Transmission studies with Sarcocystis idahoensis of deer mice (Peromyscus maniculatus) and gopher snakes (Pituophis melanoleucus)

Transmission studies with Sarcocystis idahoensis of deer mice (Peromyscus maniculatus) and gopher snakes (pituophis melanoleucus) were conducted to determine host specificity of various stages of the parasite. Sporocysts were not passed by four dogs or four cats fed infected skeletal muscle from deer mice. Seven white mice (Mus musculus) and 34 white-footed mice (Peromyscus leucopus) were negative for sarcocysts and liver meronts following oral inoculation with S. idahoensis sporocysts; however, excystation of sporocysts occurred in two white-footed mice killed four hours post inoculation (PI). A gopher snake orally inoculated with sporocysts remained negative for coccidia for two months PI. Three deer mice orally inoculated and three intraperitoneally (IP) inoculated with tachyzoites from liver meronts developed sarcocysts in their skeletal muscles similar to those seen in deer mice orally inoculated with sporocysts. Liver meronts were not found. Ten deer mice orally inoculated and 10 deer mice inoculated IP with bradyzoites from S. idahoensis sarcocysts remained negative for sarcocysts and liver meronts at necropsy 17 days PI.     

Behavior of a vigorous alpha- or beta-hemolysin-producing strain of Staphylococcus aureus in the cutaneous tissue of mice.

Two strains of Staphylococcus aureus were examined for behavior in the cutaneous tissue of mice by the fluorescent antibody technique, hematoxylin and eosin staining. When about 10(8) viable cells of an alpha-hemolysin-producing strain (Wood 46) were inoculated subcutaneously into a mouse, they multiplied in the subcutaneous tissue of the mouse and gradually entered the corium to produce alpha-hemolysin and nuclease. Edematous and necrotic lesions were observed in the cutaneous tissue where the organisms had multiplied. When 10(8) viable cells of a beta-hemolysin-producing strain (Kitami 3-9D) were inoculated into a mouse, they multiplied within a narrow extent surrounded mainly by infiltrating leukocytes and produced mainly beta-hemolysin. The changes of cutaneous tissue were weaker in mice inoculated with Kitami 3-9D strain than in mice inoculated with strain Wood 46. When 10(6) viable cells of both strains were inoculated into mice, they were phagocytized by leukocytes. Neither multiplication of organisms nor production of any active extracellular substance was observed in these mice. Edema, degeneration, and necrosis were also noticed in the cutaneous tissue of mice inoculated with alpha- and beta-hemolysin. In addition, the infiltration of leukocytes was inhibited mainly by alpha-hemolysin.     

Characterization of temperature-sensitive strains of Neospora caninum in mice

Temperature-sensitive (ts) strains of the Neospora caninum tachyzoites were selected by chemical mutagenesis and selection for growth at 32 C. Three ts strains and the parental, N. caninum wild-type strain, NC-1, were examined in the present study for their ability to cause disease in inbred BALB/c mice, outbred ICR mice, and chemically immunosuppressed ICR mice. In BALB/c mice, all 3 strains failed to induce clinical disease, whereas infection with the NC-1 strain caused central nervous system disease and death in some mice. No disease was observed in ICR mice inoculated with the 3 ts strains or the NC-1 strain. All immunosuppressed ICR mice inoculated with the NC-1 strain died, whereas no immunosuppressed mice inoculated with the NCts-4 strain and only 1 of 5 mice inoculated with the NCts-8 and NCts-12 strains died. The NCts-4 and NCts-12 strains reverted to a wild-type phenotype when grown at 37 C. Vaccination of BALB/c mice with live, but not frozen NCts-8 strain tachyzoites induced significant (P < 0.05) protection following NC-1 strain challenge.     

The effect of Bordetella pertussis lymphocytosis-promoting factor (LPF) on antibody response in mice: its enhancing and suppressive effects

The effect of lymphocytosis-promoting factor (LPF) on antibody response in mice was estimated under different sets of experimental conditions. Four- and 6-week-old mice were intravenously inoculated with LPF. Three days later these mice were inoculated either intraperitoneally or intravenously with sheep red blood cell (SRBC) or human serum albumin (HSA) as an antigen. The adjuvant effect of LPF was demonstrated on antibody response in 6-week old mice to intraperitoneally inoculated SRBC but not to intravenously-inoculated one. When 4-week-old mice were immunized, hemagglutinin production in response to intraperitoneally inoculated SRBC was not enhanced by LPF. In addition, a rather suppressive effect of LPF at a comparatively high dose was demonstrated on hemagglutinin production in response to intravenously inoculated SRBC. Anti-HSA production was enhanced by inoculation of LPF in any combination of the mouse age and the route of antigen administration. These findings indicate that the adjuvant effect of LPF on antibody response in mice depends upon experimental conditions: the age of mice, the quality of antigen and the route of antigen administration used for immunization.     

Influence of pregnancy on the course of malaria in mice infected with Plasmodium berghei

The course of malarial infection was compared in pregnant mice inoculated with Plasmodium berghei at different stages of gestation. When 12-14 wk old, pregnant BALB/c mice were inoculated with 1 x 10(6) of P. berghei NK65-infected red cells at gestation day 0, 2, 4, 6, 8, 10, 12, 14 or 16, the mice inoculated on gestation days 6-12 expired 6.5 days after inoculation compared to 9.5 days in non-pregnant mice. Parasitemia in these pregnant mice increased rapidly on day 4 after inoculation and anemia also developed earlier on day 5. However, the degree of parasitemia and anemia in the terminal stage of infection in these pregnant mice was milder than that of non-pregnant controls. Blood urea nitrogen increased at the terminal stage although the degree of increase in mice inoculated on gestation days 6-10 was comparatively small. Pregnant malarial mice died earlier with less physiological changes than non-pregnant controls. It was concluded that pregnancy makes the host susceptible to physiological changes caused by malaria.     

Infertility in mice infected genitally with a human strain of Chlamydia trachomatis

Progesterone-treated C3H and TO mice were inoculated genitally with a human C. trachomatis strain, serovar E, designated N.I. 1 or with 2SP control medium. Of the C3H mice serving as controls 93% had litters by the end of a 6-month period compared to 31% of mice infected with chlamydiae. This infertility could not be explained by tubal occlusion, since the oviducts appeared normal at autopsy. Some of the mice were induced to superovulate. Eggs were never recovered from the oviducts on the inoculated sides of infertile mice although they were sometimes found in the lumen of the uninoculated oviducts. In contrast, eggs were recovered routinely from both oviducts of control mice. In addition, eggs and/or their accompanying cumulus cells could be seen in the periovarial space of mice inoculated with chlamydiae, indicating a failure of the transportation of eggs to the oviduct. This could explain the high incidence of ectopic pregnancies in women after chlamydial infection. No adverse effect on fertility was seen in TO mice inoculated genitally with strain N.I.1. Of the mice given 2SP medium, 73% had litters, but 87% of the mice inoculated with chlamydiae were also fertile. There was, however, a significantly greater variation in the birth weights of mice born to infected TO mothers than those born to control mice. This difference in the susceptibility of mouse strains suggests that a genetic predisposition should also be considered for man.     

Suppressor and reactive lymphocytes in radiation leukemia virus (RadLV)-induced leukemogenesis

Summary Suppressor cells capable of enhancing tumor growth in vivo and of abrogating a potential anti-tumor immunity in vitro are generated in C57BL/6 mice inoculated with the high-leukemogenic A-RadLV. Mice inoculated with low-leukemogenic D-RadLV do not develop suppressor cells but contain anti-tumor reactive lymphocytes that can inhibit in vivo tumor growth. Cyclophosphamide (CyF) treatment of mice inoculated with A-RadLV hampered suppressor cell function and rendered the animals' lymphocytes responsive to A-RadLV induced tumor cells in vitro. Administration of CyF also reduced leukemia incidence in mice inoculated with A-RadLV, but had no effect on leukemia induction by D-RadLV in irradiated mice. It is suggested that the high leukemogenic activity of A-RadLV depends on the virus' ability to recruit CyF-sensitive suppressor cells early in latency and that tumor progression in mice inoculated with D-RadLV is arrested due to the host immune response.     

Dietary, bacterial, and host genetic interactions in the pathogenesis of transmissible murine colonic hyperplasia

Transmissible murine colonic hyperplasia, cuased by a variant of Citrobacter freundii (4280). was shown to be modified by diet and by host strain and species. Four different diets fed to mice inoculated with C frundii 4280 were found to have a significant but varying influence on the severity of hyperplasia. Diet also influenced the colonic crypt height of uninoculated, control mice. F344 rats, Syrian hamsters, and NIH Swiss [N:(S)], C57BL/6J, C3H/HeJ, and DBA/2J mice were inoculated with C freundii 4280. Marked strain differences were noted in the mice in mortality and severity of the colonic hyperplasia. The NIH Swiss mice had the greatest and the C57BL/6J mice had the least mucosal hyperplasia. The rats and hamsters did not develop disease or maintain infection after inoculation with the organism. Twenty isolates of Citrobacter from a range of biologic sources were inoculated into susceptible mice, but only mice inoculated with C freundii 4280 developed the disease.     

Suppressor and reactive lymphocytes in radiation leukemia virus (RadLV)-induced leukemogenesis

Suppressor cells capable of enhancing tumor growth in vivo and of abrogating a potential anti-tumor immunity in vitro are generated in C57BL/6 mice inoculated with the high-leukemogenic A-RadLV. Mice inoculated with low-leukemogenic D-RadLV do not develop suppressor cells but contain anti-tumor reactive lymphocytes that can inhibit in vivo tumor growth. Cyclophosphamide (CyF) treatment of mice inoculated with A-RadLV hampered suppressor cell function and rendered the animals' lymphocytes responsive to A-RadLV induced tumor cells in vitro. Administration of CyF also reduced leukemia incidence in mice inoculated with A-RadLV, but had no effect on leukemia induction by D-RadLV in irradiated mice. It is suggested that the high leukemogenic activity of A-RadLV depends on the virus' ability to recruit CyF-sensitive suppressor cells early in latency and that tumor progression in mice inoculated with D-RadLV is arrested due to the host immune response.     

Infections in mice with tachyzoites and bradyzoites of Neospora caninum (Protozoa: Apicomplexa)

Tachyzoites of 2 isolates of Neospora caninum (NC-1 and NC-2) were inoculated subcutaneously (s.c.), intraperitoneally (i.p.), or orally into mice to compare the effects of route of inoculation on pathogenicity. Mice developed more severe disease, and disease occurred sooner when inoculated with the NC-1 isolate compared to the NC-2 isolate. Deaths occurred earlier in mice inoculated i.p. with either isolate. Mice inoculated orally or s.c. with tachyzoites responded similarly to infection. Tissue cysts of the NC-2 isolate produced infections in mice following oral or s.c. inoculation. Lesions seen in mice inoculated with tachyzoites or bradyzoites were primarily acute pneumonia, myositis, encephalitis, ganglioradiculoneuritis, and pancreatitis. In vitro studies demonstrated that tachyzoites of both isolates were killed by incubation in pepsin-HCl solution but not 1% trypsin solution. Bradyzoites of the NC-2 isolate were able to withstand treatment with pepsin-HCl solution.     

Quantitative evaluation of anticancer agents against human melanoma cells implanted in nude mice

BRO human melanoma cells, which are exceptionally tumorigenic and lethal for nude mice, were inoculated intraperitoneally or intracerebrally in varying numbers. An inverse linear correlation was observed between the logarithm of the number of cells inoculated and host survival. In mice bearing 10(7) cells intraperitoneally, 2.4-2.8 log10 units of cell kill were obtained after a single intraperitoneal injection of vincristine, and some mice inoculated with 10(5) cells were cured by this treatment. Fewer cells were killed by L-phenylalanine mustard. Vincristine did not prolong survival of nude mice with intracerebral BRO tumors. Cell kill after administration of anticancer agents can be quantitated for BRO cells inoculated intraperitoneally or intracerebrally.     

多品系多部位腹水癌(H22)淋巴转移动物模型的研究

目的：观察多品系小鼠多部位接种H22腹水癌能否引发淋巴结转移,以及它们的差异。方法：选择KM小鼠、BALB／c小鼠、C57BL／6小鼠,分别在腋下、股部内侧和脚垫接种H22腹水癌细胞,观察腋下和腹股沟淋巴结的变化。结果：腋下、股部内侧和脚垫接种组50d动物死亡率分别是：KM小鼠为100％、60％乘0％;BALB／c小鼠为80％、60％和0％;C57BL／6小鼠为100％、50％和0％。试验组动物的淋巴结重量普遍大于空白对照,尤其是KM小鼠和BALB／c小鼠脚垫接种组,病理检查显示,右腹股沟淋巴结可见大量癌细胞淋巴结的正常结构完全被破坏,甚至消失;C57BL,／6小鼠脚垫接种组淋巴结病理检查未发现癌细胞,淋巴结结构完整。结论：KM小鼠、BALB／c小鼠脚垫接种H22腹水癌细胞能够复制存活时间在50d以上,癌细胞发生淋巴结转移的动物模型。     

HCMV大小鼠眼组织损伤模型的初步研究

目的探讨接种人巨细胞病毒(Humancytomegalovirus,HCMV)是否引起Wistar大鼠、昆明种小鼠眼组织损伤.方法将HCMVAD169毒株经静脉接种Wistar大鼠和昆明种小鼠,观察动物眼部发病情况,原位杂交检测动物眼组织中的HCMVDNA片段.结果接种病毒后部分动物缓慢出现眼部发病,局部分泌物增多、浑浊甚至失明;经原位杂交于视锥、视杆细胞和角膜内皮细胞中检出HCMVDNA片段.结论HCMV可以感染动物眼组织,并引起动物发生眼病.     

Variation in virulence of Coxsackie virus B3 in the heart of mice, II. Pathological comparison

Histopathological analysis of the heart in adult mice inoculated with Coxsackie virus B3 (CB3) strains revealed that strain SK-74 isolated from a patient suffering from severe diarrhea and fever produced severe myocarditis but strain T-70 isolated from a healthy child induced no lesion in the hearts of mice tested, and that intensities of myocardial lesions in mice inoculated with strain PMH were higher than those in mice inoculated with prototype strain Nancy. The results support the conclusion in the preceding paper that strain SK-74 is virulent but strain T-70 is avirulent in mice. The results also partially indicated that the virulence of prototype strain Nancy in the heart of mice is enhanced by passages of the strain in the heart of mice. All four strains of CB3 produced lesions in the pancreas although lesions induced by strain T-70 were less marked than those induced by the remaining three strains.     

Influence of Pregnancy on the Course of Malaria in Mice Infected with Plasmodium berghei

The course of malarial infection was compared in pregnant mice inoculated with Plasmodium berghei at different stages of gestation. When 12–14 wk old, pregnant BALB/c mice were inoculated with 1 × 10⁶ of P. berghei NK65-infected red cells at gestation day 0, 2, 4, 6, 8, 10, 12, 14 or 16, the mice inoculated on gestation days 6–12 expired 6.5 days after inoculation compared to 9.5 days in non-pregnant mice. Parasitemia in these pregnant mice increased rapidly on day 4 after inoculation and anemia also developed earlier on day 5. However, the degree of parasitemia and anemia in the terminal stage of infection in these pregnant mice was milder than that of non-pregnant controls. Blood urea nitrogen increased at the terminal stage although the degree of increase in mice inoculated on gestation days 6–10 was comparatively small. Pregnant malarial mice died earlier with less physiological changes than non-pregnant controls. It was concluded that pregnancy makes the host susceptible to physiological changes caused by malaria.     

Role of pili in the pathogenesis of Pseudomonas aeruginosa burn infection

The present study using three isogenic mutants (F+P-, F-P+, F-P-) of Pseudomonas aeruginosa indicates that the presence of pili enhances the virulence of the organisms in experimental P. aeruginosa burn infection of mice. The 50% lethal dose (LD50) value for burned mice inoculated with non-piliated (P-) mutant was at least ten times higher than those inoculated with piliated (P+) bacteria. Meanwhile the LD50 value for burned mice inoculated with non-flagellated (F-) mutant was at least 10(5) times higher than those inoculated with flagellated (F+) bacteria. At 24 hr after inoculation, the bacterial counts in burned skin of mice inoculated with P+ bacteria were ten times higher than those inoculated with P- bacteria; and at 48 hr the bacterial counts became a hundred times higher in the former mice than the latter. At 24 hr after inoculation, P+ bacteria were isolated from blood, liver (F+P+), lung (F+P+), and kidney, while P- bacteria were not present in these tissues. And at 48 hr after inoculation, P+ bacteria were isolated from all tissues, while P- bacteria were isolated from some sites only. These results suggested that pili and flagella each play an important role as virulence factors independently, and that pili-mediated enhancement of virulence of P. aeruginosa was attributed to pili-mediated enhanced colonization of the organisms at the burned skin surfaces.     

Pathological studies on encephalitis in mice experimentally inoculated with bovine coronavirus

One- to 21-day-old mice were examined pathologically after inoculated intracerebrally or subcutaneously with the Kakegawa strain of bovine coronavirus. In 1- to 4-day-old mice inoculated intracerebrally, the brain contained a small number of neutrophils and lymphocytes having infiltrated diffusely and perivascularly and some degenerative neurons. In mice inoculated intracerebrally at 7 to 21 days of age, severe necrosis of pyramidal cells was shown in Ammon's horn. Perivascular infiltrations of neutrophils and lymphocytes were moderate to severe. Some neurons were degenerative in the cerebral cortex, thalamus and midbrain. Degeneration of some neurons and mild infiltration of neutrophils and lymphocytes were observed in the brain of mice inoculated subcutaneously at 1 to 7 days of age. Perivascular infiltration of neutrophils and lymphocytes was prominent in the cerebral cortex of mice inoculated subcutaneously at 14 days of age. Cellular infiltration was also seen in the thalamus, Ammon's horn, midbrain, cerebellum and medulla oblongata. All the mice, except one, inoculated subcutaneously at 21 days of age were free from neural changes. Electron-microscopically, virus particles were observed in and outside of the degenerative neurons. They had a core 70 nm in diameter and an envelope with spikes.     

Experimental pathogenicity of isolates of Nocardia asteroides, Nocardia brasiliensis and Nocardia caviae from different sources

The experimental pathogenicity of 14 isolates of Nocardia brasiliensis, 15 of N. asteroides, and 5 of N. caviae was investigated for the white Swiss mice inoculated intraperitoneally and in the foot pad, and for the guinea-pig and the hamster (Mesocricetus auratus) both inoculated intratesticularly. The guinea-pig was remarkably sensitive to N. asteroides, with an apparent relationship between pathogenicity and thermotolerance, confirming previous observations. Mice were in general less susceptible to this species. In both guinea-pigs and hamsters it was possible to observe typical granules with or without clubs. N. caviae was highly pathogenic for the guinea-pig and the hamster but no mycetomas were produced in the mice inoculated in the foot pad. Isolates of N. brasiliensis from natural sources were scarcely virulent for the different animals. Those of human origin produced significant lesions in the mice inoculated intraperitoneally with granules. Foot pad inoculation of mice with N. brasiliensis caused mycetomas in several animals.     

Non-cytotoxic activity of pyran copolymer-induced macrophages associated with potentiation of tumour vaccine in recipient mice

Summary Mice inoculated with both L1210 murine tumour vaccine and pyran copolymer were more resistant to L1210 than those inoculated with either of these agents alone. Rabbit anti-mouse thymocyte globulin and silica reduced the augmented resistance of these mice, suggesting the involvement of activated anti-tumour T cells and macrophages in the augmented resistance. We studied the activation of these two cells separately and examined the possible contribution of pyran copolymer-induced peritoneal cells to the augmented resistance to an inoculation of live tumour. Pyran copolymer-induced peritoneal cells endowed the tumour vaccine-primed mice, but not unprimed mice, with resistance to implanted L1210 and, among those peritoneal cell populations, macrophages but not T cells were responsible for this effect since the activity was associated with a cell population which was (1) adherent to nylon wool columns, (2) sensitive to silica and (3) insensitive to anti-Thy 1.2 antibody plus complement. The pyran copolymer-induced peritoneal cells had very little antiproliferative activity when tested against L1210 in vitro and mice inoculated with these peritoneal cells did not survive a challenge of live L1210 cells much longer (<1 day) than L1210 inoculated control mice. Furthermore, the survival of L1210 vaccine-primed mice inoculated with one-tenth the amount of live L1210 (10²) was still much shorter than that of mice primed with L1210 vaccine plus pyran copolymer and challenged with ten times as many (10³) live L1210 cells. Therefore, direct tumouricidal activity was probably not a major factor in the in vivo immunological augmenting activity of the pyran copolymer-induced macrophages.     

Role of polymorphonuclear neutrophils on infectious complications stemming from Enterococcus faecalis oral infection in thermally injured mice

Thermally injured mice are susceptible to Enterococcus faecalis translocation. In this study, the role of polymorphonuclear neutrophils (PMN) on the development of sepsis stemming from E. faecalis translocation was studied in SCID-beige (SCIDbg) mice depleted of PMN (SCIDbgN mice) or macrophages (Mphi) and PMN (SCIDbgMN mice). Sepsis was not developed in SCIDbgN mice orally infected with E. faecalis, while the orally infected pathogen spread systemically in the same mice inoculated with PMN from thermally injured mice (TI-PMN). SCIDbgMN mice were shown to be greatly susceptible to sepsis caused by E. faecalis translocation, while orally infected E. faecalis did not spread into sepsis in the same mice that were previously inoculated with Mphi from unburned SCIDbg mice (resident Mphi). In contrast, orally infected E. faecalis spread systemically in SCIDbgMN mice inoculated with resident Mphi and TI-PMN, while all SCIDbgMN mice inoculated in combination with resident Mphi and PMN from unburned SCIDbg mice survived after the infection. After cultivation with TI-PMN in a dual-chamber transwell, resident Mphi converted to alternatively activated Mphi, which are inhibitory on the generation of classically activated Mphi (typical effector cells in host antibacterial innate immunities). TI-PMN were characterized as immunosuppressive PMN (PMN-II) with abilities to produce cc-chemokine ligand-2 and IL-10. These results indicate that PMN-II appearing in response to burn injury impair host antibacterial resistance against sepsis stemming from E. faecalis translocation through the conversion of resident Mphi to alternatively activated Mphi.