Hiroo Iida

Characterization of Measles Viruses in Establishment of Persistent Infections in Human Lymphoid Cell Line

Human lymphoid cells (NC-37) were infected with attenuated measles vaccine virus (Schwarz, AIK-C, and CAM-70 strains), subacute sclerosing panencephalitis virus (Mantooth and Halle strains), neurovirulent TYCSA strain, and wild type virus (Edmonston and Toyoshima strains) at an input multiplicity of 0-01. These strains were divided into two groups by their capacity to establish carrier states. CAM-70, Toyoshima, and Edmonston strains did not set up persistent infections in NC-37 cells, whereas AIK-C strain induced chronic cyclic infection and the Schwarz, TYCSA, Mantooth and Halle strains could set up persistent infections and furthermore two types of persistent infections were recognizable. Cells persistently infected with Schwarz strain contained nucleocapsid structures in both nucleus and cytoplasm, and produced infectious virus of 10(4) to 10(5) p.f.u./ml over 100 days after the inoculation of the virus but the cap-formation of measles antigens on the cell membrane was seldom observed. However, in cells persistently infected with TYCSA strain, nucleocapsid structures were rarely observed in the nucleus, but the cap-formation of measles antigens on the cell membrane was often observed. The titre of carried virus was always higher than the number of cells in the range of 10(6) to 10(7) p.f.u./ml. Mantooth strain was similar to Schwarz strain and Halle strain was similar to TYCSA strain in the properties of their carrier states. These carrier states were stable and the cells grew normally for over one year.

8 – Analysis of Antigenic Structure of Clostridium botulinum Type C1 and D Toxins by Monoclonal Antibodies

Publisher Summary This chapter presents an analysis of antigenic structure of Clostridium botulinum type C 1 and D toxins by monoclonal antibodies. Clostridium botulinum produces one of the most powerful neuroparalytic poisons that affect a great variety of animal species in all parts of the world. Clostridium botulinum cultures can be divided into four groups: (1) proteolytic, which produce toxin types A, B, or F; (2) non-proteolytic, which produce toxin types B, E, or F; (3) type C α , C β , and D cultures; and (4) proteolytic but non-saccharolytic type G. Hybridomas producing antibodies to toxins are screened by enzyme-linked immunosorbent assay. The production of a major toxin in certain type C and D cultures is governed by specific bacteriophages. Curing these cultures of their prophages results in concomitant loss of the dominant toxin production, and the non-toxigenic cultures are reconverted to toxin producers by the infection with phages.

H2S-Positive Shigella sonnel

Among genera in the family Enterobacteriaceae, genus Escherichia and genus Shigella are described as H2S-negative on triple sugar-iron (TSI) agar. The existence of Escherichia coli strains which produce H2S on TSI agar has been reported (4). Recently we isolated two groups of Shigella sonnei which produced H2S on TSI agar. S. sonnei strains. Two groups of S. sonnei strains were found to be H2S-positive. The first one was isolated from a stool specimen of a patient with diarrhea in Sapporo City in 1964. Several semi-transparent colonies on deoxycholate-citrate-lactosesucrose (DCLS) agar were picked up and transferred to TSI agar and sulfide-indolemotility (SIM) medium. On TSI agar, lactose and sucrose were not fermented and glucose was fermented without gas production. The medium was blackened at the bottom of the slant (Fig. 1). In SIM medium, H2S was positive, indole production was negative and the indole-pyruvic acid (IPA) reaction was negative. They were non-motile. Moreover, lysine-decarboxylase was negative and acetyl-methylcarbinol was not produced. The isolated organism was found to be agglutinated by antiserum against S. sonnei, form I, and it was (strain Sapporo) identified as S. sonnei by additional biochemical tests. The second group of S. sonnei strains was isolated from stool specimens of one

Thymidine metabolism in cells treated with DNA-suppressing factor (DSF).

Inhibition of thymidine incorporation into DNA in cells treated with DNA‐suppressing factor (DSF) has been studied. After 16 hr treatment with DSF, transport of labeled thymidine across the cell membrane was not inhibited, since equilibrium of labeled thymidine with the acid‐soluble pool occurred at the same rate and the radioactivity was at the same level as in untreated cells. The values of Vmax and Km in the kinetics of transport of exogenous thymidine were not changed by DSF. Phosphorylation of labeled thymidine to deoxythymidine triphosphate (dTTP) was not inhibited by DSF. After a chase of labeled thymidine, radioactivity of the acid‐soluble fraction in DSF‐treated cells decreased more rapidly but that of the acid‐insoluble fraction remained at a lower level than in untreated cells. It was assumed that DSF might block the entry of dTTP into DNA.

Complement-Dependent Cytotoxicity of Sera Obtained from Subacute Sclerosing Panencephalitis Patients

Human lymphoid cells (NC‐37) persistently infected with either measles virus (Schwarz and TYCSA strains) or subacute sclerosing panencephalitis (SSPE) virus (Halle and Mantooth strains) were destroyed in the presence of complement by anti‐measles sera as well as by sera from SSPE patients. The cytotoxic activity was demonstrated in both IgG and IgM fractions of measles convalescent sera, but only in IgG fraction of SSPE sera. Measles convalescent sera completely lost the cytotoxic activity to all the cell lines, when absorbed with any one of the cell lines, indicating that the viral surface antigens of these cell lines infected with measles or SSPE virus are identical. On the other hand, the cytotoxic activity of SSPE sera could not be readily absorbed with these cells. Thus, the affinity of SSPE sera for the viral surface antigens might be lower than that of measles convalescent sera.

The Effect of the DNA-Suppressing Factor (DSF) on Host DNA Synthesis in Synchronized Cell Cultures

Purified host DNA‐suppressing factor (DSF) produced into culture fluid of HeLa C‐9 cells infected with measles virus inhibited cellular DNA synthesis in HeLa cells. When purified DSF was added into cultures of synchronous HeLa cells at the early G1‐phase, cellular DNA synthesis was irreversibly inhibited. However, DSF did not affect the stability of native double‐stranded DNA nor the chain‐elongation of single‐stranded DNA in cells of the S‐phase.