The Experts below are selected from a list of 2121 Experts worldwide ranked by ideXlab platform
Harry W. Dickerson - One of the best experts on this subject based on the ideXlab platform.
-
immunity to Ichthyophthirius infections in fish a synopsis
Developmental and Comparative Immunology, 2014Co-Authors: Harry W. Dickerson, R. C. FindlyAbstract:Ichthyophthirius multifiliis is a ciliated protozoan parasite that infects freshwater fish. It has been the subject of both applied and basic research for over 100years, which can be attributed to its world-wide distribution and its significant economic impact on both food and aquarium fish production. I. multifiliis serves as a model for studies in fish on innate and acquired immunity, as well as on mucosal immunity. Although an obligate parasite, I. multifiliis is relatively easily passaged from infected to naive fish in laboratory aquaria, and is easily observed and manipulated under laboratory conditions. It parasitizes the epithelia of the skin and gills, which facilitates in vivo experimentation and quantification of challenge. This review provides a description of both mucosal and systemic innate and adaptive immune responses to parasite infection, a synopsis of host-parasite immunobiology, vaccine research, and suggested areas for future research to address critical remaining questions. Studies in carp and rainbow trout have shown that extensive tissue damage occurs when the parasite invades the epithelia of the skin and gills and substantial focal and systemic inflammatory responses are elicited by the innate immune response. The adaptive immune response is initiated when phagocytic cells are activated by antigens released by the parasite. It is not known whether activated T and B cells proliferate locally in the skin and gills following infection or migrate to these sites from the spleen or anterior kidney. I. multifiliis infection elicits both mucosal and systemic antibody production. Fish that survive I. multifiliis infection acquire protective immunity. Memory B cells provide long-term humoral memory. This suggests that protective vaccines are theoretically possible, and substantial efforts have been made toward developing vaccines in various fish species. Exposure of fish to controlled surface infections or by intracoelomic injection of live theronts provides protection. Vaccination with purified immobilization antigens, which are GPI-anchored membrane proteins, also provides protection under laboratory conditions and immobilization antigens are currently the most promising candidates for subunit vaccines against I. multifiliis.
-
transcriptional profiling of stage specific gene expression in the parasitic ciliate Ichthyophthirius multifiliis
Molecular and Biochemical Parasitology, 2011Co-Authors: Donna Cassidyhanley, Harry W. Dickerson, Mariemichele Cordonnierpratt, Lee H Pratt, Catherine Devine, Mozammal M Hossain, Theodore G. ClarkAbstract:The parasitic ciliate, Ichthyophthirius multifiliis (Ich), is among the most important protozoan pathogens of freshwater fish. Ichthyophthirius cannot be grown in cell culture, and the development of effective prophylactic and therapeutic treatments has been hampered by a lack of information regarding genes involved in virulence, differentiation and growth. To help address this issue, we have generated EST libraries from the two major stages of the parasite life cycle that infect and develop within host tissues. A total of 25,084 ESTs were generated from non-normalized libraries prepared from polyA+ RNA of infective theronts and host-associated trophonts, respectively. Cluster analysis identified 5311 unique transcripts (UniScripts), of which 2091 were contigs and 3220 singletons. Extrapolation of the data based on rates of EST discovery suggests that more than half the expected protein-coding genes of I. multifiliis are represented in this data. BLASTX comparisons against GenBank nr, UniProtKB (SwissProt and TrEMBL), as well as Tetrahymena thermophila, Plasmodium falciparum, and Paramecium tetraurelia protein databases produced 3694 significant (E-value ≤1e−10) hits, of which 1178 were annotated using gene ontology (GO) analysis. A high proportion of UniScripts (63%) showed similarity to other ciliate proteins. When combined with expression profiling data, GO ontology analysis of Biological Process, Cellular Component, and Molecular Function revealed interesting differences in gene families expressed in the two stages. Indeed, the most abundant transcripts were highly stage-specific and coincided with the metabolic activities associated with each stage. This work provides an effective genomics resource to further our understanding of Ichthyophthirius biology, and lays the groundwork for the identification of potential drug targets and vaccines candidates for the control of this devastating fish pathogen.
-
endosymbiotic bacteria in the parasitic ciliate Ichthyophthirius multifiliis
Applied and Environmental Microbiology, 2009Co-Authors: James Barber, Robert S Coyne, R. C. Findly, Donna Cassidyhanley, T G Clark, Harry W. DickersonAbstract:Endosymbiotic bacteria were identified in the parasitic ciliate Ichthyophthirius multifiliis, a common pathogen of freshwater fish. PCR amplification of DNA prepared from two isolates of I. multifiliis, using primers that bind conserved sequences in bacterial 16S rRNA genes, generated an ∼1,460-bp DNA product, which was cloned and sequenced. Sequence analysis demonstrated that 16S rRNA gene sequences from three classes of bacteria were present in the PCR product. These included Alphaproteobacteria (Rickettsiales), Sphingobacteria, and Flavobacterium columnare. DAPI (4′,6-diamidino-2-phenylindole) staining showed endosymbionts dispersed throughout the cytoplasm of trophonts and, in most, but not all theronts. Endosymbionts were observed by transmission electron microscopy in the cytoplasm, surrounded by a prominent, electron-translucent halo characteristic of Rickettsia. Fluorescence in situ hybridization demonstrated that bacteria from the Rickettsiales and Sphingobacteriales classes are endosymbionts of I. multifiliis, found in the cytoplasm, but not in the macronucleus or micronucleus. In contrast, F. columnare was not detected by fluorescence in situ hybridization. It likely adheres to I. multifiliis through association with cilia. The role that endosymbiotic bacteria play in the life history of I. multifiliis is not known.
-
differences in virulence between two serotypes of Ichthyophthirius multifiliis
Diseases of Aquatic Organisms, 2006Co-Authors: Alton G Swennes, Craig R Findly, Harry W. DickersonAbstract:Naive channel catfish Ictalurus punctatus were infected by 2 isolates of the parasitic cil- iate Ichthyophthirius multifiliis that differed in virulence. The isolates, NY1 and G5, Serotypes A and D, respectively, express different surface immobilization-antigens. The virulence of the 2 isolates was compared using tail-fin infections to quantitate parasite numbers and by analysis of the survival of infected fish. Although NY1 infected fish at a lower level than G5, all NY1-infected fish died, but 51% of G5-infected fish survived. The greater virulence of NY1 is apparently a consequence of its shorter life cycle, which results in overwhelming reinfection of fish before they can develop a protective immune response. This report represents the first experimental evidence for differences in virulence between serotypes of I. multifiliis.
-
Ichthyophthirius multifiliis a model of cutaneous infection and immunity in fishes
Immunological Reviews, 1998Co-Authors: Harry W. Dickerson, T G ClarkAbstract:The parasitic ciliate Ichthyophthirius multifiliis offers a useful system for the study of cutaneous immunity against an infectious microorganism. Naive fish usually die following infection, but animals surviving sublethal parasite exposure become resistant to subsequent challenge. This resistance correlates with the presence of humoral antibodies in the sera and cutaneous mucus of immune fish. A mechanism of immunity has recently been elucidated that involves antibody binding to surface proteins (referred to as immobilization antigens or i-antigens) located on the parasite cell and ciliary membranes. Antibody-mediated cross-linking of i-antigens triggers a response by the parasite resulting in its exit from the host. These effects can be observed directly on the surface of live fish. In addition to allowing the observation of effector responses in vivo, Ichthyophthirius also provides a means to study the ontogeny of the mucosal immune response. The sites of antigen capture and presentation, and the sites of antibody production, are unknown with regard to cutaneous immunity. Because the external epithelial surfaces of fish are often the points of pathogen entry, a basic understanding of the inductive immune mechanisms and immune cell interactions in the skin and gills is extremely important with regard to vaccine development. The development of Ichthyophthirius as an experimental system and how it might be used to address these issues are discussed in this review.
Kurt Buchmann - One of the best experts on this subject based on the ideXlab platform.
-
immune response to Ichthyophthirius multifiliis and role of igt
Parasite Immunology, 2020Co-Authors: Kurt BuchmannAbstract:: The parasitic ciliate Ichthyophthirius multifiliis causes white spot disease in freshwater fish worldwide. The theront penetrates external surfaces of the naive fish where it develops into the feeding trophont stage and elicits a protective immune response both at the affected site as well as at the systemic level. The present work compiles data and presents an overall model of the protective reactions induced. A wide spectrum of inflammatory reactions are established upon invasion but the specific protection is provided by adaptive factors. Immunoglobulin IgT is involved in protection of surfaces in several fish species and is thereby one of the first adaptive immune molecules reacting with the penetrating theront. IgT producing lymphocytes occur in epithelia, dispersed or associated with lymphoid cell aggregations (skin epidermis, fins, gills, nostrils and buccal cavities) but they are also present in central immune organs such as the head kidney, spleen and liver. When theronts invade immunized fish skin, they are encountered by host factors which opsonize the parasite and may result in complement activation, phagocytosis or cell-mediated killing. However, antibody (IgT, IgM and IgD) binding to parasite cilia has been suggested to alter parasite behaviour and induce an escape reaction, whereby specific IgT (or other classes of immunoglobulin in fish surfaces) takes a central role in protection against the parasite.
-
immunization of rainbow trout fry with Ichthyophthirius multifiliis sonicate protection of host and immunological changes
2002Co-Authors: Michael Dalgaard, Kurt Buchmann, Aihua LiAbstract:Rainbow trout fry (10 weeks post hatch) were immunized (injection or immersion) with sonicated formalin-killed trophonts of the fish parasitic ciliate Ichthyophthirius multifiliis. Challenge infections 22 days after immunization showed a relative protection represented by significantly fewer established parasites and lower prevalence in the immunized groups compared to the controls. Associations between the obtained protection and changes in differential leukocyte counts, haematocrit values, anti Ichthyophthirius multifiliis antibodies, mucous cell density and some epidermal cell markers were investigated. No changes in antibody titers, haematocrit values and mucous cell counts were associated with the response; however, a minor change in peripheral blood neutrophils and epidermal cell markers were found.
-
host responses against the fish parasitizing ciliate Ichthyophthirius multifiliis
Veterinary Parasitology, 2001Co-Authors: Kurt Buchmann, J Sigh, C V Nielsen, M DalgaardAbstract:Recent studies have shown that fish are able to mount protective immune responses against various parasites. One of the best characterized parasite–host system in this context is the ciliate Ichthyophthirius multifiliis (Ich) parasitizing a range of freshwater fishes. Both specific and non-specific host defence mechanisms are responsible for the protection of fish against challenge infections with this ciliate. The specific humoral components comprise at least specific antibodies. The non-specific humoral elements included are the alternative complement pathway and probably lectins. Cellular factors involved in the specific response are B-cells and putative T-cells. The non-specific effector cells recognized are various leukocytes. In addition, goblet-cells and mast cells (EGC-cells) may have a function. The NCC-cell (suggested analogue to NK-cells in mammals) seems to play a role in the non-specific response. This well documented protective response in freshwater fishes against Ich has urged the development of anti-parasitic vaccines. Indeed, such products based on formalin killed parasites have been developed and found to offer the vaccinated host a satisfactory protection. However, the collection of parasites for vaccine production is extremely laborious. It involves keeping infected fish due to the fact that in vitro propagation of the parasite is still insufficiently developed. Gaining knowledge of amino acid sequences and its encoding DNA-sequences for the protective antigens (i-antigens) in the parasite was a major breakthrough. That achievement made it possible to produce a recombinant protein in E. coli and preliminary results indicated a certain protection of fish vaccinated with this product. Recent work has shown that the free-living and easily cultivated ciliate Tetrahymena can be transformed and express the i-antigen. This path seems to be promising for future development of vaccines against Ich. A novel approach in fish is the development of DNA-vaccines. Successful DNA-vaccination trials have been conducted in fish against viral infections and the technology also makes it possible to develop a DNA-vaccine against Ich. Other approaches to immuno-protection against Ich have been the use of heterologous vaccines. Thus, both bath and injection vaccination using live or killed (un-transformed) Tetrahymena has been reported to offer treated fish a certain level of protection. Such protection could be explained by non-specific reactions and the efficacy and duration of this vaccination type should be further evaluated.
-
chemoattraction of Ichthyophthirius multifiliis ciliophora theronts to host molecules
International Journal for Parasitology, 1999Co-Authors: Kurt Buchmann, Michael Engelbrecht NielsenAbstract:Abstract Mechanisms in the host-finding process of Ichthyophthirius multifiliis were studied in vitro by a novel bioassay using 24-well multidishes supplied with bottom layers of agar with chemoattractants. It was shown that low molecular weight molecules (carbohydrates, amino acids, fatty acids, urea) did not attract theronts. In contrast, sera and mucus from a range of teleosts (including marine fish) were effective attractants. Fractionation by gel filtration of fish serum allowed determination of the molecular size of the attracting proteins. Further biochemical studies suggested the chemoattractants to be present in fractions with host immunoglobulin and some still undetermined proteins. No clear association between enzyme activity and chemotactic potential was seen. The high chemoattractive effect of serum from various unrelated teleosts corresponds to the low host specificity of I. multifiliis and suggests that serum factors in mucus could be involved in host finding of the parasite.
Dehai Xu - One of the best experts on this subject based on the ideXlab platform.
-
efficacy and antiparasitic mechanism of 10 gingerol isolated from ginger zingiber officinale against Ichthyophthirius multifiliis in grass carp
Veterinary Parasitology, 2019Co-Authors: Yaowu Fu, Qizhong Zhang, Bin Wang, Dehai XuAbstract:Abstract Ichthyophthirius multifiliis is a ciliate parasite of freshwater fish with a global distribution and results in severe economic losses in aquaculture. The present study aimed to investigate the efficacy and antiparasitic mechanism of active compounds isolated from Zingiber officinale against I. multifiliis. Three compounds were isolated from the Z. officinale extract and identified as 10-gingerol, 6-dehydroshogaol, and 6-dehydro-10-gingerol. 10-gingerol demonstrated the greatest antiparasitic efficacy in vitro. 10-gingerol resulted in 100% mortalities of theronts, nonencysted tomonts, and encysted tomonts at concentrations of 2, 8, and 16 mg/L, respectively. 10-gingerol significantly reduced theronts infectivity (p
-
molecular immune response of channel catfish immunized with live theronts of Ichthyophthirius multifiliis
Fish & Shellfish Immunology, 2016Co-Authors: Dehai Xu, Qizhong Zhang, Craig A Shoemaker, Dunhua Zhang, Gabriel S A MoreiraAbstract:The parasite Ichthyophthirius multifiliis (Ich) has been reported in various freshwater fishes worldwide and results in severe losses to both food and aquarium fish production. The fish surviving natural infections or immunized with live theronts develop strong specific and non-specific immune responses. Little is known about how these immune genes are induced or how they interact and lead to specific immunity against Ichthyophthirius multifiliis in channel catfish Ictalurus punctatus. This study evaluated the differential expression of immune-related genes, including immunoglobulin, immune cell receptor, cytokine, complement factor and toll-like receptors in head kidney from channel catfish at different time points after immunization with live theronts of I. multifiliis. The immunized fish showed significantly higher anti-Ich antibody expressed as immobilization titer and ELISA titer than those of control fish. The vast majority of immunized fish (95%) survived theront challenge. Expression of IgM and IgD heavy chain genes exhibited a rapid increase from 4 hour (h4) to 2 days (d2) post immunization. Expression of immune cell receptor genes (CD4, CD8-α, MHC I, MHC II β, TcR-α, and TcR-β) showed up-regulation from h4 to d6 post immunization, indicating that different immune cells were actively involved in cellular immune response. Cytokine gene expression (IL-1βa, IL-1βb, IFN-γ and TNF-α) increased rapidly at h4 post immunization and were at an up-regulated level until d2 compared to the bovine serum albumin control. Expression of complement factor and toll-like receptor genes exhibited a rapid increase from h4 to d2 post immunization. Results of this study demonstrated differential expression of genes involved in the specific or non-specific immune response post immunization and that the vaccination against Ich resulted in protection against infection by I. multifiliis.
-
Effect of tricaine methanesulfonate on survival and reproduction of the fish ectoparasite Ichthyophthirius multifiliis
Parasitology Research, 2008Co-Authors: Dehai Xu, Craig A Shoemaker, Phillip H KlesiusAbstract:The fish extoparasite Ichthyophthirius multifiliis was subjected to tricaine methanesulfonate (TM) exposure while fish were anesthetized for parasite collection. No information is available on the effects of TM exposure to I. multifiliis. This study evaluated the effects of TM on the survival and reproduction of I. multifiliis. Significant differences were not observed in survival and reproduction of tomonts collected from fish anesthetized using unbuffered or buffered TM or in control fish not exposed to TM. Results of the current study demonstrated that TM had no adverse effect on I. multifiliis survival and reproduction when used at concentrations and exposure times required for fish anesthetization.
-
generation and analysis of expressed sequence tags from the ciliate protozoan parasite Ichthyophthirius multifiliis
BMC Genomics, 2007Co-Authors: Jason Abernathy, Dehai Xu, Huseyin Kucuktas, Phillip H Klesius, Ping Li, Peng Xu, Covadonga R. AriasAbstract:Background The ciliate protozoan Ichthyophthirius multifiliis (Ich) is an important parasite of freshwater fish that causes 'white spot disease' leading to significant losses. A genomic resource for large-scale studies of this parasite has been lacking. To study gene expression involved in Ich pathogenesis and virulence, our goal was to generate expressed sequence tags (ESTs) for the development of a powerful microarray platform for the analysis of global gene expression in this species. Here, we initiated a project to sequence and analyze over 10,000 ESTs.
Phillip H Klesius - One of the best experts on this subject based on the ideXlab platform.
-
Effect of tricaine methanesulfonate on survival and reproduction of the fish ectoparasite Ichthyophthirius multifiliis
Parasitology Research, 2008Co-Authors: Dehai Xu, Craig A Shoemaker, Phillip H KlesiusAbstract:The fish extoparasite Ichthyophthirius multifiliis was subjected to tricaine methanesulfonate (TM) exposure while fish were anesthetized for parasite collection. No information is available on the effects of TM exposure to I. multifiliis. This study evaluated the effects of TM on the survival and reproduction of I. multifiliis. Significant differences were not observed in survival and reproduction of tomonts collected from fish anesthetized using unbuffered or buffered TM or in control fish not exposed to TM. Results of the current study demonstrated that TM had no adverse effect on I. multifiliis survival and reproduction when used at concentrations and exposure times required for fish anesthetization.
-
generation and analysis of expressed sequence tags from the ciliate protozoan parasite Ichthyophthirius multifiliis
BMC Genomics, 2007Co-Authors: Jason Abernathy, Dehai Xu, Huseyin Kucuktas, Phillip H Klesius, Ping Li, Peng Xu, Covadonga R. AriasAbstract:Background The ciliate protozoan Ichthyophthirius multifiliis (Ich) is an important parasite of freshwater fish that causes 'white spot disease' leading to significant losses. A genomic resource for large-scale studies of this parasite has been lacking. To study gene expression involved in Ich pathogenesis and virulence, our goal was to generate expressed sequence tags (ESTs) for the development of a powerful microarray platform for the analysis of global gene expression in this species. Here, we initiated a project to sequence and analyze over 10,000 ESTs.
-
antibody mediated immune response against Ichthyophthirius multifiliis using excised skin from channel catfish ictalurus punctatus rafinesque immune to Ichthyophthirius
Journal of Fish Diseases, 2002Co-Authors: Dh Xu, Phillip H KlesiusAbstract:This study investigated antibody mediated immune response against Ichthyophthirius multifiliis (Ich) by determining whether theronts would retain the potential for reinfection, both in vitro and in vivo, after treatment with the culture fluid of excised skin from channel catfish, Ictalurus punctatus, immune to Ich. The invasion was reduced significantly (P < 0.05) for theronts treated with the immune culture fluid compared with those treated with the culture fluid from naive fish. The treatment of theronts with the immune culture fluid greatly reduced the size and survival of trophonts compared with those treated with the culture fluid from naive fish. Fewer fish were infected and the infection density was less for fish exposed to theronts treated with immune culture fluid. The infection was severe for fish invaded by theronts treated with the culture fluid from naive fish, with a high number of infected fish and heavy density of trophonts per fish. All fish were infected by Ich when exposed to the theronts treated with the immunoadsorbed culture fluid. In summary, results of this study show that cutaneous antibodies in the culture fluid of excised skin from immune fish significantly reduces theront infectivity by immobilizing or weakening theronts.
Covadonga R. Arias - One of the best experts on this subject based on the ideXlab platform.
-
generation and analysis of expressed sequence tags from the ciliate protozoan parasite Ichthyophthirius multifiliis
BMC Genomics, 2007Co-Authors: Jason Abernathy, Dehai Xu, Huseyin Kucuktas, Phillip H Klesius, Ping Li, Peng Xu, Covadonga R. AriasAbstract:Background The ciliate protozoan Ichthyophthirius multifiliis (Ich) is an important parasite of freshwater fish that causes 'white spot disease' leading to significant losses. A genomic resource for large-scale studies of this parasite has been lacking. To study gene expression involved in Ich pathogenesis and virulence, our goal was to generate expressed sequence tags (ESTs) for the development of a powerful microarray platform for the analysis of global gene expression in this species. Here, we initiated a project to sequence and analyze over 10,000 ESTs.
