Spectrum of Aeromonas and Plesiomonas infections in patients with cancer and AIDS

The spectrum of infection with Aeromonas and Plesiomonas included gastroenteritis, bacteremia, biliary tract infection, perirectal infection, and disseminated disease. Most patients (86%) with bacteremia were neutropenic (less than 500 PMN/mm3). Colonization of stools and sputum also occurred. Therapy with aminoglycosides, beta-lactams, trimethoprim/sulfamethoxazole, and the newer quinolones was effective in patients with AIDS and cancer.     

In vitro proliferation of human large granular lymphocytes with v-raf/v-myc recombinant retrovirus

The effect of infection with a retrovirus carrying v-raf/v-myc oncogenes (J2 virus) on the in vitro proliferation of human large granular lymphocytes (LGL) was investigated. LGL infected with J2 virus (J2LGL), unlike uninfected cells, grew with a proliferation peak eight days after infection. Such cells retained the morphology and functional properties typical of LGL. Furthermore, 5% of J2LGL produced virus the day after infection, whereas non-virus production was detectable five days later. These data indicate that J2 virus provides a transient mitogenic signal for LGL.     

Suppression of phytohemagglutinin induced splenocyte proliferation during concurrent infection withEimeria nieschulzi andNippostrongylus brasiliensis

Summary Results suggest that infection withEimeria nieschulzi (Protozoa) interferes with splenocyte proliferation induced by infection withNippostrongylus brasiliensis (Nematoda).This study was supported by NIH MBRS Grant RR08012-15.     

Activation of GCN2 upon HIV-1 infection and inhibition of translation

Higher eukaryotic organisms have a variety of specific and nonspecific defense mechanisms against viral invaders. In animal cells, viral replication may be limited through the decrease in translation. Some viruses, however, have evolved mechanisms that counteract the response of the host. We report that infection by HIV-1 triggers acute decrease in translation. The human protein kinase GCN2 (eIF2AK4) is activated by phosphorylation upon HIV-1 infection in the hours following infection. Thus, infection by HIV-1 constitutes a stress that leads to the activation of GCN2 with a resulting decrease in protein synthesis. We have shown that GCN2 interacts with HIV-1 integrase (IN). Transfection of IN in amino acid-starved cells, where GCN2 is activated, increases the protein synthesis level. These results point to an as yet unknown role of GCN2 as an early mediator in the cellular response to HIV-1 infection, and suggest that the virus is able to overcome the involvement of GCN2 in the cellular response by eliciting methods to maintain protein synthesis.     

The course ofPlasmodium berghei infection in mice latently infected withToxoplasma gondii

Summary The course of infection with 2 different virulent strains ofPlasmodium berghei was investigated in mice latently infected withToxoplasma gondii. When given the highly virulent ANKA strain ofP. berghei all Toxoplasma-infected mice died but the survival time was prolonged. After infection with the less virulent strain K 173 mice could survive the subsequent infection. In these cases levels of parasitemia depended upon the duration of theT. gondii infection. Mice infected for about 6 weeks withT. gondii showed maximum protection. These studies were conducted in the Institut für Medizinische Parasitologie der Universit?t Bonn (D-5300 Bonn, Federal Republic of Germany).     

Gamma-glutamyl-transpeptidase in lymphatic tissues of Mastomys natalensis during an infection with Acanthocheilonema viteae

During Acanthocheilonema viteae infection, the specific activity of gamma-glutamyltranspeptidase (gamma-GT) increased in peritoneal exudate cells and bone marrow and decreased in lymph nodes of Mastomys natalensis throughout the course of infection. However, though there was an increase in specific activity of gamma-GT in thymus and spleen during the prepatent phase of A. viteae infection, the level either returned to normal or decreased during the latent phase of infection. A close correlation was observed between the host's immune status during A. viteae infection and the level of gamma-GT in lymphoid tissues.     

Die Veränderungen der Succinodehydrase-Aktivität in Detroit-6 (VA) Zellen,infolge der Infektion mit demHepatitis-infectiosa-Virus

Summary The inhibitory action ofHepatitis infectiosa virus on the SDH activity of Detroit-6 (VA) cell lines was investigated. The full inhibition of the SDH activity took place at the end of the third day after the infection. As this phenomenon precedes the cytopathogenetic effect of viral infection, it may be of some help in the early detection of the infection.     

Intestinal glucose absorption in rats after secondary infections withNippostrongylus brasiliensis

Summary A challenge infection ofNippostrongylus brasiliensis in immune rats resulted in an earlier onset of intestinal glucose malabsorption and increased glucose metabolism compared with rats receiving a primary infection. Intestinal absorption and metabolism recovered to control levels earlier during a secondary infection. The pattern of changes in absorption and metabolism was probably related to host immunological activity.     

CD11b-bearing mononuclear leucocytes and IgA levels in the staging of human immunodeficiency virus infection.

Certain immunological parameters (i.e. low CD4+ T cell numbers, high serum soluble CD8) have been described as prognostic factors for the progression of human immunodeficiency virus (HIV) infection to later clinical stages. In the present study we have found in one hundred HIV-infected Spanish patients (81% drug abusers, 7% homosexuals, 6% heterosexuals, and 6% other or unknown risk groups) that CD11b+ peripheral blood mononuclear cells are increased in those with persistent lymphadenopathy as compared to other clinical stages (asymptomatic, AIDS-related complex and AIDS). Serum IgA was significantly increased in AIDS patients, and in patients at any other clinical stage who had concomitant infections (mainly mycobacterial and fungal). CD11b (an integrin with complement receptor functions) may thus be of clinical interest for the staging of HIV-infected patients, and reflect stage-selective immunological changes in mononuclear cell biology during HIV infection. High IgA on the other hand, would be a marker of concomitant infection as well as of disease progression. The results concern mostly drug addicts (the main risk group in Spain), but may apply to the other risk groups because no significant differences were detected between drug addicts (n = 81) and non-drug addicts (n = 19) for the studied variables (p greater than 0.05).     

CD11b-bearing mononuclear leucocytes and IgA levels in the staging of human immunodeficiency virus infection

Certain immunological parameters (i.e. low CD4+ T cell numbers, high serum soluble CD8) have been described as prognostic factors for the progression of human immunodeficiency virus (HIV) infection to later clinical stages. In the present study we have found in one hundred HIV-infected Spanish patients (81% drug abusers, 7% homosexuals, 6% heterosexuals, and 6% other or unknown risk groups) that CD11b+ peripheral blood mononuclear cells are increased in those with persistent lymphadenopathy as compared to other clinical stages (asymptomatic, AIDS-related complex and AIDS). Serum IgA was significantly increased in AIDS patients, and in patients at any other clinical stage who had concomitant infections (mainly mycobacterial and fungal). CD11b (an integrin with complement receptor functions) may thus be of clinical interest for the staging of HIV-infected patients, and reflect stage-selective immunological changes in mononuclear cell biology during HIV infection. High IgA on the other hand, would be a marker of concomitant infection as well as of disease progression. The results concern mostly drug addicts (the main risk group in Spain), but may apply to the other risk groups because no significant differences were detected between drug addicts (n=81) and non-drug addicts (n=19) for the studied variables (p>0.05).     

Glycine absorption from the small intestines of rats after secondary infections with Eimeria nieschulzi

A second (challenge) infection of Eimeria nieschulzi in clinically immune rats did not produce weight gain depression but caused a decrease in the absorption of glycine from the ileum. The malabsorption due to challenge was equivalent to that caused by the primary infection which did cause weight loss.     

Does the diabetes caused by viral infection in mice depend on immune reactions?]

Normal DBA2 mice become highly diabetic after infection with the EMC virus. But 500 R X-irradiation before infection inhibits the increase of mean blood glucose levels thus indicating the participation of immune reactions in the appearance of diabetes.     

Evidence for a role of IFN gamma in control of Listeria monocytogenes in T cell deficient mice.

The role of interferon (IFN) gamma in controlling chronic infections of Listeria monocytogenes (Listeria) was studied in athymic C57BL/6 nu/nu mice, and by treating thymectomized C57BL/6 +/+ mice with monoclonal rat CD4 and CD8-specific monoclonal antibodies (Mab). Mice treated with a combination of the two T cell subset antibodies were similar to athymic, nude mice in being able to control Listeria infection, keeping the titers below 3-5 log10 bacteria per organ, but they could not eliminate them completely. Treatment with antibodies to IFN gamma of nude or CD4+ + CD8+ - T cell-depleted mice suffering from chronic Listeria infection caused a marked increase of Listeria titers in liver and spleen. This result implies a role of IFN gamma in maintaining anti-Listeria resistance in mice lacking mature T cells.     

Glycine absorption from the small intestines of rats after secondary infections withEimeria nieschulzi

Summary A second (challenge) infection ofEimeria nieschulzi in clinically immune rats did not produce weight gain depression but caused a decrease in the absorption of glycine from the ileum. The malabsorption due to challenge was equivalent to that caused by the primary infection which did cause weight loss.     

Infection of cultured intestinal epithelial cells with severe acute respiratory syndrome coronavirus

To identify a model for the study of intestinal pathogenesis of severe acute respiratory syndrome (SARS) we tested the sensitivity of six human intestinal epithelial cell lines to infection with SARS coronavirus (SARS-CoV). In permissive cell lines, effects of SARS-CoV on cellular gene expression were analysed using high-density oligonucleotide arrays. Caco-2 and CL-14 cell lines were found to be highly permissive to SARS-CoV, due to the presence of angiotensin-converting enzyme 2 as a functional receptor. In both cell lines, SARS-CoV infection deregulated expression of cellular genes which may be important for the intestinal pathogenesis of SARS.Received 23 May 2004; received after revision 23 June 2004; accepted 25 June 2004     

<Emphasis Type="Italic">Yersinia pseudotuberculosis</Emphasis> supports Th17 differentiation and limits de novo regulatory T cell induction by directly interfering with T cell receptor signaling

Adaptive immunity critically contributes to control acute infection with enteropathogenic Yersinia pseudotuberculosis; however, the role of CD4⁺ T cell subsets in establishing infection and allowing pathogen persistence remains elusive. Here, we assessed the modulatory capacity of Y. pseudotuberculosis on CD4⁺ T cell differentiation. Using in vivo assays, we report that infection with Y. pseudotuberculosis resulted in enhanced priming of IL-17-producing T cells (Th17 cells), whereas induction of Foxp3⁺ regulatory T cells (Tregs) was severely disrupted in gut-draining mesenteric lymph nodes (mLNs), in line with altered frequencies of tolerogenic and proinflammatory dendritic cell (DC) subsets within mLNs. Additionally, by using a DC-free in vitro system, we could demonstrate that Y. pseudotuberculosis can directly modulate T cell receptor (TCR) downstream signaling within naïve CD4⁺ T cells and Tregs via injection of effector molecules through the type III secretion system, thereby affecting their functional properties. Importantly, modulation of naïve CD4⁺ T cells by Y. pseudotuberculosis resulted in an enhanced Th17 differentiation and decreased induction of Foxp3⁺ Tregs in vitro. These findings shed light to the adjustment of the Th17-Treg axis in response to acute Y. pseudotuberculosis infection and highlight the direct modulation of CD4⁺ T cell subsets by altering their TCR downstream signaling.     

Suppression of intrinsic B-cell function in Dengue-infected mice.

Mice infected with Dengue virus show a depressed immune response to lipopolysaccharide (LPS), a helper T-cell-independent antigen, when LPS was administered on day 0, 6 and 12 post infection. Mice injected with inactivated virus failed to show immunosuppression.     

In vitro transmission of mouse leukemia virus to restrictive mouse cells: necessity for mixed infection by two different leukemia viruses]

The plaque formation of murine leukemia virus (MuLV) in non permissive mouse cells (N-tropic MuLV in B-type cells, or B-tropic MuLV in N-type cells) was increased by murine sarcoma virus whose plaque-forming activity was extremely low (MuSV XC-). The infection of N-tropic MuLV in B-type cells was increased by MuSV XC- propagated only in N-type cells but not in B-type cells, and the infection of B-tropic MuLV in N-type cells by MuSV XC- propagated only in B-type cells but not in N-type cells.