Shin Isomura

Pulsed-field gel electrophoretic analysis of Campylobacter jejuni DNA for use in epidemiological studies

The cleavage patterns of the genomic DNA of 42 clinical isolates of Campylobacter jejuni determined by pulsed-field gel electrophoresis (PFGE) were compared with their Lior and TCK serotypes. The fragment patterns of DNA obtained with SalI and SmaI restriction enzymes did not always accord with the corresponding serotypes but strains of the same serotype could be further divided into subtypes by their cleavage patterns. This PFGE method may prove useful for subclassifying C. jejuni.

Bactericidal effect of rat cystatin S on an oral bacterium Porphyromonas gingivalis

We tested antibacterial and antiviral activities of rat cystatin S, a cysteine proteinase inhibitor, belonging to the family 2 cystatins against 18 different bacterial species and poliovirus type 1 (Sabin). Rat cystatin S specifically inhibited the growth of a human oral anaerobic bacterium Porphyromonas gingivalis due to a bactericidal effect.

On the intracellular transport and the nuclear association of human cytomegalovirus structural proteins.

In cells productively infected with human cytomegalovirus (HCMV) AD169, large amounts of two viral proteins, the 150K major capsid and the 68K major matrix proteins, are continuously produced during the late phase of infection. In the present study, the mechanism for the intracellular transport of the 150K and 68K proteins was investigated. Infected cells were labelled for 30 min at 72 h post-infection with [35S]methionine, chased for various periods of time at 37 degrees C, and fractionated into cytoplasmic and nuclear fractions. Immediately after 30 min of labelling, the 68K protein was already associated with the nuclear fraction. In contrast, the major proportion of the 150K protein remained in the cytoplasm for more than 1 h; the migration of the 150K protein was much slower than that of the 68K protein. Both the 150K and the 68K proteins were associated with the perinuclear cytoskeletal fraction in the process of migration. After migration into the nucleus, these proteins were resistant to extraction with DNase and high salt, indicating that they were associated with the nuclear skeleton (nuclear matrix). Effects of various inhibitors on the migration of the 150K protein showed that cycloheximide inhibited the transport of the 150K protein, but other inhibitors such as arabinosyl cytosine, cytochalasin D, colchicine or sodium azide did not. The results suggest that the cytoskeletal structure may play a role in the intracellular transport of HCMV structural proteins from the cytoplasm into the nucleus.

Enzyme-linked immunosorbent assay employing monoclonal antibodies for direct identification of enteric adenoviruses (Ad40,41) in feces

For detection and identification of enteric adenovirus (Ad) types 40 and 41 in stool specimens, enzyme‐linked immunosorbent assay (ELISA) was developed with the use of three monoclonal antibodies: Ad group‐specific, Ad40 type‐specific, and Ad41 type‐specific antibodies. Of 860 fecal samples from patients with acute gastroenteritis, 44 strains of Ad were isolated using Graham 293 cell cultures. Of these isolates, 20 were typed as Ad40, 18 were Ad41, and 6 were other Ads by neutralization tests with cell cultures. Results of the ELISA tests on these 860 fecal samples resulted in good agreement to those with the cell culture method. The ELISA tests using Ad type‐specific monoclonal antibodies proved to be a specific and rapid technique for laboratory diagnosis of acute gastroenteritis caused by enteric Ads.

Adenovirus Infection and Specific Secretory IgA Responses in the Intestine of Infants

We investigated adenovirus (Ad) infection of the intestine and Ad group‐specific fecal IgA antibody responses in seven infants who were followed up from birth to 16 months to seven years of age. We isolated in tissue culture from fecal samples not only enteric Ad type 41 but also other Ads (types 2, 3, 5, 6, and 12). We also detected Ad antigens in the feces by ELISA at the times of infection with even non‐enteric Ads, suggesting that a large amount of antigens were produced in the intestine. We found that repeated Ad infections with different serotypes were occurring and there were good fecal IgA antibody responses at each time. The infection seemed usually mild or asymptomatic: only one out of 23 occasions of the detected infections required hospitalization.

Cholera toxin producibility by Vibrio cholerae isolated during the cholera outbreak in the NTT Nagoya Hall

An outbreak of cholera occurred among guests of the NTT Nagoya Hall in September 1989. Clinical findings showed that all but one were symptomatic infections out of 44 bacteriologically confirmed cases. In relation to the high incidence of symptomatic infections, we examined cholera toxin (CT) producibility of the isolated V. cholerae. 1. Strains of the NTT case produced 16-256 (mean 130) ng of CT per ml in CAYE-L medium at 30 degrees C and 32-256 (mean 142) ng of CT per ml by Polymyxin B treatment. But strains of past case produced 8-256 (mean 34), 8-128 (mean 44) ng of CT per ml, respectively. Strains of the NTT case produced a larger amount of CT than that of the past cases. 2. Strains of the NTT case produced 512-4096 (mean 2100) ng of CT per ml in CAYE-L medium at 37 degrees C and 1024-2048 (mean 1600) ng of CT per ml by Polymyxin B treatment. But strains of the past case produced 8-64 (mean 25), 8-128 (mean 45) ng of CT per ml, respectively. Strains of the NTT case produced a larger an amount of CT than them of past case. We observed the same phenomenon in AKI medium at 37 degrees C. The yield of CT in CAYE-L medium was greater at 37 degrees C than 30 degrees C. 3. Strains of NTT case grew faster than that of the past case in CAYE-L medium at 37 degrees C. But the growth rate was the same as both strains in AKI and CAYE media.(ABSTRACT TRUNCATED AT 250 WORDS)