Evaluation of a Real-time PCR-based assay using the lightcycler system for detection of Toxoplasma gondii bradyzoite genes in blood specimens from patients with toxoplasmic retinochoroiditis

Detection of Toxoplasma gondii and Sarcocystis sp. in the meat of common minke whale (Balaenoptera acutorostrata): A case of suspected food poisoning in Japan

A case of suspected food poisoning related to the consumption of raw meat from a common minke whale (Balaenoptera acutorostrata) was reported in Tokyo, Japan, in June 2020. Microscopic analysis revealed tissue cysts of Toxoplasma gondii and sarcocysts of Sarcocystis sp. in whale meat. The SAG2 and ITS1 region sequences of T. gondii were detected in the DNA extracted from the meat. Genotyping of the multilocus nested PCR-RFLP using the genetic markers SAG1, SAG2 (5'- SAG2, 3'-SAG2, and alt. SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico revealed that the genotype of T. gondii was type II, with a type I pattern for the L358 locus. In the phylogenetic analyses of the six loci (GRA6, GRA7, SAG1, HP2, UPRT1, and UPRT7), these sequences clustered into haplogroup 2. Moreover, the sequences of the virulence-related genes ROP5 and ROP18 of T. gondii isolated from whale meat were similar to those of the type II ME49 reference strain. Sequence analyses of the mtDNA cox1 gene, 18S rRNA gene, and ITS1 region indicated the highest similarity of sarcocyst isolated from whale meat to Sarcocystis species that infect birds or carnivores as intermediate hosts; however, the species could not be identified. To our knowledge, this is the first report of T. gondii and Sarcocystis spp. being detected in same whale meat ingested by patients involved in a suspected food poisoning case in Japan.

In vitro screening technologies for the discovery and development of novel drugs against Toxoplasma gondii

INTRODUCTION

Toxoplasmosis constitutes a challenge for public health, animal production and welfare. Since more than 60 years, only a limited panel of drugs has been in use for clinical applications.

AREAS COVERED

Herein, the authors describe the methodology and the results of library screening approaches to identify inhibitors of Toxoplasma gondii and related strains. The authors then provide the reader with their expert perspectives for the future.

EXPERT OPINION

Various library screening projects, in particular those using reporter strains, have led to the identification of numerous compounds with good efficacy and specificity in vitro. However, only few compounds are effective in suitable animal models such as rodents. Whereas no novel compound has cleared the hurdle to applications in humans, the few compounds with known indication and application profiles in human patients are of interest for further investigations. Taken together, drug repurposing as well as high-throughput screening of novel compound libraries may shorten the way to novel drugs against toxoplasmosis.

Evaluation of mono and combined nitrofurantoin therapy for toxoplasmosis in vivo using murine model

Toxoplasmosis is a frequent disease with an estimated prevalence of more than one billion human cases worldwide and over one million new infections each year. It is classified as a neglected tropical disease by the CDC since 2019. The disease may pass unnoticed in healthy individuals but could be fatal in the immunocompromised. Moreover, no effective treatment is available against the chronic form of the disease. Available anti-Toxoplasma drugs are associated with many side effects. Therefore, search for new more reliable, more efficient, and less toxic therapeutic agents is a continuous endeavor. This study assesses the potential use of nitrofurantoin, a compound with well-established antimicrobial properties, as a potential anti-Toxoplasma drug in vivo. It compares its efficacy to the commonly used anti-Toxoplasma agent spiramycin by molecular and histopathological methods in acute and chronic infection. The results demonstrate a significant ability to eliminate the parasite (P < 0.001) whether used as mono- or combined therapy with spiramycin in the acute and chronic stages. When compared to the anti-Toxoplasma drug spiramycin, nitrofurantoin achieved similar efficacy in the acute and chronic infection (P = 0.65 and P = 0.096, respectively). However, better results were obtained when using a combination of both drugs (P < 0.001). Additionally, nitrofurantoin showed good inhibitory effects on the inflammatory process in the liver, kidney, and uterus of the experimentally infected animals. In conclusion, nitrofurantoin can be considered as a potential anti-Toxoplasma agent. Nevertheless, further studies are recommended before consideration for clinical trials.

Protective efficacy of Toxoplasma gondii bivalent MAG1 and SAG1 DNA vaccine against acute toxoplasmosis in BALB/c mice

Toxoplasma gondii can infect a wide range of warm-blooded animals, causing a global toxoplasmosis zoonotic epidemic. Surface antigen 1 (SAG1) protein is expressed at the proliferative tachyzoite stage, whereas matrix antigen 1 (MAG1) is expressed at the bradyzoite and tachyzoite stages. These two proteins were found to perform protective roles in previous studies; however, their synergetic protective efficacy as a DNA vaccine against toxoplasmosis has not been clarified. In this study, we constructed recombinant pcDNA3.1( +)-TgMAG1 (pMAG1), pcDNA3.1( +)-TgSAG1 (pSAG1), and pcDNA3.1( +)-TgMAG1-TgSAG1 (pMAG1-SAG1) plasmids and administered them intramuscularly to immunize mice. The levels of anti-T. gondii IgG in serum and cytokines, such as Interleukin (IL)-4, IL-10, and Interferon (IFN)-γ, in splenocytes were measured using ELISA and the respective culture supernatants. Lethal doses of T. gondii (type I) RH strain tachyzoites were administered to immunized mice, and mortality was assessed. Conversely, mice infected with low doses of tachyzoites were monitored to determine their survival rates, and parasite burden analyses of the brains and livers were conducted. The bivalent TgMAG1 and TgSAG1 DNA vaccines exhibited excellent protective immunity against toxoplasmosis in mice, with higher serum IgG and splenocyte IFN-γ release levels, longer survival days, and reduced parasite burden in the brain and liver tissues (p < 0.05). These findings provide a new perspective for the development of T. gondii vaccines.

Toxoplasmosis in Human and Animals Around the World. Diagnosis and Perspectives in the One Health Approach

Toxoplasmosis is a unique health disease that significantly affects the health of humans, domestic animals, wildlife and is present in ecosystems, including water, soil and food. Toxoplasma gondii is one of the best-adapted parasites in the word. This parasite is able to persist for long periods in its hosts, in different geographic regions of the word. This review summarizes the current literature of these themes, focusing on: (1) toxoplasmosis, a zoonotic infection; (2) One health approach and toxoplasmosis; (3) human toxoplasmosis; (4) animal toxoplasmosis; (5) toxoplasmosis diagnosis, as immunological, parasitological and molecular diagnosis; (6) T. gondii outbreaks caused by infected meat, milk and dairy products, as well as, vegetables and water consume; (7) studies in experimental models; (8) genetic characterization of T. gondii strains; (9) extracellular vesicles and miRNA; and (10) future perspectives on T. gondii and toxoplasmosis. The vast prevalence of toxoplasmosis in both humans and animals and the dispersion and resistence of T. gondii parasites in environment highlight the importance of the one health approach in diagnostic and control of the disease. Here the different aspects of the one health approach are presented and discussed.

Utility of blood as the clinical specimen for the diagnosis of ocular toxoplasmosis using uracil DNA glycosylase-supplemented loop-mediated isothermal amplification and real-time polymerase chain reaction assays based on REP-529 sequence and B1 gene

BACKGROUND

Ocular infection with Toxoplasma gondii is a major preventable cause of blindness, especially in young people. The aim of the present study was to assess detection rate of T. gondii DNA in blood samples of clinically diagnosed of ocular toxoplasmosis using uracil DNA glycosylase-supplemented loop-mediated isothermal amplification (UDG-LAMP) and real-time quantitative PCR (qPCR) based on REP-529 and B1.

METHODS

One hundred and seventeen patients with clinically diagnosed ocular toxoplasmosis (OT) were participated in the study as well as 200 control patients. Peripheral blood samples were assessed using UDG-LAMP and qPCR techniques targeting REP-529 and B1.

RESULTS

Detection limits of qPCR using REP-529 and B1 were estimated as 0.1 and 1 fg of T. gondii genomic DNA, respectively. The limits of detection for UDG-LAMP using REP-529 and B1 were 1 and 100 fg, respectively. In this study, 18 and 16 patients were positive in qPCR using REP-529 and B1, respectively. Based on the results of UDG-LAMP, 15 and 14 patients were positive using REP-529 and B1, respectively. Results of the study on patients with active ocular lesion showed that sensitivity of REP-529 and BI targets included 64 and 63%, respectively using qPCR. Sensitivity of 62 and 61%, were concluded from UDG-LAMP using REP-529 and B1 in the blood cases of active ocular lesion. qPCR was more sensitive than UDG-LAMP for the detection of Toxoplasma gondii DNA in peripheral blood samples of patients with clinically diagnosed toxoplasmic chorioretinitis. Furthermore, the REP-529 included a better detection rate for the diagnosis of ocular toxoplasmosis in blood samples, compared to that the B1 gene did. Moreover, the qPCR and UDG-LAMP specificity assessments have demonstrated no amplifications of DNAs extracted from other microorganisms based on REP-529 and B1.

CONCLUSIONS

Data from the current study suggest that qPCR and UDG-LAMP based on the REP-529 are promising diagnostic methods for the diagnosis of ocular toxoplasmosis in blood samples of patients with active chorioretinal lesions.

Comparison of real-time PCR and nested PCR for toxoplasmosis diagnosis in toxoplasmic retinochoroiditis patients

Backgrounds

PCR is a proper technique that significantly improves toxoplasmosis diagnosis. However, a more sensitive technique is required. This study compared real-time PCR with nested PCR using B1, SAG-4, and MAG-1 bradyzoite genes to diagnose toxoplasmosis in toxoplasmic retinochoroiditis patients.

Methods

Blood samples were collected from 10 patients with active toxoplasmic chorioretinal lesions and 10 healthy individuals. Blood samples including peripheral blood mononuclear cells (PBMCs), serum and whole blood samples were used for DNA extraction. Serum was also used to detect anti-toxoplasma IgG and IgM antibodies. Nested PCR and real-time PCR were performed using B1, SAG-4, and MAG-1 target genes.

Results

Five (50%) out of the 10 patients were tested positive for toxoplasmosis with nested PCR using the PBMC samples. All the five patients tested positive with nested PCR were also tested positive for toxoplasmosis with real-time PCR using the PBMC samples. The real-time PCR results demonstrated that 9(90%) out of the 10 patients were positive based on B1 and the remaining one (10%) was positive only based on MAG-1. In general, of the patients, five (50%) were positive using SAG-4 and three (30%) were positive in term of MAG-1 using PBMCs with real-time PCR.

Conclusion

It appears that PBMC samples have the best performance as the PCR extraction method and are a good source for toxoplasmosis diagnosis. The use of B22 and B23 target genes due to their high sensitivity and specificity along with bradyzoite genes are recommended for toxoplasmosis diagnosis using PBMC samples with real-time PCR.

Toll-Like Receptor 2 is Involved in Abnormal Pregnancy in Mice Infected with Toxoplasma gondii During Late Pregnancy

Infection with Toxoplasma gondii during pregnancy causes failure of pregnancy maintenance, resulting in fetal death, abortion, stillbirth, or premature birth, but the mechanism of disease onset remains unclear. Although Toll-like receptor 2 (TLR2) is expressed on antigen-presenting cells and trophoblasts, the role of TLR2 in T. gondii infection during pregnancy is unknown. In this study, we investigated the role of TLR2 in congenital toxoplasmosis using TLR2-deficient (TLR2^−/−) mice. T. gondii infection on gestational day 12.5 (Gd12.5) induced more abnormal pregnancy, including premature birth and stillbirth, in wild-type mice than in TLR2^−/− mice. Multiple calcifications were observed in the placentas of the infected wild-type mice. At Gd18.5 (6days postinfection), the parasite numbers in the placenta and uterus and the histological changes did not differ significantly between the wild-type and TLR2^−/− mice. However, T. gondii infection reduced the mRNA expression of interleukin-12p40 (IL-12p40) and increased IL-4 and IL-10 mRNAs in the placentas of the wild-type mice. In contrast, the placentas of the TLR2^−/− mice showed no changes in the expression of these cytokines, including IL-6 and tumor necrosis factor α, in response to T. gondii infection. Serum interferon-γ levels were significantly lower in the infected TLR2^−/− mice than in the infected wild-type mice on Gd18.5. Thus, the TLR2^−/− mice were less susceptible to the induction of immune responses by T. gondii infection during late pregnancy. Therefore, TLR2 signaling may play a role in the development of disease states during pregnancy, specifically placental hypofunction.

Molecular diagnosis of toxoplasmosis: recent advances and a look to the future

INTRODUCTION

Toxoplasmosis is a globally distributed parasitic infection that can be particularly severe when opportunistic or congenital. Its diagnosis requires accurate and rapid techniques that rely mainly on serology and molecular methods.

AREAS COVERED

The aim of this review was to discuss the positioning of the molecular diagnosis of toxoplasmosis according to the different clinical situations possibly resulting from infection with T. gondii, and to detail recent developments in this technique. The English and French literature were searched with the following keywords: 'Toxoplasmosis', "Molecular diagnosis" and 'PCR'.

EXPERT OPINION

Molecular techniques have revolutionized the diagnosis of toxoplasmosis, and practices have considerably evolved over the past decades. However, there is still a high degree of inter-laboratory heterogeneity which impairs comparisons between results and studies. Efforts to standardize practices are underway.

Stage-Specific Oligonucleotide Primers for the Diagnosis of Toxoplasmosis Among Iranian Pediatric Heart Transplant Recipients; Evaluation of Cotrimoxazole as a Preventive Therapy

Background: Toxoplasmosis is an opportunistic infection that affects solid organ transplant (SOT) recipients. The parasite transmission may be occurred from a Toxoplasma-seropositive donor to a Toxoplasma-seronegative recipient by organ transplantation. Objectives: In this study, a nested PCR was carried out using different primers targeting the B1, SAG4, and MAG1 genes to assess Toxoplasma infection in pediatric heart transplantation at Shahid Rajaei Heart Center in Tehran. Methods: Blood samples were collected from 46 pediatric heart transplant patients aged 1 - 17 years referring to Rajaei Cardiovascular and Medical Research Center from 2018 - 2019. All patients were on oral administration of Trimethoprim-sulfamethoxazole (cotrimoxazole). Blood samples were collected, and peripheral blood mononuclear cell (PBMC) isolation using the Ficoll gradient method was performed. DNA was extracted from PBMC, and nested PCR was carried out. Serologic tests were performed using ELISA to determine IgG and IgM anti - Toxoplasma gondii antibodies. Results: The results of serologic tests showed that all 46 patients had negative anti-T. gondii IgM antibody. Furthermore, 6 (13.05%) and 3 (6.5 %) out of the 46 patients were positive for IgG T. gondii antibody before and after transplantation, respectively. All 46 patients were evaluated using PCR using B1, MAG-1, and SAG-4 genes, and PCR results were negative. Conclusions: In general, due to the negative results of Toxoplasma with PCR using B1 and bradyzoite-specific genes (SAG-4 and MAG-1), it is possible that the results obtained in this study are because of prophylaxis with cotrimoxazole.

Detection of Toxoplasma gondii bradyzoite genes in the peripheral blood mononuclear cells among patients with toxoplasmic chorioretinitis

BACKGROUND

Toxoplasmic chorioretinitis may occur as a result of acquired toxoplasmosis or reactivated congenital toxoplasmosis. In this study, Toxoplasma gondii bradyzoite genes along with the B1 gene were evaluated to detect T. gondii DNA in serum and peripheral blood mononuclear cells (PBMCs) of patients with toxoplasmic chorioretinitis.

METHODS

Blood samples were collected from 10 patients (7 cases of active chorioretinal lesions and 3 cases of old chorioretinal scars). The genomic DNA was extracted from the patients' serum and PBMCs and a polymerase chain reaction (PCR) assay was performed using bradyzoite genes along with B1. The subjects were also evaluated in terms of the T. gondii antibodies.

RESULTS

The PCR results were positive in four of seven patients (57.1%) with active ocular toxoplasmosis lesions. In three patients (42.8%), the PCR results were positive for MAG-1 and SAG-4 and in one patient (14.3%) the PCR results were only positive for the B1 gene. The PCR results were positive only in the PBMCs, whereas they were negative in the serum samples. Two patients with positive PCR results showed high Toxoplasma immunoglobulin G (IgG) antibody titres. However, none of the patients showed positive Toxoplasma IgM antibodies.

CONCLUSIONS

The PBMCs are suitable for evaluating toxoplasmic chorioretinitis. The present results showed that PCR with bradyzoite genes is useful in the diagnosis of toxoplasmic chorioretinitis in PBMCs.

Metacytofilin Is a Potent Therapeutic Drug Candidate for Toxoplasmosis

BACKGROUND

Toxoplasmosis, a parasitic disease caused by Toxoplasma gondii, is an important cause of miscarriage or adverse fetal effects, including neurological and ocular manifestations in humans. Current anti-Toxoplasma drugs have limited efficacy against toxoplasmosis and also have severe side effects. Therefore, novel efficacious drugs are urgently needed. Here, we identified metacytofilin (MCF) from a fungal Metarhizium species as a potential anti-Toxoplasma compound.

METHODS

Anti-Toxoplasma activities of MCF and its derivatives were evaluated in vitro and in vivo using nonpregnant and pregnant mice. To understand the mode of action of MCF, the RNA expression of host and parasite genes was investigated by RNAseq.

RESULTS

In vitro, MCF inhibited the viability of intracellular and extracellular T. gondii. Administering MCF intraperitoneally or orally to mice after infection with T. gondii tachyzoites increased mouse survival compared with the untreated animals. Remarkably, oral administration of MCF to pregnant mice prevented vertical transmission of the parasite. Interestingly, RNA sequencing of T. gondii-infected cells treated with MCF showed that MCF inhibited DNA replication and enhanced RNA degradation in the parasites.

CONCLUSIONS

With its potent anti-T. gondii activity, MCF is a strong candidate for future drug development against toxoplasmosis.

Characterization of a spontaneous cyst-forming strain of Toxoplasma gondii isolated from Tokachi subprefecture in Japan

Apicomplexan parasite Toxoplasma gondii has three distinct clonal lineages: high, medium and low virulent strains, type I, II and III, respectively. T. gondii avoids the immune response by transforming from fast multiplying tachyzoite to slow multiplying bradyzoite, and establishing a chronic infection. In the present study, we isolated a new strain of T. gondii from cat feces in the Tokachi subprefecture, Hokkaido, Japan and named it as TgCatJpObi1 (Obi1) strain. Genotyping analysis of 12 loci revealed atypical characters close to type II, genotype 4 according to ToxoDB classification. Phenotypically, Obi1 strain shows slow growth rate and the ability of spontaneous cyst formation in both human foreskin fibroblast (HFFs) and mouse peritoneal macrophages in vitro without bradyzoite induction. Parasite virulence was assessed by means of mouse survival upon infection with either Obi1 or ME49 strains. Obi1 strain displayed no mortalities in comparison to type II clonal lineage, ME49 at LD₅₀ to LD₁₀₀ range (1 × 10³-10⁶ tachyzoites). Although virulence of Obi1 strain is significantly lower than that of ME49, nucleotide sequences analyses revealed that genes of virulence factors such as Gra15, Rop5, 16, 17, and 18 in Obi1 strain were 100% identical to those in the type II strain. Thus, characterization of a newly isolated strain, Obi1, is crucial to clarify the development of toxoplasmosis in both humans and animals.

Evaluation of a PCR assay for diagnosis of toxoplasmosis in serum and peripheral blood mononuclear cell among HIV/AIDS patients

Cerebral toxoplasmosis is one of the neurological infections with high morbidity and mortality in patients with AIDS, so the accurate method for diagnosis of cerebral toxoplasmosis seems necessary. In this study, nested PCR assay using B1 gene was evaluated in diagnosis of toxoplasmosis in serum and peripheral blood mononuclear cell (PBMC) among HIV/AIDS patients. One hundred eight blood samples from HIV/AIDS patients, including four patients with cerebral toxoplasmosis and 104 HIV/AIDS patients without cerebral toxoplasmosis were evaluated for the Toxoplasma gondii antibodies using Enzyme Linked immunosorbent Assay. DNA of serum and PBMC of these patients were extracted and nested-PCR was carried out. Of 108 participants, 95 cases (88%) were positive for Toxoplasma IgG antibodies and one patient was found positive for Toxoplasma IgM antibody. In general, four patients, including three patients with cerebral toxoplasmosis, who were positive for Toxoplasma IgG antibodies and one patient without cerebral toxoplasmosis who was positive for Toxoplasma IgM antibody were found to be PCR positive. DNA of T. gondii was detected in both serum and PBMC in two cerebral toxoplasmosis patients; however DNA was detected in only PBMC in other cerebral toxoplasmosis patient. All cases with cerebral toxoplasmosis were also diagnosed by clinical and radiological manifestations. The results of this study showed that the numbers of positive samples by PCR in PBMC were higher than serum specimens for diagnosis of toxoplasmosis. If molecular method and immunological assay are complemented with magnetic resonance imaging, the results can be useful for diagnosis of cerebral toxoplasmosis.

Enhancing the detection of Toxoplasma gondii via an anti-SAG1 scFv-alkaline phosphatase immunoconjugate

The purpose of this study was to implement a fluorometric method for enhancing the detection sensitivity of Toxoplasma gondii in biological fluids. To address this challenge, we designed and produced a recombinant immunoconjugate tool based on a single-chain antibody fragment anti-T. gondii SAG1 antigen (scFvSG15) genetically fused to the bacterial alkaline phosphatase (AP) using 4-methyl-umbelliferyl-phosphate as fluorogenic substrate. The anti-SAG1 scFv-AP conjugate was fully bifunctional and was used successfully in different assays including immunoblot, fluorometric ELISA and direct immunofluorescence. The fluorometric immunoassay afforded an extremely low detection limit (1 tachyzoite/well), which was in agreement with the real-time PCR control test. The immunofluorescence imaging has provided captivating visual evidence of T. gondii detection. These results strongly suggest that the recombinant anti-SAG1-AP conjugate generated here might serve as useful and highly sensitive immunoassay probe to direct detect T. gondii in a one-step procedure, opening up new perspectives for diagnosis of toxoplasmosis.

Outbreak of toxoplasmosis in four squirrel monkeys (Saimiri sciureus) in Japan

Toxoplasma gondii is a protozoan parasite that causes fatal disease in New World monkeys. Several reports have described outbreaks of toxoplasmosis in squirrel monkeys. Here, we report the death of four squirrel monkeys in a captive colony from acute toxoplasmosis, one of which developed toxoplasmosis about 1 year after the initial outbreak. Serum anti-T. gondii antibody was detected by a latex agglutination test in the animals, and one presented seropositive before clinical signs were observed. Macroscopically, the lungs were severely affected and three animals showed pulmonary edema. Microscopically, interstitial pneumonia was observed in all animals. In the liver and heart, multifocal mononuclear cell infiltration with necrosis was detected. Parasite loading tended to be higher in the lungs, liver and heart than in the spleen, kidney and brain. The parasite was isolated from the brain of one animal and this isolate showed type II restriction patterns in the SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2 and PK1 genes of T. gondii and type I restriction patterns in the L358 and Apico genes by PCR-Restriction Fragment Length Polymorphism analysis. The clinical signs were reduced in mice infected with this isolate compared with those infected with reference type II strain PLK in a bioassay. To our knowledge, this is the first report of isolation of the parasite from squirrel monkeys in Japan and offers the opportunity for genomic and pathogenic analyses to aid our understanding of acute toxoplasmosis.

Detection of Toxoplasma gondii copro-prevalence by polymerase chain reaction using repetitive 529 bp gene in feces of pet cats (Felis catus) in Yogyakarta, Indonesia

Aim:

The aim of this research was to determine the copro-prevalence of Toxoplasma gondii using polymerase chain reaction (PCR) with repetitive 529 bp gene and to construct the phylogenetic tree of Toxoplasma oocyst from pet cats in Yogyakarta.

Materials and Methods:

9 of 132 pet cat samples which serologically positive for Toxoplasma were used in this research. To determine the copro-prevalence of T. gondii in pet cat, 10 g of feces samples taken from practitioners and household cats in Yogyakarta were used in the PCR method utilizing repetitive 529 bp gene sequences.

Results:

The result shows that copro-prevalence by PCR using repetitive 529 bp gene was 33.3% (3/9). The phylogenetic tree of Toxoplasma grouped into two clades, which clade 1 consists of Toxoplasma isolates collected from pet cats in Yogyakarta Indonesia and T. gondii isolates from China and in clade 2 consist of the T. gondii isolates from India.

Conclusion:

Copro-prevalence of T. gondii in pet cats in Yogyakarta by means of PCR using repetitive 529 bp gene is around 33.3%.

Isothermal PCR for Feasible Molecular Diagnosis of Primary Toxoplasmosis in Women Recently Experienced Spontaneous Abortion

AIM:

The current study aimed to assess the practicability of a simple loop-mediated isothermal amplification (LAMP) about real-time quantitative PCR to diagnose primary toxoplasmosis among high-risk pregnant women.

METHODS:

Cloned Toxoplasma samples were used to calculate the analytical sensitivity while specificity was assessed using pooled DNA samples extracted from other parasitic stages.

RESULTS:

Both techniques showed 100% sensitivity and specificity and then applied to detect recent Toxoplasma infection in peripheral blood of 77 IgG negative women out of a total 139 women lately experienced spontaneous abortion. The 2 techniques obtained positive results in 8 samples confirming primary toxoplasmosis.

CONCLUSION:

Generally, LAMP assay is a simple, cost-effective molecular technique can be completed in less than half an hour to diagnose primary Toxoplasma infection. The technique can be applied in a minimally equipped laboratory by ordinary workers to screen the vulnerable groups. Further analysis using larger samples with the quantitative approach is recommended to confirm the sensitivity of this emergent molecular technique.

CCR5 Is Involved in Interruption of Pregnancy in Mice Infected with Toxoplasma gondii during Early Pregnancy

Toxoplasmosis can cause abortion in pregnant humans and other animals; however, the mechanism of abortion remains unknown. C-C chemokine receptor type 5 (CCR5) is essential for host defense against Toxoplasma gondii infection. To investigate the relationship between CCR5 and abortion in toxoplasmosis, we inoculated wild-type and CCR5-deficient (CCR5^-/-) mice with T. gondii tachyzoites intraperitoneally on day 3 of pregnancy (embryonic day 3 [E3]). The pregnancy rate decreased as pregnancy progressed in infected wild-type mice. Histopathologically, no inflammatory lesions were observed in the fetoplacental tissues. Although wild-type mice showed a higher parasite burden at the implantation sites than did CCR5^-/- mice at E6 (3 days postinfection [dpi]), T. gondii antigen was detected only in the uterine tissue and not in the fetoplacental tissues. At E8 (5 dpi), the embryos in infected wild-type mice showed poor development compared with those of infected CCR5^-/- mice, and apoptosis was observed in poorly developed embryos. Compared to uninfected mice, infected wild-type mice showed increased CCR5 expression at the implantation site at E6 and E8. Furthermore, analyses of mRNA expression in the uterus of nonpregnant and pregnant mice suggested that a lack of the CCR5 gene and the downregulation of tumor necrosis factor alpha (TNF-α) and CCL3 expression at E6 (3 dpi) are important factors for the maintenance of pregnancy following T. gondii infection. These results suggested that CCR5 signaling is involved in embryo loss in T. gondii infection during early pregnancy and that apoptosis is associated with embryo loss rather than direct damage to the fetoplacental tissues.

Utility of the cytochrome c oxidase subunit I gene for the diagnosis of toxoplasmosis using PCR

Toxoplasmosis is caused by the protozoan parasite Toxoplasma gondii, which belongs to the phylum Apicomplexa. Since this parasite causes severe clinical symptoms in immunocompromised patients, early diagnosis of toxoplasmosis is essential. PCR is currently used for early diagnosis, but there is no consensus regarding the most effective method for amplifying Toxoplasma DNA. In this study, we considered the utility of the cytochrome c subunit I (cox1) gene, which is encoded in the mitochondrial DNA of this parasite, as a novel target of PCR for the diagnosis of toxoplasmosis. To do this, we compared its copy number per haploid nuclear genome and the detection sensitivity of cox1-PCR with the previously reported target genes B1 and 18S rRNA and the AF146527 repeat element. We found that the copy number of cox1 was high and that the PCR using cox1 primers was more efficient at amplifying Toxoplasma DNA than the other PCR targets examined. In addition, PCR using clinical samples indicated that the cox1 gene would be useful for the diagnosis of toxoplasmosis. These findings suggest that use of cox1-PCR would facilitate the diagnosis of toxoplasmosis in clinical laboratories.

The heat shock protein 90 of Toxoplasma gondii is essential for invasion of host cells and tachyzoite growth

Toxoplasma gondii is an obligate intracellular apicomplexan parasite that infects almost all warm-blooded vertebrates. Heat shock proteins (HSP) regulate key signal transduction events in many organisms, and heat shock protein 90 (Hsp90) plays an important role in growth, development, and virulence in several parasitic protozoa. Here, we discovered increased transcription of the Hsp90 gene under conditions for bradyzoite differentiation, i.e. alkaline and heat shock conditions in vitro, suggesting that Hsp90 may be connected with bradyzoite development in T. gondii. A knockout of the TgHsp90 strain (ΔHsp90) and a complementation strain were constructed. The TgHsp90 knockout cells were found to be defective in host-cell invasion, were not able to proliferate in vitro in Vero cells, and did not show long-time survival in mice in vivo. These inabilities of the knockout parasites were restored upon complementation of TgHsp90. These data unequivocally show that TgHsp90 contributes to bradyzoite development, and to invasion and replication of T. gondii in host cells.

Immunization with Toxoplasma gondii peroxiredoxin 1 induces protective immunity against toxoplasmosis in mice

To develop a vaccine against Toxoplasma gondii, a vaccine antigen with immune-stimulating activity is required. In the present study, we investigated the immunogenicity and prophylactic potential of T. gondii peroxiredoxin 1 (TgPrx1). The TgPrx1 was detected in the ascitic fluid of mice 6 days postinfection, while specific antibody levels were low in the sera of chronically infected mice. Treatment of murine peritoneal macrophages with recombinant TgPrx1 triggered IL-12p40 and IL-6 production, but not IL-10 production. In response to TgPrx1, activation of NF-kB and IL-6 production were confirmed in mouse macrophage cell line (RAW 264.7). These results suggest the immune-stimulating potentials of TgPrx1. Immunization of mice with recombinant TgPrx1 stimulated specific antibody production (IgG1 and IgG2c). Moreover, spleen cell proliferation and interferon-gamma production significantly increased in the TgPrx1- sensitized cells from mice immunized with the same antigen. Immunization with TgPrx1 also increased mouse survival and decreased cerebral parasite burden against lethal T. gondii infection. Thus, our results suggest that TgPrx1 efficiently induces humoral and cellular immune responses and is useful as a new vaccine antigen against toxoplasmosis.

Presence of Toxoplasma gondii in Drinking Water from an Endemic Region in Southern Mexico

Toxoplasmosis can be acquired through the ingestion of contaminated drinking water with oocysts of Toxoplasma gondii, highly resistant to the routinely disinfection processes; based on chlorination commonly used in the water supply industry. The aim of this study was to determine the presence of T. gondii DNA in samples of public drinking water from an endemic region of southern Mexico. In total 74 samples of water (5 L each) were collected from the three well fields (I, II, and III) and 71 independent wells, distributing public drinking water to the city of Merida Yucatan, after passing through the chlorination process. Water samples were filtered and concentrated by a sucrose solution, then DNA was extracted and evaluated through a nested-PCR (nPCR) specific for T. gondii. Positive samples were detected in 5.4% (4/74) of the water samples. This is the first report of the presence of T. gondii DNA in public drinking water from a large city in southern Mexico, where their consumption without any postpurification treatment could pose a risk for acquiring the infection in the urban population.

Involvement of Host Defense Mechanisms against Toxoplasma gondii Infection in Anhedonic and Despair-Like Behaviors in Mice

Toxoplasma gondii is a pathogen relevant to psychiatric disorders. We recently showed that reactivation of chronic T. gondii infection induced depression-like behaviors in mice. Furthermore, it has been hypothesized that depression-like behaviors are mediated via a host defense mechanism against invading pathogens; proximate mechanisms of this behavioral hypothesis remain unclear. In the present study, we investigate the contribution of indoleamine 2,3-dioxygenase (IDO), inflammation, and interferon gamma (IFN-γ) to anhedonic and despair-related behaviors in T. gondii-infected mice by using sucrose preference and forced-swim tests, respectively. First, we confirmed that BALB/c mice exhibited both sickness and depression-like behaviors during acute infection. Treatment of infected wild-type mice with minocycline (anti-inflammatory drug) abated sickness and anhedonic and despair-like behaviors, whereas in T. gondii-infected mice, treatment normalized kynurenine/tryptophan (Kyn/Trp) ratios in both plasma and brain tissue. Additionally, T. gondii infection failed to induce anhedonic and despair-like behaviors or increase the Kyn/Trp ratio in immunocompromised (IFN-γ^-/-) mice, whereas sickness behavior was observed in both immunocompetent and IFN-γ^-/- mice following infection. Furthermore, treatment with 1-methyl tryptophan (an IDO inhibitor) did not affect locomotor activity, attenuated clinical scores and anhedonic and despair-like behaviors, and resulted in normal Kyn/Trp ratios in T. gondii-infected wild-type mice. Although low levels of serotonin and dopamine were observed in the brain during acute and chronic infections, anhedonic and despair-like behaviors were not detected in the chronic stage of infection. Collectively, our results demonstrated that immune enhancement in response to infection with T. gondii resulted in IFN-γ production, IDO activation, and inflammation associated with anhedonic and despair-like behaviors.

Bipolar Disorder With Psychotic Features and Ocular Toxoplasmosis: A Possible Pathogenetic Role of the Parasite?

Recent evidence suggests the involvement of Toxoplasma gondii infection in the emergence of psychotic and affective disorders. In this report, we describe the case of a young Brazilian woman affected by recurrent ocular toxoplasmosis and presenting with a manic episode with psychotic features in the context of a diagnosis of Bipolar Disorder (BD), type I. We observed a relationship between ocular manifestations and the clinical course of bipolar illness, confirmed by molecular analyses (nested-PCR), as well as by the high level of T. gondii specific IgG. This case report is the first showing the presence of circulating parasite DNA at the time of occurrence of psychiatric symptoms, thus providing further support for a possible role of the parasite in the pathogenesis of some cases of BD.

HPV genotypes distribution in Chlamydia trachomatis co-infection in a large cohort of women from north-east Italy

Human papillomavirus (HPV) and Chlamydia trachomatis are pathogens with oncogenic potential associated with persistent infections. Epidemiological data on C. trachomatis infection status, C. trachomatis/HPV co-infection and the relationship between HPV genotypes in Italian women are only preliminary. The aim of the present study was to characterize the relationship between HPV genotypes and C. trachomatis in an extending cohort of asymptomatic immunocompetent women from an area of north-east Italy. A retrospective study was conducted using Luminex technology on cervical swabs from asymptomatic immunocompetent women, comprising 921 attending the prevention centre for the Cervical Cancer Program and 6214 who had been referred to the Sexually Transmitted Infections Center, with clinical indications of HPV and C. trachomatis infections. A quantitative real-time PCR was performed to assess chronic C. trachomatis infection by heat-shock protein 60 (Hsp60) gene expression. The overall prevalence of the investigated pathogens was 39 % (359/921) for HPV and 4 % (251/6214) for C. trachomatis. The Hsp60 gene was detected in 57 % of the women infected with C. trachomatis. HPV co-infection was present in 58 % of C. trachomatis-infected women. A high prevalence of co-infection was found in women with chronic C. trachomatis infection (68 %, P = 0.0002), especially in women ≤ 25 years (72 %) where HPV multiple infections were found in 78 % (P = 0.022). HPV genotype distribution showed that uncommon low-risk genotypes were associated with C. trachomatis. These results indicate a high frequency of co-detection of multiple HPV genotypes in chronically infected young women and suggest that the expression of the C. trachomatis Hsp60 gene may favour HPV infection.

PCR-based detection of Toxoplasma gondii DNA in blood and ocular samples for diagnosis of ocular toxoplasmosis

PCR detection of Toxoplasma gondii in blood has been suggested as a possibly efficient method for the diagnosis of ocular toxoplasmosis (OT) and furthermore for genotyping the strain involved in the disease. To assess this hypothesis, we performed PCR with 121 peripheral blood samples from 104 patients showing clinical and/or biological evidence of ocular toxoplasmosis and from 284 (258 patients) controls. We tested 2 different extraction protocols, using either 200 μl (small volume) or 2 ml (large volume) of whole blood. Sensitivity was poor, i.e., 4.1% and 25% for the small- and large-volume extractions, respectively. In comparison, PCR with ocular samples yielded 35.9% sensitivity, while immunoblotting and calculation of the Goldmann-Witmer coefficient yielded 47.6% and 72.3% sensitivities, respectively. Performing these three methods together provided 89.4% sensitivity. Whatever the origin of the sample (ocular or blood), PCR provided higher sensitivity for immunocompromised patients than for their immunocompetent counterparts. Consequently, PCR detection of Toxoplasma gondii in blood samples cannot currently be considered a sufficient tool for the diagnosis of OT, and ocular sampling remains necessary for the biological diagnosis of OT.

Overproduction of Toxoplasma gondii cyclophilin-18 regulates host cell migration and enhances parasite dissemination in a CCR5-independent manner

Background

Toxoplasma gondii hijacks host cells to allow it to disseminate throughout a host animal; however, the migratory machinery involved in this process has not been well characterized. We examined the functional role of T. gondii cyclophilin 18 (TgCyp18) in host cell recruitment using recombinant parasites transfected with TgCyp18.

Results

High levels of TgCyp18 enhanced IL-12 production in cysteine-cysteine chemokine receptor 5 (CCR5) knockout mice (CCR5^−/−) that had been infected peritoneally with T. gondii. Recruitment of CD11b⁺ cells to the infection site was enhanced in a CCR5-independent manner. T. gondii spread to several organs, particularly the liver, in a TgCyp18-dependent and CCR5-independent manner. Additionally, CCL5 levels were upregulated in macrophages treated with recombinant protein TgCyp18 and in the peritoneal fluids of the infected CCR5^−/− mice. Furthermore, the chemokines involved in macrophage migration, CCL2 and CXCL10, were upregulated in the livers of CCR5^−/− mice infected with recombinant parasites that had been transfected with TgCyp18.

Conclusion

TgCyp18 may play a crucial role in macrophage migration, and in assisting with transport of T. gondii via CCR5-independent mechanisms. TgCyp18 may also play a role with CCL5 in the migration of macrophages to the site of infection, and with CCL2 and CXCL10 in the transport of T. gondii-infected cells to the liver.

Transcriptome analysis of mouse brain infected with Toxoplasma gondii

Toxoplasma gondii is an obligate intracellular parasite that invades a wide range of vertebrate host cells. Chronic infections with T. gondii become established in the tissues of the central nervous system, where the parasites may directly or indirectly modulate neuronal function. However, the mechanisms underlying parasite-induced neuronal disorder in the brain remain unclear. This study evaluated host gene expression in mouse brain following infection with T. gondii. BALB/c mice were infected with the PLK strain, and after 32 days of infection, histopathological lesions in the frontal lobe were found to be more severe than in other areas of the brain. Total RNA extracted from infected and uninfected mouse brain samples was subjected to transcriptome analysis using RNA sequencing (RNA-seq). In the T. gondii-infected mice, 935 mouse brain genes were upregulated, whereas 12 genes were downregulated. GOstat analysis predicted that the upregulated genes were primarily involved in host immune responses and cell activation. Positive correlations were found between the numbers of parasites in the infected mouse brains and the expression levels of genes involved in host immune responses. In contrast, genes that had a negative correlation with parasite numbers were predicted to be involved in neurological functions, such as small-GTPase-mediated signal transduction and vesicle-mediated transport. Furthermore, differential gene expression was observed between mice exhibiting the clinical signs of toxoplasmosis and those that did not. Our findings may provide insights into the mechanisms underlying neurological changes during T. gondii infection.

Real-time PCR as a prognostic tool for human congenital toxoplasmosis

Real-time PCR (qPCR) was positive in 72/150 (48%) blood samples of newborns with congenital toxoplasmosis. Among infants with active retinochoroiditis, 68% had positive qPCR results, while positivity was 29% (P=0.009) in the absence of ocular involvement. Positive qPCR was associated with the presence of retinochoroidal lesions, with an odds ratio of 2.8.

Detection of Chlamydophila pneumoniae in patients with arthritis: significance and diagnostic value

The aim of this study was to assess the potential clinical implications of Chlamydophila pneumoniae in patients with acute and chronic arthritic diseases and to investigate whether blood monocytes might reflect a concomitant synovial or persistent systemic infection. C. pneumoniae was investigated with advanced PCR and reverse transcriptase (RT) PCR techniques targeting different genes and combined with cell line cultures, in synovial fluid (SF) and peripheral blood mononuclear cell (PBMC) specimens collected from 28 patients with arthritis. Five out of twenty-eight patients (17.8%) were found to have C. pneumoniae DNA in either SF or PBMC specimens. Their diagnosis was reactive arthritis (ReA), S.A.P.H.O syndrome, psoriatic arthritis, undifferentiated oligoarthritis (UOA) and ankylosing spondylitis (AS). Specimens from patients with UOA and AS had also mRNA transcripts but those from AS yielded C. pneumoniae growth after co-culture. Moreover, C. pneumoniae DNA levels measured by Real-Time PCR (LightCycler) were higher in PBMC specimens compared to those found in SF at the end of antibiotic treatment. C. pneumoniae may have a role as triggering factor also in chronic arthritides including AS. The combined use of culture and molecular tools increases detection rates and improves the overall sensitivity, suggesting their potential use to detect C. pneumoniae. The different kinetics of bacterial DNA at both peripheral and synovial levels should be taken into consideration when monitoring and evaluating the effectiveness of antibiotic treatment.

Evaluation of drug effects on Toxoplasma gondii nuclear and plastid DNA replication using real-time PCR

Toxoplasma gondii Nicolle and Manceaux, 1908 is a unicellular protozoan that can infect a broad spectrum of organisms including humans. In addition to a nuclear genome, it also carries a circular DNA within a plastid-like organelle (apicoplast) and a linear genome within its mitochondria. The plastid organelle has been shown to be the target of various anti-parasitic drugs or antibiotics. To evaluate the effects of agents on the DNA replication of T. gondii, we tested six drugs (ciprofloxacin, acetylspiramycin, clindamycin, azithromycin, artemether, and sulfadiazine) on the parasite cultured in Hela cells. After drug treatment for 48 h, the parasite growth and DNA replication were evaluated and quantitated using TaqMan real-time quantitative PCR with oligonucleotide primers synthesized based on a gene from the apicoplast genome (ycf24, Genbank accession no. U87145) and a gene from the nuclear genome (uprt, Genbank accession no. U10246). Our results showed that ciprofloxacin was the most effective in inhibiting the replication of the plastid DNA after 48 h drug treatment, with a reduction of 22% in the copy number of the plastid DNA. Artemether was the most effective drug in suppressing the proliferation of tachyzoites. This study also demonstrates that real-time quantitative PCR is a simple and useful technique for monitoring parasite growth and DNA replication.

Real-time quantitative PCR in cerebral toxoplasmosis diagnosis of Brazilian human immunodeficiency virus-infected patients

Cerebral toxoplasmosis is the most common cerebral mass lesion in AIDS patients in Brazil, and results in high mortality and morbidity, despite free access to HAART (highly active antiretroviral treatment). Molecular diagnosis based on conventional PCR (cnPCR) or real-time quantitative PCR (qrtPCR) has been indispensable for definitive diagnosis. We report here the evaluation of qrtPCR with blood and cerebrospinal fluid (CSF) samples from AIDS patients in Brazil. This prospective study was conducted for 2 years, analysing DNA samples extracted from 149 AIDS patients (98 blood and 51 CSF samples) with confirmed clinical and radiological diagnosis. The laboratory diagnosis included cnPCR (with the B22/B23 primer set) and indirect immunofluorescence (IF). For qrtPCR, two primer sets were simultaneously designed based on described genes and using a 6-carboxyfluorescein dye-labelled TaqMan MGB (minor groove binder) probe. One was B1Tg, which amplified a sequence from the B1 gene. The other was the RETg, which amplified a PCR product of the 529 bp sequence. The overall cnPCR and qrtPCR results were: positive results were observed in 33.6% (50) patients. The sensitivities were 98% for cnPCR (B22/B23), and 86 and 98% for qrtPCR (B1Tg and RETg, respectively). Negative reactions were observed in 66.4% patients. The specificities were 97% for cnPCR and qrtPCR (B1Tg), and 88.8 % for RETg. These data show that RETg PCR is highly sensitive as it amplifies a repeat region with many copies; however, its specificity is lower than the other markers. However, B1Tg PCR had good specificity, but lower sensitivity. Among the patients, 20 had blood and CSF collected simultaneously. Thus, their results permitted us to analyse and compare molecular, serological and clinical diagnosis for a better understanding of the different scenarios of laboratorial and clinical diagnosis. For nine patients with confirmed cerebral toxoplasmosis diagnosis, four scenarios were observed: (i) and (ii) negative molecular diagnosis for CSF and positive for blood with variable IF titres for the sera and CSF (negative or positive); (iii) positive molecular diagnosis with CSF and negative with blood; and (iv) positive molecular diagnosis in both samples. In the latter two situations, normally the IF titres in sera and CSF are variable. Other opportunistic infections were shown in 11 patients. Despite the IF titres in sera and CSF being variable, all of them had negative molecular diagnosis for both samples. qrtPCR allows for a rapid identification of Toxoplasma gondii DNA in patient samples; in a minority of cases discrepancies occur with the cnPCR.

Toxoplasma gondii infection and cerebral toxoplasmosis in HIV-infected patients

Cerebral toxoplasmosis is a major cause of morbidity and mortality among HIV-infected patients, particularly from developing countries. This article summarizes current literature on cerebral toxoplasmosis. It focuses on: Toxoplasma gondii genetic diversity and its possible relationship with disease presentation; host responses to the parasite antigens; host immunosupression in HIV and cerebral toxoplasmosis as well as different diagnostic methods; clinical and radiological features; treatment; and the direction that studies on cerebral toxoplasmosis will likely take in the future.

Moving towards an integrated approach to molecular detection and identification ofToxoplasma gondii

The development of simple, sensitive and rapid methods for the detection and identification ofToxoplasma gondiiis important for the diagnosis and epidemiological studies of the zoonotic disease toxoplasmosis. In the past 2 decades, molecular methods based on a variety of genetic markers have been developed, each with its advantages and limitations. The application of these methods has generated invaluable information to enhance our understanding of the epidemiology, population genetics and phylogeny ofT. gondii. However, since most studies focused solely on the detection but not genetic characterization ofT. gondii, the information obtained was limited. In this review, we discuss some widely used molecular methods and propose an integrated approach for the detection and identification ofT. gondii, in order to generate maximum information for epidemiological, population and phylogenetic studies of this key pathogen.

Detection of Toxoplasma gondii oocysts in water sample concentrates by real-time PCR

PCR techniques in combination with conventional parasite concentration procedures have potential for the sensitive and specific detection of Toxoplasma gondii oocysts in water. Three real-time PCR assays based on the B1 gene and a 529-bp repetitive element were analyzed for the detection of T. gondii tachyzoites and oocysts. Lower sensitivity and specificity were obtained with the B1 gene-based PCR than with the 529-bp repeat-based PCR. New procedures for the real-time PCR detection of T. gondii oocysts in concentrates of surface water were developed and tested in conjunction with a method for the direct extraction of inhibitor-free DNA from water. This technique detected as few as one oocyst seeded to 0.5 ml of packed pellets from water samples concentrated by Envirocheck filters. Thus, this real-time PCR may provide a detection method alternative to the traditional mouse assay and microscopy.

GRA2 and ROP1 recombinant antigens as potential markers for detection of Toxoplasma gondii-specific immunoglobulin G in humans with acute toxoplasmosis

A goal of the current study was to evaluate serological applications of Toxoplasma gondii GRA2 and rhoptry protein 1 (ROP1) antigens. Soluble recombinant GRA2 and ROP1 antigens as fusion proteins containing six histidyl residues at the N and C terminals were obtained using an Escherichia coli expression system. Purification by one-step metal affinity chromatography allowed recovery of milligram amounts of pure recombinant proteins per liter of culture. The usefulness of these antigens for diagnosis of human infections was tested on 167 serum samples obtained during routine diagnostic tests. A panel of 37 serum samples from patients with acute toxoplasmosis was compared to a panel of 90 serum samples from individuals with past infection. The results indicated that both GRA2 and ROP1 recombinant antigens detected antibodies more frequently in samples from individuals with acute infections (100% and 94.6%, respectively) than in samples from individuals with chronic infections (22.5% and 15.5%, respectively). These results suggest that immunoglobulin G antibodies against GRA2 and ROP1 antigens are produced during the acute stage of toxoplasmosis but are uncommon in the chronic phase of the infection. Hence, these recombinant proteins can be used as specific molecular markers to differentiate between acute and chronic infections.

A quantitative real-time PCR assay for Ehrlichia ruminantium using pCS20

Heartwater is a tick borne disease that affects ruminants and wild animals in Africa south of the Sahara. It is caused by Ehrlichia ruminantium and transmitted by the tick Amblyomma hebraeum. The protocols currently used to detect heartwater take several days to complete. Here, we describe the development of a pCS20 quantitative real-time PCR TaqMan probe assay to detect E. ruminantium in livestock blood and ticks from the field. The assay is based on the conserved pCS20 gene region of E. ruminantium that contains two overlapping genes, rnc and ctaG [Collins, N.E., Liebenberg, J., De Villiers, E.P., Brayton, K.A., Louw, E., Pretorius, A., Faber, F.E., Van Heerden, H., Josemans, A., Van Kleef, M., Steyn, H.C., Van Strijp, M.F., Zweygarth, E., Jongejan, F., Maillard, J.C., Berthier, D., Botha, M., Joubert, F., Corton, C.H., Thomson, N.R., Allsopp, M.T., Allsopp, B.A., 2005. The genome of the heartwater agent Ehrlichia ruminantium contains multiple tandem repeats of actively variable copy number. PNAS 102, 838-843]. The pCS20 quantitative real-time PCR TaqMan probe was compared to the currently used pCS20 PCR and PCR/32P-probe test with regards to sensitivity, specificity and the ability to detect DNA in field samples and in blood from experimentally infected sheep. This investigation showed that the pCS20 quantitative real-time PCR TaqMan probe was the most sensitive assay detecting seven copies of DNA/mul of cell culture. All three assays, however, cross react with Ehrlichia canis and Ehrlichia chaffeensis. The pCS20 real-time PCR detected significantly more positive field samples. Both the PCR and pCS20 real-time PCR could only detect E. ruminantium parasites in the blood of experimentally infected sheep during the febrile reaction. The PCR/32P-probe assay, however, detected the parasite DNA 1 day before and during the febrile reaction. Thus, because this new quantitative pCS20 real-time PCR TaqMan probe assay was the most sensitive and can be performed within 2h it is an effective assay for epidemiological surveillance and monitoring of infected animals.

Quantitative analysis of thyroid-stimulating hormone messenger RNA and heterogeneous nuclear RNA in hypothyroid rats

Thyroid-stimulating hormone (TSH) stimulates the synthesis and release of thyroid hormones including triiodothyronine (T3) and thyroxine (T4). Semiquantitative analyses using northern blot and in situ hybridization suggested that TSH gene transcription is upregulated under conditions of hypothyroidism. However, no quantitative analysis of TSH gene expression using real-time polymerase chain reaction (PCR) has been reported. In this study, we quantitated the TSHbeta messenger ribonucleic acid (mRNA) level as well as the TSHbeta heterogeneous nuclear ribonucleic acid (hnRNA) level in the anterior pituitary of hypothyroid rats, by real-time PCR using the LightCycler system. The hnRNA is the primary deoxyribonucleic acid (DNA) transcript, which reflects the transcription rate more reliably than the mRNA because of its short half-life. In the anterior pituitary of rats with methimazol-induced chronic hypothyroidism, both mRNA and hnRNA expression of TSHbeta were upregulated fourfold relative to normal rats (n=4). Our method provides a rapid and accurate measure of gene transcription. In the present report, we described a technique for accurate measurement of TSHbeta hnRNA level.