Differentiation of T cells in nude mice

Cells bearing the T-cell differentiation alloantigens TL and Thy-1 were enumerated in preparations of spleen and lymph node cells of nu/nu mice. Healthy nu/nu mice had few or no demonstrable TL+ or Thy-1+ cells whereas mice with viral hepatitis, including some born of nu/nu X nu/nu matings, had many. Healthy nu/nu mice were treated daily with the thymic hormone thymopoietin or with ubiquitin, polypeptides that induce the differentiation of TL+Thy-1" cells from TL-Thy-1- precursors in vitro. After 14 days, 20 to 40 percent of their spleen cells were of the TL+Thy-1+ phenotype typical of thymocytes and 10 to 25 percent of their lymph node cells were TL-Thy-1+, typical of later T-cell differentiation. Similar frequencies of such cells were found in untreated nu/nu mice suffering from severe viral hepatitis. These data conform to the current view that prothymocytes are preprogrammed cells whose maturation to thymocytes, normally induced in the thymus by thymopoietin, can be triggered by other agents under abnormal circumstances. Tests of T-cell function were not included in this study.

The adverse effect of environment on the response to distemper vaccination

Three standard batches of combined distemper and hepatitis vaccine tested in pups housed indoors during a constantly hot summer failed to elicit antibody to distemper virus or to protect the pups against challenge with virulent virus. The response to hepatitis vaccination was normal. When tested in pups housed outdoors, the same batches of vaccine produced antibodies to distemper and protection against the disease. It appears that high relative humidity combined with high environmental temperature caused an increase in body temperature of the pups which was deleterious to the distemper vaccine but did not affect the more heat resistant hepatitis vaccine.

Isolation of low-virulent mouse hepatitis virus from nude mice with wasting syndrome and hepatitis

Mouse hepatitis viruses were isolated on DBT cell culture from affected livers in most nude mice having wasting syndrome and chronic hepatitis. These nude isolates were pathogenic for cortisone-treated ICR weanling mice but not for non-treated ones.

Immunopathology of mouse hepatitis virus type 3 infection. III. Clinical and virologic observation of a persistent viral infection

Three types of viral sensitivity were observed in various mouse strains upon MHV3 infection: resistance, full susceptibility, and semisusceptibility. In the latter type, seen in several inbred strains including C3H, approximately 50% of the adult injected animals resisted to the acute disease. Most of the surviving mice, however, developed a chronic disease with a wasting syndrome and occurrence of paralysis. The chronic period of the disease was characterized by a persistent viral infection, since MHV3 virus was recovered from brain, liver, spleen, and lymph nodes throughout the evolution in most of the animals. In addition, a correlation was observed between the clinical evolution and the titer of virus tested 4 days after infection.

Pathogenicity of mouse hepatitis virus for mice depending upon host age and route of infection

Day-old to 4-week-old mice from a breeder colony which had been seromonitored to be free from mouse hepatitis virus infection, were tested for susceptibility to the virus by different routes of inoculation. After intraperitoneal, intravenous and intracerebral inoculation of 10(2) or more plaque-forming units of the virus, mice of all ages died of acute hepatitis. While day-old mice died also after subcutaneous, intranasal and peroral routes of inoculation, those 3 weeks or more of age resisted to infection by these routes. To intranasal inoculation mice 1 and 2 weeks of age were fully susceptible but some of the resisted to peroral inoculation. In the course of non-fatal infection in 4-week-old mice after intranasal inoculation, viremia and production of some hepatic lesions were recognized and infection became fatal in association with cortisone treatment. The results suggested that the intranasal route of infection may be of importance for spreading of infection in mouse breeding colonies in which inapparent infection is prevailing.

Studies on the cytotoxic effect of in vivo and in vitro immunized lymphocytes on liver target cells

Lymph node and spleen cells from mice immunized in vivo to allogeneic of syngeneic liver antigen are cytotoxic for syngeneic liver cells, but not for syngeneic fibroblasts or established liver cell cultures of allogeneic origin. The cytotoxic activity is mainly dependent on T-cell activity, but a non-T-cell-mediated cytotoxicity may also play a role. Lymphocytotoxicity is inhibited by preincubation of the lymphocytes with syngeneic liver antigen, but not with syngeneic kidney homogenate. The liver-specific lymphocytotoxicity corresponds to the in vivo function of lymphocytes in the development of experimental hepatitis. In vitro immunization of lymphocytes in a Mishell-Dutton culture system also induces liver-specific cytotoxicity. The results indicate that the natural tolerance to self antigens can be lost after invivo as well as in vitro immunization. The induction of self-reactivity of lymphocytes in these experiments may be attributed to regulatory mechanisms of the immune reaction at a cellular level.

Immunopathology of mouse hepatitis virus type 3mii. effect of immunosuppression in resistant mice

Normal adult A strain mice are resistant to MHV-3 infection. A strain mice immunosuppressed by 600 rads of x-irradiation or by anti-lymphocyte serum treatment became susceptible to the virus and died with specific lesions of the liver and high virus titers. However, mice immunized with MHV-3 before sublethal x-iraddiation resisted a second injection of virus. Resistant adult (A times C3H) F-1 hybrids undergoing graft-vs-host (GVH) reaction became highly susceptible to MHV-3 injected 8 days after parental cell injection. Virus titer 3 days after injection was 2 logs higher in mice undergoing GVH than in controls. However F-1 hybrid mice resisted virus challenge when the first injection of virus was given 2 weeks before GVH induction. In addition, thymectomy also modified the behavior of resistant animals toward virus infection. It appears, therefore, that cell-mediated immune functions play an important role in resistance of mice to MHV-3.

Hepatitis and brain lesions due to mouse hepatitis virus accompanied by wasting in nude mice

Severe necrotising hepatitis, with microscopic brain lesions containing multi-nucleated giant cells, was observed in specified-pathogen-free nu-nu mice, contained in a semi-protected environment, but within the same room as other, conventional, mice. An entire group of 40 nu-nu mice died within a month, with no evidence of bacterial or parasitic infection. However, cell-free liver filtrates reproduced the liver lesions in specified-pathogen-free Swiss-Schneider mice injected intraperitoneally at up to 21 days of age, but not in baby rats and hamsters.

Electronmicroscopy showed masses of particles resembling mouse hepatitis virus in the liver lesions of the recipient mice, and the identity of the virus was further confirmed serologically and by its physical properties. It was concluded that the infection was caused by a neurotropic variant of mouse hepatitis virus and could have originated from the conventional mice kept in the same room.

Isolation of a murine hepatitis virus from Swiss mice treated with antilymphocyte serum

In an attempt to transmit feline malignant lymphoma to mice, a murine hepatitis virus (MHV) was accidentally recovered from conventionally reared Swiss mice receiving prolonged treatment with antilymphocyte serum. In these mice, the virus did not require concomitant infection withEperythrozoon coccoides to produce disease. Tests for antibodies against a variety of viruses were performed on serum from control colony mice and mice that recovered from experimental infection as well as on serum pooled from vaccinated and non-vaccinated mice challenged with the recovered agent. Antibodies to the MHV complement fixing (CF) antigen(s) were demonstrated in only the last mentioned serum. Mice harbouring a hepatitis virus may thus be tolerant to their CF antigen(s) in a situation analogous to oncornavirus infection of their natural hosts. The liver pathology was that of a confluent focal-type necrosis resembling that produced by certain other MHV strains. We have labelled this newly isolated virus MHV (Swiss-Cape Town), abbreviated to MHV (S-CT).

Viral hepatitis and studies of hepatitis associated antigen in chimpanzees

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