The chromosomal DNA of Escherichia coli spheroplasts induced by penicillin G was studied biochemically and electron microscopically. Although the spheroplasts were unable to divide, they continued to synthesize chromosomal DNA for several hours even in the presence of penicillin G. Some differences were observed between the chromosomal DNA of the parent cells and that of the spheroplasts in sucrose gradient centrifugation and electron microscopy; two types of chromosomal DNA, a slower sedimenting form and a faster sedimenting form, were released from the gently lysed parent cells. The former was membrane-free folded chromosome and the latter was membrane-associated chromosome. In contrast, the chromosome from the spheroplast showed a single intermediate value of sedimentation coefficient between those of the chromosomal DNA from the parent cell. Cytochrome spreading for electron microscopy showed that the spheroplast chromosomal DNA formed an aggregated mass consisting of several chromosome-molecules of the parent cell.

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The present study describes the ability of various oral bacteria to bind human plasma fibronectin (PFN). Avid binding of ¹²⁵I-PFN was found for Streptococcus mutans (serotypes a to h), Streptococcus sanguis, group A Streptococcus pyogenes and Staphylococcus aureus, while other gram-positive bacterial species tested demonstrated only weak or negligible PFN binding ability. Two gram-negative bacterial species, Bacteroides gingivalis and Escherichia coli, did not significantly bind PFN. ¹²⁵I-PFN binding to S. mutans 6715 cells was decreased by pretreatment with unlabeled PFN, and the radiolabeled PFN bound to the cell surface was released on addition of unlabeled PFN. Strong inhibition of ¹²⁵I-PFN binding to S. mutans 6715 cells was obtained by protease pretreatment, while partial inhibition was also observed following treatment with acid, alkali, lipase, and monoclonal anti-polyglycerophosphate. These results suggest that PFN binding to S. mutans cells is reversible and that PFN receptors on the cell surface appear to be heat-stable multiple proteins.

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Rickettsia tsutsugamushi strains from three recent patients of Tsutsugamushi disease in Niigata Prefecture were isolated primarily in mice and then in L cell cultures. By this procedure, low virulent strains to mice, as well as high virulent ones, could be isolated and cultivated serially in L cell cultures, suggesting the usefulness of L cells for isolation of this species of rickettsia. Each newly isolated strain was identified as a member of R. tsutsugamushi from the results of cross immunological tests and morphological observation. On the other hand, it was recognized that one of these rickettsiae showed immunological properties distinguishable from the prototype strains of Kato, Karp, and Gilliam by the cross complement fixation test, and also had low virulence in mice.

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An outbreak of Yersinia pseudotuberculosis in Kurashiki, Japan is described. This is the first conclusive report of a community outbreak of this microorganism. A total of 535 pupils, five teachers, and one food attendant contracted the organism. Causative organisms were detected in 19 out of 30 patients. All isolated strains belonged to serotype VA. Out of 653 sera of the pupils, 488 showed elevated agglutinin titers ranging from 1:80 to 1:1, 280 or more within a period of 3 months.

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The effects of fermenting, poorly arginine-utilizing Mycoplasma fermentans and arginine-utilizing Mycoplasma salivarium on the frequency of sister chromatid exchange (SCE) in cultured human lymphocytes were examined. M. fermentans caused no apparent mitosis inhibition of lymphocytes and the increase in SCE frequency was dependent on the inoculum size of the mycoplasma. An evident increase in SCE frequency was observed in lymphocytes infected with smaller inoculum sizes of M. salivarium whereas there was mitosis inhibition of lymphocytes infected with larger inoculum sizes of the mycoplasma. In lymphocyte cultures infected with M. salivarium, the addition of arginine to the culture medium reduced mitosis inhibition but did not diminish the increase in SCE frequency, indicating that arginine depletion was not involved in causing the induction of SCEs in mycoplasma-infected lymphocytes. With regard to the genetic effectiveness of SCE, these results suggested that mycoplasmas are capable of inducing cytogenetic changes in infected host cells.

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Chitin and chitosan were found to exhibit a protective effect on mice administered these polysaccharides intraperitoneally against infection of the viable cells of Candida albicans NIH A-207 strain. A significant difference was observed between the protective effects of chitin and chitosan, i.e., chitin was much more effective than chitosan when the C. albicans cells were challenged via the intravenous route. In intraperitoneal inoculations of C. albicans cells, however, chitosan provided stronger resistance for mice than chitin.
It has also been revealed that the number of polymorphonuclear leukocytes from circulating blood of chitin-administered mice increased remarkably compared with that of untreated and chitosan-treated mice, and that the increase of active oxygen-generating phagocytic cells was significant. On the other hand, the number of peritoneal exudate cells (PEC) and the amounts of active oxygen generated from these cells in chitosan-treated mice were larger than those of chitin-treated mice. However, candidacidal activities of PEC per fixed cell number in mice treated with chitin or with chitosan were almost the same and greater than those of untreated mice.

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Leuco-adsorption occurring in influenza virus infected-cell cultures was studied morphologically to clarify the mechanisms of adsorption of leukocytes. Among the various types of chicken leukocytes studied, such as lymphocytes, monocytes, granulocytes, and thrombocytes, all were found to adhere to the virus-infected cells. The adsorption seems to occur through at least two processes, one is mediated by microvilli (microvillus-attachment), and the other is direct adherence of both cells (cell-to-cell-attachment). In the former, the leukocytes are bound to the microvilli protruding from the infected MDCK cells and in the latter both cell membranes attach directly. In the cell-to-cell-attachment, there was an electron-lucent gap of about 12nm in width in the intermembranous space of the junctional regions. This region was similar morphologically to the gap junction. As a result of leuco-adsorption no cytolytic effects occurred in the MDCK cells under the experimental conditions.

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The glycoprotein gB related to neutralization of Marek's disease virus (MDV) and herpesvirus of turkeys (HVT) is composed of several glycosylated polypeptides, which were immunoprecipitated with monoclonal antibodies and rabbit antiserum cross-reactive to MDV-gB and HVT-gB, and analyzed by SDS-polyacrylamide gel electrophoresis. The present pulse-chase experiments showed that the precursor forms of MDV- and HVT-gB were glycoproteins with molecular weights of 110K to 115K (gp115/110) and 115K (gp115), respectively. These precursor forms were processed to smaller gB's (gp63 and gp50 for MDV; gp62, gp52, and gp48 for HVT), at least in part by sialylation. The proteins synthesized in the presence of tunicamycin were two polypeptides of 88K and 83K in MDV-infected cells and a 90K polypeptide in HVT-infected cells, indicating the presence of unglycosylated precursor forms of MDV- and HVT-gB. Differences between virulent and avirulent MDV's and between HVT's with and without protective activity against Marek's disease were observed in the processed forms of MDV- and HVT-gB, especially at the processing step of sialylation.

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Four human T cell lines, MT-2, TCL-Kan, TCL-As 2, and TCL-Haz, established from normal leukocytes by cocultivation with adult T-cell leukemia (ATL) virus (ATLV)-producing cells, produced constitutively phagocytosis inducing factor(s) (PIF) that induced phagocytosis in a human monocytic cell line, THP-1. These cell lines expressed ATLV-associated antigens (ATLA) as well as numerous virus particles, whereas the other twelve leukocyte cell lines tested, including T cell lines, B cell lines, and non-T and non-B cell lines, did not produce detectable amounts of the factor(s) in the culture supernatants. PIF was produced in the absence of serum and was not related to either ATLV-particles or viral structural proteins. Its activity was stable at 56C for 30min, but labile at 80C for 30min and at pH 2 for 20hr. MT-2 and TCL-Kan produced large amounts of the factor(s) in the culture supernatants but little interferon-γ (IFN-γ) or colony stimulating factor (CSF) activity was detected; furthermore, the activity was not neutralized by rabbit anti-IFN-γ sera. These observations suggest that some ATLV-transformed Tcell lines produce PIF that is different from IFN-γ and CSF.

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