequence of the bovine blood fluke Schistosoma bovis supports interspecific hybridization with S. haematobium.

Mesenteric infection by the parasitic blood fluke Schistosoma bovis is a common veterinary problem in Africa and the Middle East and occasionally in the Mediterranean Region. The species also has the ability to form interspecific hybrids with the human parasite S. haematobium with natural hybridisation observed in West Africa, presenting possible zoonotic transmission. Additionally, this exchange of alleles between species may dramatically influence disease dynamics and parasite evolution. We have generated a 374 Mb assembly of the S. bovis genome using Illumina and PacBio-based technologies. Despite infecting different hosts and organs, the genome sequences of S. bovis and S. haematobium appeared strikingly similar with 97% sequence identity. The two species share 98% of protein-coding genes, with an average sequence identity of 97.3% at the amino acid level. Genome comparison identified large continuous parts of the genome (up to several 100 kb) showing almost 100% sequence identity between S. bovis and S. haematobium. It is unlikely that this is a result of genome conservation and provides further evidence of natural interspecific hybridization between S. bovis and S. haematobium. Our results suggest that foreign DNA obtained by interspecific hybridization was maintained in the population through multiple meiosis cycles and that hybrids were sexually reproductive, producing viable offspring. The S. bovis genome assembly forms a highly valuable resource for studying schistosome evolution and exploring genetic regions that are associated with species-specific phenotypic traits.

Echinococcosis: Advances in the 21st Century.

Echinococcosis is a zoonosis caused by cestodes of the genus Echinococcus (family Taeniidae). This serious and near-cosmopolitan disease continues to be a significant public health issue, with western China being the area of highest endemicity for both the cystic (CE) and alveolar (AE) forms of echinococcosis. Considerable advances have been made in the 21st century on the genetics, genomics, and molecular epidemiology of the causative parasites, on diagnostic tools, and on treatment techniques and control strategies, including the development and deployment of vaccines. In terms of surgery, new procedures have superseded traditional techniques, and total cystectomy in CE, ex vivo resection with autotransplantation in AE, and percutaneous and perendoscopic procedures in both diseases have improved treatment efficacy and the quality of life of patients. In this review, we summarize recent progress on the biology, epidemiology, diagnosis, management, control, and prevention of CE and AE. Currently there is no alternative drug to albendazole to treat echinococcosis, and new compounds are required urgently. Recently acquired genomic and proteomic information can provide a platform for improving diagnosis and for finding new drug and vaccine targets, with direct impact in the future on the control of echinococcosis, which continues to be a global challenge.

Parasite-derived circulating microRNAs as biomarkers for the detection of human Schistosoma japonicum infection.

Novel tools for early diagnosis and monitoring of schistosomiasis are urgently needed. This study aimed to validate parasite-derived miRNAs as potential novel biomarkers for the detection of human Schistosoma japonicum infection. A total of 21 miRNAs were initially validated by real-time-polymerase chain reaction (RT-PCR) using serum samples of S. japonicum-infected BALB/c mice. Of these, 6 miRNAs were further validated with a human cohort of individuals from a schistosomiasis-endemic area of the Philippines. RT-PCR analysis showed that two parasite-derived miRNAs (sja-miR-2b-5p and sja-miR-2c-5p) could detect infected individuals with low infection intensity with moderate sensitivity/specificity values of 66%/68% and 55%/80%, respectively. Analysis of the combined data for the two parasite miRNAs revealed a specificity of 77.4% and a sensitivity of 60.0% with an area under the curve (AUC) value of 0.6906 (P = 0.0069); however, a duplex RT-PCR targeting both sja-miR-2b-5p and sja-miR-2c-5p did not result in an increased diagnostic performance compared with the singleplex assays. Furthermore, the serum level of sja-miR-2c-5p correlated significantly with faecal egg counts, whereas the other five miRNAs did not. Targeting S. japonicum-derived miRNAs in serum resulted in a moderate diagnostic performance when applied to a low schistosome infection intensity setting.

Molecular identification of Ancylostoma ceylanicum in the Philippines.

Hookworms are some of the most widespread of the soil-transmitted helminths (STH) with an estimated 438.9 million people infected. Until relatively recently Ancylostoma ceylanicum was regarded as a rare cause of hookworm infection in humans, with little public health relevance. However, recent advances in molecular diagnostics have revealed a much higher prevalence of this zoonotic hookworm than previously thought, particularly in Asia. This study examined the prevalence of STH and A. ceylanicum in the municipalities of Palapag and Laoang in the Philippines utilizing real-time polymerase chain reaction (PCR) on stool samples previously collected as part of a cross-sectional survey of schistosomiasis japonica. Prevalence of hookworm in humans was high with 52.8% (n = 228/432) individuals positive for any hookworm, 34.5% (n = 149/432) infected with Necator americanus, and 29.6% (n = 128/432) with Ancylostoma spp; of these, 34 were PCR-positive for A. ceylanicum. Considering dogs, 12 (n = 33) were PCR-positive for A. ceylanicum. This is the first study to utilize molecular diagnostics to identify A. ceylanicum in the Philippines with both humans and dogs infected. Control and elimination of this zoonotic hookworm will require a multifaceted approach including chemotherapy of humans, identification of animal reservoirs, improvements in health infrastructure, and health education to help prevent infection.

Use of kinase inhibitors against schistosomes to improve and broaden praziquantel efficacy.

Praziquantel (PZQ) is the drug of choice for schistosomiasis. The potential drug resistance necessitates the search for adjunct or alternative therapies to PZQ. Previous functional genomics has shown that RNAi inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) gene in Schistosoma adult worms significantly improved the effectiveness of PZQ. Here we tested the in vitro efficacy of 15 selective and non-selective CaMK inhibitors against Schistosoma mansoni and showed that PZQ efficacy was improved against refractory juvenile parasites when combined with these CaMK inhibitors. By measuring CaMK activity and the mobility of adult S. mansoni, we identified two non-selective CaMK inhibitors, Staurosporine (STSP) and 1Naphthyl PP1 (1NAPP1), as promising candidates for further study. The impact of STSP and 1NAPP1 was investigated in mice infected with S. mansoni in the presence or absence of a sub-lethal dose of PZQ against 2- and 7-day-old schistosomula and adults. Treatment with STSP/PZQ induced a significant (47-68%) liver egg burden reduction compared with mice treated with PZQ alone. The findings indicate that the combination of STSP and PZQ dosages significantly improved anti-schistosomal activity compared to PZQ alone, demonstrating the potential of selective and non-selective CaMK/kinase inhibitors as a combination therapy with PZQ in treating schistosomiasis.

Serum Exosomal miRNAs for Grading Hepatic Fibrosis Due to Schistosomiasis.

Chronic infection with Schistosoma japonicum or Schistosoma mansoni results in hepatic fibrosis of the human host. The staging of fibrosis is crucial for prognosis and to determine the need for treatment of patients with schistosomiasis. This study aimed to determine whether there is a correlation between the levels of serum exosomal micro-ribonucleic acids (miRNAs) (exomiRs) and fibrosis progression in schistosomiasis. Reference gene (RG) validation was initially carried out for the analysis of serum exomiRs expression in staging liver fibrosis caused by schistosome infection. The expression levels of liver fibrosis-associated exomiRs in serum were determined in a murine schistosomiasis model and in a cohort of Filipino schistosomiasis japonica patients (n = 104) with different liver fibrosis grades. Of twelve RG candidates validated, miR-103a-3p and miR-425-5p were determined to be the most stable genes in the murine schistosomiasis model and subjects from the schistosomiasis-endemic area, respectively. The temporal expression profiles of nine fibrosis-associated serum exomiRs, as well as their correlations with the liver pathologies, were determined in C57BL/6 mice during S. japonicum infection. The serum levels of three exomiRs (miR-92a-3p, miR-146a-5p and miR-532-5p) were able to distinguish subjects with fibrosis grades I-III from those with no fibrosis, but only the serum level of exosomal miR-146a-5p showed potential for distinguishing patients with mild (grades 0-I) versus severe fibrosis (grades II-III). The current data imply that serum exomiRs can be a supplementary tool for grading liver fibrosis in hepatosplenic schistosomiasis with moderate accuracy.

Live imaging of collagen deposition during experimental hepatic schistosomiasis and recovery: a view on a dynamic process.

Hepatic fibrosis is the central cause of chronic clinical pathology resulting from infection by the blood flukes Schistosoma japonicum or S. mansoni. Much has been elucidated regarding the molecular, cellular and immunological responses that correspond to the formation of the granulomatous response to trapped schistosome eggs. A central feature of this Th2 response is the deposition of collagen around the periphery of the granuloma. To date, traditional histology and transcriptional methods have been used to quantify the deposition of collagen and to monitor the formation of the hepatic granuloma during experimental animal models of schistosomiasis. We have investigated the dynamic nature of granuloma formation through the use of a transgenic mouse model (B6.Collagen 1(A) luciferase mice (B6.Coll 1A-luc+)). With this model and whole-animal bioluminescence imaging, we followed the deposition of collagen during an active schistosome infection with Chinese and Philippines geographical strains of S. japonicum and after clearance of the adult parasites by the drug praziquantel. Individual mice were re-imaged over the time course to provide robust real-time quantitation of the development of chronic fibrotic disease. This model provides an improved method to follow the course of hepatic schistosomiasis-induced hepatic pathology and effectively supports the current dogma of the formation of hepatic fibrosis, originally elucidated from static traditional histology. This study demonstrates the first use of the B6.Coll 1A-luc+ mouse to monitor the dynamics of disease development and the treatment of pathogen-induced infection with the underlying pathology of fibrosis.

T cell-mediated immunity in CBA mice during Schistosoma japonicum infection.

Characterisation of the cellular immune response to schistosomiasis is well established for Schistosoma mansoni but a comprehensive description of T cell-mediated immune responses against S. japonicum infection is lacking. Accordingly, 20 CBA mice were infected with cercariae of S. japonicum and the immune response at different time points was determined. Mouse spleen and liver lymphocytes were isolated from the mice and stimulated with schistosomal adult worm antigen preparation (SWAP) and schistosomal soluble egg antigen (SEA). There was a relatively higher Th1 immune response to SWAP compared to SEA at the early phase of infection (up to week 5 post challenge). However, a Th2 immune response directed against SEA was dominant at week 6 post-infection, a time point when the highest IgG response against both SWAP and, especially, SEA was generated. The regulatory immune response was highest at the early phase of the immune response (up to week 5 post challenge) followed by a rapid decline at week 6-post infection. Before egg-laying, S. japonicum induced a regulatory T cell immune response which may limit the early Th1-mediated immune response that is believed to be protective in murine schistosomiasis. Following egg laying, the immune response was polarized to a Th2 immune response mainly directed against the eggs and this may contribute to parasite survival.