Histopathology of BALB/c mice infected with the D variant of encephalomyocarditis virus.

BALB/c mice infected with 10(5) pfu of the D variant of encephalomyocarditis virus were examined histopathologically during the subacute stage of infection. Main pathologic changes were observed in the brain, heart (massive myocardial necrosis with subsequent organization (i.e., replacement of necrotic myocardium by connective tissue) and congestion and dilatation of the right ventricle) and pancreas (moderate degranulation of beta-cells resulting in elevation of blood glucose level). The brain lesions were found most frequently in the pyramidal layer of the hippocampus and the granular layer of the cerebellum and were characterized by degeneration of neurons containing virus antigens. Perivascular mononuclear cell infiltration, spreading to the adjacent brain tissue, and thrombosis in small vessels were also frequently seen. Focal loss of neurons and gliosis developed later in these lesions.     

N-acetyl-l-cysteine reduces the parasitism of BALB/c mice infected with Leishmania amazonensis

Leishmania amazonensis infection leads to progressive diseases in a majority of inbred strains of mice. Glutathione (GSH) participates in a large number of cellular phenomena and seems to be essential for several immune functions, including host defense during leishmaniasis. In this study, we evaluated the effects of N-acetyl-l-cysteine (NAC), as GSH supplement, on the course of L. amazonensis infection in susceptible BALB/c mice. The treatment with NAC (200 mg/kg daily) was effective in raising GSH levels in both lymph node and spleen cells. Although this treatment did not change the footpad swelling development in L. amazonensis-infected mice, it caused a significant decrease in the number of parasites recovered from the footpad lesion and draining popliteal lymph node. Our data suggest that intracellular Leishmania killing in vivo was improved by the augment of GSH levels through NAC administration.     

Hepatic extracellular matrix in BALB/c mice infected with Leishmania donovani

The development of the extracellular matrix (ECM) in the liver of the BALB/c mouse infected with Leishmania donovani was observed by histology, immunocytochemistry and electron microscopy at 1, 2, 4, 8, 14 and 20 weeks after infection. Collagen III and proteoglycan were detected in granulomas and in the portal spaces from 4 to 20 weeks after infection. Laminin was not detected in granulomas but was observed in the basement membrane of new small blood vessels in the granulation tissue around the portal spaces from 8 to 20 weeks after infection. The ECM components in the space of Disse showed no changes in distribution throughout the entire period of study. Systemic fibrosis in the hepatic lobule was not evident in the BALB/c mice. This mouse strain does not appear to be an appropriate model to study the role of ECM in chronic visceral leishmaniasis.     

Suppurative gastritis in BALB/c mice infected with Listeria monocytogenes via the intragastric route

Suppurative gastritis was demonstrated in BALB/c mice 3 days after intragastric inoculation with 10(9) organisms of Listeria monocytogenes strain ATCC19113 (serotype 3). Also tested were four other strains of mice (C3H, C57BL/6, FVB and ICR) and three other strains of L. monocytogenes (HPB 3 [serotype 4b], HPB 410 [serotype 1/2a] and HPB 503 [serotype 1/2b]). After inoculation with ATCC19113 the numbers of bacteria found in the stomach wall were greater in C57BL/6 and ICR mice than in C3H and FVB mice; moreover, the gastritis produced in BALB/c and C57BL/6 mice was more severe than that produced in the other mouse strains. The gastritis produced in BALB/c mice with L. monocytogenes HPB 3, HPB 410 and HPB 503 was much more severe than that produced by ATCC19113. The inflammatory response occurred in the lamina muscularis and mucosa of the fundus. Massive necrosis of the gastric epithelium was observed, and there was oedema in a large part of the mucosal layer of the fundus. In addition, the submucosal layer was apparently expanded due to oedema, and in the cardia, the mucosal layer had become thin and flattened. Immunohistochemically, a polyclonal antibody against Listeria spp. produced labelling in areas of the gastric mucosa in which there was an inflammatory response and gastric epithelial necrosis.     

Outbred mice infected by an encephalomyocarditis virus variant: A model for studying chronic viral heart disease

Male 8 to 20-week-old NMRI mice (an outbred strain) infected with the encephalomyocarditis virus (EMCV) plaque variant (PV) 7 consistently develop a distinct myocarditis with a relatively low mortality (21%). Myocarditis occurs in essence independent of the virus dose applied, and other internal organs are not affected. Nevertheless, 3.5-week-old NMRI mice perished within 5 days of virus inoculation and exhibited disseminated myofibrillar degeneration (MFD); this obviously virus-induced myocardial damage was accompanied by scanty inflammatory infiltrates. EMCV PV7 infection of adult male C57B1/6 and DBA/2 mice causes myocarditis comparable to that seen in NMRI mice. In DBA/2 mice, however, the virus-induced myocardial necrosis is complicated by subtotal calcification. This strain has a genetically determined spontaneous calcification of the myocardium, as shown by the study of uninfected controls. EMCV PV7-infected NMRI mice appear a promising model for study of long-term effects of viral myocarditis, possibly including cardiomyopathy. Furthermore, this outbred mouse strain offers the possibility of examining the pathogenesis of direct viral cytolysis and its relation to MFD as well as immunologically mediated cell damage.     

BALB/c鼠和裸鼠呼吸道合胞病毒感染比较研究

目的 比较普通BALB/c鼠和裸鼠呼吸道合胞病毒(RSV)感染免疫及炎症反应特点.方法 BALB/c鼠和裸鼠感染RSV后不同时间空斑形成试验检测肺组织病毒滴度,计数支气管肺泡灌洗液(BALF)白细胞总数和分类,HE染色分析肺组织病理学改变,免疫组化检测肺组织F4/80+细胞和CD49b+细胞.ELISA检测BALF中TNF-α、IFN-r、IL-12和IL-10浓度.结果 BALB/c鼠和裸鼠感染RSV后肺组织病毒滴度在第3天达峰值,感染裸鼠带毒时间更长,在感染后各天病毒滴度明显高于BALB/c鼠(P＜0.05),肺组织病理改变也更重.感染BALB/c鼠和裸鼠BALF白细胞总数明显升高,分类以淋巴细胞为主.感染裸鼠与感染BALB/c鼠比较,肺组织检测到更多的F4/80+巨噬细胞和CD49b+NK细胞(P＜0.05),BALF中TNF-α、IL-12和IL-10水平更高(P＜0.05).结论 RSV感染裸鼠与BALB/c鼠比较,病毒复制水平更高,时间更持久,炎症反应更重.单核巨噬细胞和NK细胞是RSV感染重要的免疫细胞和炎症细胞,炎症反应强度并不一定与T细胞免疫应答平行.     

The early immune response in the liver of BALB/c mice infected with S. typhimurium

Gram-negative bacteria acquired through gastrointestinal infection can be a serious cause for the development of septic shock especially in immunosuppressed patients. Thus, the aim of this study was to examine the early events of the immune reaction against S. typhimurium. Bacteria were injected into mice at different concentrations. Four animals from each group were killed at five different points of time. Liver cytokine mRNA expression was determined by semiquantitative rt-PCR and liver histology was examined. Serum cytokine levels of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-4 and IL-10 were determined. intravenous (i.v.) infection with 109 bacteria led to lethal septic shock within 24 h. A delayed production of IFN-gamma, TNF-alpha, IL-18 and IL-10 and milder histological alterations in the liver were observed in these animals. The highest expression of cytokines in the liver and the strongest histological alterations were seen after infection with 107 bacteria. Here, an increased mRNA expression of all proinflammatory cytokines began 1 h after infection. Animals infected with 1 x 102 bacteria had the highest detectable serum levels of IL-6 and IL-10. These data indicate that the immediate events in the immune reaction within the liver after infection with S. typhimurium are associated with the outcome of the subsequent sepsis.     

登革病毒E蛋白抗原基因肌肉注射诱导小鼠免疫应答的初步研究

目的：研究登革病毒Ｅ基因免疫的可行性,方法：用脂质体转染法将构建的Ｅ基因重组真核表达质粒ｐｃＤＮＡ３－Ｅ导入小鼠成纤维细胞ＮＨ３Ｔ３细胞,ＳＤＳ－ＰＡＧＥ和蛋白质印迹试验检测Ｅ基因的体外表达。然后将该重组真核表达质粒经肌肉注射免疫ＢＡＬＢ／ｃ小鼠,检测其诱发特异性免疫应答水平。结果：重组真核表达质粒ｐｃＤＮＡ３－Ｅ在小鼠体内诱发一定水平的体液和细胞免疫应答,且持续时间较长。结论：登革病毒Ｅ基因免疫可诱发特异性免疫应答。为登革病毒疫苗的研制提供了实验依据。     

Pathogenesis of the B variant of encephalomyocarditis virus

Variants of encephalomyocarditis virus (EMCV) are immunologically indistinguishable by hyperimmune serum, but, with the exception of EMCV-B, each produces a different disease syndrome and infects the central nervous system in mice infected via the intraperitoneal route of inoculation. The B variant is benign in that it does not produce any overt signs of infection at doses as high as 10⁶ pfu per animal. The present study was carried out to determine if EMCV-B was pathogenic when administered via the intracranial route and, if so, to delineate the area(s) of the brain infected. The results show that, when given i.c., EMCV-B is similar to other variants of EMCV in that it infects and replicates in the brain, causing encephalitis, neuronal necrosis in Ammon's horn of the hippocampus, and clinical signs of infection. The data indicate that receptor sites for EMCV-B are present on brain cells and suggest that its benign nature when given by the intraperitoneal route reflects an inability to cross the blood-brain barrier. © 1993 Wiley-Liss, Inc.     

Protective effect of isoprinosine in genetically susceptible BALB/c mice infected with Leishmania major.

The effects of an immunopotentiating drug Inosine Pranobex (isoprinosine) were investigated in an experimental cutaneous leishmaniasis model. The highly susceptible BALB/c mice treated orally with isoprinosine developed significantly delayed onset of disease when infected with Leishmania major compared to untreated mice. The drug itself is not toxic to the parasite up to millimolar levels in vitro. The increase in resistance to L. major infection is accompanied by a marked decrease in the CD4+/CD8+ ratio and the leishmanial antigen-specific proliferative response of the spleen cells of isoprinosine-treated mice compared to untreated mice. There was a significant increase in the production of IFN-gamma but a decrease in the secretion of IL-3 and IL-4 by the spleen cells of isoprinosine-treated mice in response to concanavalin A with or without L. major infection compared to untreated controls. There was, however, no significant difference in the level of IL-2 production by the spleen cells between mice with or without isoprinosine treatment. These data are consistent with the interpretation that isoprinosine potentiates the resistance to leishmanial infection by up-regulating the host-protective Th1 cells and down-regulating the disease-promoting Th2 cells or, alternatively, by increasing CD8+ T-cell function.     

Dendritic cells infected with adenovirus expressing the thyrotrophin receptor induce Graves' hyperthyroidism in BALB/c mice

Dendritic cells (DCs) are the most potent antigen-presenting cells and a prerequisite for the initiation of primary immune response. This study was performed to investigate the contribution of DCs to the initiation of Graves' hyperthyroidism, an organ-specific autoimmune disease in which the thyrotrophin receptor (TSHR) is the major autoantigen. DCs were prepared from bone marrow precursor cells of BALB/c mice by culturing with granulocyte macrophage-colony stimulating factor and interleukin-4. Subcutaneous injections of DCs infected with recombinant adenovirus expressing the TSHR (but not beta-galactosidase) in syngeneic female mice induced Graves'-like hyperthyroidism (8 and 35% of mice after two and three injections, respectively) characterized by stimulating TSHR antibodies, elevated serum thyroxine levels and diffuse hyperplasitc goiter. TSHR antibodies determined by ELISA were of both IgG1 (Th2-type) and IgG2a (Th1-type) subclasses, and splenocytes from immunized mice secreted interferon-gamma (a Th1 cytokine), not interleukin-4 (a Th2 cytokine), in response to TSHR antigen. Surprisingly, IFN-gamma secretion, and induction of antibodies and disease were almost completely suppressed by co-administration of alum/pertussis toxin, a Th2-dominant adjuvant, whereas polyriboinosinic polyribocytidylic acid, a Th1-inducer, enhanced splenocyte secretion of IFN-gamma without changing disease incidence. These observations demonstrate that DCs efficiently present the TSHR to naive T cells to induce TSHR antibodies and Graves'-like hyperthyroidism in mice. In addition, our results challenge the previous concept of Th2 dominance in Graves' hyperthyroidism and provide support for the role of Th1 immune response in disease pathogenesis.     

Inoculation of BALB/c mice with fish-pathogenic nodaviruses

To investigate the pathogenicity of fish-pathogenic nodaviruses (betanodaviruses) in mammals, weanling mice were inoculated with striped jack nervous necrosis virus (SJNNV; the type species of the genus Betanodavirus) or redspotted grouper nervous necrosis virus (RGNNV), which belong to different genotypes. After inoculation with 10(7.5) TCID50, either intramuscularly or intraperitoneally, mice remained clinically normal for the 14-day observation period. In a subsequent short-term (72 h) experiment, mice inoculated intramuscularly with 10(7.5) TCID50 yielded virus (10(6) to 10(5) TCID50/g) from muscle at the site of injection at 3, 24 and 72 h post-infection; they also yielded virus from the kidneys (10(5) TCID50/g) at 3 and 24 h post-infection, but by 72 h virus had become almost undetectable at this site. Throughout the experiment, no virus was detected in the sites that are target organs of betanodaviruses in fish, namely, the brain, spinal cord and eye. The results indicate that the mouse is not susceptible to betanodaviruses.     

BALB/c mice infected with Angiostrongylus cantonensis: A new model for demyelination in the brain

In this study, we present a new model for demyelination of the central nervous system (CNS). BALB/c mice were infected with Angiostrongylus cantonensis and analyzed 7, 14, and 21 days postinfection. Neurological scale evaluation, magnetic resonance imaging (MRI), histology, real-time quantitative polymerase chain reaction, and western blotting were all performed on days 7, 14, and 21. The results showed that the neurological functions and weight of A. cantonensis-infected mice decreased markedly after 21 days of infection. MRI showed subdural effusion and white high signals in the corpus callosum in both T1WI and T2WI, while hematoxylin and eosin and luxol fast blue staining showed hemorrhage and demyelination in the corpus callosum. Transmission electron microscopy revealed that the ultrastructure of the myelin sheath in the corpus callosum was dispersed or disintegrated. The percentage of myelinated axons was significantly decreased, and the g-ratio was lower than that in the normal group. Both protein and mRNA levels of myelin basic protein decreased markedly at 21 days postinfection. Immunofluorescence revealed that the number of CC1 positive cells in the corpus callosum also decreased, which confirmed the damage of A. cantonensis to oligodendrocytes. Our experiments confirmed that A. cantonensis infection caused demyelination in the CNS of BALB/c mice after 21 days, and its clinical manifestations and pathological changes were similar to those of multiple sclerosis and other CNS demyelination models. Thus, mice infected with A. cantonensis could be used as a new model to study acute demyelination of the CNS.     

Immune responses in mice infected with lactic dehydrogenase virus. I. Antibody response to DNP-BGG and hyperglobulinaemia in BALB/c mice.

The humoral immune response to DNP-BGG of BALB/c mice acutely infected with lactic dehydrogenase virus (LDV) has been investigated. Virus-infected mice injected with antigen in saline exhibit a greater anti-DNP response than uninfected controls. When this antigen is presented in Freund''s complete adjuvant (FCA) the anti-DNP response is greater than obtained with antigen in saline, but significant differences between infected and uninfected controls are not observed. These data are consistent with the view that acute LDV infection can have an adjuvant-like effect when this T-dependent antigen is introduced in saline. In addition, the effect of viral infection on plasma Ig class and subclass levels has been investigated. LDV infection leads to a gradual increase in plasma Ig concentration. This effect is restricted to the IgG2a subclass in most animals, but occasionally is restricted to IgG1. The mechanisms responsible for these changes have not been delineated.     

The elimination of mycoplasma from infected hybridomas by passaging in BALB/c mice

Hybridomas, which were found to be infected with mycoplasma, were cleared of contamination by passaging in BALB/c mice. This procedure was successfully applied to four of five cultures examined. The procedure offers a simple and effective means of eliminating mycoplasma from valuable and sometimes irreplaceable hybridoma cell cultures.     

禽流感病毒感染BALB／c小鼠的动态病理观察

目的将H5N1亚型禽流感病毒（AIV）鼻腔接种BALB／c小鼠,动态观察小鼠每个时期主要器官组织的病理变化。方法将100μlH5N1亚型禽流感病毒原液滴入经麻醉后BALB／c小鼠鼻腔,观察14d,每天取材1次,固定、包埋、切片后HE染色观察各组织病理变化。结果H5N1亚型禽流感病毒感染BALB／c小鼠后,产生一系列与禽流感病毒感染有关的动态病理改变：第1～2天（前驱期）,肺轻微出血、水肿、炎性细胞浸润;第3～7天（发作期）,肺损伤逐渐严重．大量出血、炎性细胞浸润、严重水肿、淤血、肺泡实变塌陷或者气肿;第8～14天（恢复期）,各种损伤逐渐减轻,出血渗出减少,水肿减轻,肺间质出现纤维化而趋于恢复正常。肝、。肾、脑出现病理改变。结论通过动态观察病理,弄清了禽流感病毒每个时期在BALB／c小鼠体内造成的病理损伤。     

Immunophenotyping of leukocytes in peripheral blood of BALB/c mice infected with mouse herpesvirus isolate 72

We characterized leukocytes in peripheral blood of BALB/c mice infected with mouse herpesvirus isolate 72 (MHV-72) representing an isolate of mouse herpesvirus strain 68 (MHV-68, species Murid herpesvirus 4, genus Rhadinovirus, subfamily Gammaherpesvirinae, family Herpesviridae) (van Regenmortel et al., 2000). In acute infection (up to day 30 post infection (p.i.)) the number of CD8+ T cells increased, reaching a maximum at day 11 p.i. This increase correlated with that of CD4+ T, activated CD 19+ B and natural killer (NK) cells. At day 30 p.i. the numbers of CD4+, CD8+, CD14+ and CD19+ cells decreased to normal values. A similar increase in the number of these cells was observed at day 730 p. i. In the course of persistent infection (after day 30 p.i.) some of the mice developed a leukemia-like syndrome characterized by an increase in the number of leukocytes and appearance of atypical, blastic immature forms of leukocytes. The latter forms of leukocytes were characteristic by an increased amount of argyrophilic proteins. These results show further similarities between MHV-72 (another isolate of MHV-68) and EBV infections and justify the use of MHV-68 or MHV-72 as an appropriate mouse model for the study of EBV infection of humans.     

Glomerular filtration rate and plasma solutes in BALB/c mice infected withPlasmodium berghei

Immune-complex glomerular nephritis (ICGN) is known to develop during malarial infections, but little is known of its impact on renal function. A total of 24 male BALB/c mice were infected withPlasmodium berghei, and measurements of the glomerular filtration rate (GFR), parasitemia, and plasma solute concentrations were made on days 0, 7, 14, and 19 post-infection. Identical observations were made on 24 uninfected controls. The GFR declined progressively in infected mice from a mean of 201±2.1 (day 0) to 51±3 l/min (day 19), whereas parasitemia rose to 47%±4.2% infected erythrocytes. In controls, the GFR remained unchanged, averaging 205±3.4 l/min. Plasma osmolality rose in infected mice (326±1 vs 310±0.6 mosmol/kg in controls) as a result of increased chloride (123±0.7 vs 117±0.6 mEq/l) and urea (17.8±2.8 vs 9.3±0.7 mM/l levels). The data reveal a substantial deterioration of renal function during the course of a malarial infection that is short of outright renal failure.