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C J Secombes

Publications and source records attributed to C J Secombes.

At least 73 records · Page 4Linked to original sources
PubMed1996

Effects of in vitro addition of infectious pancreatic necrosis virus (IPNV) on rainbow trout Oncorhynchus mykiss leucocyte responses.

Infectious pancreatic necrosis virus (IPNV) did not replicate in rainbow trout macrophages cultured in vitro, but a limited increase in viral titer was observed when total leucocytes were infected with the virus. Macrophages did not respond directly to IPNV, in that IPNV did not trigger the respiratory burst of these cells, even when the macrophages were previously stimulated. Supernatants were generated from leucocytes and macrophages exposed to the virus, using a variety of incubation periods and viral titers, to investigate whether virus stimulation induced the secretion of any immunomodulatory substances from these cells. No effect on macrophage responses was detected when these supernatants were added to new macrophage monolayers. However, IPNV produced a significant reduction of LPS-induced B cell proliferation, in a dose-dependent manner, indicative of at least one immunosuppressive effect induced by this virus.

Animals↗
PubMed1996

Immunisation of rainbow trout Oncorhynchus mykiss with a multiple antigen peptide system (MAPS).

To test the effectiveness of a multiple antigen peptide system (MAPS) as a method of vaccinating fish against peptides, rainbow trout were immunised with two MAPS containing the decapeptide GnRH. The first (MAPS 1) was homologous for GnRH, whereas the second (MAPS 2) was heterologous and contained alternating sequences of GnRH and a measles virus T cell epitope. Following vaccination with varying concentrations of the MAPS, serum antibody titres were monitored for 10 weeks. Only MAPS administered in adjuvant elicited an antibody response against GnRH. Whilst the kinetics of the responses mirrored those seen in sera from fish vaccinated against GnRH coupled to a carrier protein, the magnitude of the responses were significantly lower in sera from fish vaccinated with both MAPS. Interestingly, higher titres were seen against the MAPS than against GnRH in ELISA, possibly reflecting additional epitopes. The data are discussed with respect to the need to define T cell epitopes in fish, to allow the synthesis of more effective heterologous MAPS for future studies.

Adjuvants, Immunologic↗
PubMed1996

Dietary lipid affects phospholipid fatty acid compositions, eicosanoid production and immune function in Atlantic salmon (Salmo salar).

Atlantic salmon (Salmo salar) post-smolts were fed diets containing either Fosol (FO), a North Sea fish oil, sunflower oil (SO), linseed oil (LO) or Marinol K (MO), a southern hemisphere fish oil rich in 20:5(n-3) for 12 weeks. A macrophage-enriched leucocyte preparation was obtained from head kidney and the fatty acid compositions of the individual membrane phospholipids measured. In general phospholipids from SO- and LO-fed fish had increased 18:2(n-6), 20:2(n-6) and 20:3(n-6) compared to the fish oil treatments while LO-fed fish had lower 20:4(n-6) than any other dietary treatment. Fish fed LO also had increased 18:3(n-3), 18:4(n-3), 20:3(n-3) and 20:4(n-3). The 20:5(n-3) content of kidney macrophage-enriched leucocyte phospholipids was highest in MO-fed fish followed by FO- and LO-fed fish with the lowest level in fish fed SO. The overall effect on the ratio of eicosanoid precursors, 20:4/20:5, showed the highest value in SO-fed fish and the lowest in fish fed LO. Production of LTB5 by kidney macrophage-enriched leucocytes stimulated with A23187 was highest in MO-fed fish and lowest in those fed SO. Production of LTB4 was greatest in SO-fed fish and lowest in fish fed LO. Serum Ig levels were significantly affected by dietary treatment with highest values in fish fed FO and SO and lowest in fish fed MO and LO.

Animals↗
PubMed1996

A partial sequence for nitric oxide synthase from a goldfish (Carassius auratus) macrophage cell line.

Expression of inducible nitric oxide synthase (iNOS) mRNA was detected in a recently developed goldfish macrophage cell line by RT-PCR, using degenerate primers designed against conserved nucleotide motifs within the different mammalian isoforms of NOS. Increased expression of iNOS poststimulation with LPS was found, and suggests that it is a functional enzyme in goldfish macrophages, supporting the view that iNOS regulation is pretranslational. The nucleotide sequence translated in one reading frame with no stop codons to produce a partial peptide containing 164 amino acids, with highest homology (85%) to a recently identified rainbow trout iNOS sequence. The peptide translation also gave an insight into the conservation of binding motifs, since two cofactor binding sites were present in the amplified PCR product (FMN and calmodulin). In addition, a 42 aa motif present in the region just upstream of the FMN binding motif of mammalian endothelial and neuronal NOS isoforms was absent in the translation, in agreement with every published sequence for iNOS. Finally, the translation was used to construct an unrooted phylogenetic tree.

Animals↗
PubMed1996

A live (delta aroA) Aeromonas salmonicida vaccine for furunculosis preferentially stimulates T-cell responses relative to B-cell responses in rainbow trout (Oncorhynchus mykiss).

We have previously described (L. M. Vaughan, P. R. Smith, and T. J. Foster, Infect. Immun. 61:2172-2181, 1993) the construction of a kanamycin-resistant aromatic-dependent mutant of Aeromonas salmonicida, the causative agent of furunculosis, and its use as a live vaccine. Here we describe the construction of an unmarked aroA deletion mutant and examine the nature and magnitude of immune responses in rainbow trout (Oncorhynchus mykiss) to this vaccine strain. Good proliferative and antibody responses were elicited by using a range of vaccine doses from 2 x 10(6) to 2 x 10(9) live bacteria per fish, and a clear vaccine dose effect was apparent. A significant positive effect of using live bacteria to prime for lymphocyte proliferation and antibody production was apparent. However, the problem of directly comparing the vaccine doses of live and killed bacterial preparations is discussed, since some replication of live bacteria in vivo is expected. Most importantly, the live vaccine preferentially stimulated enhanced T-cell responsiveness, as evidenced by significantly greater increases in T-cell proliferation than in B-cell proliferation, compared with responses by the respective cell populations from fish given a killed vaccine. The manner in which live vaccines elicit strong cell-mediated immune responses and the relevance to fish vaccine design are discussed.

Aeromonas↗
PubMed1995

Elevation of rainbow trout Oncorhynchus mykiss macrophage respiratory burst activity with macrophage-derived supernatants.

A variety of supernatants were prepared by stimulating rainbow trout Oncorhynchus mykiss head kidney macrophages with lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-alpha), or a leucocyte-derived macrophage-activating factor (I-MAF), individually and in combination. If generated using a 12-h stimulation period, such supernatants were found to elevate significantly the respiratory burst activity of target macrophages; that is, they contained a macrophage-derived MAF (m-MAF), but supernatants generated using a shorter incubation period showed no significant activity. Combinations of these treatments were particularly effective in generating m-MAF-containing supernatants. The elevation of respiratory burst activity by supernatants generated using combined treatments could be partially inhibited by prior treatment of the target macrophages with anti-TNF-alpha receptor 1 (TNFR1) monoclonal antibodies (mAbs). Similarly, treatment of macrophages with combinations of 1-MAF and m-MAF generated supernatants with potent m-MAF activity and this activity was partially inhibited by prior treatment of the target cells with anti-TNFR1 mAb. In addition, the presence of anti-transforming growth factor beta 1 (TGF-beta 1) serum while generating these latter supernatants resulted in significantly increased m-MAF activity. Such data suggest that fish leukocytes secrete a variety of potent macrophage-activating (TNF-alpha) and -deactivating (TGF-beta) factors.

Animals↗
PubMed1995

The effects of diesel oil-based drilling mud extracts on immune responses of rainbow trout.

The potential suppressive effect of oil-pollution in the aquatic environment on fish immune responses was investigated by injecting rainbow trout (Oncorhychus mykiss) with an extract obtained from diesel oil-based drilling mud. To investigate the effect of the extract dose, 4 groups of 6 fish were exposed to 0, 0.6, 1.2, and 2.4 mL extract/Kg body weight (B.W.). To keep the injection volume constant, each extract dose was made up 2.4 mL/Kg B.W. with olive oil. Six weeks later the fish were sacrificed and a number of immmune parameters monitored. In a second experiment, the effect of exposure times was investigated. Fish wee exposed to 2.4 mL extract/Kg B.W., 2.4 mL olive oil/Kg B.W., or 2.4 mL saline/Kg B.W. and immune parameters were monitored 2, 4, 6 and 8 weeks post-injection. In the dose response experiment, there was no significant effect of the extract on serum immunoglobulin (Ig) levels and haemolytic complement (CH50) activity, but a suppressive effect on serum lysozyme level was found using the 0.6 mL/Kg dose. This dose also elevated proliferative activity of head kidney lymphocytes in response to the mitogen PHA. In the second experiment, investigating exposure time, again no significant overall effect on serum Ig or lysozyme level and CH50 activity was observed, although Ig levels were significantly lower at week two relative to the other groups. However, both extract- and olive oil-injected fish showed significantly lower lysozyme levels compared with the saline-injected (control) fish throughout the experiment. In contrast, at week six post-exposure, head kidney lymphocyte proliferation was significantly elevated in both the extract- and olive oil-exposed fish relative to the control fish.

Animals↗
PubMed1994

Effects of dietary fatty acids on eicosanoid-generating capacity, fatty acid composition and chemotactic activity of rainbow trout (Oncorhynchus mykiss) leucocytes.

Rainbow trout, Oncorhynchus mykiss, were maintained on isocalorific diets in which either sunflower, menhaden or Fosol oils were used as the dietary source of fatty acids. At intervals over a period of 6 months, head kidney leucocytes were isolated and used for the analysis of their fatty acid composition and eicosanoid-generating capacity. Major changes in fatty acid composition were apparent within 4 weeks on the diets, with fish fed sunflower oil diets showing a 2.1-fold increase in total n-6 fatty acids and a 2.3-fold decrease in n-3 fatty acids, compared with the original basal levels. By week 8 the fatty acid composition changes were greater in the sunflower-fed fish, but thereafter remained relatively stable to the end of the experiment at week 24. Leucocytes from the fish maintained for > 8 weeks on the sunflower oil containing diet produced significantly lower percentages of 5-series lipoxygenase products derived from eicosapentaenoic acid including 12-hydroxyeicosapentaenoic acid, leukotriene B5 and lipoxin A5 compared with those cells from fish fed either menhaden or Fosol based diets. Unlike the fatty acid composition, differences in lipoxygenase product profiles between the dietary groups increased throughout the experiment and by week 24 the arachidonic acid/eicosapentaenoic acid derived product ratios were approx. 14:1 in the sunflower oil-fed fish compared with approx. 1:1.5 in the menhaden oil-fed fish. A functional consequence of these differing ratios was seen in the ability of supernatants containing these products to cause the in vitro locomotion of trout neutrophils. Supernatants from sunflower oil-fed fish were less chemo-attractive than supernatants from menhaden or Fosol oil-fed fish.

Animals↗
PubMed1994

Antigen-induced release of macrophage activating factor from rainbow trout Oncorhynchus mykiss leucocytes.

The production of macrophage-activating factor (MAF) by rainbow trout, Oncorhynchus mykiss, head kidney leucocytes at varying times post-immunisation, with the fish bacterial pathogen, Aeromonas salmonicida, was investigated and correlated with head kidney lymphocyte proliferation and serum antibody production. MAF production was preceded by lymphocyte proliferation and both responses were highest using whole bacterial cells as the in vitro stimulant. MAF production and antibody production increased 2-3 weeks post-immunisation, and peaked 4-5 weeks post-immunisation. The relative importance of MAF activated phagocytes in the immunological armoury of disease-resistant, vaccinated fish requires further investigation.

Aeromonas↗
PubMed1994

Human tumor necrosis factor alpha influences rainbow trout Oncorhynchus mykiss leucocyte responses.

Human recombinant tumor necrosis factor alpha (rTNF alpha) and rainbow trout macrophage activating factor (postulated gamma-interferon (gamma-IFN) analogue) synergised to elevate the respiratory burst activity of trout macrophages. This elevated response may parallel phenomena described in mammals where TNF alpha and gamma-IFN commonly synergise. Human rTNF alpha also synergised with mitogenic stimuli to heighten proliferation responses of trout head kidney leucocytes. These data are indicative of a conserved TNF alpha receptor on trout leucocytes (and possibly the TNF alpha molecule itself) and support the notion of an interactive cytokine network regulating immune responses in fish.

Animals↗
PubMed1994

The effect of eicosanoids on rainbow trout, Oncorhynchus mykiss, leucocyte proliferation.

Proliferation of rainbow trout head kidney leucocytes in response to the mitogen phytohaemagglutinin-P (PHA-P) was modulated in the presence of inhibitors of eicosanoid synthesis and by exogenous eicosanoids. The presence of indomethacin, a cyclooxygenase inhibitor, resulted in a stimulatory effect, whereas the presence of nordihydroguiaretic acid, a lipoxygenase inhibitor, resulted in an inhibitory effect on mitogenicity. The addition of prostaglandins and lipoxins was also found to be inhibitory, whilst the addition of leukotrienes was stimulatory. Some class/series effects of the eicosanoids were also apparent. Prostaglandin E2 was a more potent inhibitor than prostaglandin E3, and proliferation was more sensitive to the effects of leukotriene B4 than to leukotriene B5. Whilst PHA-P was able to directly induce the release of prostaglandins from head kidney leucocytes, it did not induce the release of lipoxygenase products.

Animals↗
PubMed1992

Lipoxin-induced migration of fish leukocytes.

The migration-inducing abilities of both synthetic lipoxin A4 (LXA4) and leukotriene B4 (LTB4) for rainbow trout neutrophils were examined with an in vitro assay. LXA4 caused enhanced migration of these cells with a three- to fourfold greater response than that observed toward LTB4 at most concentrations tested. Checkerboard assays showed that synthetic LXA4 was chemokinetic for trout leukocytes, while LTB4 was chemotactic. The chemokinetic ability of LX synthesized by rainbow trout macrophages maintained in short-term culture was also determined. These cells produced both 4-and 5-series LX, namely LXA4, LXA5, 11-trans-LXA4, 11-trans-LXA5, 7-cis-11-trans-LXA4 and 6(S)-LXA4. Although greater migration was found to LXA4 than to most of the other 4-series positional isomers, at least at some concentrations, this did not exhibit the degree of stereospecificity previously reported in some studies for mammalian leukocytes. Little difference was found between the chemokinetic responses of rainbow trout leukocytes to 4- and 5-series LX. These findings suggest that LXs are important migration-inducing molecules in trout and have a relatively long evolutionary history.

Animals↗
PubMed1992

Sequential development of the immune response in rainbow trout [Oncorhynchus mykiss (Walbaum, 1792)] to experimental plerocercoid infections of Diphyllobothrium dendriticum (Nitzsch, 1824).

Development of the inflammatory response of rainbow trout to experimental infections with Diphyllobothrium dendriticum plerocercoids is described using light and electron microscopy. The cellular response to plerocercoids occurred within 2 weeks post-infection (p.i.). This was followed by an increase in leucocyte numbers during weeks 3-6 p.i., with full encapsulation of plerocercoids by week 6 p.i. Neutrophils were the first leucocytes to engage the developing plerocercoid, followed by large influxes of macrophages which transformed into epithelioid cells. With longer times p.i. the accumulation of different leucocyte types increased, and a blood vascular network developed. Full development of the composite cyst was characterized by fibroplasia, particularly at the periphery of the cyst, and the subsequent deposition of a collagenous tissue matrix. Enzyme-linked immunosorbent assay (ELISA) examination of serum samples taken over the 20 week period showed that specific anti-D. dendriticum antibody titres were first detected at 5 weeks p.i. and increased to a maximum by 11 weeks p.i.

Animals↗
PubMed1991

Synthesis of lipoxins and other lipoxygenase products by macrophages from the rainbow trout, Oncorhynchus mykiss.

Rainbow trout macrophages maintained in short term culture when incubated with either calcium ionophore, A23187, or opsonized zymosan synthesize a range of lipoxygenase products including lipoxins and leukotrienes. These cells are unusual in that they generate more lipoxin than leukotriene following such challenge. The main lipoxin synthesized was lipoxin (LX) A4. This compound was identified by cochromatography with authentic standard during reversephase high performance liquid chromatography, by ultra violet spectral analysis, radiolabeling following incorporation of [14C]arachidonic acid substrate into macrophage phospholipids, and gas chromatography electron impact mass spectrometry of the methyl ester, trimethylsilyl ether derivative. Other 4-series lipoxins synthesized by trout macrophages were identified as 11-trans-LXA4, 7-cis-11-trans-LXA4, and 6(S)-LXA4. These cells also produced 5-series lipoxins tentatively identified as LXA5, 11-trans-LXA5 and possibly 6(S)-LXA5. No LXB4 or LXB5 was, however, detected. The dynamics of leukotriene and lipoxin release were also determined. Lipoxin generation was slower than leukotriene generation the latter reaching a maximum after 30 min of exposure to ionophore (5 microM, 18 degrees C) compared with 45 min for the former.

Animals↗
PubMed1991

Leucocyte migration in rainbow trout (Oncorhynchus mykiss [Walbaum]): optimization of migration conditions and responses to host and pathogen (Diphyllobothrium dendriticum [Nitzsch]) derived chemoattractants.

A rainbow trout leucocyte-derived chemoattractant(s) was prepared and tested as a stimulant of leucocyte migration. It was used to optimize an in vitro leucocyte migration assay using a 48-well micro chemotaxis chamber. This assay has subsequently been used to test the chemoattractant activity of antigen extracts from the tegument of Diphyllobothrium dendriticum plerocercoids and conditioned medium obtained after in vitro maintenance of live plerocercoids. Leucocytes were found to have an increased directional motility (chemotactic response) to the host-derived chemoattractant(s) but a random increased motility (chemokinetic response) following stimulation/contact with parasite-derived antigens.

Animals↗
PubMed1991

Immunocompetence as a measure of the biological effects of sewage sludge pollution in fish.

1. Dab, Limanda limanda, exposed to nominal concentrations of 0 (control), 0.0032% (low) and 0.032% (high) sewage sludge in seawater for 12 weeks, were assessed for their immunological competence. 2. No effect upon total blood leucocyte and erythrocyte numbers was found, although significantly fewer thrombocytes were seen in the high-exposure group. 3. A decreased serum protein level was found in the high exposure group, but lysozyme and immunoglobulin levels showed non-significant differences between the groups. 4. Melano-macrophage centres were also affected in the high-exposure dab, which had increased numbers in the spleen and kidney. No effect upon spleen weights or oxygen free radical production by splenocytes was noted. However, oxygen free radical production by kidney leucocytes was inhibited in the low-exposure dab.

Animals↗
PubMed1991

Studies on the infectivity of Diplostomum spathaceum in rainbow trout (Oncorhynchus mykiss).

The infectivity of Diplostomum spathaceum (Digenea: Trematoda) cercariae to rainbow trout and the efficacy of the diplostomule migration to the lens following different routes of administration was examined. The optimum age of infectivity for cercariae was between 0-5 h after liberation from the snail and for intraperitoneally injected diplostomules, 5 h post-transformation in vitro through fish skin. After exposure of the entire fish body or head to cercariae, metacercariae first appeared in the lens at 5 h and their numbers gradually increased until 22 h. Following exposure of the tail region of rainbow trout to cercariae, metacercariae first appeared in the lens at 14 h. Significantly more metacercariae established in the lens of fish following exposure of the fish head compared with the tail region; 40% of penetrating cercariae reached the lens of fish following exposure of the head or entire body, 20% of cercariae or diplostomules injected either intraperitoneally, intramuscularly or intracardially reached the lens while only 5% of cercariae established as metacercariae following exposure of the tail region.

Animals↗