Granulomas In Spleen Research Articles

Comparative pathogenicity and histopathological analysis of Edwardsiella anguillarum intraperitoneal infection in milkfish (Chanos chanos), Nile tilapia (Oreochromis niloticus) and Asian seabass (Lates calcarifer).

Edwardsiella anguillarum, a highly virulent species within the Edwardsiella genus, causes significant mortality in milkfish farms in Taiwan. This study aimed to investigate the comparison of milkfish susceptibility, a newly identified host species in Taiwanese aquaculture, with other species Nile tilapia (Oreochromis niloticus) and Asian seabass (Lates calcarifer), to E. anguillarum, elucidating its pathogenicity across both seawater and freshwater aquaculture environments. The results showed milkfish exhibited the highest mortality rate of 85% within 48 h of infection, whereas Nile tilapia exhibited a mortality rate of 70% between the second- and tenth-day post challenge, and seabass exhibited a mortality rate of 25% between the second- and sixth-day post challenge. Gross lesions observed in milkfish included splenomegaly and haemorrhage, whereas Nile tilapia exhibited signs of ascites, exophthalmia and brain haemorrhage. Seabass displayed spleen granulomas and haemorrhage at the injection site. Histopathological analysis revealed common features across all three species, including multifocal necrosis, bacterial presence in the necrotic areas, serositis and oedema. Asian seabass also exhibited chronic lesions in the form of splenic granulomas. This study highlights the high susceptibility of milkfish and Nile tilapia to E. anguillarum, emphasizing the urgent need for further investigation into targeted vaccine development for these fish species. These results not only deepen our understanding of the differing levels of pathogenicity among the three species but also offer valuable insights for improving disease prevention and management strategies in aquaculture, including those applied within polyculture systems and for the maintenance of aquaculture water environments.

Systemic mycobacteriosis along with concurrent fibroma in Goldfish, Carassius auratus from India

Aim: Goldfish (Carassius auratus L.), a freshwater fish belonging to the family Cyprinidae, is an important ornamental fish species in the world. Herewith, we report a case of systemic mycobacteriosis along with concurrent fibroma in goldfish. Methodology: The protruding mass and internal organs exhibiting lesions were collected for histopathology and molecular diagnosis. The sections of cutaneous mass were stained with haematoxylin and eosin (H&E) and Masson trichrome, whereas sections from spleen as well as kidney were stained with H&E and Ziehl-Neelsen. For identifying the etiological agent, 16S rRNA gene fragment was amplified and sequenced, using genus-specific primers for Mycobacterium sp. Results: In histopathology, multiple granulomas could be observed in kidney and spleen sections. Importantly, typical acid-fast bacilli were demonstrated in granulomas in spleen. The sequence of 16S rRNA gene fragment amplified from spleen and kidney showed maximum similarity to Mycobacterium stomatepiae. Besides, the histopathological characteristics of the protruding mass were consistent with cutaneous fibroma. Interpretation: These findings assume significance as several Mycobacterium species, including the current one from ornamental fish are reported to be of zoonotic significance.

Histological Changes of Electric Yellow Cichlid (Labidochromis caeruleus) Exposed to Acute and Chronic Cadmium Concentrations

In this study, electric yellow cichlid were (Labidochromis caeruleus) exposed to acute cadmium (Cd) concentrations (0, 50, 60, 70, 80 mg l-1) for 72 h, and chronic Cd concentrations (0.00, 0.25, 0.50, 1.00, 2.00 mg l-1) for 20 d to examine histological alternation. In addition to the recovery was detected after 10 d. After chronic trial, rest of the fish were exposed to just water not containing cadmium for 10 day for recovery. Gills, liver, muscle, and spleen samples were collected from randomly selected fish. The tissue samples prepared with standard techniques for haematoxylin and eosin (H&E). Cadmium depending on concentrations increase caused severe disorders on fish. After acute exposure, several changes were detected such as edema, hyperplasia, breakdown in epithelial tissues of gills; vacuolation and necrosis in liver; increase of hemosterin clustering and necrosis in spleen. After chronic exposure, some symptoms were also found such as edema, aneurysm, degermation of secondary lamellae in gills; degeneration and necrosis in liver; degeneration and granulomas in spleen. Additionally, after recovery of chronic Cd exposure some of the same symptoms were observed such as edema, hyperplasia and aneurysm in gills; vacuolar degeneration and necrosis in liver; granulomas and degeneration in spleen.

Spleen and head kidney differential gene expression patterns in trout infected with Lactococcus garvieae correlate with spleen granulomas

Lactococcus garvieae is a significant pathogen in aquaculture with a potential zoonotic risk. To begin to characterize the late immune response of trout to lactococcosis, we selected infected individuals showing clinical signs of lactococcosis. At the time lactococcosis clinical signs appeared, infection by L. garvieae induced a robust inflammatory response in the spleen of rainbow trout, which correlated with abundant granulomatous lesions. The response in kidney goes in parallel with that of spleen, and most of the gene regulations are similar in both organs. A correlation existed between the early inflammatory granulomas in spleen (containing macrophages with internalized L. garvieae) and up-regulated gene sets, which defined the presence of macrophages and neutrophils. This is the first analysis of the immune transcriptome of rainbow trout following L. garvieae infection during the initiation of adaptive immune mechanisms and shows a transcriptome induction of antibody response by both IgM (+) and IgT (+) spleen B cells to respond to systemic infection. These results increase our understanding of lactococcosis and pave the way for future research to improve control measures of lactococcosis on fish farms.

BCG infection in mice is promoted by naïve mesenchymal stromal cells (MSC) and suppressed by poly(A:U)-conditioned MSC

Mesenchymal stromal cells (MSC) transplantation is an actively studied therapeutic approach used in regenerative medicine and in the field of control of immunoinflammatory response. Conditioning of MSC in culture can form their predominantly pro- or anti-inflammatory phenotypes. We demonstrated that poly(A:U)-conditioning of bone marrow-derived mouse MSC induced predominantly pro-inflammatory phenotype. The effects of administration of naïve MSC (nMSC) or conditioned MSC (cMSC) on the course of mycobacterial infection were studied. BALB/c mice infected i.p. with 5×106M. bovis BCG were successively injected i.v. with 0.75×106 of nMSC or cMSC in 11 and 12.5 weeks after infection and sacrificed at the week 14. Histological and bacteriological examination of BCG-infected animals revealed low bacterial loads in liver, lungs and spleen; the bacterial load in spleen was higher than in other organs. Treatment with nMSC induced 3-fold increase of the number of bacteria in spleen granulomas, while cMSC decreased significantly the number of bacteria in BCG-positive granulomas. Analysis of preparations of organ homogenates by luminescent microscopy, MGIT cultures and CFU count on Lowenstein-Jensen medium revealed that nMSC promoted mycobacterial growth whereas cMSC suppressed mycobacterial growth significantly. We concluded that MSC therapy can be effective in mycobacterial infection, but only in a case of appropriate conditioning of the cells.

Pathogenesis of mixed infection by Spironucleus sp. and Citrobacter freundii in freshwater angelfish Pterophyllum scalare

The present study was carried out to identify and describe the pathology of the freshwater angelfish Pterophyllum scalare during chronic mortality in an in-door aquaculture system. Scraping of the integument and gills and the collection of intestinal contents to search for external and internal parasites were performed. Kidneys were collected aseptically for the microbiological analysis and the isolates were subjected to antibiotics to test for susceptibility. Subsequently, necropsy for macroscopic assessment and collection of internal organs for histopathology were performed. The fish exhibited lethargy, lip tumor, hemorrhage and liver granuloma. No ectoparasites were diagnosed. Endoparasites of the genus Spironucleus were found in large numbers in the intestine of the affected fish. In the microbiological analysis, Citrobacter freundii was isolated from the kidney and identified by colony PCR. This bacterium showed susceptibility to three of the eight antibiotics evaluated: ciprofloxacin, cefoxitin and tetracycline. For the pathological analysis, liver and spleen granulomas were present. In the intestinal tissue, a large and unusual amount of mast cells and their free granules were described and discussed in detail. The present study showed that mast cells play an important role during the chronic infection of freshwater angelfish.

Dynamics of piscine francisellosis differs amongst tilapia species (Oreochromis spp.) in a controlled challenge with Francisella noatunensis subsp. orientalis.

A 25-week immersion challenge was conducted exposing Oreochromis mossambicus, Oreochromis aureus and Oreochromis urolepis hornorum to Francisella noatunensis subsp. orientalis (Fno). Two populations were compared for each fish species; 'resident fish' were defined as fish maintained in tanks since week 0 of challenge, whereas 'naïve fish' were defined as fish added to tanks once temperature in water reached <26°C at 21weeks post-challenge. Fno genome equivalents (GEs) in water were similar in all treatments 1h post-challenge; however, significantly lower Fno GEs were detected 2weeks post-challenge in all tanks, and the only treatment with detectable Fno GE after 4weeks of challenge were the O.mossambicus tanks. Twenty-one weeks post-challenge, naïve fish were stocked with 'resident' cohorts. Over a 4-week period, mortalities occurred consistently only in O.mossambicus naïve cohorts. Overall presence of granulomas in spleen of survivors was similar (>55%) in all resident populations; however, in naïve populations, only O.mossambicus presented granulomas. Similarly, only O.mossambicus presented viable Fno in the spleen of survivors, and Fno GEs were only detected in O.mossambicus, and in resident O.aureus. In conclusion, the results of this study suggest different susceptibility of tilapia species to piscine francisellosis.

In vitro Study of BCG Granuloma Macrophage Morphofunctional Status

We studied the morphofunctional and cytophysiological status of macrophages emigrating from BCG granulomas forming in spleen and free splenic macrophages that are not associated with granulomas. The experimental BCG granulomatosis was induced by intravenous injection of male BALB/c mice with BCG vaccine mycobacteria. The number of granulomas in spleen, their diameter, the proportion of granuloma macrophages with mycobacteria, the number of mycobacteria in granuloma macrophages, the proportion of live bacteria in granuloma macrophages and the number of granulomas macrophages capable of expressing IL-1α, TNF-α, GM-CSF were evaluated. BCG granulomas were explanted in cultures in vitro. Fractions, containing free splenic macrophages from BCG-infected animals, were explanted in separate cultures in vitro. The phagocytic activity of macrophages that migrated from BCG granulomas explanted in cultures one month after mycobacterial infection of mice, was much higher than those of splenic macrophages of intact mice. The phagocytic activity of free macrophages and macrophages from granulomas decreased with time after infection. By contrast, the antimycobacterial activity of free splenic macrophages and macrophages from BCG granulomas increased with time after infection. The correlational analysis showed that there are different correlational relationships between the number of granuloma macrophages expressing IL-1α, TNF-α, GM-CSF and phagocytic activity of macrophages from BCG granulomas. The results of the study are important for understanding the molecular and cellularmechanisms of development of chronic granulomatous inflammation induced by mycobacterial infection.

Detection of Cyprinid herpesvirus 2 in association with an Aeromonas sobria infection of Carassius carassius (L.), in Italy

Sixteen specimens of female crucian carp, Carassius carassius (L.), during the breeding season, were investigated for post-mortem and full diagnostic examination during a mortality outbreak in a tributary stream of the Arno River in Tuscany in 2011. Necropsy highlighted the presence of a swollen anus and widespread haemorrhages in the body, fins, gills and eyes. Haemorrhages in internal organs and spleen granulomas were also observed. Bacteria isolated from the brain, kidney and spleen of affected fish were identified as A.sobria. Microscopic lesions observed in gills were characterized by necrosis of the secondary lamellae, congestion and multifocal lamellar fusion. The kidney showed necrosis, oedema, fibrin exudation and areas of haemorrhages, while in the spleen the main lesions were by multifocal necrosis of the lymphoid tissue. In the gills, transmission electron microscopy revealed herpesvirus-like particles, subsequently identified as Cyprinid herpesvirus-2 (CyHV-2) with a nested PCR protocol. Although it was not possible to attribute a pathogenic role to CyHV-2 in this mortality event, the identification of this herpesvirus in crucian carp increases the concern about its potential role in this species.

English

Mesenchymal chondrosarcoma (MSC) is rare form of chondrosarcoma which usually arises in bone. Extraskeletal mesenchymal chondrosarcomas are far less common and accounts approximately 30-50% of all mesenchymal chondrosarcomas. We report a rare case of intra-abdominal extraskeletal MSC in a 10 yr old girl who presented with biliary vomitings and abdominal pain. Ultrasound abdomen showed 42x24 mm hypoechoic mass in right iliac fossa. CT abdomen showed calcified granulomas in spleen, Soft tissue dense lesion in right iliac fossa, suggestive of lymphadenopathy. Histopathology and immunohistochemistry confirmed the

Letter to the Editor

Letter to the Editor

Lactobacillus fermentum ME-3 - an antimicrobial and antioxidative probiotic.

The paper lays out the short scientific history and characteristics of the new probiotic Lactobacillus fermentum strain ME-3 DSM-14241, elaborated according to the regulations of WHO/FAO (2002). L. fermentum ME-3 is a unique strain of Lactobacillus species, having at the same time the antimicrobial and physiologically effective antioxidative properties and expressing health-promoting characteristics if consumed. Tartu University has patented this strain in Estonia (priority June 2001, patent in 2006), Russia (patent in 2006) and the USA (patent in 2007). The paper describes the process of the identification and molecular typing of this probiotic strain of human origin, its deposition in an international culture collection, and its safety assessment by laboratory tests and testing on experimental animals and volunteers. It has been established that L. fermentum strain ME-3 has double functional properties: antimicrobial activity against intestinal pathogens and high total antioxidative activity (TAA) and total antioxidative status (TAS) of intact cells and lysates, and it is characterized by a complete glutathione system: synthesis, uptake and redox turnover. The functional efficacy of the antimicrobial and antioxidative probiotic has been proven by the eradication of salmonellas and the reduction of liver and spleen granulomas in Salmonella Typhimurium-infected mice treated with the combination of ofloxacin and L. fermentum strain ME-3. Using capsules or foodstuffs enriched with L. fermentum ME-3, different clinical study designs (including double-blind, placebo-controlled, crossover studies) and different subjects (healthy volunteers, allergic patients and those recovering from a stroke), it has been shown that this probiotic increased the antioxidative activity of sera and improved the composition of the low-density lipid particles (LDL) and post-prandial lipids as well as oxidative stress status, thus demonstrating a remarkable anti-atherogenic effect. The elaboration of the probiotic L. fermentum strain ME-3 has drawn on wide international cooperative research and has taken more than 12 years altogether. The new ME-3 probiotic-containing products have been successfully marketed and sold in Baltic countries and Finland.

Eradication of Salmonella Typhimurium infection in a murine model of typhoid fever with the combination of probiotic Lactobacillus fermentum ME-3 and ofloxacin

BackgroundThe aim of the study was to detect whether in experimental Salmonella enterica Typhimurium infection the probiotic Lactobacillus fermentum ME-3 in combination with fluoroquinolone therapy would eradicate S. Typhimurium, prevent the development of liver and spleen granulomas and improve the indices of oxidative stress in the ileum mucosa.The selected bacteriological, histological and biochemical methods were applied.ResultsCombined treatment with L. fermentum ME-3 and ofloxacin eradicated Salmonella Typhimurium from blood, ileum and liver, decreased the number of animals with liver and spleen granulomas and reduced the value of lipid peroxides in the ileum mucosa. Higher total counts of intestinal lactobacilli in all experimental groups were associated with the absence of liver granulomas.ConclusionThe antimicrobial and antioxidative probiotic L. fermentum ME-3 combined with ofloxacin enhances the eradication of experimental S. Typhimurium infection. These observations on probiotic and antimicrobial co-action may serve as basis to develop new strategies for treatment of invasive bacterial infections of the gut.

Vanin‐1 controls granuloma formation and macrophage polarization in Coxiella burnetii infection

Q fever is caused by Coxiella burnetii, a bacterium that survives in MPhi. Vanin-1 is a membrane-anchored pantetheinase that controls tissue inflammation. Consequently, Vanin-1-deficient mice represent a unique mouse model in which stress-induced inflammation is limited by the reaction of resident tissue cells. To investigate the contribution of host tissues in the control of a bacterial infection, we infected Vanin-1-deficient mice with C. burnetii. Mortality and morbidity of mice were not affected. The lack of Vanin-1 had no effect on C. burnetii clearance but decreased the formation of granulomas in spleen and liver. Granuloma formation depends upon MPhi recruitment and activation in these tissues. Whereas the former was slightly impaired in mutant mice, the lack of Vanin-1 significantly affected the activation pattern of BM-derived MPhi stimulated by C. burnetii. While their microbicidal activity against C. burnetii was moderately impaired, they exhibited decreased inducible nitric oxide synthase (iNOS) and MCP-1 gene expression, and increased IL-10 and arginase expression. In liver from mutant mice, increased arginase expression and decreased expression of MCP-1 and iNOS were reminiscent of MPhi data. These results suggest a role of Vanin-1 in granuloma formation in response to C. burnetii by skewing MPhi activation toward an M2 program.

Examination of Mycobacterium tuberculosis sigma factor mutants using low-dose aerosol infection of guinea pigs suggests a role for SigC in pathogenesis

Secondary sigma factors in bacteria direct transcription of defence regulons in response to specific stresses. To identify which sigma factors in the human respiratory pathogen Mycobacterium tuberculosis are important for adaptive survival in vivo, defined null mutations were created in individual sigma factor genes. In this study, in vitro growth virulence and guinea pig pathology of M. tuberculosis mutants lacking functional sigma factors (SigC, SigF, or SigM) were compared to the parent strain, H37Rv. None of the mutant strains exhibited a growth deficiency in Middlebrook 7H9 broth, nor were any impaired for intracellular replication in the human monocytic macrophage cell-line THP-1. Following low-dose aerosol infection of guinea pigs, however, differences could be detected. While a SigM mutant resulted in lung and spleen granulomas of comparable composition to those found in H37Rv-infected animals, a SigF mutant was partially attenuated, exhibiting necrotic spleen granulomas and ill-defined lung granulomas. SigC mutants exhibited attenuation in the lung and spleen; notably, necrotic granulomas were absent. These data suggest that while SigF may be important for survival in the lung, SigC is likely a key regulator of pathogenesis and adaptive survival in the lung and spleen. Understanding how SigC mediates survival in the host should prove useful in the development of anti-tuberculosis therapies.

Interaction of Bartonella henselae with the murine macrophage cell line J774: infection and proinflammatory response.

Bartonella henselae is the causative agent of cat scratch disease (CSD), a self-limiting condition characterized by a subacute regional lymphadenopathy that may develop into disseminated bartonellosis in immunocompromised subjects. Mice experimentally infected with B. henselae display typical liver and spleen granulomas rich in T cells and macrophages. So far there are no data on the interaction between bartonellae and macrophages. In order to clarify this topic, we investigated the interaction of B. henselae with J774, a mouse macrophage cell line. Analysis of bacterial uptake by functional assays and transmission electron microscopy indicates that bartonellae can enter and survive inside J774. Entry occurred within 30 min postinfection and reached a plateau at 160 min. Infection of J774 was followed by a dose-dependent release of the proinflammatory cytokines tumor necrosis factor alpha, interleukin 1beta (IL-1beta), and IL-6. Bartonellae persisted intracellularly without loss of viability for at least 8 h, and their number slightly decreased 24 h postinfection. Gamma interferon (IFN-gamma) treatment of J774 significantly decreased the number of recoverable bacteria at 8 and 24 h. This enhancement of macrophage bactericidal activity was associated with nitric oxide (NO) release and was prevented by the addition of the competitive inhibitor of NO synthesis N(G)-monomethyl L-arginine. These findings suggest that IFN-gamma-mediated activation of macrophages may be important for the clearing of B. henselae infection and that anti-B. henselae microbicidal activity of IFN-gamma-activated macrophages is mediated to a large extent by NO production.

A Hyphomycete Fungus,Paecilomyces lilacinus, Associated with Wasting Disease in Two Species of Tilapia from Puerto Rico

The hyphomycete Paecilomyces lilacinus was isolated from internal tissue samples of a hatchery-raised blue tilapia Tilapia aurea and three of nine feral Mozambique tilapias T. mossambica suffering from tilapia wasting disease in Puerto Rico. Gross cultural and microscopical features of this fungus closely resemble those of P. farinosis and P. marquandii, both of which have been previously isolated from fish tissues. They also resemble features of P. fumoso-roseus, a species that has been isolated from a captive tortoise. However, the species from tilapia can be distinguished from these other species of Paecilomyces by its production of a brown exudate on Czapek yeast agar (CYA), its deep brown reverse coloration on CYA and Blakeskee malt extract agar (MEA), and its longer, more slender, solitary phialides. It can be further differentiated from these species by growth at 37°C, which is absent in the other three species. Externally, infected fish were emaciated and had sunken eyes and relatively large heads. They also had eroded fins and hemorrhagic, occasionally scaleless lesions up to 5 cm wide on their flanks. Internally, their gastrointestinal tracts and body cavities contained a clear, light amber fluid. Infections were also marked by the presence of numerous golden to reddish-brown granulomas, 0.3–1.3 mm wide, throughout the internal organs. Histopathology revealed that granulomas in spleen, kidney, and liver samples from the blue tilapia and from 12 of 18 Mozambique tilapias collected between 1992 and 1998 were composed of necrotic foci containing invading hyphae, hyphal fragments, conidia, and mixed cellular and caseous material. Bacteria were not observed in the lesion material. As tilapia wasting disease is an apparently common and fatal disease in the Mandri and Santa Teresa lagoons, we recommend that further studies be undertaken to determine the source and route of infection for possible control measures.

A role for lymphotoxin beta receptor in host defense against Mycobacterium bovis BCG infection.

To investigate the role of membrane lymphotoxin (LT)alpha1 / beta2 and its LTbeta receptor (LTbetaR) in the protective immune response to Mycobacterium bovis bacillus Calmette-Guérin (BCG) infection, we have used a soluble fusion molecule (LTbetaR-IgG1). LTbetaR-Ig treatment interferes with granuloma formation mainly in the spleen by inhibiting macrophage activation and nitric oxide synthase activity. In addition, a large accumulation of eosinophils was observed in the spleen of LTbetaR-Ig-treated infected mice. Decreased blood levels of IFN-gamma and increased IL-4 were also observed, suggesting that the LTbetaR pathway is important in BCG infection to favor a Th1 type of immune response. The treatment of transgenic mice expressing high blood levels of a soluble TNFR1-IgG3 fusion protein with LTbetaR-Ig resulted in a still higher sensitivity to BCG infection, and extensive necrosis in the spleen. In conclusion, these results suggest that the LTbetaR and the TNFR pathways are not redundant in the course of BCG infection and protective granuloma formation: the LTbetaR pathway appears to be important in spleen granuloma formation, whereas the TNFR pathway has a predominant role in other tissues.

Cytokines and the immune response.

Cytokines participate in many physiological processes including the regulation of immune and inflammatory responses. These effector molecules are produced transiently and locally controlling the amplitude and duration of the response. A variety of experiments has shown that excessive or insufficient production may significantly contribute to the pathophysiology of a range of diseases. Particularly cytokines released by CD4+ T cells at the onset of an immune response are thought to be decisive for pathological or physiological consequences. The meeting in Budapest was focussed on cytokines known to contribute to the pathophysiology of autoimmune diseases, infectious diseases and allograft rejection (e.g., IL-1, IL-4, IL-6, IL-10, IL-12, TNF-alpha and IFN-alpha, -beta, -gamma). A central role for IFN-gamma in autoimmunity was suggested by blocking experiments in vivo using monoclonal antibodies and soluble forms of the IFN-gamma receptor (IFN-gamma SR). These agents ameliorated disease development in a variety of experimental autoimmune diseases in rodents. In a mouse model for the human disease Myasthenia gravis, IFN-alpha was found to reduce both the incidence and progression of the disease. Treatment of R. aurantiacus-infected mice with anti-IL-4 monoclonal antibodies (mAbs) was reported to interfere with the regression of granulomas in spleen and liver, most likely through inadequate IL-4-mediated suppression of IFN-gamma production. In addition, it was shown that mice with disrupted IFN-gamma R genes died rapidly after infection with the BCG strain of M. bovis, whereas normal mice survived the infection. IL-12 was found to be the main inductor of IFN-gamma during the lethal Shwartzman reaction. TNF-alpha was identified as the principal cause of mortality after the second injection with LPS. In a variety of studies examining the role of cytokines in the pathogenesis of AIDS, much attention was given to the in vitro effects of HIV-1 and/or the HIV-1 viral membrane protein gp120 on triggering cytokine production by peripheral blood leukocytes (PBLs) and purified monocytes/macrophages (Mø) originating from healthy donors. Gp120 as a sole agent significantly suppressed IFN-gamma production by mitogen-stimulated PBLs and induced the production of IFN-alpha in cultures of normal human peripheral blood mononuclear cells (PBMCs). In a human macrophage cell line, TNF-alpha exerted a stimulatory effect on viral replication and programmed cell death induced by HIV-1 which was potentiated by the simultaneous incubation with IFN-gamma. Upon transfection of human PBLs and CD4+ T cells with a retroviral vector encoding human IFN-beta, a notable reduction in reverse transcriptase activity after HIV-1 challenge was observed. Gp120 was also found to induce both IL-6 and TNF-alpha expression and to induce morphological changes reminiscent for apoptosis in primary astrocytes and in a re-aggregated human brain cell model, suggesting a role for these cytokines in the neuropathology of AIDS dementia. Moreover, data were presented indicating that cytokine-induced expression of cell adhesion molecules (e.g., ICAM-1) in HIV-1 infected U 937 cells leads to high level incorporation of this molecule in the membrane of the viral progeny which may play a role in the attachment of such virions to CD4-negative cells.

Histopathology of experimental Streptococcus sp. infection in tilapia, Oroochromis niloticus (L.), and channel catfish, Ictafurus punctatus (Ratinesque)

AbstractNile tilapia, Oreochromis niloticus (L.), and channel catfish, Ictalurus punctatus (Rafinesque), were experimentally infected by immersion with three isolates (Lake, DL8O5 and MS91452) of Streptococcus sp. from diseased fish. To enhance infection, the lateral body surface of each fish was scraped prior to bacterial exposure. The Lake and DL8O5 isolates caused exophthalmia, ocular opacity and ocular haemorrhage in some tilapia. Histopathology of these fish revealed; meningitis; polyserositis of heart, liver, spleen, ovary and kidney; splenitis; ovaritis; and myocarditis. Isolate MS91452 induced only mild granulomas in spleen, kidney and ovary of tilapia. The Lake and DL8O5 isolates induced endophthalitis, Channel catfish infected with the Lake and DL805 isolates developed similar eye lesions to tilapia. Histologic lesions caused by all three isolates in channel catfish consisted of meningoencephalitis, mild myocarditis, splenitis and ovaritis, but these lesions were not as severe as in Nile tilapia.