Plesiomonas shigelloides is considered to be a waterborne agent of human gastroenteritis. An ecological study was carried out in five ponds in Dhaka city over a period of one year to elucidate the distribution and seasonality of this organism in various components of pond ecosystems. Samples were collected from hydrophytes, water, phytoplankton and sediment every 15 days over 12 months and cultured for P. shigelloides. P. shigelloides was isolated from a total of 120 samples including 25 (20.8%), 16 (13.3%), 22 (18.3%) and 35 (29.2%) of hydrophytes, water, phytoplankton and sediment samples, respectively. Distinct seasonal patterns of isolation of P. shigelloides were observed in the four components with two distinct peaks. The highest peaks were observed in hydrophytes and water samples in May and in phytoplankton and sediment in November. P. shigelloides was isolated from all components from all ponds during the study period. These results suggest that P. shigelloides is an autochthonous member in the freshwater pond ecosystems in Dhaka, Bangladesh.

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The platelet aggregation capability of whole cells of Enterococcus faecalis, E. faecium and E. avium was tested. The optimum ratios of bacteria to platelets in E. faecalis (strain SMU-37), E. faecium (strain SMU-138) and E. avium (strain SMU-197) were 1.0, 1.2 and 2.0, respectively. During the platelet aggregation induced by the three strains of enterococci, 65-69% of total serotonin was released. The aggregation was totally inhibited by ethylenediaminetetraacetate (10mM) and apyrase (1mg/ml), while no effect was shown by aspirin (10mM), indomethacin (10mM) and quinacrine (1mM). By pretreatment of platelet-poor plasma with heat (56C, 30min) or zymosan, the reactivities with platelets of each strain of species were markedly diminished. These results suggest that enterococci-induced platelet aggregation was an ion-dependent, cyclooxygenase-insensitive event, and plasma component(s) was (were) required for the reaction.

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A highly specific competitive enzyme-linked immunosorbent assay for the epimastigote of Tulahuen strain was developed by using the usual 3 immunological reagents, a rabbit antiserum specific for T. cruzi, epimastigote of Tulahuen strain, β-D-galactosidase-labeled goat anti-rabbit immunoglobulin G and the solid-phase cell fragments of the epimastigote of Tulahuen strain. A new method, the selected antibody enzyme immunoassay (SAEIA) which generally detected all strains of the epimastigote tested with the same working range, was developed by changing only the solid-phase antigen to the epimastigote of Y strain among the 3 immunological reagents. Both assays permitted us to measure accurately as little as 1, 000 parasites per assay tube. Scope of the SAEIA was limited to the epimastigote. Both lifecycle forms of T. cruzi which appear in mammals, amastigote and trypomastigote, and other kinetoplastids showed low cross-reaction values by the assay. The assay principle of the new method and a preliminary study to apply the SAEIA for findingthe field T. cruzi-infected insect vectors were also reported.

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Chronic rotavirus infection of an infant with severe combined immunodeficiency (SCID) was studied by virological examinations in association with long-term observation of his symptoms and immune status. During eleven months of hospitalization, the patient was suffering from incurable severe diarrhea with persisting excretion of rotaviruses detected by electron microscopy and the reversed-passive hemagglutination (R-PHA) test and had transient hepatitis symptom despite multiple administrations of human gammaglobulin and high calorie fluids. The detected viruses were morphologically recognized as rotavirus with double capsid structure. Polyacrylamide gel electrophoretic (PAGE) analysis of their genomic RNAs showed the long electropherotype of group A virus with abnormal migration profiles changing considerably from the early to the late phase of illness: (1) The 11th segment became undetectable; (2) the molecular weight of the 6th segment slightly increased; (3) seven to fourteen extra segments appeared; and (4) PAGE patterns of viral genomic RNAs changed every three or four months. These findings suggest that chronic infection with rotavirus accompanied the generation of extra viral genomic segments and their unusual assortments in an immunodeficient host.

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Antiviral potencies against herpes simplex virus type 1 (HSV-1) of 1-β-D-arabinofuranosyl-E-5-(2-bromovinyl)uracil (BV-araU) and ten other nucleoside analogues in human embryonic lung fibroblast (HEL) cells were compared with those in Vero cells. 5-Halogenovinylarabinosyluracils, highly active in HEL cells, were inactive against all three laboratory-stocked strains of HSV-1 but exerted moderate antiviral effects on three clinical isolates in Vero cells. The reduction in anti-HSV-1 potencies of other representative nucleoside analogues in Vero cells was much less than those of 5-halogenovinylarabinosyluracils. However, significant antiviral potencies of BV-araU against laboratory strains were observed in other human and monkey fibroblast cells including an immortalized cell line. Significant enhancement of antiviral activity of BV-araU against a laboratory strain and a clinical isolate was demonstrated in Vero cells by the addition of 0.1μM aminopterin or FUdR, an inhibitor of thymidylate synthesis. The potentiated anti-HSV-1 activity in Vero cells was comparable to the potency in HEL cells without the inhibitor. These results suggested that high activity of thymidylate synthesis and a large thymidylate pool size in Vero cells seem to be related to loss of anti-HSV-1 potency of BV-araU. Original tissue type, species, and the immortality may not be responsible for the reduced antiviral activity of BV-araU in Vero cells.

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Serum levels of C-reactive protein (CRP) and plasma levels of fibronectin (Fn) were studied in 74 untreated leprosy patients. CRP was detected by latex agglutination in 25.6% of the patients. A significant increase in Fn levels was seen in all the groups of leprosy patients, as compared to the controls.

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A human T-cell hybridoma (KC8-1.10), whose culture supernatant augments peripheral blood lymphocytes (PBL)-mediated spontaneous cytotoxicity against K562 cells, was established. This activity [natural killer (NK) cell activating activity] appears to be not due to interferon-γ (IFN-γ) and interleukin-2 (IL-2) for the following reasons: 1) KC8-1.10 produced negligible or small amounts of IFNs and IL-2. 2) The NK cell activating activity in the KC8-1.10 culture supernatant was not neutralized by anti-IFN-γ antiserum and stable even after pH 2 treatment for 24hr, which is known to destroy IFN-γ activity. 3) IL-2-dependent cell line absorbed IL-2 more efficiently than it absorbed the NK cell activating activity, and the latter activity was not retained by Blue Sepharose column in contrast with IL-2. The NK cell activating factor in the KC8-1.10 culture supernatant appears to be a glycoprotein, because the activity was abolished with pronase treatment or with boiling for 5min and because the activity was retained by concanavalin A- and Pisum sativum agglutinin-agarose. Finally it was found that the NK cell activating activity requires Leu 11b⁺ cells to exert its effect.

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A mycobacterial 65kDa molecule is a member of the GroEL heat shock protein family. We developed mAbs reacting against recombinant 65kDa protein by using a gene (pTB12) which encodes this protein. Three mAbs (B20, B97 and B167) reacted selectively with 65kDa proteins of Mycobacterium tuberculosis, BCG and Mycobacterium leprae, although B20 and B167 may weakly react with a 15kDa molecule of mammalian cells. One (B108) was obviously cross-reactive between mycobacterial 65kDa and the mammalian intracytoplasmic protein. We also developed deletion mutants of pTB12. The localization of these mAb-defined epitopes was determined by using truncated proteins of the Mycobacterium tuberculosis 65kDa molecule produced in E. coli. Immunohistochemical analysis showed that B20, B97 and B167 mAbs could detect this antigen in experimental granulomas induced by injection of BCG in the subcutaneous tissue of rats. These mAbs should be useful for analyzing the immunobiologic roles of mycobacterial 65kDa molecules.

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Toxin production, cell-surface hydrophobicity and fibronectin-binding properties of 21 Salmonella strains of different species, isolated from Swedish travelers to different parts of the world, were studied. Cell sonicate supernatants from blood agar grown cultures of 80% of the strains induced rabbit skin permeability reaction in the form of induration and/or blueing while 33% of the strains also produced cell necrotizing factor on rabbit skin. Four strains were negative in the rabbit skin permeability test, while only two were negative when tested on CHO cells. When cultured on blood agar, a majority of the strains (17/21) showed low cell-surface hydrophobicity, showing no aggregation even at 1.5M ammonium sulfate concentration in salt aggregation test (SAT), while only four strains showed high cell-surface hydrophobicity. Furthermore, these strains could be classified as low fibronectin binders due to their poor interaction with fibronectin or its 29kDa N-terminal fragment.

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Direct immunoperoxidase technique using a horseradish peroxidase (HRP)-conjugated Fab' fragment of human monoclonal antibody (humab C7), designated HRP-C7, was evaluated as a rapid diagnosis of cytomegalovirus (CMV) infection. A total of 138 clinical specimens consisting of 124 urine samples and 14 oral swabs were examined for CMV by the direct HRP-C7 staining in comparison with conventional virus isolation. The number of CMV-positive samples by each method was 40 (29.0%) for the former and 37 (26.8%) for the latter, respectively. By HRP-C7 staining, CMV was identifiable within 24hr after inoculation. By conventional isolation method, an average of 10.3 days had passed before cytopathic effect characteristic of CMV appeared in the cell culture. Some false-positive and false-negative cases were discussed in relation to toxicity of urine samples, storage of the samples, and amount of CMV in the sample. The sensitivity and specificity of HRP-C7 method against conventional isolation method were 89.2% and 93.1%, respectively. Thus, HRP-C7 staining is useful for a rapid diagnosis of CMV infections.

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The seroprevalence of human herpesvirus 6 (HHV-6) infection was examined for 434 Brazilians and 250 Japanese immigrants living in Recife and its vicinity, in the North-East of Brazil. A total of 684 sera from the healthy individuals were screened for IgG antibodies to HHV-6 by anticomplement immunofluorescence (ACIF) test. The seropositivity rate to HHV-6 showed little difference between the two groups: namely, it was 76.5% for Brazilians and 77.2% for Japanese immigrants. The seropositivity rate was constantly higher in females than in males. The high prevalence of anti-HHV-6 antibodies among children indicates that HHV-6 infection occurs very early in life.

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