Direct genotyping of Toxoplasma gondii from amniotic fluids based on B1 gene polymorphism using minisequencing analysis

Dual quantitative PCR assays for the rapid detection of Trichophyton indotineae from clinical samples

Trichophyton indotineae is an emerging species of the Trichophyton mentagrophytes complex (TMC), responsible for an epidemic of widespread hairless skin infections that is frequently (50-70%) resistant to terbinafine. In order to initiate appropriate treatment as quickly as possible without waiting for culture positivity (10-15 days) and molecular identification from the strain, we developed a dual quantitative PCR (qPCR) for the direct detection of T. indotineae in clinical samples. We first designed a T. indotineae-specific qPCR assay (TI-qPCR) targeting a single specific polymorphism in the internal transcribed spacer region. Although none of the 94 non-dermatophyte and 7 dermatophyte species were amplified, this TI-qPCR allowed amplification of other TMC species at a lower yield. With equal amounts (0.1 ng) of DNA per reaction, the mean quantitative cycle (Cq) values for T. indotineae and non-indotineae TMC were 27.9 (±0.1) and 38.9 (±0.3), respectively. Therefore, we normalized this assay against a previously validated pan-dermatophyte qPCR assay (PD-qPCR) and relied on the ΔCq [(TI-qPCR) - (PD-qPCR)] to identify T. indotineae versus other TMC species. Dual assay was validated using 86 clinical samples of culture-confirmed T. indotinea and 19 non-indotineae TMC cases. The mean ΔCq for non-indotineae TMC was 9.6 ± 2.7, whereas the ΔCq for T. indotinea was -1.46 ± 2.1 (P < .001). Setting the ΔCq at 4.5 as a cutoff value resulted in 100% specificity for the detection of T. indotineae. This dual qPCR assay quickly detects T. indotineae from skin scrapings, aiding in early diagnosis and treatment for patients with suspected infection.

Systematic Review and Meta-Analysis of Congenital Toxoplasmosis Diagnosis: Advances and Challenges

Objective

To understand how congenital toxoplasmosis (CT) diagnosis has evolved over the years, we performed a systematic review and meta-analysis to summarize the kind of analysis that has been employed for CT diagnosis.

Methods

PubMed and Lilacs databases were used in order to access the kind of analysis that has been employed for CT diagnosis in several samples. Our search combined the following combining terms: "congenital toxoplasmosis" or "gestational toxoplasmosis" and "diagnosis" and "blood," "serum," "amniotic fluid," "placenta," or "colostrum." We extracted data on true positive, true negative, false positive, and false negative to generate pooled sensitivity, specificity, and diagnostic odds ratio (DOR). Random-effects models using MetaDTA were used for analysis.

Results

Sixty-five articles were included in the study aiming for comparisons (75.4%), diagnosis performance (52.3%), diagnosis improvement (32.3%), or to distinguish acute/chronic infection phases (36.9%). Amniotic fluid (AF) and placenta were used in 36.9% and 10.8% of articles, respectively, targeting parasites and/or T. gondii DNA. Blood was used in 86% of articles for enzymatic assays. Colostrum was used in one article to search for antibodies. In meta-analysis, PCR in AF showed the best performance for CT diagnosis based on the highest summary sensitivity (85.1%) and specificity (99.7%) added to lower magnitude heterogeneity.

Conclusion

Most of the assays being researched to diagnose CT are basically the same traditional approaches available for clinical purposes. The range in diagnostic performance and the challenges imposed by CT diagnosis indicate the need to better explore pregnancy samples in search of new possibilities for diagnostic tools. Exploring immunological markers and using bioinformatics tools and T. gondii recombinant antigens should address the research needed for a new generation of diagnostic tools to face these challenges.

Detection of Giardia duodenalis and Toxoplasma gondii in soil and water samples in the Quindío River basin, Colombia

Two zoonotic protozoan pathogens, Giardia duodenalis and Toxoplasma gondii, are important causes of waterborne infections in the Quindío region in Colombia. No previous data exist on how contamination occurs at the source for drinking water consumed by the human population in this region. Our aim was to describe the frequency of G. duodenalis and T. gondii DNA in 11 sampling points during a five-month period in water and adjacent soil at the Quindío River basin (Andean region in the central western part of Colombia). The study employed nested PCR for T. gondii, using the B1 gene as the amplification target, and single-round PCR for G. duodenalis assemblage A and assemblage B, amplifying the gdh gene, followed by DNA sequencing. In 50 soil samples, 28% (14/50) were positive for T. gondii. For G. duodenalis, distribution was in equal parts for assemblage A (8%; 4/50) and assemblage B (8%, 4/50). Genotyping of T. gondii sequences showed two soil samples with type I strain, another two samples of soil with type III strain, but most samples were of unidentified strains. In water samples, T. gondii was detected in 9.1% (5/55), G. duodenalis assemblage A in 34.5% (19/55), and G. duodenalis assemblage B in 12.7% (7/55). T. gondii DNA positivity was associated with lower soil temperature (p = 0.0239). Presence of G. duodenalis and T. gondii was evidenced in soil and water samples in the Quindío River basin, indicating soil as the potential source of contamination for the river that it is destined for human consumption. Monitoring these protozoa in drinking water is necessary to prevent public health risks in human populations.

Development of High Resolution Melting Analysis as a Diagnostic Tool for Molecular Detection of Toxoplasma Infection in Pregnant Women and HIV Positive Cases

Background

Toxoplasma gondii is an obligate intracellular protozoan with worldwide distribution. Diagnosis of toxoplasmosis is a very critical issue, especially in pregnant women and immunocompromised patients. The aim of this study was rapid detection of T. gondii DNA in peripheral blood samples (PBS) employing HRM technique and using RE gene.

Methods

Totally, 242 samples from pregnant women and human immunodeficiency virus (HIV) patients were collected from different hospitals and medical centers of Tehran during Oct 2017 to Dec 2018. High resolution melting analysis (HRM) using partial sequences of repetitive element (RE) gene was done and compared with ELISA test.

Results

Overall, 51 were positive for acute toxoplasmosis that among them, 12 and 20 reported as positive in pregnant women and HIV⁺ patients, respectively using HRM technique. Among 70 patients in chronic phase of disease, 10 and 3 samples were reported as positive for pregnant women and HIV⁺ patients respectively. From 121 negative control, 3 (4.62%) samples associated with HIV⁺ patients, showed positive real-time PCR and HRM analysis results.

Conclusion

For the first time, HRM technique via employing RE gene was used for detection of T. gondii infection in PBS. This method is suitable, helpful and in parallel with serological methods for early diagnosis of acute as well as active form of toxoplasmosis in pregnant women and HIV⁺ patients. The use of techniques based on melt curve and through employing next-generation dyes for diagnosis of T. gondii would be accessible for patients in developing countries.

Molecular Genotyping of Toxoplasma gondii in Sheep Aborted Fetuses Reveals Predominance of Type I Infection in Southwest of Iran

Background

We aimed to detect Toxoplasma gondii in ovine aborted fetuses and evaluate its genetic variations in the southwest of Iran.

Methods

This cross-sectional study was performed on 100 aborted ovine fetuses collected from the different region of Kohgiluyeh and Boyer-Ahmad Province, Iran, in lambing season during 2017 and 2018. DNA was extracted from the brain samples of all of the aborted fetuses and PCR amplified, targeting a 529 bp repetitive element gene of T. gondii. Moreover, to find out the heterogeneity of the positive samples, PCR-DNA amplification of the two main genetic markers, B1 and GRA6, of T. gondii were performed. Nucleotide sequencing and phylogenetic analysis were performed, using the BLAST program and MEGA-X software.

Results

The 529 bp gene of T. gondii was detected in 2 out of 100 (2%) of the ovine aborted samples. The sequences analysis of GRA6 and B1 genes revealed that both isolates from the aborted fetuses of sheep belonged to type I of T. gondii. Intra-divergence was more seen in GRA6 gene whereas less divergence was observed in B1 gene.

Conclusion

Congenital infection with Type I of T. gondii during the neonatal period is associated with abortion in ovine. Evaluation of more aborted samples from broader geographical areas is needed to elucidate the molecular epidemiology and also the genotypes of T. gondii associated with abortion.

Seroprevalence, DNA isolation, and genetic characterization of Toxoplasma gondii from black bear (Ursus americanus) sera collected in Eastern Oklahoma

Black bears (Ursus americanus) are commonly exposed to Toxoplasma gondii. However, there are no reports of exposure or infection with T. gondii in black bears from Oklahoma. The purpose of our project was to determine the seroprevalence of T. gondii antibodies in black bears collected in Oklahoma. Additionally, since only serum was available from these bears, we sought to determine if DNA extraction and PCR amplification for T. gondii was possible on serum samples from bears with positive titers. Seroprevalence was determined using modified agglutination test (MAT). Serum was collected from 44 live-trapped bears in southeastern Oklahoma; 32 (73% ± 58-84%) had antibodies against T. gondii. Seroprevalence in adult bears (85% ± 67-95%) was significantly higher (p = 0.028) than yearlings (33.0% ± 56-80%). Adult bears were 3.4 times more likely to have antibodies to T. gondii than yearlings. From the bears with positive titers, T. gondii DNA was detected in 12 of the 32 seropositive samples by PCR of the B1 gene, with two of the samples showing variation in two nucleotide positions when compared with available sequences. Multilocus PCR-RFLP genotyping of these 12 samples revealed three ToxoDB genotypes, including #2 (type III, haplogroup 3), #4 (type XII, haplogroup 12), and #74 (haplogroup 12). To the best of our knowledge, this is the first report of T. gondii seroprevalence in black bears from Oklahoma. Our results indicate that exposure and infection with T. gondii in black bears from Oklahoma is common.

Performance of Zika Assays in the Context of Toxoplasma gondii, Parvovirus B19, Rubella Virus, and Cytomegalovirus (TORCH) Diagnostic Assays

Infections during pregnancy that may cause congenital abnormalities have been recognized for decades, but their diagnosis is challenging. This was again illustrated with the emergence of Zika virus (ZIKV), highlighting the inherent difficulties in estimating the extent of pre- and postnatal ZIKV complications because of the difficulties in establishing definitive diagnoses. We reviewed the epidemiology, infection kinetics, and diagnostic methods used for Toxoplasma gondii, parvovirus B19, rubella virus, and cytomegalovirus (TORCH) infections and compared the results with current knowledge of ZIKV diagnostic assays to provide a basis for the inclusion of ZIKV in the TORCH complex evaluations. Similarities between TORCH pathogens and ZIKV support inclusion of ZIKV as an emerging TORCH infection. Our review evaluates the diagnostic performance of various TORCH diagnostic assays for maternal screening, fetal screening, and neonatal screening. We show that the sensitivity, specificity, and positive and negative predictive value of TORCH complex pathogens are widely variable, stressing the importance of confirmatory testing and the need for novel techniques for earlier and accurate diagnosis of maternal and congenital infections. In this context it is also important to acknowledge different needs and access to care for different geographic and resource settings.

High-resolution melt curve analysis: A real-time based multipurpose approach for diagnosis and epidemiological investigations of parasitic infections

BACKGROUND

Real-time PCR coupled with high resolution melting curve analysis is a practical technique that could be employed in multipurpose studies. During the recent decade, this technique has been practiced for different targets, worldwide.

METHODS

In the current study three major database centers consisted of PubMed, Scopus and Web of Science were searched until Aug 2019 for applications of HRM real-time PCR in parasitology studies using terms: "Parasite" AND "HRM real-time PCR" OR "High Resolution Melting curve analysis" OR "Real-time PCR", "Protozoan parasites" AND "HRM real-time PCR" OR "High Resolution Melting curve analysis" OR "Real-time PCR", "Helminth" AND "HRM real-time PCR" OR "High Resolution Melting curve analysis" OR "Real-time PCR".

RESULTS

Totally, 83 papers met our criteria and were included in our study. This method was more frequently used for protozoan parasites (52/83; 62.65%), while lower (31/83; 37.35%) studies were incorporated on helminths parasites. Furthermore, Plasmodium spp., and Leishmania spp., were the most prevalent protozoan parasites, and Taenia spp., and filers were the most frequent helminths that were studied by HRM real-time PCR.

CONCLUSION

HRM real-time PCR is a sensitive, flexible and cost-effective method that could be used for multipurpose studies.

Optimal non-invasive diagnosis of fetal achondroplasia combining ultrasonography with circulating cell-free fetal DNA analysis

OBJECTIVES

To assess the performance of non-invasive prenatal testing (NIPT) for achondroplasia using high-resolution melting (HRM) analysis, and to propose an optimal diagnostic strategy combining ultrasound examination and cell-free fetal DNA (cffDNA) analysis.

METHODS

In this prospective multicenter study, cffDNA was extracted from blood of pregnant women at risk for fetal achondroplasia (owing to paternal achondroplasia, previous affected child or suspected rhizomelic shortening) and of pregnant low-risk controls. The presence of either one of the two main fibroblast growth factor receptor 3 gene (FGFR3) mutations was determined using HRM combined with confirmation by SNaPshot minisequencing. Results were compared with phenotypes obtained using three-dimensional computed tomography or postnatal examination, and/or molecular diagnosis by an invasive procedure. Fetal biometry (head circumference and femur length) was analyzed in order to develop a strategy in which cffDNA analysis for diagnosis of achondroplasia is offered only in selected cases.

RESULTS

Eighty-six blood samples from women at risk for fetal achondroplasia and 65 from controls were collected. The overall sensitivity and specificity of NIPT were 1.00 (95% CI, 0.87-1.00) and 1.00 (95% CI, 0.96-1.00), respectively. Critical reduction in femur length of affected fetuses could be observed from 26 weeks' gestation.

CONCLUSIONS

HRM combined with SNaPshot minisequencing is a reliable method for NIPT for achondroplasia. Its implementation in routine clinical care combined with ultrasonography is an efficient strategy for the non-invasive diagnosis of achondroplasia. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Toxoplasma gondii Lineages Circulating in Slaughtered Industrial Pigs and Potential Risk for Consumers

Toxoplasma gondii is a cosmopolitan zoonotic protozoan parasite, and the consumption of raw or undercooked pig meat is one of the most important sources of T. gondii infection. Three predominant lineages, types I, II, and III, are widespread in Europe. Although still poorly understood, a relationship between each type and the severity of illness represents a public health issue. To gain further knowledge of the genotypes in circulation and of the potential risk for consumers, one heart sample and one diaphragm sample (206 total) were taken from each of 103 pig carcasses at an abattoir in Italy. Then, we used 529-bp repetitive element PCR and a B1 real-time PCR high-resolution melting assay coupled with sequencing to detect and genotype T. gondii isolates. T. gondii DNA was detected in 14 pigs (13.6%, 95% confidence interval = 7 to 20.2%), and types I (3.9%), II (5.8%), and III (3.9%) were identified. We found that heart tissue had a significantly higher PCR positivity rate for T. gondii than did diaphragm tissue. This is Europe's largest study on genotyping of T. gondii from pigs, and it demonstrates that all three main lineages are present in carcasses of industrially reared pigs in Italy. There is a potential risk to consumers of infection with any or all of the three lineages, and the related clinical consequences should be taken into account. This study suggests that monitoring of T. gondii types in meat is essential, especially in meat that is traditionally eaten raw or that is minimally processed.

Toxoplasma and Africa: One Parasite, Two Opposite Population Structures

Exploring the genetic diversity of Toxoplasma gondii is essential for an understanding of its worldwide distribution and the determinants of its evolution. Africa remains one of the least studied areas of the world regarding T. gondii genetic diversity. This review has compiled published data on T. gondii strains from Africa to generate a comprehensive map of their continent-wide geographical distribution. The emerging picture about T. gondii strain distribution in Africa suggests a geographical separation of the parasite populations across the continent. We discuss the potential role of a number of factors in shaping this structure. We finally suggest the next steps towards a better understanding of Toxoplasma epidemiology in Africa in light of the strains circulating on this continent.

Sequence variation in the B1 gene among Toxoplasma gondii isolates from swine and cats in Italy

The evaluation of the genetic variations of Toxoplasma gondii among isolates of a wide variety of animal hosts can provide significant information for better understanding the epidemiology and population structure of the parasite in different geographical areas. The aim of this study was to provide information on T. gondii genetic diversity in host species living in central Italy, which could act as a potential source of human infection. Seventy-seven feline faecal samples, and 36 and 20 diaphragm pillar tissue samples from pigs and wild boars were collected in Umbria (central Italy). The samples were tested by a nested-PCR protocol amplifying an informative region within the B1 gene, a multi-copy genetic target, showing a good rate of variability. Thirty-six specimens (27.07%) belonging to 10 pigs, 13 wild boars and 13 cats, tested positive to the B1 nested-PCR screening. Of these, 23 good quality sequences (8 from wild boars, 5 from pigs, and 10 from cats) were analyzed. A comparison of the B1 DNA sequences showed that a single homogeneous nucleotide substitution (C/T) was present at position 31 in the isolates from pigs and wild boars compared with the sampled cats and other hosts (including humans) available in GenBank™. The present results suggest the existence of a T. gondii genetic diversity for swine host species, based on a SNP (C/T) of the B1 gene. Further studies are needed to draw more solid conclusions on the discriminatory power of the B1 target by collecting more swine samples from much broader geographical areas.

Diagnosis of toxoplasmosis and typing of Toxoplasma gondii

Toxoplasmosis, caused by the obligate intracellular protozoan Toxoplasma gondii, is an important zoonosis with medical and veterinary importance worldwide. The disease is mainly contracted by ingesting undercooked or raw meat containing viable tissue cysts, or by ingesting food or water contaminated with oocysts. The diagnosis and genetic characterization of T. gondii infection is crucial for the surveillance, prevention and control of toxoplasmosis. Traditional approaches for the diagnosis of toxoplasmosis include etiological, immunological and imaging techniques. Diagnosis of toxoplasmosis has been improved by the emergence of molecular technologies to amplify parasite nucleic acids. Among these, polymerase chain reaction (PCR)-based molecular techniques have been useful for the genetic characterization of T. gondii. Serotyping methods based on polymorphic polypeptides have the potential to become the choice for typing T. gondii in humans and animals. In this review, we summarize conventional non-DNA-based diagnostic methods, and the DNA-based molecular techniques for the diagnosis and genetic characterization of T. gondii. These techniques have provided foundations for further development of more effective and accurate detection of T. gondii infection. These advances will contribute to an improved understanding of the epidemiology, prevention and control of toxoplasmosis.