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B Novoa

Publications and source records attributed to B Novoa.

32 records · Page 2Linked to original sources
PubMed1999

Role of nitric oxide on the replication of viral haemorrhagic septicemia virus (VHSV), a fish rhabdovirus.

In the present work, we have studied the role of nitric oxide (NO) on the replication of viral haemorrhagic septicemia virus (VHSV), a virus which produces high mortalities in fish aquaculture worldwide and that is known to replicate in turbot (Scophthalmus maximus) head kidney macrophages. Viral infection of turbot kidney macrophages in vitro induced an up-regulation of NO production and we have tested whether this endogenous NO production induced by VHSV on macrophages had an antiviral effect using the NO synthase inhibitor, N-omega-nitro-L-arginine (L-NAME). When L-NAME was added to the VHSV-infected cultures, no increase on VHSV titer was observed, even though the inhibitor was capable of decreasing NO production. When exogenous NO was apported by the nitric oxide donor, glycerin trinitrate (GTN) an antiviral effect on VHSV was observed. The NO donor significantly inhibited VHSV replication on a turbot fibroblast cell line (TV-1) and on turbot kidney macrophages.

Animals↗
PubMed1999

Epizoic amoebae from the gills of turbot Scophthalmus maximus.

Species of amoebae belonging to the genera Platyamoeba Page, 1969, Vannella Bovee, 1965 and Flabellula Schaeffer, 1926 were found to accompany Paramoeba sp., the agent of amoebic gill disease (AGD), in clinically diseased turbots. The same community of epizoic gymnamoebae was found on the gills of turbots which revealed no gill abnormalities but slight behavioral signs indicative of suboptimal health status. The assemblage of the above-mentioned free-living amoebae capable of colonizing gill tissue of turbots was supplemented with species recognized in samples fixed from primary isolates for transmission electron microscopy. The pathogenic potential of epizoic gill amoebae in turbots is discussed.

Amebiasis↗
PubMed1999

Production of leukotriene B4 and prostaglandin E2 by turbot (Scophthalmus maximus) leukocytes.

Production of two eicosanoids derived from lipoxygenase and cyclooxygenase activities: leukotriene B4 (LTB4) and prostaglandin E2 (PGE2), respectively, have been simultaneously determined in turbot (Scophthalmus maximus) blood leucocyte and kidney macrophage supernatants by a reverse phase high performance liquid chromatography (HPLC) system coupled with a Diode-Array detector. Levels of LTB4 after calcium ionophore challenge were 4.08 ng ml-1 in blood leukocyte supernatants and 0.25 ng ml-1 in kidney macrophage supernatants. The levels found for PGE2 were 428.23 and 606.67 ng ml-1 in blood leukocytes and kidney macrophage supernatants, respectively. When blood leukocytes were treated with the respective inhibitors for the enzymes implicated on the synthesis of both compounds an inhibition of 90.35% was observed for PGE2 and 76.44% for LTB4. The detection limit of the method was 0.15 ng ml-1 for LTB4 and 50 ng ml-1 for PGE2.

Animals↗
PubMed1998

Influence of the sequence of administration of beta-glucans and a Vibrio damsela vaccine on the immune response of turbot (Scophthalmus maximus L.).

Yeast (Saccharomyces cerevisae) beta-1,3 glucans were used as adjuvant in a Vibrio damsela vaccine for turbot (Scophthalmus maximus L.). Turbot were injected with the adjuvant prior, at the same time and after the vaccine. Several immune parameters (index and rate of phagocytosis, passive haemolytic plaque numbers, and agglutinating antibody titers) were determined at different times postinoculation. The highest activity of all the immune parameters was obtained when glucans were injected after the bacterin. It is concluded that the sequence of glucan administration is critical when used as a vaccine adjuvant.

Adjuvants, Immunologic↗
PubMed1998

Paramoeba sp., an agent of amoebic gill disease of turbot Scophthalmus maximus.

Amoebic gill disease of turbot Scophthalmus maximus L. associated with mortalities was repeatedly diagnosed at culture facilities in NW Spain. The agent was assigned to the genus Paramoeba Schaudin, 1896. Trophozoites found in the gill tissue as well as those cultured displayed most of the principal characteristics of P. pemaquidensis Page, 1970. The identity with P. pemaquidensis, known as an agent of gill diseases of salmonids, is yet to be assessed using non-morphological criteria.

Amebiasis↗
PubMed1998

In vitro interaction of viral haemorrhagic septicaemia virus and leukocytes from trout (Oncorhynchus mykiss) and turbot (Scophthalmus maximus).

Viral haemorrhagic septicaemia virus (VHSV), a well known salmonids pathogen, has also been reported to be pathogenic for turbot (Scophthalmus maximus). In the present work, the replication of VHSV was studied in vitro in turbot head kidney macrophages and blood leukocytes. VHSV was able to infect both primary cultures and viral titer increased with time, either inside the cells or in the supernatant. However, no cytopathic effect was observed during the experiments and the titers were always lower than those obtained in the fish cell lines. The number of trout and turbot macrophages after several days of in vitro infection with VHSV was compared with uninfected controls by viable cell count but no significant differences were observed. The number of cells supporting viral replication evaluated by immunofluorescence in trout and turbot was low (8 and 1.7%, respectively). Respiratory burst activity of head kidney macrophages was assayed at different days post-infection, but no significant differences were found between the control and the infected cultures neither in trout nor turbot.

Animals↗
PubMed1998

Characterization and Infectivity of Four Bacterial Strains Isolated from Brown Ring Disease-Affected Clams

Four bacterial strains isolated from carpet-shell clams (Ruditapes decussatus) and manila clams (R. philippinarum) exhibiting Brown Ring Disease (BRD) symptoms in Galicia (Northwest of Spain) were characterized using biochemical and serological techniques. Moreover their pathogenicity for clams and resistance against clam hemolymph were determined. All of the Vibrio isolates exhibited biochemical characteristics typical of the genus. Strains GR1703RP and GR6301RP, isolated from R. philippinarum showing signs of BRD, shared phenotypical and antigenic characteristics and bacterial extracellular products enzymatic activities with the Vibrio tapetis. Strains GR0705RD and GR0202RD, isolated from R. decussatus showing BRD signs, although biochemically similar to V. tapetis, did not show positive agglutination with V. tapetis antiserum. The virulence of the bacteria varied depending on the bacterial strain and clam species assayed. Mortalities were recorded for a 30-day period, reaching values ranging from 6 to 80%. Strain GR0202RD was the most virulent for R. philippinarum with a cumulative mortality rate of 45%, while the strain GR0705RD induced the highest prevalence of BRD signs, affecting 75% of the survivors. In the case of R. decussatus, the four bacterial strains produced a cumulative mortality rate higher than 45%. In general, bacterial strains, showed resistance to clams hemolymph. Copyright 1998 Academic Press. Copyright 1998 Academic Press

Journal Article↗
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↗
PubMed1995

Comparison of different procedures for serotyping aquatic birnavirus.

The current classification of aquatic birnaviruses is based on seroneutralization assays with polyclonal antibodies. In this study a comparison of several procedures used for serotyping aquatic birnaviruses was made with 10 virus strains (4 reference strains from salmonids and 6 birnaviruses isolated from turbot [Scophthalmus maximus]). The relationships among the birnavirus strains were studied by seroneutralization assay with polyclonal antibodies and by immunodot assay with both polyclonal and monoclonal antibodies. The results were compared with a presumptive classification obtained from analysis of restriction enzyme patterns of cDNA products obtained by PCR amplification. No correlation was found among the results obtained by the different procedures. The seroneutralization and the immunodot assays with polyclonal antibodies were not useful in classifying these birnaviruses strains; however, patterns of reaction with monoclonal antibodies emphasized the individuality of the strains, particularly in the case of two strains (231 and 460) whose patterns did not correspond to established serotypes. The application of PCR and restriction enzyme analysis is a promising system for approaching the classification of this viral group on the basis of genomic differences and similarities. The variable results obtained in this comparison lead us to think that the current classification of aquatic birnavirus may not be the most accurate and there is a need for modification incorporating recent isolates, not only from salmonid species but also from marine fish.

Animals↗
PubMed1995

Application of 3 techniques for diagnosing birnavirus infection in turbot.

Three procedures for avoiding viral amplification by cell culture were evaluated for the diagnosis of birnavirus infections of turbot (Scophthalmus maximus) tissues. Immunodot assay using monoclonal and polyclonal antibodies was not satisfactory as a detection system because of false positive reactions. Although immunofluorescent assay of liver and kidney smears was an adequate method for a rapid diagnosis of the infection, blood smears from infected fish did not show higher levels of fluorescence than those from uninfected fish. However, the detection of birnavirus by polymerase chain reaction (PCR) amplification directly in fish tissues was successful and seems to be a promising system for the diagnosis of fish birnavirus.

Animals↗
PubMed1995

Amoebic gill infection of turbot, Scophthalmus maximus.

Amoebae were found to cause severe gill tissue damage in turbot, Scophthalmus maximus L, from a grow-out facility in northwestern Galicia (Spain). The nature and extent of lesions along with negative results of bacteriological and virological examination made this agent responsible for mortalities in four turbot stocks supplied with water from a single source. We present our findings, although we failed to isolate amoebae, since there was a clear evidence of their primary role in the development of disease condition and occurrence of mortalities. In addition, this is a record both of a new host endangered by amoebae in intensive cultures and pathogenesis of the gill lesions.

Amebiasis↗
PubMedDate not supplied

In vitro studies on the regulation of rainbow trout (Oncorhynchus mykiss) macrophage respiratory burst activity.

Modulation of the respiratory burst activity of head kidney macrophages isolated from rainbow trout (Oncorhynchus mykiss) was observed following treatment with several biologically active substances. Macrophage-activating factor (MAF) induced the highest increment if respiratory burst activity relative to treatment with lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF alpha) or beta-glucans from Saccharomyces cerevisiae. Increased responses were more evident when these molecules were combined in pairs. Negative regulation of respiratory burst activity was observed when diMePGE2 was added to the macrophages, with maximal inhibition seen using a concentration of 2.6 microM. Inhibition was also seen using stimulated macrophages, either by co-incubation of stimuli and diMePGE2 or by adding diMePGE2 to previously stimulated cells. The inhibitory effect on macrophages was detectable with 3 h of incubation with diMePGE2 and by 24 h the level of the response was even lower than that from unstimulated (control) macrophages. Of significance was the finding that the inhibitory effect of prostaglandin on macrophage function could be overcome by co-incubation with stimulatory molecules or by pre-treatment with MAF and LPS or MAF and TNF alpha Thus, the regulation of macrophage activation in fish is likely to be as complex as in mammals.

16,16-Dimethylprostaglandin E2↗
PubMedDate not supplied

Requirements for nitric oxide production by turbot (Scophthalmus maximus) head kidney macrophages.

The effect of different cytokines and bacterial lipopolysaccharide (LPS) on turbot (Scophthalmus maximus) macrophage nitric oxide (NO) production has been studied. We have found two different responses concerning NO production in response to LPS. We have studied 43 turbot and only macrophage cultures derived from 30.2% of these turbot were significantly stimulated by LPS. The macrophage populations that did not respond to LPS, showed a constitutive production that was significantly reversed by NO inhibitors like N(G)-methyl-L-arginine (L-NMMA) and N-omega-nitro-L-arginine (L-NAME), and was dependent on intracellular calcium concentration. We studied the effect of other stimuli combined with LPS on the NO production of these otherwise non-responsive macrophages. LPS combined with turbot macrophage activating factor (MAF) containing supernatants, was capable of significantly stimulating some of these macrophage populations. The same response was observed when LPS was combined with turbot IFN-alphabeta-like substances. When LPS was combined with human recombinant tumor necrosis factor alpha (hrTNF-alpha), the NO production was significantly induced in all macrophage populations studied.

Animals↗