Microbiologica最新文献

This study suggests the possibility that the intracellular parasite Chlamydia trachomatis (Ct) may facilitate the transmission of the human immunodeficiency virus (HIV) during vaginal or rectal intercourse. This is based on the following findings: a) elevated titers of anti-Ct IgG are present in symptomatic acquired immunodeficiency syndrome (AIDS) patients; b) elevated titers of anti-Ct IgA are found in asymptomatic AIDS patients; c) low anti-Ct IgA titers were observed during the progression of the disease; d) high titers of anti-Ct IgA were found in patients suffering from autoimmune diseases; e) high levels of C3 fraction of the complement are found in many of the Ct patients. The presence of anti-Ct IgA and high C3 may be crucial since IgA inactivates Ct and C3 which may increase the invasion of HIV into the cells. This activity of IgA and C3 in Ct patients may increase the susceptibility of male homosexuals and other risk groups in the population to AIDS.

Serum antibody assay of 1045 serum samples from birds vaccinated with Newcastle Disease vaccine by HI test and ELISA was carried out. Five hundred and twenty seven birds were challenged with virulent virus and data on HI test, ELISA and challenge test results were used for comparison. A good correlation between HI titres, ELISA absorbance and potency was observed indicating the usefulness of ELISA for potency estimation of vaccines and determination of immunization level in vaccinated flocks.

Analysis of the growth requirements of Epstein-Barr virus (EBV)-transformed B lymphocytes shows that interleukin 1 and thioredoxin, a disulfide reducing enzyme, are able to induce a marked increase in DNA synthesis in the early phases of in vitro culture. By contrast, interleukin 6 induces a steady increase in DNA synthesis comparable to that observed with crude conditioned supernatant. Furthermore, EBV-transformed B cells exhibit a density-dependent responsiveness to autocrine growth factors, thus suggesting that growth regulation of EBV-transformed B cells might result from the interplay between different self-stimulating soluble factors and from the competence of the cells to respond to autocrine growth factors.

The production of granulocyte/macrophage-colony stimulating factor (GM-CSF), interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) were evaluated in the supernatants of short-term cultures of purified CD4+ T-lymphocytes and enriched monocytes obtained from peripheral blood (PB) of 35 HIV-1 seropositive (+) asymptomatic individuals, stages I-II of the Walter Reed (WR) classification, 15 HIV (+) symptomatic patients (WR V-VI) and 40 HIV-1 seronegative normal blood donors. IL-1 beta and TNF-alpha production by either enriched monocytes or isolated CD4+ T-cells, was similar in HIV-1 (+) asymptomatic, symptomatic subjects and normal controls. GM-CSF level in enriched monocyte culture supernatants did not show any significant difference in the three groups of subjects under investigation. On the other hand, GM-CSF production by isolated CD4+ T-lymphocytes was two-fold decreased in HIV-1 (+) asymptomatic subjects and five-fold decreased in HIV-1 (+) symptomatic patients with respect to normal blood donors. The decline in GM-CSF production was clearly correlated with viral isolation from patient's PB light density mononuclear cells (r = -0.920, p less than 0.01). The selective and progressive decline in GM-CSF production by CD4+ T-lymphocytes, starting from early stages of HIV-1 infection, suggest a preferential lesion of a specific subset of CD4+ T-lymphocytes characterized by an intense production of GM-CSF and may contribute to explain the deranged inflammatory and immune responses which characterize the course of HIV-1 infection.

We produced a large panel of murine monoclonal antibodies against surface determinants of Trichomonas vaginalis using the hybridoma technique. An immunoenzymatic technique (E.L.I.S.A.) was used to screen positive hybrid cells producing specific antibodies against the protozoan surface. Eleven monoclonal antibodies (Mabs) out of seventy-seven positives were further characterized. We tested antibody reactivity in order to investigate the antigenic variance among 13 different strains of Trichomonas vaginalis of different geographic origin. To elucidate the complexity of antigenic expression in Trichomonas vaginalis, further characterization of the antigenic pattern in our 13 clinical isolates was carried out by immunoblotting techniques. We demonstrate that some monoclonal antibodies react with antigens varying in molecular weight in the different strains tested. We also demonstrate the pivotal role of protozoan proteases in antigenic rearrangement.

A technique for the detection and typing of genital infections with human papilloma virus (HPV) is described. Following a non-invasive sampling and a simplified preparation procedure, the analysis was performed as a combined dot-blot and Southern blot analysis, where the former test was used to exclude cases without demonstrable content of HPV DNA. The subgenomic probes used in the Southern blot analyses have a higher specificity than can be achieved with genomic ones, and only one band is obtained for each of HPV types 6, 11, 16, 18, 31, 33 and 35. Extra bands indicating the presence of cross-reacting HPV of undetermined type occurred in only 0.7% of the 1,268 cases tested. HPV was demonstrated in 7.8% of the 612 health control samples and in 16% of 634 consecutive samples from patients with symptoms. All but type 18 occurred more commonly in symptomatic than in asymptomatic patients. Presence of HPV also correlated to cervical intraepithelial neoplasia (CIN) in simultaneously collected smears. The HPV was demonstrated in 13% of patients with normal cytology, in 45% with CIN and in 82% of patients with invasive carcinoma. All types of HPV occurred more commonly in CIN patients, while only types 16, 18, 31 and 33 were found in the patients with cancer.

Sera from 2790 0-15 aged infants and children were titrated for antibodies to Toxoplasma gondii by indirect immunofluorescent test. Maternal-derived antibodies were found at high rates in the first six months of life (32.9%). The positivity rate declined during the second semester of life (7.5%) and increased again with time (7.8% between 1 and 5 years, 11.2% between 5 and 10 years, 14.4% between 10 and 15 years). No statistically significant differences were found between the sexes. IgM specific antibodies were found at a titre of 1:32 or greater in 41 subjects (1.5%), who also exhibited IgG antibody titres ranging from 1:512 to 1:1024. Our results indicate a remarkable diffusion of toxoplasma infection in our area.

In this report, we demonstrate an interaction between macrophages and T lymphocytes during A. nigr infection. Supernatants obtained after 48 hrs adherence of infected peritoneal macrophages were able to increase the cytotoxicity of T lymphocytes. Our results also indicate that macrophage supernatant (MS) from mice, in the first 5 days after challenge, is more active on T cell than MS produced later. Splenic T cells activated by IL-1 from mice at 5 days of infection show a significantly increased cytotoxicity, at 10 days after challenge, the cytotoxicity of T cells activated by IL-1 did not significantly differ from non-activated T cells.

The Staphylococcus aureus isolates were all susceptible to vancomycin. More than 90% of the isolates were susceptible to rifampicin, ampiclox, methicillin, erythromycin and clindamycin. The isolates were highly resistant to the beta-lactamase-sensitive penicillins, that is 91, 93.2 and 70.4% of the isolates were resistant to penicillin, ampicillin and carbinicillin. Twelve plasmids were found in the isolates, the 35 and 11 Mdal plasmids coded for aminoglycosides and tetracycline resistances, respectively.

The production frequency of toxic shock syndrome toxin-1 (TSST-1) amongst Staphylococcus aureus strains isolated from humans, animals and foods in Nigeria was investigated. Of 1015 strains tested, 120 (11.8%) were positive for TSST-1. Thirty one (16.0%) of 194 strains from human diarrhoea and wounds were positive compared to 47 (7.1%) of 666 isolates from eight animal species. Goat strains were most often positive for this toxin (17.0%). A total of 42 (27.1%) of 155 strains from foods were positive for TSST-1. Regardless of source, phage non-typable strains (48.3%) were most common amongst TSST-1 producers followed by strains sensitive to phages in several groups (mixed), 18.3%, and phage group III strains (17.5%). Only 6 were phage group I strains (5.0%). TSST-1 producing strains were mostly resistant to penicillin. Eighty-four (70.0%) TSST-1 producers were also enterotoxigenic with staphylococcal enterotoxin C (SEC) most frequently elaborated as 46 (38.9%) strains were positive. However, 42 (35.5%) and 39 (32.5%) strains producing TSST-1 were also positive for SEA and SEB, respectively. It was concluded that TSST-1 producing strains of S. aureus are widespread in humans, animals and foods in Nigeria and such distribution may play some role in the epidemiology of toxic shock syndrome, the prevalence of which is currently unknown in the environment.