Tsukasa Murakami

Prevalence of Norwalk-Like Virus Infections in Cases of Viral Gastroenteritis among Children in Osaka City, Japan

ABSTRACT Surveillance of Norwalk-like virus (NLV) infections in cases of pediatric gastroenteritis between April 1996 and March 2000 showed that NLVs were an important causative agent in viral gastroenteritis cases among children between November and January in those years. The predominant type of NLV was closely related to Lordsdale virus in genogroup 2. During the 1999-2000 season, Arg320-like strains, which may be genetic recombinants, suddenly appeared and spread.

Genotyping of Norovirus strains detected in outbreaks between April 2002 and March 2003 in Osaka City, Japan.

Noroviruses (NVs) are the major cause of food‐ and waterborne nonbacterial gastroenteritis in Japan. Between April 2002 and March 2003, a total of 111 fecal specimens from 40 outbreaks of acute nonbacterial gastroenteritis in Osaka City, Japan were subject to NV detection. Seventy‐two samples (64.9%) from 31 outbreaks (77.5%) were NV positive by a real time reverse transcription (RT)‐PCR assay. To further determine the genotype of individual NV strains, we sequenced the capsid N‐terminal/shell (N/S) domain of some representative strains from each outbreak. The 51 NV strains detected in this study were segregated into 15 genotypes (6 in genogroup I and 9 in genogroup II), and GII/5 genotype NV was a dominant outbreak genotype.

Serial Observations of Chronic Rotavirus Infection in an Immunodeficient Child

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.

Pattern of shedding of small, round-structured virus particles in stools of patients of outbreaks of food-poisoning from raw oysters

The pattern of shedding of the small, round‐structured virus (SRSV) particles in the stools of patients who suffered from food‐poisoning due to raw oysters was investigated. The duration and concentration of fecal shedding of the SRSV particles were studied by electron microscopic examinations of stool specimens obtained during the course of illness to see a relation of viral shedding to day of illness. It was found that the fecal shedding of the SRSV particles occurred within five days of illness; thereafter, the concentration of the SRSV particles in feces rapidly decreased within a few days during the course of illness.

Epidemic of Genotype GII.2 Noroviruses during Spring 2004 in Osaka City, Japan

ABSTRACT Between March and May 2004, a GII.2 genotype norovirus strain caused an epidemic of acute gastroenteritis in Osaka, Japan. Phylogenetic analysis showed that this strain was distinct from all other GII.2 strains detected in Osaka City between April 1996 and March 2005.

Cell surface expression of immature H glycoprotein in measles virus-infected cells

Two forms of hemagglutinin (H) protein, one with an apparent molecular mass of 78 kDa (78K H protein) and the other with that of 74 kDa (74K H protein), are present in cells infected with measles virus (MV). We previously observed that only the mature 78K H protein, a completely glycosylated form of the 74K H protein, was expressed on the cell surface of the infected cells. In the present study, we detected transient expression of the 74K H protein on the cell surface of infected cells by pulse-chase studies, although the level of this expression was much lower than that of the 78K H protein. On the cell surface the 74K H protein was present as dimers and sensitive to endo-beta-N-acetylglucosaminidase H digestion. Treatment with brefeldin A, which blocks the transport of membrane and secretory proteins from the endoplasmic reticulum to the Golgi apparatus, inhibited the cell surface expression of the 78K H protein, but not that of the 74K H protein. These data suggest that a part of the MV 74K H proteins could be transported directly to the cell surface - probably via an alternative pathway - without processing to the complex form in the Golgi apparatus.