Suppression of inflammatory genes expression in the injured host intestinal wall during Mesocestoides vogae tetrathyridium larvae migration.

Mesocestoides vogae is a cestode parasite of the family Mesocestoididae (order Cyclophyllidea). Its larvae, tetrathyridium, are approximately 1 mm long and 300 µm wide and infect a wide range of host species including humans. Tetrathyridium migrate through the intestinal wall to invade the peritoneal cavity. Despite intestinal penetration by such a large-sized parasite, symptomatic intestinal disorders are not common during the migration period. In this study, the dynamics of tetrathyridia migration and their pathogenicity towards intestinal tissues were examined in mice infected orally with these parasites. Most tetrathyridia were found to migrate through the intestinal wall, moving into the peritoneal cavity or liver 24 to 48 hours after the oral infections. Next, the pathogenicity of tetrathyridium in the intestinal wall was histopathologically evaluated, and tissue injury from tetrathyridium migration was confirmed. Inflammatory foci were observed as tetrathyridium migration tracks from 48 hours after oral infection; however, the number of inflammatory foci had decreased by half more than 48 hours later. Therefore, we examined the gene expression levels of the macrophage driving cytokine, IL-1ß, and the eosinophil recruiting chemokine, CCL11, by quantitative reverse-transcriptase PCR. The expression levels of these genes in the infected group were significantly lower than those of the non-infected group at 48 hours post-infection. Although the immunomodulating ability of the excretory-secretory products released from tetrathyridium has been previously shown by in vitro assays, the significance of this ability in their lifecycle has remained unclear. In this study, we discovered that tetrathyridium causes temporal inflammation in the intestinal wall during penetration and large-scale migration in this organ, but tetrathyridium simultaneously suppresses the host's inflammatory gene expression, might to be a strategy that reduces inflammatory responses and increases survival of the parasite.

Adhesion of Toxoplasma gondii tachyzoite-infected vehicle leukocytes to capillary endothelial cells triggers timely parasite egression.

Intracellular pathogens have numerous strategies for effective dissemination within the host. Many intracellular pathogens first infect leukocytes, which they use as a vehicle to transport them to target organs. Once at the target organ, intracellular parasite Toxoplasma gondii can cross the capillary wall in extracellular form by infecting endothelial cells. However, after egression from leukocytes, extracellular parasites face the risk of host immune attack. In this study, observation of infected mouse organs, using a method that renders tissue transparent, revealed that adhesion of tachyzoite-infected leukocytes to endothelial cells triggers immediate egression of the parasite. This signal enables the parasite to time egression from its vehicle leukocyte to coincide with arrival at a target organ, minimizing the opportunity for immune attack during the transition from a vehicle leukocyte to capillary endothelial cells.

Prevalence and dynamics of antibodies against NcSAG1 and NcGRA7 antigens of Neospora caninum in cattle during the gestation period.

Bovine abortion caused by the Apicomplexan parasite Neospora caninum is a major economic problem in the livestock industry worldwide. Our study measured the prevalence and temporal changes in levels of antibodies specific for two N. caninum derived antigens, NcSAG1 and NcGRA7, to determine an appropriate strategy for serodiagnosis. Using an enzyme-linked immunosorbent assay (ELISA), blood samples showed that 71 cows out of 129 were positive for anti-NcSAG1 antibodies and that only nine cows were positive for anti-NcGRA7 antibodies. By longitudinal sampling, it was revealed that positive and negative antibody conversion occurred frequently for anti-NcGRA7, but that anti-NcSAG1 antibodies persisted for a long-term. These results indicate the usefulness of measuring anti-NcSAG1 antibody levels for the detection of chronically infected cows. Twelve cows showed positive seroconversion during pregnancy, nine of which showed seropositivity for anti-NcGRA7 antibody at the sixth and/or seventh month of pregnancy; serum samples were not obtained from the remaining three cows during this period. Therefore, the optimal time for detection of anti-NcGRA7 antibodies appears to be between the fifth and eighth month of pregnancy.

Toxoplasma gondii tachyzoite-infected peripheral blood mononuclear cells are enriched in mouse lungs and liver.

The intracellular parasite Toxoplasma gondii is thought to disseminate throughout the host by circulation of tachyzoite-infected leukocytes in the blood, and adherence and migration of such leukocytes into solid tissues. However, it is unclear whether T. gondii-infected leukocytes can migrate to solid organs via the general circulation. In this study, we developed a real-time quantitative PCR (qRT-PCR) method to determine the rate of infection of peripheral blood mononuclear cells (PBMCs) flowing into and remaining within solid organs in mice. A transgenic T. gondii parasite line derived from the PLK strain that expresses DsRed Express, and transgenic green fluorescent protein-positive PBMCs, were used for these experiments. Tachyzoite-infected PBMCs were injected into mouse tail veins and qRT-PCR was used to measure the infection rates of the PBMCs remaining in the lungs, liver, spleen and brain. We found that the PBMCs in the lungs and liver had statistically higher infection rates than that of the original inoculum; this difference was statistically significant. However, the PBMC infection rate in the spleen showed no such enhancement. These results show that tachyzoite-infected PBMCs in the general circulation remain in the lungs and liver more effectively than non-infected PBMCs.

Toxoplasma gondii seroprevalence in domestic animals and humans in Mymensingh District, Bangladesh.

The seroprevalence of Toxoplasma gondii was examined in adult women and domestic animals used for meat products from the Mymensingh District, Bangladesh. Cattle, goats and sheep showed a high seroprevalence (12, 32 and 40%, respectively), while the sera from all fifteen women examined in the same area were seronegative. Considering that primary infection in women during pregnancy can cause abortion and congenital defects, accidental ingestion of T. gondii infected meat products from domestic animals represents a risk factor for adult women living in the same area.

Detection of Babesia gibsoni by reaction of phage display single chain antibodies with P50 proteins.

Babesia gibsoni (B. gibsoni) is a tick-borne hemoprotozoan parasite, which causes piroplasmosis in dogs. Diagnosis of canine babesiosis is commonly carried out using Giemsa-stained thin blood smears. However, at low levels of infection, it is difficult to detect Babesia organisms by observation of Giemsa-stained thin blood smears. We constructed a monoclonal phage display single chain antibody (scFv) against a B. gibsoni merozoite antigen, P50 protein. Intraerythrocytic B. gibsoni organisms are clearly stained using this antibody. The monoclonal scFv facilitated the detection of B. gibsoni organisms in canine blood samples.

Cell surface expression of a chimeric protein containing mouse immunoglobulin G1 Fc domain and its immunological property.

Recently we reported that a chimeric molecule containing mouse transferrin receptor and immunoglobulin G1 (IgG1) Fc, mTR-Fc, induced higher immune responses and can be used as a vaccine adjuvant. In this study, the immunological property of the molecule was investigated. Although, the mTR-Fc did not activate complement classical pathway, it was recognized by activated macrophage as like intact IgG Fc, which is recognized by macrophage via Fcgamma receptor. In addition, we found that splenocyte simultaneously exposed to lipopolysaccaride (LPS) and mTR-Fc produced higher amount of interleukin-10, comparing to that exposed to only LPS. These results suggest that the mTR-Fc molecules conserved the IgG Fc property to biasing immune responses via modulation of cytokine production by antigen presenting cell.