Genotyping of toxoplasma gondii isolates from México reveals non-archetypal and potentially virulent strains for mice

Genotyping and virulence studies of Toxoplasma gondii are essential to investigate the pathogenesis of strains circulating worldwide. In this study, eight T. gondii isolates obtained from a congenitally infected newborn, a calf, two cats, three dogs, and a wallaby from five states of México were genotyped by Mn-PCR-RFLP with 11 typing markers (SAG1, SAG2 5'3', alt. SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico), five virulence markers (CS3, ROP16, ROP17, ROP18 and ROP5), 15 microsatellite markers (TUB-2, W35, TgM-A, B18, B17, M33, IV.1, XI.1, M48, M102, N60, N82, AA, N61, N83), and sequencing. A phylogenetic network was built to determine the relationship between Mexican isolates and those reported worldwide. Six different genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), ToxoDB #8, #10, #28 (n = 3), #48, #116, and #282. Genotyping by microsatellite analysis differentiated the three PCR-RFLP genotype #28 isolates into two strains, revealing a total of seven microsatellite genotypes. Three different allele combinations of ROP18/ROP5 virulence markers were also found, 3/3, 1/1, and 4/1. The last two combinations are predicted to be highly virulent in the murine model. According to the phylogenetic network, the T. gondii strains studied here are related to archetypal strains I and III, but none are related to the strains previously reported in México. The genotypes identified in this study in different species of animals demonstrate the great genetic diversity of T. gondii in México. The ToxoDB-PCR-RFLP #28 genotype was found in three isolates from different hosts and states. Additionally, four of the isolates are predicted to be highly virulent in mice. The next step will be to perform in vitro and in vivo assays to determine the phenotype of these T. gondii isolates in murine models.

Maternal anti-Toxoplasma gondii antibodies IgG2, IgG3 and IgG1 are markers of vertical transmission and clinical evolution of toxoplasmosis in the offspring

Toxoplasma gondii can be transmitted vertically during pregnancy and may cause neurological, ocular, and even systemic damage to the offspring. Congenital toxoplasmosis (CT) can be diagnosed during gestation and/or after birth in the postnatal period. The timely diagnosis is highly relevant for efficient clinical management. The most common laboratory methods for diagnosing CT are based on Toxoplasma-specific humoral immune responses. However, these methods are of low sensitivity or specificity. In a previous study with a small number of cases, the comparison of anti-T. gondii IgG subclasses between mothers and their offspring showed promising results for CT diagnosis and prognosis. Thus, in this work, we analyzed specific IgG subclasses and IgA in 40 T. gondii-infected mothers and their children, of which 27 were congenitally infected and 13 uninfected. A higher frequency of anti-Toxoplasma IgG2, IgG3, IgG4, and IgA antibodies was observed in mothers and congenitally infected offspring. Of these, IgG2 or IgG3 were statistically the most conspicuous. In the CT group, maternal IgG3 antibodies were significantly associated with severe disease of the infants and IgG1 and IgG3 with disseminated disease. The results support that maternal anti-T. gondii IgG3, IgG2 and IgG1 are markers of congenital transmission and severity/spread of disease in the offspring.

Anti-Toxoplasma gondii IgM Long Persistence: What Are the Underlying Mechanisms?

Diagnosis of Toxoplasma gondii acute infection was first attempted by detection of specific IgM antibodies, as for other infectious diseases. However, it was noted that this immunoglobulin declines slowly and may last for months or even years. Apart from the diagnostic problem imposed on clinical management, this phenomenon called our attention due to the underlying phenomena that may be causing it. We performed a systematic comparison of reports studying IgM antibody kinetics, and the data from the papers were used to construct comparative plots and other graph types. It became clear that this phenomenon is quite generalized, and it may also occur in animals. Moreover, this is not a technical issue, although some tests make more evident the prolonged IgM decay than others. We further investigated biological reasons for its occurrence, i.e., infection dynamics (micro-reactivation–encystment, reinfection and reactivation), parasite strain relevance, as well as host innate, natural B cell responses and Ig class-switch problems inflicted by the parasite. The outcomes of these inquiries are presented and discussed herein.

SAG3 Toxoplasma gondii cloning reveals unexpected fivefold infection in the blood of feral cats in the Mexican Caribbean

Background

Currently, more than 300 genotypes of Toxoplasma gondii (T. gondii) have been described throughout the world, demonstrating its wide genetic diversity. The SAG3 locus is one of the genes included in the genotyping panel of this parasite. It is associated with its virulence since it participates during the invasion process of the host cells. Therefore, cloning, sequencing, and bioinformatic analysis were used to deepen the understanding of the SAG3 locus genetic diversity of T. gondii in blood samples from feral cats.

Results

Six different SAG3 sequences were detected, five of which were detected in one feline. Three sequences were first reported here; one of them was an intragenic recombinant. In the cladogram, four out of ten SAG3 sequences did not share nodes with others reported worldwide.

Conclusions

Cloning and sequencing of samples with more than one restriction pattern by PCR-RFLP were very helpful tools to demonstrate the presence of more than three genotypes of T. gondii in the blood of feral cats from southeastern Mexico. This suggests a potential mixed infection of multiple T. gondii strains and high genetic diversity of the parasites in felines in this tropical region of Mexico.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-03129-9.

Umbilical Cord-derived Mesenchymal Stem Cells modulate TNF and soluble TNF Receptor 2 (sTNFR2) in COVID-19 ARDS patients

OBJECTIVE

We aimed at explaining the mechanism of therapeutic effect of Umbilical Cord Mesenchymal Stem Cells (UC-MSC) in subjects with COVID-19 Acute Respiratory Distress Syndrome (ARDS). Patients with COVID-19 ARDS present with a hyperinflammatory response characterized by high levels of circulating pro-inflammatory mediators, including tumor necrosis factor α and β (TNFα and TNFβ). Inflammatory functions of these TNFs can be inhibited by soluble TNF Receptor 2 (sTNFR2). In patients with COVID-19 ARDS, UC-MSC appear to impart a robust anti-inflammatory effect, and treatment is associated with remarkable clinical improvements. We investigated the levels of TNFα, TNFβ and sTNFR2 in blood plasma samples collected from subjects with COVID-19 ARDS enrolled in our trial of UC-MSC treatment.

PATIENTS AND METHODS

We analyzed plasma samples from subjects with COVID-19 ARDS (n=24) enrolled in a Phase 1/2a randomized controlled trial of UC-MSC treatment. Plasma samples were obtained at Day 0 (baseline, before UC-MSC or control infusion), and Day 6 post infusion. Plasma concentrations of sTNFR2, TNFα, and TNFβ were evaluated using a quantitative multiplex protein array.

RESULTS

Our data indicate that at Day 6 after infusion, UC-MSC recipients develop significantly increased levels of plasma sTNFR2 and significantly decreased levels of TNFα and TNFβ, compared to controls.

CONCLUSIONS

These observations suggest that sTNFR2 plays a mechanistic role in mediating UC-MSC effect on TNFα and TNFβ plasma levels, determining a decrease in inflammation in COVID-19 ARDS.

Autoantibodies Against Ubiquitous and Confined Antigens in Patients With Ocular, Neuro-Ophthalmic and Congenital Cerebral Toxoplasmosis

Toxoplasma gondii infection can trigger autoreactivity by different mechanisms. In the case of ocular toxoplasmosis, disruption of the blood-retinal barrier may cause exposure of confined retinal antigens such as recoverin. Besides, cross-reactivity can be induced by molecular mimicry of parasite antigens like HSP70, which shares 76% identity with the human ortholog. Autoreactivity can be a determining factor of clinical manifestations in the eye and in the central nervous system. We performed a prospective observational study to determine the presence of autoantibodies against recoverin and HSP70 by indirect ELISA in the serum of 65 patients with ocular, neuro-ophthalmic and congenital cerebral toxoplasmosis. We found systemic autoantibodies against recoverin and HSP70 in 33.8% and 15.6% of individuals, respectively. The presence of autoantibodies in cases of OT may be related to the severity of clinical manifestations, while in cases with CNS involvement they may have a protective role. Unexpectedly, anti-recoverin antibodies were found in patients with cerebral involvement, without ocular toxoplasmosis; therefore, we analyzed and proved cross-reactivity between recoverin and a brain antigen, hippocalcin, so the immunological phenomenon occurring in one immune-privileged organ (e.g. the central nervous system) could affect the environment of another (egg. the eye).

NF-κB and Its Regulators During Pregnancy

The transcriptional factor NF-κB is a nuclear factor involved in both physiological and pathological processes. This factor can control the transcription of more than 400 genes, including cytokines, chemokines, and their modulators, immune and non-immune receptors, proteins involved in antigen presentation and cell adhesion, acute phase and stress response proteins, regulators of apoptosis, growth factors, other transcription factors and their regulators, as well as different enzymes; all these molecules control several biological processes. NF-κB is a tightly regulated molecule that has also been related to apoptosis, cell proliferation, inflammation, and the control of innate and adaptive immune responses during onset of labor, in which it has a crucial role; thus, early activation of this factor may have an adverse effect, by inducing premature termination of pregnancy, with bad outcomes for the mother and the fetus, including product loss. Reviews compiling the different activities of NF-κB have been reported. However, an update regarding NF-κB regulation during pregnancy is lacking. In this work, we aimed to describe the state of the art around NF-κB activity, its regulatory role in pregnancy, and the effect of its dysregulation due to invasion by pathogens like Trichomonas vaginalis and Toxoplasma gondii as examples.

Toxoplasma gondii infection in European mouflons (Ovis musimon) and captive wild felines from Puebla, México

The presence of Toxoplasma gondii in zoos is cause of alert because many susceptible species kept in captivity die of clinical toxoplasmosis. Moreover, excretion of T. gondii oocysts by infected captive wild felines into the facilities could pose a risk to workers. Herbivores in wild collections can serve as sentinels of local transmission, since they get infected by the consumption of oocysts present in ground or water. Both herbivores and felids may reveal the parasite variants which are circulating in the region. We determined the seroprevalence of T. gondii in European mouflons (n = 55) and wild felines (n = 15) from a private zoological collection located in the Eastern region of México, as well as the incidence in 41 of the mouflons using ELISA. The prevalence of T. gondii in mouflons was 14.5% (n = 55) and 17.1% (n = 41) in 2011 and 19.5% in 2012. The estimated incidence was 9.8%–12.2%. In wild felines the frequency was 80%. Four sero-positive animals (two mouflons and the two oldest African lions) were euthanized. Histopathology, conventional PCR (for B1 and SeqRep529 loci) and molecular characterization were carried out. All euthanized animals were positive to T. gondii by PCR. We identified a triple infection (I + II + III) in the brain of a mouflon. In conclusion, a high infective pressure of T. gondii in the collection was found, supported by changes in its prevalence in European mouflons. A high prevalence of infection in wild felines was determined. At least four genotypes of T. gondii are present in herbivores and carnivores, and one mouflon had a mixed infection.

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High infective pressure of T. gondii in mouflons and wild felines of a private collection in Puebla, Mexico.

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Four genotypes of T. gondii are present in herbivores and carnivores.

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A triple infection was found in one mouflon.

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First prospective cross-sectional study, not using serum banks.

Intervertebral disc and endplate cells response to IL-1β inflammatory cell priming and identification of molecular targets of tissue degeneration

Inflammation represents an important factor leading to metabolic imbalance within the intervertebral disc (IVD), conducive to degenerative changes. Therefore, a thorough knowledge of the IVD and endplate (EP) cell behaviour in such pathological environments is essential when designing regenerative therapeutic strategies. The present study aimed at assessing the molecular response of the IVD constitutive nucleus pulposus (NPCs)-, annulus fibrosus (AFCs)- and endplate (EPCs)-derived cells to interleukin (IL)-1β treatment, through large-scale, high-throughput microarray and protein analysis, identifying the differentially expressed genes and released proteins. Overall, the inflammatory stimulus downregulated stemness genes while upregulating pro-inflammatory, pro-angiogenic and catabolic genes, including matrix metalloproteases, which were not balanced by a concomitant upregulation of their inhibitors. Upregulation of anti-inflammatory and anabolic tumour necrosis factor inducible gene 6 protein (TNFAIP6), of IL-1 receptor antagonist (IL-1Ra) (at gene and protein levels) and of trophic insulin-like growth factor 1 (IGF1) was also observed in all cell types; IGF1 particularly in AFCs. An overall inhibitory effect of tumour necrosis factor alpha (TNFα) signal was observed in all cell types; however, EPCs showed the strongest anti-inflammatory behaviour. AFCs and EPCs shared the ability to limit the activation of the signalling mediated by specific chemokines. AFCs showed a slightly senescent attitude, with a downregulation of genes related to DNA repair or pro-mitosis. Results allowed for the identification of specific molecular targets in IVD and EP cells that respond to an inflammatory environment. Such targets can be either silenced (when pathological targets) or stimulated to counteract the inflammation.

Umbilical Cord-derived Mesenchymal Stem Cells for COVID-19 Patients with Acute Respiratory Distress Syndrome (ARDS)

The coronavirus SARS-CoV-2 is cause of a global pandemic of a pneumonia-like disease termed Coronavirus Disease 2019 (COVID-19). COVID-19 presents a high mortality rate, estimated at 3.4%. More than 1 out of 4 hospitalized COVID-19 patients require admission to an Intensive Care Unit (ICU) for respiratory support, and a large proportion of these ICU-COVID-19 patients, between 17% and 46%, have died. In these patients COVID-19 infection causes an inflammatory response in the lungs that can progress to inflammation with cytokine storm, Acute Lung Injury (ALI), Acute Respiratory Distress Syndrome (ARDS), thromboembolic events, disseminated intravascular coagulation, organ failure, and death. Mesenchymal Stem Cells (MSCs) are potent immunomodulatory cells that recognize sites of injury, limit effector T cell reactions, and positively modulate regulatory cell populations. MSCs also stimulate local tissue regeneration via paracrine effects inducing angiogenic, anti-fibrotic and remodeling responses. MSCs can be derived in large number from the Umbilical Cord (UC). UC-MSCs, utilized in the allogeneic setting, have demonstrated safety and efficacy in clinical trials for a number of disease conditions including inflammatory and immune-based diseases. UC-MSCs have been shown to inhibit inflammation and fibrosis in the lungs and have been utilized to treat patients with severe COVID-19 in pilot, uncontrolled clinical trials, that reported promising results. UC-MSCs processed at our facility have been authorized by the FDA for clinical trials in patients with an Alzheimer's Disease, and in patients with Type 1 Diabetes (T1D). We hypothesize that UC-MSC will also exert beneficial therapeutic effects in COVID-19 patients with cytokine storm and ARDS. We propose an early phase controlled, randomized clinical trial in COVID-19 patients with ALI/ARDS. Subjects in the treatment group will be treated with two doses of UC-MSC (l00 × 10⁶ cells). The first dose will be infused within 24 hours following study enrollment. A second dose will be administered 72 ± 6 hours after the first infusion. Subject in the control group will receive infusion of vehicle (DPBS supplemented with 1% HSA and 70 U/kg unfractionated Heparin, delivered IV) following the same timeline. Subjects will be evaluated daily during the first 6 days, then at 14, 28, 60, and 90 days following enrollment (see Schedule of Assessment for time window details). Safety will be determined by adverse events (AEs) and serious adverse events (SAEs) during the follow-up period. Efficacy will be defined by clinical outcomes, as well as a variety of pulmonary, biochemical and immunological tests. Success of the current study will provide a framework for larger controlled, randomized clinical trials and a means of accelerating a possible solution for this urgent but unmet medical need. The proposed early phase clinical trial will be performed at the University of Miami (UM), in the facilities of the Diabetes Research Institute (DRI), UHealth Intensive Care Unit (ICU) and the Clinical Translational Research Site (CTRS) at the University of Miami Miller School of Medicine and at the Jackson Memorial Hospital (JMH).

A Proinflammatory Immune Response Might Determine Toxoplasma gondii Vertical Transmission and Severity of Clinical Features in Congenitally Infected Newborns

Toxoplasma gondii is the etiological agent of toxoplasmosis. Mother-to-child transmission of this parasite can occur during pregnancy. Newborns with congenital toxoplasmosis may develop central nervous system impairment, with severity ranging from subclinical manifestations to death. A proinflammatory/regulated specific immune profile is crucial in the defense against the parasite; nevertheless, its role in the infected pregnant women and the congenitally infected offspring has been poorly explored, and there is still no consensus about its relation to parasite vertical transmission or to severity and dissemination in the congenitally infected newborns. This work aimed to characterize these relations by means of principal component and principal factor analyses. For this purpose, we determined the specific production of the four immunoglobulin G antibody subclasses, cytokines, and lymphocyte proliferation in the T. gondii–infected pregnant women−10 who transmitted the infection to their offspring and seven who did not—as well as in 11 newborns congenitally infected and grouped according to disease severity (five mild and six moderate/severe) and dissemination (four local and seven disseminated). We found that the immune response of nontransmitter women differed from that of the transmitters, the latter having a stronger proinflammatory response, supporting a previous report. We also found that newborns who developed moderate/severe disease presented higher levels of lymphocyte proliferation, particularly of CD8⁺ and CD19⁺ cells, a high proportion of tumor necrosis factor α producers, and reduced expression of the immune modulator transforming growth factor β, as opposed to children who developed mild clinical complications. Our results suggest that a distinctive, not regulated, proinflammatory immune response might favor T. gondii vertical transmission and the development of severe clinical manifestations in congenitally infected newborns.

Stray dogs in the tropical state of Chiapas, Mexico, harbour atypical and novel genotypes of Toxoplasma gondii

Genotyping of Toxoplasma gondii remains a relevant topic of study, since genotypes can be related to the presentation and severity of toxoplasmosis. To date, 292 restriction fragment length polymorphism genotypes have been described around the world. Serosurveys in southeastern Mexico have documented exposure in over 70% of people and certain animals. Recently, we have described new genotypes and mixed infections in feral cats from Quintana Roo. Thus, the aim of this study was to genotype T. gondii and to describe its genetic variability, from naturally infected stray dogs of Chiapas, which has different geographical and climatic conditions from those found at the Yucatan Peninsula and the other parts of the country. Eleven stray dogs were captured and bled to obtain DNA, and then they were euthanized to perform necropsies and to collect target tissues. Diagnosis of T. gondii was done by quantitative real-time PCR (qPCR) and endpoint PCR. Genotyping was carried out, amplifying 12 polymorphic markers and 15 microsatellites. Atypical SAG3 gene products were cloned and sequenced. All blood samples of dogs were positive to T. gondii DNA by PCR. Two isolates were obtained from pooled heart and diaphragm tissue of two dogs. Two complete PCR-RFLP genotypes were identified (type BrIII and #28). Four animals had mixed infections. A new RFLP atypical allele for the SAG3 marker was observed; cloning and sequencing analysis of this locus revealed mixed infection by a strain identical to GT1, and one type I × II intragenic recombinant. The microsatellite analysis revealed that both isolates are atypical. Thus, atypical new genotypes of T. gondii and mixed infections were found in dogs of Chiapas. The results found here and in genotyping studies in México suggest that the southeastern region favours wide genetic diversity of T. gondii and the possible presence of virulent genotypes such as those found in central and South America.

Testing New Peptides From Toxoplasma gondii SAG1, GRA6, and GRA7 for Serotyping: Better Definition Using GRA6 in Mother/Newborns Pairs With Risk of Congenital Transmission in Mexico

Toxoplasma gondii variant influences clinical profile in human congenital and ocular toxoplasmosis. Parasite genotyping represents a challenge due to insufficient amount of genetic material of the protozoan in the host samples, and isolates are hard to obtain, especially from pediatric patients. An alternative is serotyping, which is based on the presence of specific antibodies against polymorphic proteins related to virulence; the more widely used are GRA6 and GRA7, but most works report cross reactions among the classical strains (I, II, and III). We designed new peptides of GRA6, GRA7, and SAG1 proteins, with more SNPs among the three clonal strains than those previously designed. This was done by identifying BcR and polymorphic epitopes by means of bioinformatics; then we designed peptides with linkers joining the specific regions and predicted their 3D structure. With the commercial molecules synthesized on the basis of these designs, we tested 86 serum samples from 42 mother/newborn pairs and two congenitally infected newborns, by indirect ELISA. We implemented a strategy to determine the serotype based on scatter plots and a mathematical formula, using ratios among reactivity indexes to peptides. We found low frequency of samples reactive to GRA7 and SAG1, and cross reactions between GRA6 serotypes I and III; we modified these later peptides and largely improved distinction among the three clonal strains. The chronicity of the infection negatively affected the reactivity index against the peptides. Serotyping both members of the mother/child pair improves the test, i.e., among 26% of them only one member was positive. Serotype I was the most frequent (38%), which was congruent with previous genotyping results in animals and humans of the same area. This serotype was significantly more frequent among mothers who transmitted the infection to their offspring than among those who did not (53 vs. 8%, p = 0.04) and related to disease dissemination in congenitally infected children, although non-significantly. In conclusion, serotyping using the improved GRA6 peptide triad is useful to serotype T. gondii in humans and could be implemented for clinical management and epidemiological studies, to provide information on the parasite type in specific areas.

Mixed Toxoplasma gondii infection and new genotypes in feral cats of Quintana Roo, México

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii that infects homeothermic animals, including humans. To date, as many as 287 genotypes have been described worldwide. Genetic characterization of the parasite is crucial because the parasite type can determine the presentation and severity of toxoplasmosis. Previously, we reported that the Yucatán Peninsula has a frequency of infection of over 70% in humans and other animals; moreover, there are seven species of felids, including domestic cats; thus, we hypothesized that this might be a region with a high diversity of the parasite. Nevertheless, no genotyping of this protozoan has been performed in this region. Thus, the aim of this study was to genotype T. gondii from naturally infected feral cats of Quintana Roo, within the Yucatán Peninsula, and to describe its genetic variability. Eleven feral cats were captured and bled to obtain the buffy coat; then, they were euthanized to collect target organs or tissues to extract DNA. Samples were processed by PCR for diagnosis, and ten polymorphic markers were genotyped by PCR-RFLP. Atypical GRA6 gene products were cloned and sequenced. Ten of the eleven cats were PCR positive for toxoplasmosis in blood; of these, seven had mixed infections. Also, two isolates were obtained from the heart and diaphragm of two animals. At least 23 different genotypes were detected, from which 18 are new worldwide. From the atypical GRA6 gene cloning and sequencing analysis, a mixed infection was discovered, due to one strain identical to GT1 and another to VAND. In conclusion, T. gondii genetic diversity in the region is high and different from that in other regions, with new genotypes exclusive to México and some others shared with USA and South America.

Maternal Immune Response During Pregnancy and Vertical Transmission in Human Toxoplasmosis

Toxoplasmosis is a parasitic zoonosis distributed worldwide, caused by the ingestion of contaminated water/food with the parasite Toxoplasma gondii. If a pregnant woman is infected with this parasite, it may be transmitted to the fetus and produce ocular, neurological, or systemic damage with variable severity. The strength and profile of mother's immune response have been suggested as important factors involved in vertical transmission rate and severity of clinical outcome in the congenitally infected fetus. The aim of this work was to evaluate a possible relation between the mother's immune response during pregnancy and congenital transmission to the fetus. We obtained peripheral blood from T. gondii infected pregnant woman and tested it for anti T. gondii (IgG1, IgG2, IgG3, IgG4, and IgA) in serum. Peripheral blood mononuclear cells (PBMCs) were isolated to analyze the in vitro effect of soluble T. gondii antigens on proliferation and production of cytokines. We found that IgG2-4 and IgA antibodies and lymphocytes proliferation, especially CD4⁺, CD8⁺, and CD19⁺ were positive in a higher proportion of cases in transmitter than in non-transmitter women. Furthermore, IgG2-3 and IgA anti-Toxoplasma antibody levels were higher in those mothers who transmitted the infection than in those who did not. Interestingly, a higher proportion of positive cases to IFN-γ and negatives to the immunoregulatory cytokine TGF-β, were related to T. gondii vertical transmission. Our descriptive results are consistent with the paradoxical previous observations in murine models of congenital toxoplasmosis, which suggest that an increased immune response that protects the mothers from a disseminated or severe disease, and should protect the fetus from infection, is positively related to parasite transmission.

Potential public health benefits from cat eradications on islands

Cats (Felis catus) are reservoirs of several pathogens that affect humans, including Toxoplasma gondii. Infection of pregnant women with T. gondii can cause ocular and neurological lesions in newborns, and congenital toxoplasmosis has been associated with schizophrenia, epilepsy, movement disorders, and Alzheimer's disease. We compared seroprevalence of T. gondii and risk factors in people on seven islands in Mexico with and without introduced cats to determine the effect of cat eradication and cat density on exposure to T. gondii. Seroprevalence was zero on an island that never had cats and 1.8% on an island where cats were eradicated in 2000. Seroprevalence was significantly higher (12-26%) on the five islands with cats, yet it did not increase across a five-fold range of cat density. Having cats near households, being male and spending time on the mainland were significant risk factors for T. gondii seroprevalence among individuals, whereas eating shellfish was protective. Our results suggest that cats are an important source of T. gondii on islands, and eradicating, but not controlling, introduced cats from islands could benefit human health.

Toxoplasmosis congénita en el valle de México. Resultados de una serie de casos

ANTECEDENTES: En México prevalecen cepas “virulentas” de Toxoplasma gondii, por lo que el cuadro clínico puede ser diferente a los reportados para regiones donde circulan cepas no virulentas, como Europa, Estados Unidos y Canadá.MÉTODOS: Se reporta una serie de casos con toxoplasmosis congénita reclutados a partir de 2005 por tamiz prenatal o postnatal, o porque llegaron como casos clínicos al INP, y que conforman parte de una serie de casos.RESULTADOS: Todos los pacientes presentaron manifestaciones clínicas, pero el  grupo de tamiz prenatal presentó una infección más localizada y menos grave, principalmente con espasticidad y retraso psicomotor leve. El grupo de tamiz postnatal presentó características clínicas intermedias, con retraso psicomotor leve, moderado o grave, bajo peso al nacimiento, micro o hidrocefalia, ictericia, hepatomegalia, esplenomegalia, calcificaciones intracraneales y espasticidad. Los pacientes más afectados fueron aquellos que se presentaron como casos clínicos, con una amplia variedad de manifestaciones clínicas y el peor pronóstico, incluida la muerte. Seis pacientes presentaron comorbilidades. Veinte casos fueron positivos para dos o más pruebas de laboratorio; el resto sólo para una.CONCLUSIONES. Nuestros resultados apoyan que la toxoplasmosis congénita en México es más grave que en otros países, y que urge implementar tamiz prenatal efectivo, para prevención y profilaxis.PALABRAS CLAVE: complejidad diagnóstica; evaluación prenatal; heterogeneidad clínica; tamiz postnatal; tamiz prenatal; toxoplasmosis congénita; Toxoplasma gondii 

High heterogeneity, mixed infections and new genotypes in human congenital toxoplasmosis cases in the mega-metropolis of Central Mexico

Mexico presents high prevalence of Toxoplasma gondii infection, including the congenital form, but there are few data about the genetic diversity of the parasite, so we attempted parasite isolation and genotyping in nine mother/children pairs with congenital toxoplasmosis (CT), living in the Valley of Mexico, who were part of a 30 cases cohort that started 12 years ago. They were recruited through research projects which included pre- and postnatal screening of congenital infections or directly CT, and cases referred to INP for management because they had clinical abnormalities. Genotyping was performed by PCR-RFLP of SAG1, SAG2, SAG3, BTUB GRA6, c22-8, c29-2, L358, PK1 and Apico markers, followed by sequencing. Sixty seven percent of samples were typed for the SAG3 locus, 39% for Apico and 33% for BTUB, while Alt. SAG2, GRA6 and c29-2 types could be labelled in less cases. Type I alleles predominated, followed by II and III. We isolated the first strain obtained from humans in Mexico and found three genotypes not previously found in the world. The presence of ToxoDB#10 clonal type was documented in one pair, as well as mixed infections in five mothers. No relation of genotype or parasite load with clinical signs was found. In conclusion, we encountered great genetic diversity and mixed T. gondii infections among mother/children pairs with congenital toxoplasmosis in the mega-metropolis of the Valley of Mexico.

Report of an unsual case of anophthalmia and craniofacial cleft in a newborn with Toxoplasma gondii congenital infection

Background

We present one unusual case of anophthalmia and craniofacial cleft, probably due to congenital toxoplasmosis only.

Case presentation

A two-month-old male had a twin in utero who disappeared between the 7^th and the 14^th week of gestation. At birth, the baby presented anophthalmia and craniofacial cleft, and no sign compatible with genetic or exposition/deficiency problems, like the Wolf-Hirschhorn syndrome or maternal vitamin A deficiency. Congenital toxoplasmosis was confirmed by the presence of IgM abs and IgG neo-antibodies in western blot, as well as by real time PCR in blood. CMV infection was also discarded by PCR and IgM negative results. Structures suggestive of T. gondii pseudocysts were observed in a biopsy taken during the first functional/esthetic surgery.

Conclusions

We conclude that this is a rare case of anophthalmia combined with craniofacial cleft due to congenital toxoplasmosis, that must be considered by physicians. This has not been reported before.

Genotyping Toxoplasma gondii with the B1 Gene in Naturally Infected Sheep from an Endemic Region in the Pacific Coast of Mexico

Toxoplasma gondii is a protozoan parasite with a broad ecological valence, which has been detected in a wide range of hosts and landscapes. Although the genus is considered monospecific, in recent years it has been demonstrated to exhibit more genetic variability than previously known. In Mexico, there are few genotyping studies, which suggest that classical, autochthonous, and atypical strains are circulating. The goal of this study was to describe T. gondii genetic diversity in naturally infected sheep from Colima, Mexico. This is a good site to study ecological aspects of this parasite since it is located between the Nearctic and Neotropical ecozones and it includes domestic and wild risks for transmission. We analyzed 305 tissue samples of semicaptive sheep from six coastal and central zones of Colima and border zones of Michoacán. We used an 803 bp amplicon of the B1 gene to genotype T. gondii and seroprevalence was determined by ELISA. Indexes for genetic diversity and genetic differentiation were calculated and compared with reference strains from North America (NA) and South America (SA). Twenty-three tissue samples were positive for the B1 gene by PCR, which were sequenced. Crude prevalence was 24.4%. The genetic analysis showed 16 variable sites along the 803 bp region that grouped all sequences into 13 haplotypes in the phylogenetic tree. Bayesian and haplotype network analysis showed nine new B1-types, of which three were frequent and six had unique alleles. Comparisons among sequence sets revealed that the Mexican population had lower differentiation than SA and an intermediate genetic variability between South America and North America. The B1 gene analysis showed new T. gondii haplotypes in naturally infected sheep; therefore, this marker could be initially used in molecular screening studies to identify potentially virulent genotypes of this parasite using natural host samples directly.

Immunoglobulin Concentrations in Plasma and Saliva During the Neonatal Period

BACKGROUND

Screening for infectious diseases in newborns using immunoglobulin (Ig)A-, IgM-, and IgE-specific antibodies is expensive and impractical. To determine if total levels of these Igs can be used for screening purposes, thus simplifying the process, their basic levels in the 1(st) month of extrauterine life need to be determined. Additionally, the ability to simplify screening by using saliva also needs to be determined. The aim of this study was to determine IgA, IgM, and IgE concentrations in plasma and saliva in newborns, correlation between the samples, and relationship between Ig levels and newborn age.

METHODS

We enrolled 53 apparently healthy newborns, paired samples of plasma and saliva were collected, and total IgA, IgM, and IgE concentrations determined by capture enzyme-linked immunosorbent assay. The correlation between plasma and saliva values was calculated by Spearman's rank correlation coefficient and the IgA, IgM, and IgE distributions were analyzed by the Shapiro-Wilk test. We also determined the level of each Ig concentration according to age.

RESULTS

IgA and IgM levels in plasma and IgA levels in saliva increased significantly during 1(st) month of life, especially in the 2(nd) week and 3(rd) week, with a good correlation of IgA between plasma and saliva. IgE levels in both plasma and saliva and IgM levels in saliva were very low or absent.

CONCLUSION

These results suggest that Igs in saliva could be good biomarkers for newborn screening programs during the 1(st) week of life. This study established reference values for Igs according to age in the neonatal period.

Vertical transmission and fetal damage in animal models of congenital toxoplasmosis: A systematic review

In humans, the probability of congenital infection and fetal damage due to Toxoplasma gondii is dependent on the gestation period at which primary infection occurs. Many animal models have been used for vaccine, drug testing, or studies on host or parasite factors that affect transmission or fetal pathology, but few works have directly tested fetal infection and damage rates along gestation. So, the purpose of this work was to perform a systematic review of the literature to determine if there is a model which reflects these changes as they occur in humans. We looked for papers appearing between 1970 and 2014 in major databases like Medline and Scopus, as well as gray literature. From almost 11,000 citations obtained, only 49 papers fulfilled the criteria of having data of all independent variables and at least one dependent datum for control (untreated) groups. Some interesting findings could be extracted. For example, pigs seem resistant and sheep susceptible to congenital infection. Also, oocysts cause more congenitally infected offspring than tissue cysts, bradyzoites or tachyzoites. In spite of these interesting findings, very few results on vertical transmission or fetal damage rates were similar to those described for humans and only for one of the gestation thirds, not all. Moreover, in most designs tissue cysts - with unknown number of bradyzoites - were used, so actual dose could not be established. The meta-analysis could not be performed, mainly because of great heterogeneity in experimental conditions. Nevertheless, results gathered suggest that a model could be designed to represent the increase in vertical transmission and decrease in fetal damage found in humans under natural conditions.

Mouse model of congenital infection with a non-virulent Toxoplasma gondii strain: Vertical transmission, "sterile" fetal damage, or both?

Congenital transmission of Toxoplasma gondii may occur if the mother gets infected for the first time while pregnant. The risk of mother-to-child transmission depends on the gestation trimester at infection, being lowest in the first and highest in the last. Conversely, fetal damage is frequent and more severe at the beginning of pregnancy. The objective of this study was to evaluate congenital transmission and pathological aspects in the placenta and the fetus using a mouse model of congenital infection of the second gestation third. Forty-five female BALB/c mice were infected intravenously with 2.5-10.0 × 10(6) tachyzoites of the ME49 strain at middle gestation. Samples of maternal spleen and fetal/placental units were taken 72 h later. We determined parasite load and vertical transmission by qPCR, as well as damage macroscopically and by histopathology. With the lowest dose, 18% of the fetuses were infected. Also, 40% of fetuses/litter were altered, while this value was 10% in the control group (P < 0.05). These results are similar to those described in humans in terms of vertical transmission and fetal damage during the second third of gestation. The maternal spleen had 10-1000 times more tachyzoites than the placenta, and the later retained 90-99% of the parasites that could reach the fetus. Nevertheless, we found resorptions, abortions or fetal tissue damage in the presence but also in the absence of parasites. Our data indicate a strong protective effect of maternal organs and the placenta against fetal infection, but extensive damage of the later may led to resorption or abortion without vertical transmission.

Successful capture of Toxocara canis larva antigens from human serum samples

Background

Toxocara canis is a nematode that parasitizes dogs, while humans are paratenic hosts. When humans are infected the migrating larvae damage the liver, lungs and even the nervous system. Larva migrans diagnosis is based on immunological techniques; however, the commercial immunodiagnostic kits detect anti-T. canis antibodies which may cross-react with other parasites, mainly nematodes with extra-intestinal migration. Moreover, antibodies do not necessarily reflect an active infection; so detection and quantification of circulating antigens may provide appropriate and timely information for treatment, which prevents irreversible damage. Here we report the standardization of a monoclonal antibody based antigen capture ELISA to diagnose human toxocariasis without cross-reaction.

Methods

We developed anti-T. canis polyclonal antibodies in rabbits and a monoclonal antibody in mouse which did not cross-react with 15 antigens from several parasites. The sandwich ELISA standardization was performed using sera from mice experimentally infected. We tested the method using 29 positive and 58 negative human sera previously typified with a commercial kit, which detects antibodies.

Results

Only 5.0 μg/mL and 10 μg/mL polyclonal antibodies and monoclonal antibody, respectively, were needed in the sandwich ELISA standardization, detecting since 440 pg/mL larva antigens. Nine out of 29 antibody-positive sera were also positive for antigens and no false positive were found. Taking the antibody kit as the reference standard, the sensibility and specificity of the antigen test were 31% and 100%, respectively.

Conclusions

With these tools we established a detection threshold as low as 440 pg/mL antigen. Monoclonal antibody is specific, and did not cross-react with antigens from other parasites. Detection of circulating antigens helps provide appropriate and timely treatment and prevents irreversible damage.

First isolation of Toxoplasma gondii from cats of Colima, Mexico: tissue distribution and genetic characterization

Toxoplasma gondii is among the commonest zoonotic infectious agents worldwide. It infects many warm-blooded animals, including felines, the definitive hosts. This parasite is now classified in 15 haplogroups spread out around the world. Few reports reveal a predominance of genotypes I and III in Mexico, although recombinant and atypical variants have also been found in humans and animals. The aim of this study was to detect, isolate and genotype T. gondii from cats of Colima Mexico, and to analyze tissue distribution of the parasite. IgG specific antibodies were investigated in 48 serum samples from unwanted and stray cats by indirect ELISA. Isolation in mice and molecular characterization by PCR-RFLP and sequencing were attempted using pools of brain, heart, liver, lung, spleen and brachiocephalic muscle samples of seropositive cats. Fourteen animals (29.2%) were seropositive, the frequency ranged between 27.3 and 40% among the different localities. Ten seropositive animals were euthanized, eight of them were positive for the B1 gene by conventional PCR. More frequently infected tissues were the brachiocephalic muscle (75.0%) the brain (63.0%) and the spleen (63.0%). Genotype III was determined for the SAG3 locus of the parasite infecting an unwanted cat. Tachyzoites were isolated from the peritoneal cavity of two mice inoculated with the tissue pool of one kitten. Type I alleles were found in SAG1, SAG2, SAG3, BTUB, GRA6, c29-2 and PK1 loci, while c22-8 was type II, and L358 and Apico were type III. This genotype corresponds to ToxoDB genotype #28. This is the first T. gondii isolate genetically characterized in Colima, Mexico and is different to other isolations of the country.

Toxoplasmosis seroprevalence in wild small rodents, potentially preys of ocelots in north-eastern Mexico

The aim of this study was to assess the prevalence of Toxoplasma gondii infection in rodents that coexist with ocelots in north-eastern Mexico. Eighty rodents of five genera were captured and their serum samples tested for specific IgG antibodies to T. gondii by in-house indirect ELISA using three different conjugates. Prevalences of 7% (3/44) and 33% (4/12) were found in Sigmodon hispidus and Liomys irroratus, respectively, and were significantly different. All Baiomys taylori and Oligoryzomys fulvescens were negative for the presence of anti-T. gondii IgG antibodies. The samples from Peromyscus spp. could not be analyzed because none of the three conjugates tested recognized their immunoglobulins. Infection was confirmed in one single specimen of L. irroratus by qPCR, which generated an estimate of 146 parasites per mg of muscle tissue. The results strongly support the notion of active T. gondii transmission between rodents and felines in this zone of Mexico and an important role of some rodent species in the sylvatic cycle of T. gondii.

Diagnostic-test evaluation of immunoassays for anti-Toxoplasma gondii IgG antibodies in a random sample of Mexican population

INTRODUCTION

There are few articles on evaluation of Toxoplasma gondii serological tests. Besides, commercially available tests are not always useful and are expensive for studies in open population. The aim of this study was to evaluate in-house ELISA and western blot for IgG antibodies in a representative sample of people living in Mexico.

METHODOLOGY

Three hundred and five serum samples were randomly selected from two national seroepidemiological survey banks; they were taken from men and women of all ages and from all areas of the country. ELISA cut-off was established using the mean plus three standard deviations of negative samples. Western blots were analysed by two experienced technicians and positivity was established according to the presence of at least three diagnostic bands. A commercial ELISA kit was used as a third test. Two reference standards were built up: one using concordant results of two assays leaving the evaluated test out and the other in which the evaluated test was included (IN) with at least two concordant results to define diagnosis.

RESULTS

the lowest values of diagnostic parameters were obtained with the OUT reference standards: in-house ELISA had 96.9% sensitivity, 62.1% specificity, 49.6% PPV, 98.1% NPV and 71.8% accuracy, while western blot presented 81.8%, 89.7%, 84.0%, 88.2% and 86.6% values and the best kappa coefficient (0.72-0.82).

CONCLUSIONS

The in-house ELISA is useful for screening people of Mexico, due to its high sensitivity, while western blot may be used to confirm diagnosis. These techniques might prove useful in other Latin American countries.

The seroprevalence ofTaenia soliumcysticercosis among epileptic patients in León, Nicaragua, as evaluated by ELISA and western blotting

The Taenia solium taeniasis/cysticercosis complex is an important public-health problem in several countries, where many epileptic seizures appear to be associated with neurocysticercosis. As few data on this problem in Nicaragua exist, the seroprevalence of antibodies reacting with antigens from T. solium cysticerci was investigated among 88 Nicaraguan epileptics (45 males and 43 females, aged 6-53 years). In questionnaire-based interviews, each adult subject and a caregiver of each child investigated were asked about potential risk factors for taeniasis/cysticercosis. When a serum sample from each subject was then checked for anti-cysticercus antibodies, 8.0% of the subjects were found seropositive by ELISA and 14.8% by western blotting. Five samples (all from individuals who had been epileptic for > 5 years) were positive in both tests. When the level of association between each potential risk factor and seropositivity (in ELISA or by blotting) was evaluated, the only statistically significant association detected was that between a positive ELISA and the subject living in a household where pigs were raised (odds ratio = 5.18; 95% confidence interval = 0.8-41.6; P = 0.05). The bands most frequently recognized in the western blots (of 50, 42-39, 24 and 14 kDa) were those previously reported. The results indicate that, in the city of Léon, cysticercosis may be endemic and the cause of a significant proportion of the epilepsy recorded.

Endothelial cell invasion by Toxoplasma gondii: differences between cell types and parasite strains

Toxoplasma gondii disseminates and causes congenital infection by invasion of the endothelial cells. The aim of this study was to analyze the ability of two strains to invade two endothelial cell types. Tachyzoites of the RH and ME49 strains were expanded in Balb/c and C57BL6-RAG2-/- mice, respectively. Tachyzoites were harvested from 72 h Vero cell cultures and incubated for 30 min to 4 h at 10:1 parasite/cell ratio in 24-well plates, containing monolayers of either HMEC-1 line or human umbilical cells (HUVECs). The number of infected cells and parasitic vacuoles per infected cell were counted in Wright stained slides. A slow increase in the proportion of infected cells occurred but varied according to cell type-parasite strain combination: ME49 tachyzoites invaded up to 63% HMEC-1 cells, while RH parasites infected up to 19% HUVECs. ME49 and RH tachyzoites invaded 49 and 46% HUVECs and HMEC-1 cells, respectively. Reinvasion and formation of new parasitophorous vacuoles of infected cells was more frequent than invasion of noninfected cells. The results support that the factors influencing invasion, and thus dissemination and vertical transmission, are parasite type, host cell type/subtype, and activation state. Interestingly, T. gondii virulence does not seem to relay on its invasion efficiency, but probably on replication speed.

HIV testing and counselling in Colombia: evidence from a national health survey and recommendations for health-care services

The purpose of this study was to assess the prevalence of, and the factors associated with HIV testing and pre- and post-test counselling (PPTC) in Colombia. Cross-sectional data from the National Health Survey carried out during 2007 were analysed. Data were gathered from records of 29,760 individuals between the ages of 18 and 69 from the main regions of the country. Only 19.7% of the sample had taken an HIV test. Men, people with no education, those not affiliated with the health-care system, residents of rural areas and those aged older than 65 were less likely to have been tested for HIV; 42% of those tested did not receive pre-test counselling and 56.9% received no report of the results. Considering the low prevalence of HIV testing among the Colombian population, it is necessary to design and apply guidelines for HIV screening in all health-care settings and to conduct targeted testing in high-risk sub-populations. A national norm of PPTC in those who undergo HIV testing should be examined.

Seroprevalence and national distribution of human toxoplasmosis in Mexico: analysis of the 2000 and 2006 National Health Surveys

Global warming has had serious implications on dispersion of infectious diseases like toxoplasmosis. Since the frequency of Toxoplasma gondii largely depends on climatic conditions, we studied its prevalence by means of 3599 samples of the National Health Survey 2000 (NHS-2000) and 2916 of the National Health and Nutrition Survey 2006 (NHNS-2006) serum banks, obtained from 1-98 year old subjects of both genders and all states of Mexico. Anti-T.gondii IgG antibodies were determined by ELISA and confirmed by western blot. Crude, epidemiologically weighted and diagnosis-performance-adjusted prevalence values were calculated. Seroprevalence changes were compared between both surveys and among regions (north, center and coast). Also, correlations between changes in temperature or humidity and those in prevalence were measured. National crude prevalence was 60.1% and 62.6% for NHS-2000 and NHNS-2006, respectively. Weighted and adjusted values were 62.5% and 40.0% for NHS-2000, and 63.7 and 43.1% for NHNS-2006. Coastal states and children presented the largest increases between surveys, while the center of the country showed a decrease. An apparently higher prevalence of T. gondii infection was observed in both surveys compared to that performed in 1987, while a geographical re-distribution was found from 2000 to 2006, with a positive correlation between temperature and frequency deltas in 21 states where prevalence increased.

Toxoplasma gondii invasion and replication in astrocyte primary cultures and astrocytoma cell lines: systematic review of the literature

Toxoplasma gondii is a cosmopolitan protozoan which infects all homoeothermic species, including humans. This parasite may cause severe neurological problems in congenitally infected newborns or immunocompromised individuals, but it also provokes psychiatric and neurological disorders as well as behavioural and sensory deficit. There is controversy regarding the effect of T. gondii upon astrocytes, which may serve as parasite proliferation recipients or protective immune response activators within the central nervous system. This apparent contradiction could partially be due to the infection degree obtained in the different experiments reported. Thus, we decided to systematically review the in vitro models used to study these phenomena. Fifteen articles from which direct invasion and replication data could be gathered were found. Very heterogeneous results emerged, mainly due to diversity of models in relation to parasite strain (virulence), host species, parasite dose and evaluation times after infection. Also, the results were measured in diverse ways, i.e. some reported percent infected cells, while others informed parasites pervacuole or cell, or parasitic vacuoles per cell. Very few conclusions could be drawn, among them that human astrocytoma cell lines and mouse astrocytes seem more susceptible to infection and less resistant to tachyzoite proliferation than human primary culture astrocytes. The present study supports the need to reanalyse T. gondii astrocyte invasion and replication processes, especially with the use of actual technology, which allows detailed mechanistic studies.