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

Genotyping of Toxoplasma gondii in domestic animals from Campeche, México, reveals virulent genotypes and a recombinant ROP5 allele

Toxoplasma gondii has at least 318 genotypes distributed worldwide, and tropical regions usually have greater genetic diversity. Campeche is a state located in the southeastern region of México and has favourable climate conditions for the replication and dissemination of this protozoan, similar to those in South American countries where broad genetic diversity has been described. Thus, in this study, 4 T. gondii isolates were obtained from tissues of stray dogs and free-range chickens in Campeche, México, and were genotyped by Mn-PCR-RFLP with 10 typing markers (SAG1, altSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) and 5 virulence markers (CS3, ROP16, ROP17, ROP18 and ROP5) to provide new information about the distribution and virulence prediction of T. gondii genotypes. Two isolates of T. gondii genotype #116 and 2 of genotype #38 were obtained from stray dogs and chickens, respectively. The parasite load found in these species was between <50 and more than 35 000 tachyzoites per mg of tissue. Virulence marker genotyping revealed a recombinant 1&3 ROP5 RFLP pattern in 2 ToxoDB #116 isolates with no prediction of virulence in a murine model, while in the 2 ToxoDB #38 isolates, the ROP18/ROP5 combination predicted high virulence. Considering all the typed markers, there is a predominance of type I and III alleles, as constantly reported for the isolates characterized in various regions of México. It is crucial to determine their phenotype to corroborate the genetic virulence profile of the T. gondii isolates obtained in this study.

Is GRA6 Gene a Suitable Marker for Molecular Typing of Toxoplasma Gondii? A Scoping Systematic Review

Toxoplasmosis is a zoonotic disease with a worldwide prevalence that is caused by Toxoplasma gondii. This study aimed to summarize available data on genotyping T. gondii strains based on the GRA6 gene marker in different hosts around the world. We conducted a comprehensive literature search using five international databases (PubMed, Scopus, Science Direct, Web of Science, and Google Scholar) from inception until December 2021. We identified 32 papers eligible for inclusion in this systematic review. The majority of studies (50%) were carried out in Iran (n = 16) to identify T. gondii genotypes based on the GRA6 gene. Other countries with reported studies include China, Japan, Sweden, and Italy (n = 2 each). Out of 3,434 samples collected from various hosts, most studies (n = 11) focused on human samples (34.4%), followed by ovine (n = 7), pig (n = 4), goat (n = 3) and soil and cattle (n = 2).Using various molecular methods such as conventional PCR, nested-PCR, real-time PCR, microsatellite analysis, and Restriction Fragment Length Polymorphism (RFLP), we found DNA positive results in 805 out of 3,434 samples. Of these, 285 (35.40%), 207 (25.71%), 182 (22.60%), 65 (8.07%), and 18 (2.23%) were infected with types I, II, III, mix I, II, III, and mix II, III, respectively. Our data demonstrate that the GRA6 gene marker has sufficient polymorphism to detect three types of T. gondii genotypes in various hosts. Identifying the specific genotype could be valuable in developing new strategies for treatment, vaccination, diagnosis, control, and prevention of T. gondii infection.

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.

Can cloning and sequencing help to genotype positive Toxoplasma gondii clinical samples? Results and validation using SAG3 as a model

Genotyping of T. gondii in human cases is relevant to understand the transmission patterns and epidemiology of this parasitosis. However, this genetic characterization can be hampered by the difficulty of isolating the parasite from mild or asymptomatic cases and by the detection efficiency of molecular assays such as the multilocus nested-polymerase chain reaction-restriction fragment length polymorphism (Mn-PCR-RLFP). To propose an alternative for the genotyping of positive clinical samples of T. gondii with a low amount of the parasite DNA mixed within the host DNA or mixed infections, we carried out this study to validate the sequences of the SAG3 gene of T. gondii obtained after two rounds of amplification cloned into a bacterial model, thereby achieving the separation and identification of more than one genotype of T. gondii. Also, the detection limit of the parasite DNA and the fidelity of the reagents used in the nested PCR-RFLP in artificial clinical samples by sequencing were determined. T. gondii DNA was detected from 6.25 ng of DNA and 200 parasites/mL of blood. The fidelity of the AmpliTaq Gold™ polymerase after 65 cycles of amplification was 100%. Denaturation of the products obtained after two rounds of nested PCR amplification showed no evidence of chimera or artifact production. The cloning efficiency was 97.5% (39/40 clones), and none of the experiments produced recombinant sequences. Thus, the generation of chimeras with this methodology could be ruled out. Genotyping of clinical samples is important because there is no strain selection bias, as can occur in the bioassay (where more virulent strains can be selected over nonvirulent strains), and therefore, mixed infections can be detected through cloning and sequencing. Furthermore, these two techniques could be useful tools to genotype weak amplicons of any T. gondii gene obtained during nested PCR.

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.

A systematic review of Toxoplasma gondii genotypes in Gallus gallus domesticus worldwide: The focus is Brazil

Toxoplasma gondii was initially classified in three main lineages related to its virulence: Types I, II, and III. The recombination of genes during sexual cycle in felids gut led to more than 200 genotypes, found in ToxoDB database, using 11 RFLP markers. Free-range chickens are good bioindicators of soil contamination with T. gondii oocysts. In this sense, there are systematic reviews regarding data of genetic characterization of this parasite in felines and ruminants, but not in chickens heretofore, what makes this work necessary. A systematic review of the literature was performed with papers published prior to September 21, 2020. The main inclusion criteria were the presence of T. gondii genotypes, isolated strictly from free-range chickens, in experimental works. Initially, a total of 1,343 studies related to the terms were identified on databases and 30 studies were selected to be systematically reviewed. A total of 561 isolates of T. gondii from 6,356 free-range chickens were analyzed for genotyping, revealing 190 genotypes. ToxoDB #59 and #2 were the most frequent in America, #1 was the most frequent in Africa and three atypical isolates from genotype ToxoDB #9 were found in Asia. There is no data from Europe and Oceania. The majority of studies were Brazilian (16/30). A total of 68 RFLP genotypes were recognized among the 561 isolates' DNAs analyzed from the 30 studies. Some studies showed new genotypes never described before, which reinforces the idea that in some years even more new genotypes will be identified, due to gradual genetic recombination. A large number of undefined genotypes makes it necessary to perform Nested PCR technique when genotyping. Moreover, the lack of data in Continents such as Europe, Asia, and Oceania makes it necessary to perform new isolating and genotyping studies in these places.

Foodborne Parasitic Diseases in the Neotropics - A Review

Within the Universal Declaration of Human Rights, it is stated that everyone has the right to an adequate standard of living, which ensures, as well as their family, health and well-being, and food, thereby ensuring adequate nutrition. One of the major threats to overcome this is to ensure food security, which becomes particularly challenging in developing countries due to the high incidence of parasitic diseases. The World Health Organization (WHO), considers it one of the main causes of morbidity, closely linked to poverty and related to inadequate personal hygiene, consumption of raw food, lack of sanitary services, limited access to drinking water and fecal contamination in the environment. It is estimated that more than a fifth of the world’s population is infected by one or several intestinal parasites, and that in many countries of Central and South America the average percentage of infected people is 45%, being Taenia solium, Echinococcus granulosus, Toxoplasma gondii, Cryptosporidium spp, Entamoeba histolytica, Trichinella spiralis, Ascaris spp, Trypanosoma cruzi and Fasciola hepatica some of the most important ones in the neotropics. One of the main reasons why these diseases are diffi cult to control is t he ignorance of their lifecycles, as well as symptoms and current epidemiology of the disease, which contributes to a late or erroneous diagnosis. The present work aims to discuss and make public the current knowledge as well as the general characteristics of these diseases to the general audience.

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.

All about toxoplasmosis in cats: the last decade

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasmosis continues to be of public health concern. Cats (domestic and wild felids) are the most important host in the epidemiology of toxoplasmosis because they are the only species that can excrete the environmentally resistant oocysts in feces. Cats can excrete millions of oocysts and a single cat can spread infection to many hosts. The present paper summarizes information on prevalence, persistence of infection, clinical signs, and diagnosis of T. gondii infections in domestic and wild cats for the past decade. Special emphasis is paid to genetic diversity of T. gondii isolates from cats. Review of literature indicates that a unique genotype (ToxoDB genotype #9 or Chinese 1) is widely prevalent in cats in China and it has been epidemiologically linked to outbreaks of clinical toxoplasmosis in pigs and deaths in humans in China; this genotype has rarely been detected in other countries. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

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.

A systematic review of Toxoplasma gondii genotypes and feline: Geographical distribution trends

Toxoplasma gondii (T. gondii) is well known for its ability to virtually infect all warm-blooded vertebrates. Although felines as the definitive hosts have an important role in the epidemiology of toxoplasmosis, there are few descriptions of genetic diversity in the world. The present review study aimed to describe the population structure of T. gondii in these animal species. For the purpose of the study, five English language databases reporting data on T. gondii genotyping in cats were searched within March-June 2019. This study is registered on the site of CAMARADES-NC3Rs (15-Jan-2018). The searching process resulted in the inclusion of 50 reports published from 1992 to June 2019. The data revealed that 47,390 samples were genotyped into 662 T. gondii DNA/isolates. Globally, atypical genotypes were predominant (47.7%, n = 316); in addition, Type II clonal strains were the second most common genotype (37%, n = 244). These results suggested an epidemic population structure in America and Asia, and a clonal population structure in Europe and Africa. Genotype #3 was found to be dominant in Africa, Europe and Oceania continents. Furthermore, genotypes #9 and #5 were prevalent in Asia and America, respectively. Additionally, genotypes #2, #3, #5 and #20 were common genotypes in domestic and sylvatic cycles from family Felidae. Collectively, this systematic review indicated a large degree of genetic diversity and circulation of mouse-virulent T. gondii strains in this family. However, further studies are necessary to better understand the population structure of T. gondii in these animal species and determine the significance of their features.

Environmental transmission of Toxoplasma gondii: Oocysts in water, soil and food

Toxoplasma gondii is a zoonotic protozoan parasite that can cause morbidity and mortality in humans, domestic animals, and terrestrial and aquatic wildlife. The environmentally robust oocyst stage of T. gondii is fundamentally critical to the parasite's success, both in terms of its worldwide distribution as well as the extensive range of infected intermediate hosts. Despite the limited definitive host species (domestic and wild felids), infections have been reported on every continent, and in terrestrial as well as aquatic environments. The remarkable resistance of the oocyst wall enables dissemination of T. gondii through watersheds and ecosystems, and long-term persistence in diverse foods such as shellfish and fresh produce. Here, we review the key attributes of oocyst biophysical properties that confer their ability to disseminate and survive in the environment, as well as the epidemiological dynamics of oocyst sources including domestic and wild felids. This manuscript further provides a comprehensive review of the pathways by which T. gondii oocysts can infect animals and people through the environment, including in contaminated foods, water or soil. We conclude by identifying critical control points for reducing risk of exposure to oocysts as well as opportunities for future synergies and new directions for research aimed at reducing the burden of oocyst-borne toxoplasmosis in humans, domestic animals, and wildlife.