Toru Urano

Development of maternal IgG-free chick obtained from surgically bursectomized hen

IgG-free eggs and chicks were developed, so as to study the role of maternal IgG in the development of the immune system. Surgical bursectomy on the 18th day of incubation deprived chickens of B cells and eliminated IgG synthesis. Bursectomized chickens are usually dead before sexual maturity under conventional conditions. When surgically bursectomized chickens were housed in an isolated clean room and antibiotics were administered to them, they could survive to sexual maturity. Finally, we succeeded in obtaining IgG-free fertilized eggs and maternal IgG-free chicks from surgically bursectomized hens. The amount of yolk IgG in IgG-free eggs was one-ten thousandth less than that in normal eggs. The level of IgM in the serum of maternal IgG-free chicks reached six times higher than that of normal chicks 5 days after hatching.

Acute hepatic failure in IFN-γ-deficient BALB/c mice after murine coronavirus infection

Abstract We previously showed that an intraperitoneal infection with mouse hepatitis virus (MHV) persists in interferon-γ (IFN-γ)-deficient C57BL/6 (B6-GKO) mice and results in subacute fatal peritonitis, which bears a resemblance to feline infectious peritonitis. To examine the role of other host factors in MHV infection in mice, IFN-γ-deficient mice with a BALB/c background (BALB-GKO) were infected intraperitoneally with MHV and compared with B6-GKO mice. In contrast to B6-GKO mice, BALB-GKO mice died within 1 week due to acute hepatic failure. The viral titer of the liver in BALB-GKO mice was significantly higher than that in B6-GKO mice. All hepatocytes in BALB-GKO mice were necrotic at 5 days post-infection, which was clearly distinct from large but limited lesion in the liver from infected B6-GKO mice. The serum alanine aminotransferase activity of infected BALB-GKO mice were higher than that of B6-GKO mice and was paralleled with the severity of the pathological changes and viral titers in infected mice. Administration of exogenous IFN-γ to BALB-GKO partially inhibited the acute death. These results indicate that BALB-GKO and B6-GKO mice clearly show different diseases following MHV infection, although wild type counterparts of both mice apparently showed the same clinical course after MHV infection.

Natural infection of murine norovirus in conventional and specific pathogen-free laboratory mice

Noroviruses cause most cases of acute viral gastroenteritis worldwide. The lack of a cell culture infection model for human norovirus necessitates the use of molecular methods and/or viral surrogate models amenable to cell culture to predict norovirus inactivation. Murine norovirus (MNV) may be used to construct a small animal model for studying the biology and pathogenesis of noroviruses because MNV is the only norovirus that replicates in cell culture and a small animal model. However, recent studies have shown that natural MNV infection is widespread in laboratory mouse colonies. We investigated MNV infection in both conventional and specific pathogen-free (SPF) genetically modified mice from Japan and the US, and commercial mice from several animal breeders in Japan, using serological and molecular techniques. MNV antibodies were detected in 67.3% of conventional mice and 39.1% of SPF mice from Japan and 62.5% of conventional mice from the US. MNV antibodies were also found in 20% of commercial SPF C57BL/6 mice from one of three breeders. Partial gene amplification of fecal isolates from infected animals showed that the isolates were homologous to reported MNV sequences. These results suggest that both conventional and SPF laboratory mice, including commercial mice, are widely infected with MNV, which might require considerable attention as an animal model of human disease.

Rapid tumor death model for evaluation of new therapeutic agents for adult T-cell leukemia.

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell neoplasm. The health of ATL patients rapidly deteriorates resulting in death; however, the induction of death in a small animal model due to tumor has not yet been reported. SCID mice, 5 weeks old, younger than those previously used, which were inoculated with ATL cells, eliminated NK cell activity and showed rapid tumor formation resulting in death. Age is the crucial factor influencing tumor formation and death in the SCID mice model for cancer.

Differentiation of mouse hepatitis virus genotypes by restriction fragment length polymorphism analysis

Reverse transcriptase–polymerase chain reaction (RT–PCR) amplification of the nucleocapsid (N) gene of mouse hepatitis virus (MHV) successfully detected 36 strains from the faeces of mice that had been housed in animal facilities in Japan from 2000 to 2003. Subsequent restriction fragment length polymorphism (RFLP) analysis, using the enzymes Acc I, Alu I, EcoR I and Mbo I, demonstrated that these strains could be divided into five distinct subgroups and that the same MHV strains were detected from closely related mouse facilities. Furthermore, strains from the same facility showed the same RFLP pattern, irrespective of the year of detection, but this pattern varied between different locations. This study shows that RFLP analyses are a rapid and useful method for differentiation of MHV strains.

Bacterial Translocation from the Gastrointestinal Tract in Various Mouse Models for Human Diabetes

Bacterial translocation from the gastrointestinal (GI) tract to other internal organs was examined in multiple low‐dose streptozotocin‐injected (M‐STZ), single large‐dose streptozotocin‐injected (S‐STZ), alloxan‐injected (Alloxan), and non‐obese diabetic (NOD) mice. The incidence of bacterial translocation from the GI tract to the tested organs among diabetic mice was in the order of M‐STZ mice>S‐STZ mice>NOD, Alloxan, and control mice. The injections of insulin to M‐STZ mice did not decrease the incidence of translocation. These results suggest that bacterial translocation from the GI tract in diabetic mice is not induced by diabetes.

The Severity of Hepatic Lesion after Intraperitoneal JHMV Infection in IFN-gamma Deficient Mice is Parallel to Viral Replication in Hepatocytes in Vitro

Several factors affect MHV infection in mice (Table 1). They can be classified into two groups, viral factors and host factors. Although JHMV induces a fatal encephalitis in mice after intracerebral infection, it does a mild hepatitis when it is inoculated intraperitoneally. On the other hand, host genetic factor is a critical determinant. Among MHV researchers, it is well known that SJL mice are relatively resistant to intracerebral infection with JHMV (Stohlman & Frelinger 1978). In addition, the immune system is one of the key players that determine MHV infection in mice.