In the 77 reference strains for Klebsiella K types, there are 17 strains (22.1%) of Klebsiella planticola, 6 strains (7.8%) of Klebsiella oxytoca, 1 strain (1.3%) of Klebsiella terrigena, and 53 strains (68.8%) of Klebsiella pneumoniae. The species K. planticola, which was originally isolated from botanical and aquatic environments and hence thus named, was also identified at high incidence (81 strains, 18.5%) among the 439 recent clinical isolates of Klebsiella species. Among these K. planticola strains of hospital origin, 52 (64%) were isolated from sputum, 17 (21%) from urine, and the remaining 12 (15%) from other sources. The capsular types of these isolates were determined by the gel precipitation reaction. Seventy of 81 K. planticola isolates (86.4%) were typable by antisera to Klebsiella reference strains for K types and the K types of the clinical isolates distributed to 35 kinds of K types. The proportion of typable strains among clinical isolates of K. planticola was very similar to those in K. pneumoniae (87.5%) and K. oxytoca (86.0%).

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Monoclonal antibodies against the surface antigens of Shigella flexneri 1b and S. dysenteriae 1 were prepared. The specificities of the antibodies were evaluated by enzyme-linked immunosorbent assay (ELISA), and quantitative agglutination using microtiter plate. Monoclonal antibodies against S. flexneri 1b, designated Sf2B2 and Sf2G4, belonged to IgG2a and IgG1 subclass, respectively. The former was specific for S. flexneri 1b, whereas the latter was reactive not only to S. flexneri 1b, but also weakly to 3a and 4b. Monoclonal antibody against S. dysenteriae 1, Sd5E1 (IgM), reacted with S. dysenteriae 1, 3, 6, 7, and S. boydii 2.

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In one-step growth experiment of measles virus (MV) in Vero cells at 39C, the appearance of MV infectivity was delayed for 24hr and the maximum titer was reduced by approximately 1, 000-fold, when compared with those at 35C. MV infectivity was thermolabile at the high temperature. Penetration was rather enhanced at 39C. By Northern blot hybridization, viral RNAs including 50S genome-sized RNA and mRNAs were first detectable 24hr post-infection (PI) at 35C and 36hr PI at 39C, respectively. Rapid degradation of viral mRNAs was not observed in the infected cells at 39C. The synthesis of N, F, and M proteins was relatively reduced at the high temperature and appearance of the other viral protein was delayed, in agreement with the time course of viral RNA synthesis. All these data suggest that less efficient synthesis of viral RNA, restriction of synthesis of N, F, and M proteins at translational level and thermolability of infectivity are all involved in the suppressed MV production in Vero cells at 39C.

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The mechanism of cooperation between the L3T4⁺ and Lyt-2⁺ T cella subsets in effective clearance of Sendai virus from infected mouse lungs was studied by adoptive cell transfer using nude mice. Simultaneous transfer of a long-term-cultured Sendai virus-specific L3T4⁺ T cell line with L3T4⁺ cell-depleted immune spleen cell (L3T4^-) fraction to infected nude mice could result in viral clearance, although single injection with either of these cells was not effective. Instead of the L3T4⁺ T cells, culture supernatants of the L3T4⁺ T cell line or concanavalin A-stimulated mouse spleen cells and mouse serum immunized with the virus were also active in the cooperative viral clearance with L3T4^- fraction. The role of the Sendai virus-sensitized L3T4^- cell fraction in cooperative viral clearance with humoral factors could be replaced by neither T cell-deprived immune spleen cell fraction nor normal spleen cells. The 1, 500 units of recombinant mouse interleukin 2 (IL-2), which was more than 12 times the IL-2 activity present in the supernatants of the T cell line or concanavalin A-stimulated spleen cells, failed to clear the virus in combination with the L3T4^- fraction. Monoclonal antibodies to Sendai or mouse hepatitis viruses were also effective in the cooperative antiviral activity. IL-2 activity was not detected in these monoclonal antibodies and the mouse immune serum. Single injection of any humoral factors failed to clear the virus. These results indicate that Sendai virus-sensitized Lyt-2⁺ subset of T cells acts cooperatively with humoral factor(s) other than IL-2 or Sendai virus-specific antibody present in supernatants of the T cell line, of concanavalin A-stimulated spleen cells or bybridomas, and in mouse serum immunized with the virus.

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Intradermal injection of MY-1, a nucleic acid fraction extracted from Mycobacterium bovis strain BCG, induced in situ infiltration of mononuclear cells, most of which were asialo GM1 (GA1)-positive as determined by immunofluorescence microscopy. The infiltration occurred with as little as 1μg of MY-1 and lasted for a week. Double immunofluorescence microscopy revealed that the infiltrating GA1-positive cells were all positive for Ly-5, and partially positive for Thy-1.2, but negative for Mac-1, Ia, μ-chain, Lyt-1, Lyt-2, L3T4, and Fc receptor II. They contained neither peroxidase nor nonspecific esterase. The infiltrating cells thus markedly resembled natural killer (NK) cells in their cytochemical characteristics and surface markers. DNase and RNase destroyed the GA1-positive cell-inducing activity of MY-1. These results indicate that the nucleic acid components of MY-1 are responsible for this effect.

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Effects of LPS on primary and secondary antibody responses to typical TI-2 antigens were investigated in mice. Simultaneous injection of LPS with a TI-2 antigen showed only little adjuvant effect on the following primary antibody response to the antigen. In contrast, either a single or multiple injections of LPS, prior to the immunization with a TI-2 antigen, significantly augmented the following primary antibody response to the antigen. LPS, however, inhibited the development of B-cell memory to a TI-2 antigen when administered together with the antigen. Moreover, an injection of LPS in mice, which had strong IgM and IgG B-cell memories to a TI-2 antigen, caused disappearance or profound reduction of the memories. The results suggest that LPS produced by gram-negative bacteria exerts inhibitory effects on the development and continuation of B-cell memory to bacterial infections.

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Antigenic relation between Mycobacterium bovis strain BCG and experimental animal tumor cells was analyzed with BCG monoclonal antibodies (BCG-MoAbs). Four BCG-MoAbs of 602, 603, 609, and 612 were successfully established and applied for the antigenic analysis of Meth A, RL _??_ 1, colon tumor 26 of mouse, and line 10 of guinea pig tumor. MoAb 602 showed broad reactivity against all types of tumor cells. BCG antigen(s) was clearly recognized as small granules on the tumor cell surface under the fluorescence microscope, indicating that the animal tumor cells shared the common antigen(s) with BCG.

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The suppressive effects of mouse recombinant interferon-β (IFN-β) on B cell differentiation of MRL/Mp-1pr/1pr (MRL/1) mouse, a model of autoimmune diseases, and C₃H/H₂ mice, a normal situation, were investigated. Spleen mononuclear cells were cultured in the presence of lipopolysaccharide (LPS), and the suppressive effect of IFN-β was examined on differentiation of B cells to plaque-forming cells (PFCs) by highly sensitive reversed hemolytic plaque assay. IFN-β (5, 000-10, 000units/ml) suppressed more than 50% of PFCs of both MRL/1 and C₃H/H₂ mice. This suppressive activity as well as the cytotoxicity of natural killer (NK) cells enhanced by IFN-β was abrogated by treatment of the spleen cells with anti-asialo GM1 antibody in the presence of complement. This suppressive activity was also abrogated by intravenous administration of 20μl/mouse of anti-asialo GM1 12hr before cultivation of spleen cells. These results suggest that NK cells activated by IFN might be responsible for the immunoregulation in autoimmune diseases.

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Coxiella burnetii was isolated from a patient with Q fever. It could not be determined whether this was an imported case or an indigenous one. Identification of the isolate was made by electron microscopic morphology and the indirect fluorescent antibody test with convalescent-phase serum from a Q fever patient having a known titer of antibody to C. burnetii. The isolated strain, named TK-1, caused no symptoms in ddY and BALB/c mice except when the mice were treated with cyclophosphamide.

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The serological status to cytomegalovirus (CMV) was examined for 616 Brazilians and 399 Japanese immigrants living in the North-East of Brazil. The sera were screened for IgG antibodies to CMV by enzyme-linked immunosorbent assay (ELISA). The overall prevalence of CMV antibodies was higher in the Japanese population (83.7%) than in the Brazilian population (69.8%). The seropositivity was analyzed by factors of age, sex, ethnic background, and socioeconomic status. Mother-baby contact seems to be a factor of significance in the seroepidemiology of CMV infection.

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