Geology topics

D. Mulcahy

Publications and source records attributed to D. Mulcahy.

14 recordsLinked to original sources

USGS2006

Titre distribution patterns of infectious haematopoietic necrosis virus in ovarian fluids of hatchery and feral salmon populations

Infectious haematopoietic mecrosis virus (IHNV) is enzootic in virtually all populations of sockeye salmon, Oncorhynchus nerka (Walbaum), and in populations of chinook salmon, O. tshawytscha (Walbaum), of the Sacramento River drainage in California. This disease is an obstacle in hatcheries using brood stocks from these populations. However, naturally spawning sockeye salmon are highly successful and are the most important commercially fished salmon species in the United States. Most of the commercial landings of sockeye salmon are of feral fish originating in Alaska. The success of natural populations of salmon in which IHNV is enzootic, and the recurrent outbreaks of the disease in hatchery fish, led us to compare IHNW prevalence rates in hatchery and feral salmon populations.

Journal of Fish Diseases↗

USGS2006

Effect of loading density of sockeye salmon, Oncorhynchus nerka (Walbaum), eggs in incubation boxes on mortality caused by infectious haematopoietic necrosis

Infectious haematopoietic necrosis (IHN) can cause massive mortalities of sockeye salmon, Oncorhynchus nerka (Walbaum), cultured in hatcheries. One method of enhancing sockeye salmon populations is to use a streamside egg incubation box from which the fry are automatically released into the stream as they emerge from the gravel. In this system, however, IHN epizootics occur as the fry emerge and continue for up to two months after the fry leave the box (Mulcahy, unpublished data). In as much as the high density of eggs and alevins in incubation boxes might be conducive to the fulmination of an IHN epizootic, we varied the egg density in incubation boxes and studied the cffect on mortality caused by IHN.

Washington↗

USGS2006

Detection of infectious haematopoietic necrosis virus in river water and demonstration of waterborne transmission

In a study of the possible role of waterborne infectious haematopoietic necrosis virus in transmission of the disease among spawning sockeye salmon, Oncorhynchus nerka (Walbaum), both infection rates and virus titres were higher in fish held at high density in a side channel than in fish in the adjacent river. Virus was never isolated from river water, but was found in water from the side channel at levels ranging from 32.5 to 1600 plaque-forming units (p.f.u.)/ml. Uninfected yearling sockeye salmon held in a box in the side channel developed localized gill infections with IHN virus. The disease did not progress to the viscera until a threshold titre of about 10 5 p.f.u./g was reached in the gill. The effectiveness of the gill as a barrier limiting development of systemic infections means that waterborne IHN virus probably does not greatly increase the infection rate in a sockeye salmon population during spawning.

Journal of Fish Diseases↗

USGS2006

Retention of infectious haematopoietic necrosis virus infectivity in fish tissue homogenates and fluids stored at three temperatures.

Pools of brain, kidney, spleen, liver and gut tissues from several rainbow trout, Salmo gairdneri Richardson, and whole sockeye salmon, Oncorhynchus nerka (Walbaum), fry were homogenized with a known amount of infectious haematopoietic necrosis virus (IHNV). Virus was also added to ovarian fluids and sera pooled from several rainbow trout. The plaque assay was used to determine the retention of IHNV infectivity after different storage periods at 20°C, 4°C and —20°C. The work was used to evaluate homogenization as a remote field treatment of IHNV samples before shipment to the laboratory. Maintenance of viral infectivity varied widely among different homogenates and fluids. For short-term storage, 4°C was generally the most efficient temperature for preserving infectious virus in ovarian fluids, Sera and homogenates of eggs, spleen, whole fry and brain, while infectivity was most efficiently preserved in kidney and liver homogenates by storage at −20°C. Infectious virus was not detected in any sample stored for one year at −20°C. Variations in retention of viral infectivity make homogenization of samples in the field followed by transfer to the laboratory unacceptable.

Journal of Fish Diseases↗

USGS2006

Vertical transmission of infectious haematopoietic necrosis virus in sockeye salmon, Oncorhynchus nerka (Walbaum): isolation of virus from dead eggs and fry

The control of epizootics of infectious haematopoietic necrosis (IIHN) virus in salmonid fishes is presently based on examination and certification of adult brood fish to prevent the introduction of virus-infected eggs into hatcheries (Canadian Fisherics and Marine Service 1976; McDaniel 1979). This strategy is based on the assumption that the virus is vertically transmitted in association with the gametes. However, evidence for vertical transmission of lHN virus is circumstantial, based mostly on the appearance of the disease outside the enzootic area (the west coast of North America) in fish hatched from eggs obtained from within that area (Plumb 1972; Holway & Smith 1973; Wolf, Quimby, Pettijohn & Landolt 1973, Sano, Nishimura, Okamoto, Yamazaki, Hanada & Watanabe 1977. Carlisle, Schat & Elston 1979). An indirect demonstration of vertical transmission was made by placing known virus-free fish in the water above and below raceways containing fish that suffered an IEEN epizootic in an cffort to climinate waterborne virus as a source of infection (Wingficid & Chan 1970). The fish placed below the raceway developed IHN, due to waterborne virus released from the affected fish in the raceway, but the fish placed above the raceway failed to develop IHN. These results suggested that the source of infection of the fish in the raceway was not the water supply, although it is possible that the virus was no longer present in the water supply at the time the sentinel fish were exposed to the water.

Journal of Fish Diseases↗

USGS1987

Enzyme-linked immunosorbent assay for a soluble antigen of Renibacterium salmoninarum , the causative agent for salmonid bacterial kidney disease

A double-antibody enzyme-linked immunosorbent assay (ELISA) for detection of a soluble fraction of Renibacterium salmoninarum was developed from components extracted from the supernatant of an R . salmoninarum broth culture. The Costar ® Serocluster™ EIA microplate gave the highest absorbance and signal-to-noise ratios among seven types tested. Including Tween 80 in the wash buffer resulted in higher absorbances than Tween 20 when antigen was present. Background absorbance did not increase when Tween 80 was added to the wash buffer, but did when Tween 80 replaced Tween 20 in antigen and conjugate diluents. Adsorption of coating antibody peaked within 4 h at 37 °C and 16 h at 4 °C. Antigen attachment to antibody-coated microplate wells depended more on incubation temperature than duration; we adopted a 3-h incubation at 25 °C. Conjugate incubation for longer than 1 h at 37 °C or 3 h at 25 °C resulted in unacceptable background levels. No cross-reactions resulted from heat-extracted antigens of 10 other species of bacteria. The optimized ELISA is a 6-h test that enables detection of levels of soluble antigen as low as 2–20 ng.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1987

Infectious hematopoietic necrosis virus detected by separation and incubation of cells from salmonid cavity fluid.

Infectious hematopoietic necrosis (IHN) virus is usually detected by inoculating susceptible cell cultures with cavity ("ovarian") fluid (CF) from spawning females. We identified additional adult carriers of virus in spawning populations of steelhead trout ( Salmo gairdneri ) and sockeye salmon ( Oncorhynchus nerka ) by collecting nonerythrocytic cells from CF samples by low-speed centrifugation, culturing the cells for at least 7 d at 15 °C, and then testing the culture medium for virus. Virus appeared in the cultured cells from some samples of CF that remained negative during incubation. In additional samples of CF from these species, the virus titer increased in cultured cells compared with the titer in the original CF sample. With chinook salmon ( O . tshawytscha ), no negative samples converted to positive during incubation, but the virus titer was retained in incubated CF cells, but not in cell-free CF.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1987

Testing of male sockeye salmon ( Oncorhynchus nerka ) and steelhead trout ( Salmo gairdneri ) for infectious hematopoietic necrosis virus

Infectious hematopoietic necrosis (IHN) virus has been isolated only rarely from whole milt samples of male sockeye salmon ( Oncorhynchus nerka ). In 3 yr of testing, virus incidences in males ranged from 0 to 13% when milt was sampled but were 60–100% with spleen or kidney. When IHN virus was isolated from sockeye salmon milt at titers less than 3.00 log 10 plaque-forming units (pfu)/mL, the level of virus in the kidney or spleen exceeded 7.00 log 10 pfu/g. Higher rates of IHN virus isolation from kidney or spleen than from milt were also generally found in steelhead trout ( Salmo gairdneri ), although the differences were less pronounced than in sockeye salmon. Furthermore, virus was sometimes isolated from steelhead trout milt when the level of virus in kidney or spleen samples was very low, and was recovered from some milt samples when none was isolated from the corresponding spleen sample. When male salmonids are tested for IHN virus, kidney or spleen samples are superior to whole milt, but milt should be included for critical examinations.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1987

Comparison of five techniques for the detection of Renibacterium salmoninarum in adult coho salmon.

Samples of kidney, spleen, coelomic fluid, and blood from 56 sexually mature coho salmon Oncorhynchus kisutch were examined for infection by Renibacterium salmoninarum by five methods. The overall prevalence (all sample types combined) of R. salmoninarum in the fish was 100% by the enzyme-linked immunosorbent assay, 86% by the combined results of the direct fluorescent antibody and the direct filtration-fluorescent antibody techniques, 39% by culture, 11% by counterimmunoelectrophoresis, and 5% by agarose gel immunodiffusion. There was a significant positive correlation (P < 0.001) between the enzyme-linked immunosorbent assay absorbance levels and the counts by fluorescent antibody techniques for kidney, spleen, and coelomic fluid, and significant positive correlations (P < 0.001) in enzyme-linked immunosorbent assay absorbance levels for all four of the sample types.

Transactions of the American Fisheries Society↗

USGS1984

Appearance and quantification of infectious hematopoietic necrosis virus in female sockeye salmon ( Oncorhynchus nerka ) during their spawning migration

The incidence and amount of infectious hematopoietic necrosis (IHN) virus was determined in 10 organs and body fluids from each of 100 female sockeye salmon (Oncorhynchus nerka) before, during, and after their spawning migration into freshwater. Virus was found in high concentrations only in fish sampled during and after spawning. Infection rates increased from nil to 100 percent within 2 weeks. In spawning fish, incidences of IHN virus were high in all organs and fluids except brain and serum, and the highest concentrations were in the pyloric caeca and lower gut. Immediately before spawning, IHN virus was found most frequently in the gills, less frequently in the pyloric caeca and spleen, and rarely in other organs.

Archives of Virology↗

USGS1984

Comparison of in vitro growth characteristics of ten isolates of infectious hematopoietic necrosis virus

Ten isolates of infectious haematopoietic necrosis from salmonid fishes of different locations on the West Coast of North America from California to Alaska were compared by plaque size, single-step growth curves at 15 and 18 °C, rate of appearance of cytopathic effects in cell cultures, and growth over a range of temperatures. All isolates were distinguishable on the basis of each growth characteristic examined. The CO isolate from the Sacramento River drainage of California was the most singular of the 10 because of its diminutive plaque size and sensitivity to slightly elevated temperatures. The mean plaque diameter of the l0 isolates increased as the latitude of the geographic source of the isolate increased. Although the maximum titre obtained by all isolates was depressed at temperatures above approximately 18 °C, half of the isolates were not inhibited by temperatures as low as 0.5 °C. t.

Journal of General Virology↗

USGS1984

Adsorption to fish sperm of vertically transmitted fish viruses

More than 99 percent of a vertically transmitted fish rhabdovirus, infectious hematopoietic necrosis virus, was removed from suspension in less than 1 minute by adsorption to the surface membrane of sperm from two genera of salmonid fishes. The vertically transmitted, infectious pancreatic necrosis virus adsorbed to a lesser degree, but no adsorption occurred with a second fish rhabdovirus that is not vertically transmitted. Such adsorption may be involved in vertical transmission of these viruses.

Science↗

USGS1983

Mortality due to infectious hematopoietic necrosis of sockeye salmon ( Oncorhynchus nerk a) fry in streamside egg incubation boxes

Infectious hematopoietic necrosis virus caused mortality of sockeye salmon ( Oncorhynchus nerka ) in streamside egg incubation boxes. Virus was not detectable in eggs or alevins; its first isolation coincided with the appearance of dead fish in a trap on the outflow from the box. Mortality due to the virus did not occur in every egg box studied. However, when fry from the boxes were held in the laboratory, epizootics began as much as 3 wk later, with total mortality exceeding 90%. More than 96% of the dead fry had titers exceeding 10 5 plaque-forming units per gram. The peak incidence of virus in fry migrating in the river coincided with the arrival of hatchery-produced fry, although some fry believed to have been produced by natural spawning were also infected.Englis

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1972

Location and description of spiral-shaped microorganisms in the normal rat cecum

Some indigenous microorganisms have been shown to localize in certain anatomical sites of the digestive tract of mammals. We studied the ceca of normal adult rats by light and electron microscopy to determine whether any specific bacterial population localizes in this area. All rats studied showed that the crypt was packed with organisms whose morphological character differs from those of the cecal lumen. Organisms localized in the crypt were often identified topographically close to the microvilli of the epithelial cells. These organisms could be differentiated into three types according to their characteristic ultrastructure. Type 1 was a thin spiral-shaped microbe that resembled a Borrelia. Type 2 possessed helically coiled fibers and flagella-like appendages. Type 3 was spiral-shaped but lacked axial fibers. Types 1 and 2 were both capable of penetrating through the crypt epithelium into the lamina propria where they were found in either phagocytes or extracellular locations. These observations are discussed in relation to other host-microflora localization patterns.

Infection and Immunity↗