Progress 07/01/06 to 06/30/12
Outputs
OUTPUTS: Bolbophorus infected catfish have been documented in Arkansas, Louisiana, and Mississippi. One species, Bolbophorus damnificus, causes disease and significant economic losses in channel catfish but another species known as Bolbophorus species Type 2 does not. Several types of trematode cercariae have been collected and studied. PARTICIPANTS: C. Panuska, M. O'Hear, L. Pote, M. Yost, B. George, C. Doffitt, L. Khoo, D. Wise TARGET AUDIENCES: The information generated is important to parasitologists, biologists, and fish health professionals. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Molecular and histological data are being reviewed. Understanding how catfish can withstand infection will help in the development of controls for pathogenic species. Channel catfish are host to a number of parasites many of which are poorly understood. Improved options for the control of these parasites are needed to reduce the significant economic loss of catfish.
Publications
- No publications reported this period
|
Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Bolbophorus infected catfish have been documented in Arkansas, Louisiana, and Mississippi. One species causes disease and significant economic losses in channel catfish but another species does not. Several types of trematode cercariae have been collected and studied. Oral presentations have been given to parasitologists at two scientific meetings thus far. PARTICIPANTS: C. Panuska, M. O'Hear, L. Pote, M. Yost, B. George, C. Doffitt, L. Khoo, D. Wise TARGET AUDIENCES: Parasitologist, biologist, and fish health professionals PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Bolbophorus damnificus causes disease and significant economic losses in commercial channel catfish but another species, known as Bolbophorus species Type 2 does not. Aftifical infection studies were performed to determine if the infective stages of Bolbophours species Type 2 are unable to infect catfish or if they can penetrate the host successfully but are unable to develop due to host defenses. Molecular and histological data are being reviewed. Understanding how the catfish can withstand infection by closely related parasites will help in the development of controls for pathogenic species. Channel catfish are also host to nematode parasites. Larval nematodes causing lesions in the skin of channel catfish have been detected in the Mississippi Delta. Light microscopy, scanning electron microscopy, histology, and molecular techniques were used to study these unknown nematodes. Results of these studies suggest these larvae are dracunculid in type. Further studies are neede to dientify all the life stages of this nematode, determine the hosts involved in its life cycle, and determine the extent of pathology resulting from infection. Channel catfish are host to a number of parasites many of which are poorly understood. Defining complete life cycles, examining the mechanisms which parasites infect the fish, and the pathology they generate are foundational to developing new means of parasite control to enhance fish health and benefit the catfish industry.
Publications
- No publications reported this period
|
Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: An oral presentation was given to parasitologists at a regional scientific meeting: O'Hear, M., L. Pote, M. Yost, B. George, C. Doffitt, L. Khoo. D. Wise, C. Panuska. An overview of host-parasite interactions of the digenetic trematode, Bolbophorus damnificus. Southeastern Society of Parasitologists. Apr 15-17, 2009, Murray, KY. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: The information generated by this project is of interest to parasitologists, biologists in general, and fish health professionals. This year results were presented at the annual meeting of the Southeastern Society of Parasitologists. Future results will be presented to parasitology and fish health professionals at similar regional and national meetings. Results will be published in peer-reviewed journals such as the Journal of Parasitology, Diseases of Aquatic Organisms, and Journal of Aquatic Animal Health. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Outcomes: Bolbophorus infected catfish have been documented in Arkansas, Louisiana, and Mississippi. One species, Bolbophorus damnificus, causes disease and significant economic losses in commercial channel catfish but another species, known as Bolbophorus species Type 2, does not. Artificial infection studies were performed to determine if the infective stages of Bolbophorus species Type 2 are unable to infect catfish or if they can penetrate the host successfully but are unable to develop due to host defenses. Molecular and histological data are currently being reviewed. Understanding how the catfish can withstand infection by closely related parasites will help in the development of controls for pathogenic species. Channel catfish are also host to nematode parasites. Larval nematodes causing lesions in the skin of commercial channel catfish have been detected in several locations in the Mississippi Delta. Light microscopy, scanning electron microscopy, histology, and molecular techniques were used to study these unknown nematodes. Results of these studies suggest these larvae are dracunculid in type, but final identification depends on finding adult stages. Efforts were made to identify definitive and intermediate hosts in the life cycle of this nematode but these were unsuccessful. Further studies are needed to identify all the life stages of this nematode, determine the hosts involved in its life cycle, and determine the extent of pathology resulting from infection. Impacts: Channel catfish are host to a number of helminth parasites many of which are poorly understood. Improved options for the control of Bolbophorus damnificus, a known pathogen, are needed to reduce the significant economic losses the catfish industry currently suffers due to this parasite. Additionally, newly recognized parasites, such as the larval nematode, must be studied to determine their impact on the catfish industry. Defining complete life cycles, examining the mechanisms by which parasites infect and survive in the fish host, as well as the pathology they generate are foundational to developing new means of parasite control thereby enhancing fish health and benefiting the commercial catfish industry.
Publications
- No publications reported this period
|
Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Results, thus far, were disseminated to professional parasitologists at a national scientific meeting through an oral presentation: Panuska C., L.M. Pote. Characterization of carbohydrates in the cercariae of two species of Bolbophorus. 53rd Annual Meeting of the American Association of Veterinary Parasitologists. July 2008. New Orleans LA. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: The information generated by this project is of interest to parasitologists and other biologists as well as fish health professionals. Results were presented at the annual national meeting of the American Association of Veterinary Parasitologists this year. Future results will be presented to parasitology and fish health professionals and published in peer-reviewed journals such as the Journal of Parasitology, Diseases of Aquatic Organisms, and Journal of Aquatic Animal Health. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Outcomes: Knowledge of the mechanisms involved in the successful completion of life cycles will help us better understand the distribution of trematode parasites and the epidemiology of parasitic disease. Additionally, it will identify vulnerabilities in the life cycles that can serve as the basis for new methods of trematode control. Because the natural recognition system of carbohydrates and lectins has been implicated in the recognition, attachment and penetration of hosts by parasites, the carbohydrates present in cercariae of two species of the trematode Bolbophorus, one which causes disease in catfish (Bolbophorus damnificus) and one which does not (Bolbophorus species Type 2), were assessed. Carbohydrates were detected through the binding of a panel of lectins with a variety of carbohydrate specificities; binding in the presence of inhibiting sugars indicated specific binding. Differences were detected in the specific binding of mannose, glucose, galactose, and alpha and beta N-acetylgalactosamine residues in the two species. As surface or secreted molecules are more apt to be important in host-parasite interactions, studies examining surface carbohydrates of live cercariae are underway. Preliminary efforts show differences in surface galactose residues in the two species. These differences may be important in the differential infection outcome of these two parasites. Impacts: Bolbophorus damnificus causes high mortality and significant economic losses in the commercial channel catfish industry. Bolbophorus infected catfish have been documented in Arkansas, Louisiana, and Mississippi. Delineation of the mechanisms involved in host recognition for infective stages of this parasite will facilitate the development of novel controls that interfere with host location and invasion thereby preventing and reducing infection, enhancing fish health and benefiting the commercial catfish industry.
Publications
- No publications reported this period
|
Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Several types of trematode cercariae were successfully collected and banked during this year's field season. Preliminary polyacrylamide gel electrophoresis and lectin binding experiments were performed using Bolbophorus damnificus cercariae, which infect and cause disease in catfish, and Bolbophorus Type 2 cercariae, which do not cause disease in catfish. Due to the preliminary nature of these experiments, results have not been disseminated to interested groups. PARTICIPANTS: No Participant information reported. TARGET AUDIENCES: The information generated by this project will be of interest to parasitologists and other biologists as well as fish health professionals. Understanding the mechanism of host recognition and penetration could provide candidate targets for the development of novel parasite control methods based on the disruption of the parasite life cycle thus this information will also be of interest to the catfish industry. Ultimately, results will be presented at regional or national meetings and published in peer-reviewed journals such as the Journal of Parasitology, Diseases of Aquatic Organisms, and Journal of Aquatic Animal Health. PROJECT MODIFICATIONS: No Project Modifications information reported.
Impacts
Change in Knowledge: Initial efforts directed at defining molecules involved in the attraction and recognition of the fish host by cercariae of the catfish trematode Bolbophorus damnificus were begun. Cercariae of two species of the trematode Bolbophorus, one which causes disease in catfish (Bolbophorus damnificus) and one which does not (Bolbophorus species Type 2), are being compared. Polyacrylamide gel electrophoresis of these cercariae revealed shared and unique protein bands. Because lectins and their specific glycoconjugates are important in host recognition for some parasites, preliminary experiments were performed to determine if the pattern of lectin binding varied between these two species. The binding pattern and intensity of ConA, PNA, and WGA differed for the two species although ConA bound to the greatest number of bands and PNA bound to the fewest number of bands in both species. More extensive controlled studies with these and other lectins will be conducted to better define the differences in the two types of Bolbophorus. Ultimately, how these differences relate to infectivity and outcome of infection for these parasites will be assessed. Impacts: Bolbophorus damnificus causes high catfish mortalities and significant economic losses in the catfish industry. Bolbophorus infected catfish have been documented in Arkansas, Louisiana, and Mississippi. The life cycle of this parasite involves free-living stages (cercariae) that infect the channel catfish. Delineating the mechanism of host recognition for these stages will facilitate the development of novel control mechanisms that interfere with host location and invasion thereby enhancing fish health and benefiting the commercial catfish industry.
Publications
- No publications reported this period
|
Progress 01/01/06 to 12/31/06
Outputs
The goal of this program is to examine various aspects of host-parasite interactions. The ability of a parasite to complete its life cycle depends on the parasite recognizing the host, gaining entry to the host and surviving in the host in spite of the host's protective immune response. Multiple parasite species exist in and around commericial channel catfish (Ictalurus punctatus) ponds. A trematode parasite, Bolbophorus damnificus, is a recognized channel catfish pathogen that is present in Mississippi catfish ponds. Other, as yet unidentified, parasite species are also present in these ponds; however, their effect on channel catfish still needs to be determined. This summer, several types of cercariae (free-living juvenile stages of trematodes) were shed from snails (Planorbella trivolvus) collected from channel catfish ponds. While many of these cercariae were frozen for future studies examining their constituent proteins and glycoproteins, preliminary studies were
performed on live cercariae using lectin probes to characterize the carbohydrates on the parasite surface. Glycoproteins present on parasite surfaces have been shown to be important in host-parasite recognition and penetration in some host-parasite systems. Small amphistome cercariae of an unidentified species were collected and exposed to FITC-conjugated ConA; binding occurred and fluorescence was detected on the tail, anterior body and posterior body of the cercariae indicating the presence of mannose residues in these areas. Staining with other lectins (soybean agglutinin, SBA; dolichos biflorus agglutinin, DBA; peanumt agglutinin, PNA; ulex europaeus agglutinin I, UEA1; and wheat germ agglutinin, WGA) was unsuccessful. This assay was repeated with a different kind of cercariae (an unidentified furcocercous cercariae) that were collected from P. trivolvus from the same catfish pond. In this case, ConA consistently bound to the forked tail, the anterior tail stem, and the mouth of
the cercariae again indicating the presence of mannose residues. WGA bound inconsistently to the body surface indicating the presence of N-acetylglucosamine residues. Lack of binding in the presence of inhibiting sugars indicates that these lectin-carbohydrate interactions are specific. The free-living stage of a myxozoon parasite of channel catfish, Aurantiantinomyxon ictaluri, was also exposed to FITC-conjugated lectins. In this case ConA and WGA bound inconsistently while DBA, PNA, SBA, and UEA1 did not bind. The binding of ConA and WGA in the presence of inhibiting sugars was not tested in this case. These preliminary studies need to be extended to definitively identify carbohydrate residues present on the surface of these parasite stages and to determine their importance in the host-finding ability of the parasite. Host surface molecules and secreted molecules will also be examined in an effort to understand the different host-parasite interactions present in commercial channel
catfish ponds.
Impacts
Economic losses due to parasitic infections in commercial channel catfish can be devastating to the catfish producer. Parasites such as Henneguya ictaluri and Bolbophorus damnificus have been recognized as important pathogens in commercial channel catfish ponds in the southeastern United States. Control of such pathogenic parasites is often difficult, especially in food animal species. However, many of these parasites have free-living stages (such as cercariae or myxospores) which may be more vulnerable to control efforts than the parasitic stages present in host animals. These free-living stages are generally short-lived and if methods can be developed to delay or interfere with their ability to find a susceptible host, the life cycle of the parasite can be broken. Disruption of the parasite life cycle will ultimately result in fewer infections and a decrease in disease and mortality in the host species. A thorough understanding of the mechanisms and molecules
involved in the host-finding behavior of these parasites is critical to the development of these types of novel control methods.
Publications
- No publications reported this period
|
|