Infection In Immunosuppressed Mice Research Articles

LB1580. Efficacy Assessment of MAT2203 Encochleated Oral Formulation of Amphotericin B, in the Neutropenic Mouse Model of Pulmonary Mucormycosis

Abstract Background Invasive mucormycosis (IM) is associated with high mortality and morbidity. MAT2203 is an encochleated oral formulation of amphotericin B which has been shown to be safe and effective against murine aspergillosis and murine cryptococcal meningoencephalitis. We sought to compare the efficacy of MAT2203 to liposomal amphotericin B (LAMB) treatment in a neutropenic mouse model of IM. Methods ICR mice were immunosuppressed with cyclophosphamide and cortisone acetate on days -2, -3 and +8, relative to infection with intratracheally instilled Rhizopus delemar 99-880 or M. circinelloides f. jenssenii DI15-131. Treatment with placebo (diluent control), oral MAT2203 (5 to 45 mg/kg, given qd or bid for 7 days) or LAMB (10 mg/kg, iv, qd for 4 days), began 16 h post infection. Survival (n=10-20/group from 1/2 experiments) through Day +21 and tissue fungal burden of lungs or brain (n=10/group) euthanized on Day +4 post infection (conidial equivalents using qPCR) served as a primary and secondary endpoint, respectively. Results For Rhizopus delemar infection, doses of MAT2203 5,15 mg/kg qd or 7.5 mg/kg bid, significantly prolonged median survival time (MST) and enhanced overall survival vs. placebo-treated mice (MST of 9 Days and 0% survival for placebo-treated mice vs. 13 Days, and 20-40% for MAT2203 doses, P< 0.05 by Log-Rank). Importantly, MAT2203 treatments were as effective as LAMB (MST of 16 days and overall survival of 45%). For mice infected with M. circinelloides, MAT2203 at 15 mg/kg, qd significantly prolonged MST and enhanced overall survival vs. placebo-treated mice (MST of 5 Days and 0% survival, for placebo-treated mice vs. 13.5 Days and 50% survival for MAT2203, P< 0.05). In both infection models MAT2203 treatment of 15 mg/kg or LAMB resulted in significant ∼1.0-1.5 log reduction and ∼2.0-2.2 log reduction in lung and brain fungal burden vs. placebo, respectively (Wilcoxon Rank Sum). Conclusion MAT2203 demonstrated in vivo efficacy in treating R. delemar or M. circinelloides pulmonary infection in immunosuppressed mice, which was equivalent to the LAMB current standard of care. Continued investigation and development of MAT2203 as a novel, and oral formulation of amphotericin antifungal agent against mucormycosis is warranted. Disclosures Theresa Matkovits, PhD, Matinas BioPharma: Employee Jenel Cobb, PhD, Matinas BioPharma: Employee Raphael J. Mannino, PhD, Matinas BioPharma: Employee Ashraf S. Ibrahim, PhD, Matinas BioPharma: Advisor/Consultant|Matinas BioPharma: Grant/Research Support|SFunga: Grant/Research Support.

Chitosan Protects Immunosuppressed Mice Against Cryptosporidium parvum Infection Through TLR4/STAT1 Signaling Pathways and Gut Microbiota Modulation.

Cryptosporidium parvum infection is very common in infants, immunocompromised patients, or in young ruminants, and chitosan supplementation exhibits beneficial effects against the infection caused by C. parvum. This study investigated whether chitosan supplementation modulates the gut microbiota and mediates the TLR4/STAT1 signaling pathways and related cytokines to attenuate C. parvum infection in immunosuppressed mice. Immunosuppressed C57BL/6 mice were divided into five treatment groups. The unchallenged mice received a basal diet (control), and three groups of mice challenged with 1 × 106 C. parvum received a basal diet, a diet supplemented with 50 mg/kg/day paromomycin, and 1 mg/kg/day chitosan, and unchallenged mice treated with 1 mg/kg/day chitosan. Chitosan supplementation regulated serum biochemical indices and significantly (p < 0.01) reduced C. parvum oocyst excretion in infected mice treated with chitosan compared with the infected mice that received no treatment. Chitosan-fed infected mice showed significantly (p < 0.01) decreased mRNA expression levels of interferon-gamma (IFN-γ) and tumor necrosis factor-α (TNF-α) compared to infected mice that received no treatment. Chitosan significantly inhibited TLR4 and upregulated STAT1 protein expression (p < 0.01) in C. parvum-infected mice. 16S rRNA sequencing analysis revealed that chitosan supplementation increased the relative abundance of Bacteroidetes/Bacteroides, while that of Proteobacteria, Tenericutes, Defferribacteres, and Firmicutes decreased (p < 0.05). Overall, the findings revealed that chitosan supplementation can ameliorate C. parvum infection by remodeling the composition of the gut microbiota of mice, leading to mediated STAT1/TLR4 up- and downregulation and decreased production of IFN-γ and TNF-α, and these changes resulted in better resolution and control of C. parvum infection.

Aspergillus fumigatus Fumagillin Contributes to Host Cell Damage

The activity of fumagillin, a mycotoxin produced by Aspergillus fumigatus, has not been studied in depth. In this study, we used a commercial fumagillin on cultures of two cell types (A549 pneumocytes and RAW 264.7 macrophages). This toxin joins its target, MetAP2 protein, inside cells and, as a result, significantly reduces the electron chain activity, the migration, and the proliferation ability on the A549 cells, or affects the viability and proliferation ability of the RAW 264.7 macrophages. However, the toxin stimulates the germination and double branch hypha production of fungal cultures, pointing out an intrinsic resistant mechanism to fumagillin of fungal strains. In this study, we also used a fumagillin non-producer A. fumigatus strain (∆fmaA) as well as its complemented strain (∆fmaA::fmaA) and we tested the fumagillin secretion of the fungal strains using an Ultra High-Performance Liquid Chromatography (UHPLC) method. Furthermore, fumagillin seems to protect the fungus against phagocytosis in vitro, and during in vivo studies using infection of immunosuppressed mice, a lower fungal burden in the lungs of mice infected with the ∆fmaA mutant was demonstrated.

Морфологическая характеристика экспериментальной катетер-ассоциированной инфекции на фоне иммуносупрессии и применения низкомолекулярного катионного пептида семейства лантибиотиков – варнерина

Introduction. Catheter-associated infection is caused by microorganism colonization of the surface of the implanted catheter with a biofilm formation that significantly increases their resistance to antiseptics and antibiotics, especially in immunosuppression. Low-molecular antibacterial peptides are compounds capable of combating biofilm formation. The aim of the study was to describe morphological characteristics of a catheter-associated infection model on laboratory mice secondary to immunosuppression and to assess the efficacy of the low-molecular cationic antibacterial peptide (warnerin). Materials and methods. An experiment included white outbred mice (25–30 g body weight) under ether anesthesia that received 1.0-cm fragments of intravascular catheters under the skin of the backs. The animals underwent preliminary immunosuppression with cyclophosphamide. We used Staphylococcus epidermidis 33 (in the form of suspensions or biofilms previously grown on catheter segments) and low-molecular cationic peptide warnerin. All animals were sacrificed by ether overdose on days 1, 2, and 3 after the manipulation. We took the tissues surrounding the catheter for histological and immunohistochemical studies with antibodies to CD34, vimentin, CD68, CD3, and CD20. Results. The warnerin administration at the site of the catheter implantation led to disappearance of or a significant decrease in the number of bacterial. In the infiltrate, the number of neutrophils significantly increased, whereas that of fibroblasts decreased. Immunohistochemistry confirmed the features of the cellular reactions around the catheters with bacterial contamination with warnerin administration. Conclusion. In a model of catheter-associated infection in immunosuppressed mice, the warnerin antibacterial manifests in characteristic histological alterations in the inflammatory infiltrate composition. Keywords: catheter-associated infection model, morphology of inflammation, warnerin antibacterial cationic peptide

The Protective Effect of Artemisia spicigera Ethanolic Extract against Cryptosporidium parvum Infection in Immunosuppressed Mice.

Background:A specific treatment has not yet developed for cryptosporidiosis, and some of the used drugs had side effects in immunodeficient patients. The goal of an appropriate remedy is to remove symptoms and improve immune responses in hosts. The current study was designed to evaluate the therapeutic efficacy of Artemisia spicigera ethanolic extract in experimentally infected immunosuppressed mice.Methods:Thirty six NMRI mice, 4–6 wk old, were randomly divided into six equal groups. C1: uninfected, treated control; C2: infected, untreated control; T1, T2, T3, and P: infected, treated with 0.2, 2, and 20 mg/ml extract, and 5mg/ml paromomycin, respectively. Mice were experimentally infected by oral administration of 104 oocysts/animal of Cryptosporidium parvum and treated orally for eight days per 12h, starting 12h before experimental infection. The presence of oocyst shedding, weight gain/loss, and the histopathology of ileum sections were examined.Results:Results revealed that oocyst shedding was significantly (P<0.05) reduced in treatment groups. There was no significant difference between the mean of weight gain/loss in the infected control and treated groups. Histopathological analysis of ileum sections further supported the parasitological findings.Conclusion:Artemisia spicigera had acceptable efficacy as a therapeutic agent for cryptosporidiosis.

Experimental murine model of intra-abdominal infections caused by some non-albicans &lt;i&gt;Candida&lt;/i&gt; species

Background: Even though intra-abdominal candidiasis (IAC) has been increasingly recognized, with associated high morbidity and mortality rates, its pathogenesis remains poorly understood. This model aims to study the pathogenicity and invivo susceptibility of non-albicans Candida species associated with IAC in human in order to predict the frequency of infections, outcome of clinical disease and response to antifungal therapy.Methodology: Both immunosuppressed and immunocompetent female CD-1 mice were challenged intraperitoneally with 5 x 108 CFU/ml inoculum of five non-albicans Candida strains; Candida glabrata, Candida parapsilosis, Candida lipolytica, Candida tropicalis and Candida guilliermondii. Mice were closely observed for symptoms. Treated groups received voriconazole (40 mg/kg/day) or micafungin (10 mg/kg/day) 24 hours after infection depending on invitro susceptibility results. Survival rate, mean survival time and fungal tissue burdens were recorded for all groups.Results: All infected groups developed hepatosplenomegaly, peritonitis and multiple abscesses on intra-abdominal organs and mesenteries. C. glabrata and C. lipolytica represented the most and the least virulent strains respectively in terms of survival rate, mean survival time and fungal burden in both immunosuppressed and immunocompetent models. Following treatment, all immunocompetent animals survived the entire duration of experiments (0% mortality rate), while mortality rate was relatively high (20-60%) in immunosuppressed mice. Treatment failed to eradicate the infection in immunosuppressed mice despite significant decrease of the fungal burden and increase mean survival time.Conclusion: This study reports an increasing pathogenicity of non-albicans Candida species, with persistent infection among immunosuppressed animals.Keywords: Intra-abdominal, Candidiasis, non-albicans, invivo, mice

Effects of Echinacea Purpurea on Cryptosporidiosis in Immunosuppressed Experimentally Infected Mice

AbstractBackground: Cryptosporidium species are worldwide coccidian parasites. They are considered the second cause of diarrhea and death in children after rotavirus. Current treatment options for cryptosporidiosis are limited. There is an urgent need to develop new anti-cryptosporidial agents.Aim of the Study: To assess the activity of Echinacea purpurea in treatment of experimental cryptosporidiosis in immunosuppressed mice.Methods: Ninety mice were immunosuppressed using oral dexamethasone and divided into 5 groups. Echinacea was used as 100 mg/kg/day on day 15 post infection for five consecutive days. Stool samples from all survived mice were subjected to modified Ziehl-Neelsen staining. All mice were sacrificed for histopathological examination and immuno-histochemical staining of their ilea sections for IL-17 and Cox-2.Results: The least mortality rate (0%), the least oocysts shedding (1.10±2.31), the least endogenous developmental stages (3.50±2.24), the most improved pathological changes and the highest cure rate (90%) were observed in mice treated with Echinacea/nitazoxanide combination. Moreover, combi-nation therapy significantly reduced IL-17 and Cox-2 expres-sion in ileum sections compared to the positive control group. Echinacea monotherapy significantly reduced fecal oocyst shedding and ileal endogenous developmental stages with improved pathological changes compared to the positive control group. Echinacea increased the cure rate with no significant difference when compared to nitazoxanide. It significantly decreased IL-17 and Cox-2 in ileum sections compared to the positive control group.Conclusion: Echinacea purpurea/nitazoxanide combina-tion represents significant advances in treatment of experi-mental cryptosporidiosis infection in immunosuppressed mice.

Effects of Enterococcus faecalis CECT 7121 on Cryptosporidium parvum infection in mice.

Cryptosporidium is an opportunistic protozoan parasite of humans and animals worldwide and causes diarrheal disease that is typically self-limiting in immunocompetent hosts but often life threatening to immunocompromised individuals. However, there is a lack of completely efficient therapy available. Probiotics have attracted the attention as potential antiparasite compounds against protozoa involved in intestinal infections. This study investigated the effects of administration of probiotic Enterococcus faecalis CECT 7121 on Cryptosporidium parvum infection in immunosuppressed mice. Effects on C. parvum infection at the intestinal mucosa were studied and scored at each portion of the gut. It was demonstrated that Ef CECT 7121 interfered with C. parvum infection when both probiotic and parasite were present in the same intestinal location suggesting that Ef CECT 7121 supplementation can alleviate the negative effects of C. parvum infection.

Recombinant Murine Gamma Herpesvirus 68 Carrying KSHV G Protein-Coupled Receptor Induces Angiogenic Lesions in Mice

Human gamma herpesviruses, including Kaposi’s sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV), are capable of inducing tumors, particularly in in immune-compromised individuals. Due to the stringent host tropism, rodents are resistant to infection by human gamma herpesviruses, creating a significant barrier for the in vivo study of viral genes that contribute to tumorigenesis. The closely-related murine gamma herpesvirus 68 (γHV68) efficiently infects laboratory mouse strains and establishes robust persistent infection without causing apparent disease. Here, we report that a recombinant γHV68 carrying the KSHV G protein-coupled receptor (kGPCR) in place of its murine counterpart induces angiogenic tumors in infected mice. Although viral GPCRs are conserved in all gamma herpesviruses, kGPCR potently activated downstream signaling and induced tumor formation in nude mouse, whereas γHV68 GPCR failed to do so. Recombinant γHV68 carrying kGPCR demonstrated more robust lytic replication ex vivo than wild-type γHV68, although both viruses underwent similar acute and latent infection in vivo. Infection of immunosuppressed mice with γHV68 carrying kGPCR, but not wild-type γHV68, induced tumors in mice that exhibited angiogenic and inflammatory features shared with human Kaposi’s sarcoma. Immunohistochemistry staining identified abundant latently-infected cells and a small number of cells supporting lytic replication in tumor tissue. Thus, mouse infection with a recombinant γHV68 carrying kGPCR provides a useful small animal model for tumorigenesis induced by a human gamma herpesvirus gene in the setting of a natural course of infection.

Effect of Three Drugs against Encephalitozoon cuniculi Infection in Immunosuppressed Mice

Microsporidia comprise a large group of obligate intracellular parasites. The microsporidian Encephalitozoon cuniculi causes disseminated infection in immunosuppressed patients with HIV, cancer, or transplants and in the elderly. In vivo and in vitro studies on the effectiveness of drugs are controversial. Currently, there is no effective treatment. We tested albendazole, albendazole sulfoxide, metronidazole, and cyclosporine in mice immunosuppressed with cyclophosphamide and inoculated by the intraperitoneal route with 10(7) E. cuniculi spores. One week after experimental inoculation, the mice were treated with albendazole, albendazole sulfoxide, metronidazole, and cyclosporine. Histological and morphometric analyses were performed to compare the treated groups. The state of immunosuppression was evaluated by phenotyping CD4(+) and CD8(+) T cells by flow cytometry. Nontreated mice showed acute disseminated and fatal encephalitozoonosis. The treatment with benzimidazoles significantly reduced infection until 30 days posttreatment (p.t.), but at 60 days p.t., the infection had recurred. Metronidazole decreased infection by a short time, and cyclosporine was not effective. All animals were immunosuppressed by all the experiments, as demonstrated by the low number of CD4(+) and CD8(+) T cells. We conclude that no drug was effective against E. cuniculi, but the benzimidazoles controlled the infection transiently.

Efficacy of Repeated Intravenous Injection of Peramivir against Influenza A (H1N1) 2009 Virus Infection in Immunosuppressed Mice

The efficacy of intravenous peramivir against influenza A (H1N1) 2009 virus infection was evaluated in mice in which the immune system was suppressed by cyclophosphamide (CP) treatment. The mortality rate of the vehicle control group was 100%, and the mice lost 20% of their body weight on average by day 13 postinfection (p.i.). Repeated administration of peramivir (40 mg/kg of body weight once a day, given intravenously for 20 days), starting at 1 h p.i., significantly reduced mortality, body weight loss, viral titers, and cytokine production in infected mice compared with results for administration of vehicle (P < 0.01). In addition, repeated administration of peramivir, starting at 24 h, 48 h, or 72 h p.i., also resulted in increases in survival rates and reduction of viral titers in the lungs (P < 0.01). The mean days to death (MDD) of the vehicle group was 14.5 days, while in the groups treated with peramivir starting at 24 h, 48 h, and 72 h p.i., the MDDs were >23.0, 20.9, and 21.8 days, respectively. In comparison, repeated administration of oseltamivir phosphate (5 mg/kg twice a day, given orally for 20 days), starting at 24 h, 48 h, and 72 h p.i., also significantly prevented body weight loss, whereas no significant differences in mortality rates and viral titers in the lungs were observed compared with results for the vehicle group. These data indicated that repeated administration of peramivir was effective in promoting the survival and reducing virus replication in immunosuppressed mice infected with influenza A (H1N1) 2009 virus.

New Insight into Amphotericin B Resistance in Aspergillus terreus

Amphotericin B (AMB) is the predominant antifungal drug, but the mechanism of resistance is not well understood. We compared the in vivo virulence of an AMB-resistant Aspergillus terreus (ATR) isolate with that of an AMB-susceptible A. terreus isolate (ATS) using a murine model for disseminated aspergillosis. Furthermore, we analyzed the molecular basis of intrinsic AMB resistance in vitro by comparing the ergosterol content, cell-associated AMB levels, AMB-induced intracellular efflux, and prooxidant effects between ATR and ATS. Infection of immunosuppressed mice with ATS or ATR showed that the ATS strain was more lethal than the ATR strain. However, AMB treatment improved the outcome in ATS-infected mice while having no positive effect on the animals infected with ATR. The in vitro data demonstrated that ergosterol content is not the molecular basis for AMB resistance. ATR absorbed less AMB, discharged more intracellular compounds, and had better protection against oxidative damage than the susceptible strain. Our experiments showed that ergosterol content plays a minor role in intrinsic AMB resistance and is not directly associated with intracellular cell-associated AMB content. AMB might exert its antifungal activity by oxidative injury rather than by an increase in membrane permeation.

Effect of Oral Administration of β-D-glucan from Aureobasidium pullulans ADK-34 on Candida and MRSA Infections in Immunosuppressed Mice

We examined the effect of the oral administration of β-D-glucan derived from Aureobasidium pullulans ADK-34 (AP-FBG) on Candida albicans or methicillin-resistant Staphylococcus aureus (MRSA) infection in immunosuppressed mice. Mice pretreated with cyclophosphamide (CY) were intraperitoneally administered AP-FBG for 4 days and then infected with 6×10(4) C. albicans cells. In a preliminary experiment, the survival time of the Candida-infected mice treated with AP-FBG was clearly prolonged. Similarly, the effect of the oral administration of AP-FBG was examined. Mice were orally given 2.5% AP-FBG in feed for 42 days from 14 days prior to 2×10(4) C. albicans cells infection. The survival time of mice treated with AP-FBG was significantly prolonged and the viable cell count in the kidneys of the survivors was significantly decreased at 30 days after infection. The effects of the oral administration of AP-FBG on intestinal MRSA infection were also examined. Mice were given 2.5% AP-FBG orally in feed for 30 days before and after oral MRSA infection and treated with CY 12 days after the infection. The number of viable MRSA cells or the IgA production in feces did not significantly change, while AP-FBG administration seemed to relieve temporally the loss of body weight of mice. These results suggest that oral pre-administration of AP-FBG promoted resistance of CY-treated mice to C. albicans and lessened the weight reduction of CY-mice infected by MRSA.

Gamma Radiation Effects on Sporothrix schenckii Yeast Cells

Sporotrichosis is a subcutaneous mycosis caused by Sporothrix schenckii. Zoonotic transmission to man can occur after scratches or bites of animals, mainly cats. In this study, the gamma radiation effects on yeast of S. schenckii were analyzed with a view of developing a radioattenuated vaccine for veterinary use. The cultures were irradiated at doses ranging from 1.0 to 9.0 kGy. The reproductive capacity was measured by the ability of cells to form colonies. No colonies could be recovered above 8.0 kGy, using inocula up to 10(7) cells. Nevertheless, yeast cells irradiated with 7.0 kGy already were unable to produce infection in immunosuppressed mice. Evaluation by the FungaLight™ Kit (Invitrogen) indicated that yeast cells remained viable up to 9.0 kGy. At 7.0 kGy, protein synthesis, estimated by the incorporation of [L-(35)S] methionine, continues at levels slightly lower than the controls, but a significant decrease was observed at 9.0 kGy. The DNA of 7.0 kGy irradiated cells, analyzed by electrophoresis in agarose gel, was degraded. Cytoplasmic vacuolation was the main change verified in these cells by transmission electron microscopy. The dose of 7.0 kGy was considered satisfactory for yeast attenuation since irradiated cells were unable to produce infection but retained viability, metabolic activity, and morphology.

Alternative dosing regimens of liposomal amphotericin B (AmBisome) effective in treating murine systemic candidiasis

This study was done to determine whether high dose AmBisome (4-20 mg/kg), given intermittently, could reduce the frequency of dosing needed to treat murine systemic candidiasis when compared with conventional daily treatment. Mice were immunosuppressed with cyclophosphamide every 3 days, beginning day -3 before challenge with log(10) 5.0 cfu Candida albicans. Treatment was begun 48-72 h post-challenge with daily or intermittent dose regimens of AmBisome, followed by determination of kidney cfu for up to 1 month post-treatment. A single AmBisome dose of 4 mg/kg was as effective as four daily, 1 mg/kg treatments. A total of 8 mg/kg, given as 4 mg/kg on days 2 and 4, or as 5 mg/kg on day 2 followed by 1 mg/kg on days 3, 4, and 5, also produced comparable efficacy. While 20 mg/kg given day 2, 4 and 6 post-challenge as a 1 week loading dose, followed by one 10 mg/kg treatment on day 13, decreased the fungal burden by up to 5 logs compared with controls (log(10) 2.3 cfu/g and log(10) 7.5 cfu/g, respectively), 20 mg/kg given Monday, Wednesday and Friday for 5 weeks, reduced the fungal burden to undetectable levels (i.e. log(10) 1.0 cfu). Significant reduction or clearance of kidney cfu, following intermittent, high dose AmBisome treatment, indicated that non-daily dosing regimens could be successfully used instead of conventional daily dosing to treat established C. albicans infection in immunosuppressed mice.

Potential of colony-stimulating factors to improve host defense in organ transplant recipients

Purpose of review Although immunosuppressive drugs prevent graft rejection, they also predispose patients to infection, representing a major complication in organ transplantation. It would thus be highly desirable to attain true immune tolerance without increasing the risk of infections and malignancies. Before the background of current strategies in the management of infections, the novel concept of differential reactivation of immunity, ie, boosting the innate immune response while continuing suppression of the adaptive immune response, is introduced. Recent findings Present clinical experience, feasibility, and potential risks of applying factors that potentially display such dichotomal properties (eg, granulocyte colony-stimulating factor [G-CSF] or granulocyte-macrophage colony-stimulating factor [GM-CSF]) are discussed. Summary In dexamethasone-treated PBMC isolated from control patients, or in cells obtained from immunosuppressed liver transplant patients, GM-CSF was found to selectively restore the innate immune response, without activating the specific immune response implicated in graft rejection. Moreover, GM-CSF efficiently restored the immune response against an otherwise lethal bacterial infection in immunosuppressed mice, without inducing the rejection of a skin transplant. These recent data could have implications for clinical practice and suggest a more detailed evaluation of agents with similar actions to GM-CSF in the restoration of innate immunity in organ transplant patients.

Coccidial infection in immunosuppressed mice: prophylaxis and treatment with dehydroepiandrosterone

Cryptosporidiosis and toxoplasmosis are diseases caused by opportunistic coccidial parasites that can lead to life-threatening infection in immunocompromised patients. We evaluated dehydroepiandrosterone as prophylaxis and therapy in immunosuppressed mice infected with Cryptosporidium parvum and avirulent Toxoplasma gondii. Mice were infected with either Cryptosporidium oocysts or Toxoplasma cysts. Assessment was by mortality rates, parasitic counts and electron microscopic studies. Mortality rates were significantly reduced in all treated groups. A significant reduction in the cryptosporidial oocyst count in stool and intestinal villi and in Toxoplasma cysts in the brains of infected mice was observed in all the groups. The effect of the drug was greater when given prior to infection.

Protective effect of oral administration of several traditional Kampo-medicines on lethal Candida infection in immunosuppressed mice

The protective effects of a "hozai" type of Kampo medicine, Juzen-taiho-to (Shi-quan-da-bu-tang, TJ-48), Hochu-ekki-to (Bu-zhong-yi-qi-tang, TJ-41) or Ninjin-yoei-to (Ren-shen-yang-rong-tang, TJ-108) on experimental candidiasis in immunosuppressed mice were investigated. ICR mice, which were immunosuppressed by injection of cyclophosphamide or prednisolone, were given these medicines orally andchallenged intravenously with Candida albicans (day 0). Treatments with a daily dose of 1 g/kg/day of TJ-48 or that of 1 or 2 g/kg/day of TJ-108 for 4 consecutive days from day-4 significantly prolonged the survival time of the Candida-infected mice pretreated with cyclophosphamide. Treatments with a daily dose of 1 g/kg/day of TJ-48 for 4 consecutive days from day 0, but not from day -4, significantly prolonged the life span of the Candida-infected mice pretreated with prednisolone. On the basis of these results and previous findings, characteristics of these kampo medicines as therapeutic agents against candidiasis in immunosuppressed hosts were discussed.

A Revised Arithmetic Model of Long Slender to Short Stumpy Transformation in the African Trypanosomes

An arithmetic model that closely approximates an African trypanosome infection in immunosuppressed mice is presented. The final model was based on an examination of the following parameters: the rate of long slender to short stumpy transition, the maximum percentage of long slender to short stumpy stages that can be induced, the survival time or half life of the short stumpy stage in vivo, and the rate (%) of long slender to short stumpy stage transition following the peak in transformation. The model is based on the assumption that the long slender to short stumpy transition is parasite population dependent and that in mice the long slender to short stumpy transition only begins when the trypanosome population reaches a density of 1 x 10(7) trypanosomes/ml. The model predicts that the parasitemia during the first several days of an infection is controlled solely by the kinetics of the transition of the dividing long slender stage to the nondividing short stumpy stage. It was not necessary to include in the model the host's immune response in order to simulate the early growth kinetics of pleomorphic trypanosomes in infected mice.

Efficacy of RD3-0028 aerosol treatment against respiratory syncytial virus infection in immunosuppressed mice.

RD3-0028, a benzodithiin compound, has antiviral activity against respiratory syncytial virus (RSV) in cell culture. We used a mouse model of RSV infection to determine the in vivo effect of RD3-0028. Cyclophosphamide (CYP)-treated, immunosuppressed mice were inoculated intranasally. The lungs of the mice were removed on day 4. The virus titers of the lungs of RD3-0028-treated mice were compared to the virus titers of the lungs of virus-inoculated, untreated control mice. In an effort to increase the therapeutic effectiveness of this compound, RD3-0028 was administered by aerosol to RSV-infected mice by using a head-exposure system. Aerosols generated from reservoirs containing RD3-0028 (7 mg/ml) administered for 2 h twice daily for 3 days significantly reduced the pulmonary titer of RSV-infected mice. It is clear that the minimal effective dose of RD3-0028 for RSV-infected mice is significantly less than that of ribavirin, the only compound currently available for use against RSV disease. Furthermore, the RD3-0028 aerosol administration appeared to protect the lungs of infected, CYP-treated mice against tissue damage, as evidenced by the preservation of the lung architecture and a reduction in pulmonary inflammatory infiltrates. RD3-0028 aerosol was not toxic for mice at the therapeutic dose. The present study demonstrates the effectiveness of aerosol administration of RD3-0028 for RSV-infected mice.