Microbiologica最新文献

A cell line (BS/BEK) which was obtained from bovine embryo kidney tissue, when studied at its 140th passage level it showed the following properties: 1. An epithelial-like morphology, possessing a heteroploid karyotype with a modal chromosome number ranging between 70 and 75 chromosomes. 2. It failed to produce tumors in mice and in hamster. 3. It was shown to be ready susceptible to the replication of several viral agents originated from a variety of animal species. 4. It was not contaminated by mycoplasma or other bacterial spp.

The effect of mengo virus replication on cell morphology and cytoskeletal organization has been studied in LW murine fibroblasts. Cell modifications were followed by scanning electron microscopy. The cytoskeleton was stained by immunofluorescence using antitubulin antibodies for microtubules, antivimentin antibodies for intermediate filaments and rhodamine-conjugated phalloidin for microfilaments. Cytopathic effects began in the early phase of virus infection amd were correlated with broad modifications of the microfilament network. Immunofluorescence experiments showed a rapid decrease in the number of bundles and clumps of filaments in the early stages of infection. Antibodies to tubulin and vimentin revealed no change in the pattern of microtubules and intermediate filaments. Viral protein synthesis was required for the morphological changes observed after viral infection.

The specificity of protective immunity against Salmonella typhimurium in mice immunized with porins from S. typhimurium, Salmonella enteritidis and Escherichia coli was studied. High levels of protection against S. typhimurium-infection were achieved in mice immunized with porins from S. typhimurium but not from S. enteritidis and E. coli. However, our serological studies demonstrated that porins from S. typhimurium, S. enteritidis and E. coli had antigenic cross-reactivity with each another; in particular, porins immunized with porins from S. typhimurium but not from S. enteritidis or E. coli exhibited the most significant levels of delayed type hypersensitivity reaction, interleukin-2 production and interferon-gamma production when they were elicited with whole cells of S. typhimurium. These observations suggested that the high levels of protection obtained by porin-immunization resulted from the induction of serovar specific cell-mediated immunity.

Five strains of Salmonella typhimurium were examined to determine the parameters of virulence. The virulent species significantly resisted the macrophage bactericidal activity (p less than 0.05). The chemiluminescent (CL) response was studied to determine the level of Oxygen-free radicals (OFR) generated and the antioxidant enzymes superoxidase dismutase (SOD), catalase and glutathione peroxidase were assayed to determine the antioxidant mechanism of S. typhimurium to subvert these microbicidal pathways. The levels of the various enzymes were correlated with the virulence (as determined by LD50) and the ability of the microorganisms to induce diarrhoea. Oxygen free radical (OFR) generation elicited by macrophages, in the presence of virulent and avirulent salmonellae was not statistically significant (p greater than 0.05). No correlation was found between the levels of the antioxidant enzymes and the LD50 values. Thus the oxygen-dependent pathways do not appear to play a role in the pathogenesis of salmonellosis, and do not specify the virulence of the microorganism. Immunological and biological assays revealed the virulent strain to be more toxigenic than the avirulent strain. Therefore, the basis of differing virulence in S. typhimurium may be the ability to make and release more toxin in vivo.

To obtain "functionally" CD4 negative human monocytes (0-5 CD4 +/1 x 10(6)/cells), 50 ng/5.10(5) cells of OKT4A were added daily after a pre-incubation with OKT4A (100 ng/5.10(5) cells. In our experimental conditions the blocking the CD4 receptor of human monocytes with OKT4A monoclonal antibody did not prevent HIV-1 infection, although the level of virus replication appeared lower than that in cultures without OKT4A. "Naturally"CD4 negative rabbit monocytes infected with HIV-1 also released a detectable level of virus after 12-15 up 28-30 days. In "naturally" CD4 negative rabbit monocytes and "functionally" CD4 negative human monocytes, the virus particles entering via phagocytosis are not infectious because multiple well defined virions were observed in phagocytic vacuoles and the envelopes of these particles did not appear to interact with the vacuolar membrane. The infectious particles were represented by endocytic vesicles containing only the core of HIV after fusion between the viral envelope and endocytic membrane. Fusion between the viral envelope and plasma membrane on the cellular surface was never observed, in spite of examining greater than 1000 virions bound the surface of human and rabbit macrophage monocytes. The absence of cytopathic effect in the rabbit and human CD4 negative monocytes infected with HIV-1, and conversely the presence of specific sequences of HIV in the genomic DNA may indicate that the macrophages-monocytes serve as an important reservoir for the persistence of HIV in infected hosts, similar to the other related Lentiviruses. Our virological data have also demonstrated that virus infection can be transmitted from rabbit and human infected monocytes to uninfected H9 cells. This preliminary study may offer important evidence for the development and testing of vaccines and compounds that inhibit HIV penetration of susceptible cells.

The efficacy of the Acridine-orange stain (AOS) in identifying Helicobacter pylori (HP)-like organisms in biopsy smears from adults with gastroduodenal disease was studied. The results obtained indicate that AOS can replace Gram Stain in HP organism identification in gastroduodenal mucosa specimen.

Rectal Lymphogranuloma venereum (LGV) due to Chlamydia trachomatis (Ct) serotype L2 is reported. LGV was isolated from the lymph node biopsy of a bisexual male and was cultured on McCoy cycloheximide treated-cells. Serological tests such as the Micro-immunofluorescent test and the indirect immunoperoxidase assay for Chlamydia trachomatis done on the patient's serum were positive with a titer of 1/200 and 1/256 respectively. Smears taken from the rectal discharge were stained by the direct immunoperoxidase assay and showed inclusion bodies with positive staining. The search for the origin source of infection as well as the diagnostic and follow-up strategy in the male and female partners is also discussed.

Poly(ADP-ribose)polymerase is a chromatin-bound enzyme which is activated by free DNA ends and is therefore stimulated by a variety of DNA-damaging agents. The enzyme transfers the ADP moiety of NAD to nuclear proteins to create protein-bound ADP-ribose polymers. Under conditions favouring an accelerated poly(ADP-ribose) polymer formation, the enzyme may exhaust cellular NAD pools. At the same time, or shortly thereafter ATP levels drop and cell viability eventually declines. As a series of chemical and physical agents which may play a role in activating latent HIV-1 infection or favouring HIV-1 replication, have a DNA-damaging activity, we investigated the behaviour of poly(ADP-ribose)polymerase activity in various types of HIV-1-infected cells. The results obtained show that HIV-1-infected cells to possess an increased poly(ADP-ribosol)ating activity together with an accentuated fragmentation of cellular DNA which are associated with the time course of HIV-1 replication. These data give circumstantial support to the hypothesis that a NAD-depdendent cellular suicide response to DNA damage, could play a role in the death of HIV-1 infected cells. In this respect, the impared immunocompetence of HIV-1-infected patients could bear some resemblance to immune attribution that sometimes accompanies some inborn errors affecting DNA precursor metabolism and DNA integrity.

The Authors report the isolation in Italy of Feline Immunodeficiency Virus (FIV) from a cat inoculated with whole blood from a naturally FIV infected cat. The virus was isolated in feline circulating leucocytes cultured in RPMI medium and stimulated with concanavalin-A and recombinant human interleukin-2. The infected cultures showed a characteristic cytopathic effect (ballooning degeneration, giant cell formation, cell death) and a specific fuorescence using FIV-positive cat serum and monoclonal antibodies against FIV. Furthermore, the culture supernatants contained magnesium-dependent reverse transcriptase activity.

In order to establish whether endothelial cells are involved in immunodeficiency virus type 1 (HIV-1) infection, we performed a virological study on endothelial cells isolated from human adipose tissue and infected with HIV-1 in vitro. Supernatants from cultures showed a reverse transcriptase activity starting one day after HIV inoculation. Viral rescue was significantly impaired in cycloheximide treated cells confirming a de novo synthesis of viral products.