Investigation of the effects of Toxoplasma gondii on behavioral and molecular mechanism in bradyzoite stage

Toxoplasma gondii is a single-celled parasite that causes a disease called toxoplasmosis. It can reach the central nervous system, but the mechanism of T. gondii disrupting the functioning of these brain regions occurs in bradyzoite stage of parasite, causing brain damage by forming tissue cysts in brain. In our study, the effects of T. gondii on locomotor activity, anxiety, learning and memory, and norepinephrine (NE), levodopa (L-DOPA), dopamine (DA) and 3,4-D-dihydroxyphenylacetic acid (DOPAC) catecholamines in amygdala, striatum, prefrontal cortex and hippocampus regions of the brain were investigated in bradyzoite stage. Twenty male Albino mice Mus musculus, 4-5 weeks old, weighing 20-25 g, were used. T. gondii inoculated to mice intraperitonealy with 48-50-hour passages of T. gondii RH Ankara strain. For intraperitoneal inoculation of mice 5x104 tachyzoites per mouse. No inoculation was made in control group (n: 20). Locomotor activity behavior in open field test (OFT), anxious behavior in elevated plus maze (EPM), and learning behavior in novel object recognition (NOR) tests were evaluated. NE, L-DOPA, DA and DOPAC were measured by HPLC in brain tissues of amygdala, striatum, prefrontal cortex and hippocampus. A decrease was observed in the locomotor activity, anxiety and learning values of the T. gondii group compared to the control group (p < 0.05). The heighten in NE and L-DOPA levels in amygdala tissue of T. gondii group compared to control group, an elevation in NE, L-DOPA, DA and DOPAC levels in striatum tissue, and an increase in levels of NE in prefrontal cortex tissue were detected in monoamine results. In hippocampus tissue, an increase was observed in DA levels, while a decrease was observed in NE, L-DOPA and DOPAC levels. In our study, it has been shown that T. gondii in bradyzoite stage reduces locomotor activity, causes learning and memory impairment, and has anxiogenic effects.

Importance of NK Cells in Cellular and Humoral Responses Triggered by Pneumococcus Vaccination

INTRODUCTION

Despite the success of vaccination in reducing overall rate of pneumococcal pneumonia, Streptococcus pneumoniae is still held responsible for high mortality and modality rates worldwide. Our study aimed to investigate the potential role played by NK cells in immune response generated by pneumococcal vaccination, which could contribute to the development of more effective vaccines.

METHODS

The study included mice with and without NK cell depletion which were immunized with pneumococcus polysaccharide-conjugated vaccine followed by pneumococcus polysaccharide vaccine (PPV). Serum samples and splenocytes were collected from mice sacrificed 4 weeks after the last PPV dose. Serum samples were used for antibody level quantification by ELISA assay, while splenocytes were treated with PPV in vitro before monitoring CD4+ T-cell subsets (TH1, TH2, and TH17) and cytokine (IFN-γ, IL-4, and IL-17) secretion levels by flow cytometry and ELISA analysis, respectively.

RESULTS

Results demonstrated reduced pneumococcal IgG and TH1 cell levels due to NK cell depletion. Nevertheless, in contrast to these observations, IFN-γ secretion levels after in vitro PPV-23 treatment of splenocytes did not exhibit any statistically significant difference between the two mice groups.

CONCLUSIONS

The data indicate a positive contribution of NK cells to both T-cell and B-cell responses triggered against pneumococcal vaccination. Further studies are required to confirm our data and investigate the potential benefit of NK cell targeting in promoting vaccine efficacy, especially in the elderly population who continues to be affected significantly by pneumococcal pneumonia.

Molecular Survey of Babesia microti (Aconoidasida: Piroplasmida) in Wild Rodents in Turkey

Babesia microti (Aconoidasida: Piroplasmida) (Franca, 1910) is an important tick-borne zoonotic parasite with rodents serving as reservoir hosts. In the present study, 536 rodents were captured from Burdur, Bartin, Giresun, and Yozgat provinces of Turkey between the years 2010 and 2012, and blood samples were examined for the presence of Babesia spp. using conventional PCR which targeted the 18S rRNA gene. The sequence analysis of PCR amplicons was tested for B. microti as well as for Hepatozoon spp., and Sarcocystis spp. Overall, 5.8% of the rodents were positive for B. microti: 41% in Myodes glareolus, 7.7% in Chionomys roberti, and 2% in Apodemus spp., whereas no Babesia DNA was detected in Mus macedonicus and Microtus spp. Six rodents were positive for Hepatozoon spp. and one rodent was positive for Sarcocystis spp. Overall, 14.9 and 4.5% of rodents captured from Bartin and Giresun provinces, respectively, were PCR positive for B. microti, whereas none of rodents captured in Burdur and Yozgat were positive for Babesia spp. The sequence data of B. microti from rodents revealed that all sequences belonged to the zoonotic genotype. Sequences of B. microti obtained from rodents of the Bartin province were genotypically closer to European isolates, whereas those obtained from rodents of the Giresun province were closer to Russian and Mongolian isolates.

The effect of splenectomy on the levels of PCV-13-induced memory B- and T cells

AIM

Splenectomised patients are associated with lifelong risk of fatal overwhelming post-splenectomy infection (OPSI), which is mostly caused by Streptococcus pneumoniae. Today OPSI cases can still be reported even in patients with appropriate vaccination. In our study, the levels of vaccine-specific memory B- and T cells were compared between control and splenectomised patients to enlighten the underlying reason.

MATERIALS AND METHODS

Five healthy and 14 post-traumatic splenectomised individuals were vaccinated with 13-valent pneumococcal conjugate vaccine (PCV-13) followed by 23-valent pneumococcal polysaccharide vaccine (PPV-23). The levels of memory B- and T cells were compared by ELISPOT analysis.

RESULTS

Splenectomised patients generated reduced levels of memory IgG B cells in response to PCV-13 vaccination, while the memory IFN-γ T-cell levels were undetectable in asplenic patients. This was despite the detection of vaccine-induced memory T-cell levels in control patients, which were analysed simultaneously following the same experimental protocol.

CONCLUSION

Our results suggest that spleen is important, but not essential, for survival and/or generation of memory IgG B cells. In contrast, it seems to be indispensable for PCV-13-specific memory T_H 1-cell levels. Studies enhancing the levels of vaccine-induced memory cells and further enlightening the immune responses in asplenic individuals are required to develop more effective vaccination strategies against OPSI.

The role of Treg population in pathogenesis of Crimean Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a severe human infection caused by CCHF virus (CCHFV). Today, although the literature on CCHF pathogenesis is still limited, it is thought to be associated with immunosuppression in the early phase of infection followed by pro-inflammatory immune response that may lead to fatal outcomes. The aim of this study is to investigate the role of regulatory T-cells (T_reg cells) in the pathogenesis of CCHFV. Peripheral blood mononuclear cell samples collected from 14 acute CCHF patients with mild disease course and 13 healthy subjects were included in this study. T_reg expression and functional levels were analyzed by flow cytometry. T_reg cells were identified as CD4+CD25 + CD127dim cells, and their functional levels were compared by measuring their ability to suppress CD69 and CD154 expression by activated T-cells. The flow cytometry analysis revealed that total T-cell and helper T-cell levels did not vary between the two groups. In contrast, CCHF patients displayed higher T_reg cell levels but lower T_reg suppressive activities when compared with control subjects. This is the first study on the involvement of T_reg cells in CCHF pathogenesis. Our results indicate that even though T_reg cell levels are elevated during acute phase of CCHF infection, not all generated T_reg cells has immunosuppressive capacity, and therefore may not represent 'true' T_reg cell population. Future studies on the intrinsic mechanisms responsible for the reduced T_reg inhibitory activities are required for further enlightening the CCHF pathogenesis, especially in the acute phase of the disease.

Pediatric Visceral Leishmaniasis Caused by Leishmania infantum in Northern Cyprus

Visceral leishmaniasis (VL) is a vector-borne disease widespread in the Mediterranean basin, including Cyprus. During the last decades no cases were notified from northern Cyprus, but herein three cases of VL (female: 2, male: 1, median age: 24.6 months) diagnosed during their hospital admission between January 2011 and December 2012 are reported. Diagnosis was based on clinical findings; 1 ≥ 1/64 titer positivity of immunofluorescence antibodies, Leishmania amastigotes in Giemsa-stained slides of bone marrow, as well as molecular identification confirmed that in all three the infecting pathogen was Leishmania infantum Fever, splenomegaly, and hepatomegaly were the typical clinical findings. First-line treatment with liposomal amphotericin B (AmBisome^®; intravenous, 3 mg/kg) on days 1-5, followed by the same on days 10 and 21 yielded a successful outcome with no relapse in all cases. These confirmed VL cases found within 2 years demonstrate the presence of VL on the island.

Encephalitozoonosis in New Zealand rabbits and potential transmission risk

Encephalitozoon cuniculi is a small protozoan parasite in the phylum Microspora. It has been shown to naturally infect several host species, including humans. Encephalitozoonosis is routinely diagnosed in vivo by serological examination or post mortem by histopathology. In a conventional rabbit colony, two animals suddenly showed clinical signs (torticollis and asthenia of limbs). Serum samples of these rabbits were seropositive for E. cuniculi after definitive diagnosis (Toxoplasma gondii and Listeria monocytogenes). The animals in the same breeding facility were also clinical examined, and the present study evaluated the prevalence of specific anti-E. cuniculi antibodies using serological testing, both in animals and in people working with animals, after two clinical cases. The rabbits showed no clinical symptoms of the disease. Blood samples were taken for E. cuniculi infection from 50 clinically healthy rabbits. Anti-E. cuniculi antibodies were found in two asymptomatic and two clinically affected animals belonging to the same rabbit colony. Finally, the present study found that the 7.7% (4/52) prevalence of CIA, test positive in rabbits. E. cuniculi spores were detected in the urine of one clinically affected rabbit, and one seropositive animal caretaker after staining with the modified trichrome stain. In conclusion, the presence of seropositive, but apparently healthy rabbits indicates the need for screening examinations to detect the anti-E. cuniculi antibody in rabbits, especially considering the potential zoonotic risk. Therefore, persons should avoid contact with the urine of infected or healthy animals, and always use good personal hygiene when handling animals.

Visceral leishmaniasis in 13 pediatric patients in Turkey: treatment experience

Visceral leishmaniasis (VL) is a life-threatening systemic infection caused by protozoa of the genus Leishmania and transmitted by phlebotomine sandflies. Leishmaniases are widespread in most countries in the Mediterranean basin, including Turkey. Leishmania infantum is responsible for VL in Turkey. We previously reported 19 children with VL who were diagnosed during the period of January 2000 to December 2003. In this study, 13 consecutive cases of VL admitted to our hospital between December 2003 and January 2008 were analysed retrospectively. Fever, splenomegaly and hepatomegaly were most common findings in physical examination while anemia, elevated erythrocyte sedimentation rate and C-reactive protein were the most common laboratory findings. Bone marrow aspirate was obtained in all cases and Leishmania amastigotes were detected in 9 of them (69.2%). Leishmania antibodies by the immunofluorescent antibody test were positive in all cases. All of the patients were treated initially with meglumine antimonate. Treatment failure occurred in two children, who were subsequently cured with liposomal amphotericin B. One additional child was treated with liposomal amphotericin B because of the side effects of meglumine antimonate. All the children were finally cured. Meglumine antimonate still seems to be the first choice in the treatment of pediatric VL in Turkey.

Serological and entomological survey in a zoonotic visceral leishmaniasis focus of North Central Anatolia, Turkey: Corum province

In the present study, we aimed to carry out an epidemiological and entomological survey on a visceral leishmaniasis (VL) focus located on the northern central part of Anatolia, Turkey. Five villages of Corum province, where five confirmed cases of human visceral leishmaniasis (HVL) (one patient/village) were reported between June 1998 and August 2001 were included in the study. A total of 625 children and 131 dogs were sampled and the physical examination was carried out by authorized physicians and veterinarians. An indirect fluorescent antibody test (IFAT) was performed by standard procedures for human and dog sera, while the direct agglutination test (DAT) was only performed for dog sera. Sand fly collection was performed in three villages by CDC miniature light traps. Hepatosplenomegaly and hepatomegaly were detected in two and eight children, respectively. The seropositivity rate among children was found to be 0.16% (1/625) in the region. The seroprevalence of canine infection in these five villages ranged between 0.0% and 28.26%. In two villages, named Ahlatcik and Asagifindikli, no seropositive dogs were found. A total of 1218 sand flies were collected throughout the study. Six species of Phlebotomus were identified: P. transcaucasicus, P. neglectus, P. halepensis, P. tobbi, P. papatasi, and P. jacusieli. P. transcaucasicus was found to be the predominant species in Cevizli (47.44%; 343/723) and Ucoluk (79.95%; 351/439) villages, while P. tobbi was abundant in Kucukerikli (42.85%; 24/56).