Genetic characterization of Toxoplasma gondii isolates from pigs intended for human consumption in Brazil

First identified Toxoplasma gondii Type I in market-sold ducks in Fujian province, China: a significant for public health

Toxoplasma gondii (T. gondii) is an intracellular protozoan that can cause toxoplasmosis in all warm-blooded hosts. This study focused on the prevalence and genetic characterize of T. gondii in ducks from Fujian province, China. Genomic DNA was extracted from duck tissue samples (heart, liver, lung, and muscle). To assess the genetic diversity of the T. gondii isolates, it was determined by using multilocus polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology. A total of 586 ducks from 5 cities in Fujian province were tested, and 35 (6.0%) of which were found to be positive for the T. gondii B1 gene. Further genotyping of these positive samples at 10 genetic markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) using PCR-RFLP revealed that one tissue samples (heart samples from Fuzhou ducks) were identified as Type I (ToxoDB#10). This study is the first report on the prevalence and genetic characterization of T. gondii in ducks in Fujian province, and Type I (ToxoDB#10) is found in ducks in China for the first time. The findings document the genetic characterization of T. gondii in free-range ducks from Fujian Province, thereby enriching the understanding of T. gondii genetic diversity in China. Moreover, these results provide essential data support for further prospective studies and underscores the "One Health" concept, emphasizing the integral link among human, animal, and environmental health.

Detection of Toxoplasma gondii in artisanal salted meat products sold in street markets of the Ilhéus-Itabuna microregion

This study aimed to detect Toxoplasma gondii in artisanal salted meat products sold in street markets in the Ilhéus-Itabuna microregion and to assess the salt concentration used in their preparation and its influence on the parasite's viability. A total of 125 samples of various artisanal meat products sold in street markets located in the Ilhéus-Itabuna microregion were collected during 2021. Serological analysis using indirect hemagglutination (HAI) and molecular analysis (PCR) were performed on these samples to detect the presence of the parasite. Möhr's method was utilized to determine the sodium chloride concentration in the samples. Of all samples, 21 were subjected to a bioassay in albino mice to verify the viability of possible tissue cysts. Among the 125 meat products, 10 (8%) tested positive in the serological analysis including four cured pork sausages, five beef sun-dried meats, and one mixed fresh sausage (pork and chicken). None of 125 samples tested positive in the molecular analysis. On bioassay, all mice tested negative for the presence of the parasite. The NaCl concentration in the positive samples ranged from 2.9% to 8%. The results demonstrated that the salt concentration in the collected samples was sufficient to inactivate the parasite T. gondii.

Genetic diversity of Toxoplasma gondii in South America: occurrence, immunity, and fate of infection

Toxoplasma gondii is an intracellular parasite with a worldwide distribution. Toxoplasma gondii infections are of great concern for public health, and their impact is usually most severe in pregnant women and their foetuses, and in immunocompromised individuals. Displaying considerable genetic diversity, T. gondii strains differ widely according to geographical location, with archetypal strains predominantly found in the Northern Hemisphere and non-archetypal (atypical) strains, with highly diverse genotypes, found mainly in South America. In this review, we present an overview of the identification and distribution of non-archetypal strains of T. gondii. Special attention is paid to the strains that have been isolated in Brazil, their interaction with the host immunological response, and their impact on disease outcomes. The genetic differences among the strains are pivotal to the distinct immunological responses that they elicit. These differences arise from polymorphisms of key proteins released by the parasite, which represent important virulence factors. Infection with divergent non-archetypal strains can lead to unusual manifestations of the disease, even in immunocompetent individuals.

Presence of atypical genotypes of Toxoplasma gondii isolated from cats in the state of Bahia, Northeast of Brazil

In this study, 20 blood, heart, and brain samples were collected from euthanized cats at the Zoonosis Control Centers and Veterinary Clinics in the state of Bahia, Brazil. The sera were examined for anti-T. gondii antibodies using the indirect hemagglutination test. The brains and hearts of seven seropositive cats were ground, and peptide digestion was performed for bioassay in mice. Toxoplasma gondii was isolated in 5/7 (71.42%) of seropositive cats. In these isolates, the parasite was genotyped using the Polymerase chain reaction, associated with the DNA fragment polymorphism obtained by restriction enzyme PCR-RFLP technique with 11 markers (SAG1, 5’-SAG2, 3’-SAG2, alt. SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, Apico, and CS3) and 15 microsatellite markers (TUB-2, W35, TgM-A, B18, B17, M33, IV.1, XI.1, M48, M102, N60, N82, AA, N61, N83). The analysis of the isolates by PCR-RFLP revealed five distinct genotypes. Three of these genotypes have never been reported before; one corresponded to the TgDgCo13 genotype, and one incomplete genotype. In genotyping analysis using microsatellite markers, it was observed that the isolates showed atypical alleles in the typing and fingerprint markers. This revealed five atypical genotypes. The typing marker B17 showed the highest degree of atypia. This study is the first to report the genotyping of T. gondii obtained from naturally infected cats in Bahia, Northeast Brazil. The genotypes found in this study were different from those found in other studies conducted in Bahia, which included different species of animals. None of the clonal lineages I, II, or III were found. This study demonstrates the diversity of T. gondii in the study region, with the presence of unusual genotypes, reaffirming the genetic variability of the parasite in Brazil.

Ocular Disease in Mice Inoculated with Pork Heart Samples Infected with Toxoplasma gondii

PURPOSE

We analyzed the frequency, viability, and genetic characteristics of T. gondii in pork heart samples.Methods: Thirty-five fresh pork samples were purchased in a slaughterhouse in Erechim city. The DNA was extracted and qPCR was performed. T. gondii genotyping was performed using PCR-RFLP analysis. Positive samples were digested and inoculated in mice for viability analysis.Results: Our results showed that T. gondii DNA was detected in 25.7% of the pork heart samples and genotyping revealed one new atypical strain. The viability analyses demonstrated that 40% of mice presented clinical signs of T. gondii infection. qPCR was positive in the lung, liver, and brain of mice that presented clinical signs of T. gondii infection. Also, the histopathology analysis showed retinal disorganization, retinal detachment, inflammatory cell infiltration, and fibrosis in the eyes analyzed.Conclusion: Our findings have shown that pork eat from southern Brazil may contain live T. gondii that could be associated with toxoplasmosis.

All about Toxoplasma gondii infections in pigs: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasma gondii infection in pigs continues to be of public health concern. Pigs are important for the economy of many countries, particularly, USA, China, and European countries. Among the many food animals, pigs are considered the most important for T. gondii transmission in USA and China because viable parasites have rarely been isolated from beef or indoor raised chickens. Besides public health issues, T. gondii causes outbreaks of clinical toxoplasmosis in pigs in China, associated with a unique genotype of T. gondii (ToxoDB genotype #9 or Chinese 1), rarely found in other countries. The safety of ready to eat pork products with respect to T. gondii infection is a matter of recent debate. Here, we review in detail seroprevalence, prevalence of viable and nonviable T. gondii, epidemiology, risk assessment, diagnosis, and curing of pork products containing T. gondii for the past decade. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

A new strain of Toxoplasma gondii circulating in southern Brazil

Recently, an outbreak of human toxoplasmosis was identified in Santa Maria city, Southern Brazil. However, the suspected vehicle of Toxoplasma gondii contamination in this region remains unclear. This study was conduct to analyze whether pork meat samples collected in supermarkets from Santa Maria city, RS, could be infected with T. gondii. Thus, we analyzed the presence of T. gondii DNA in 20 pork hearts, 20 pork tongues and 20 sausages. DNA was extracted from each sample and real-time PCR was performed using 529-bp and B1 markers. T. gondii genotyping was performed by PCR-RFLP analysis. T. gondii DNA was detected in 2 of 20 (10%) heart samples and in 1 of 20 (5%) tongue samples using 529-bp marker. Besides, those 2 (10%) heart samples also were positive for T. gondii using B1 marker. All sausage samples were negative for both markers. Genotyping revealed a new atypical genotype in the pork meat. Our findings were not able to confirm whether these food samples were involved in some outbreak. However, we can conclude that food samples containing T. gondii can be displayed in Santa Maria supermarkets. In addition, a new T. gondii genotype was identified circulating in southern Brazil.

Genotyping and virulence analysis of Toxoplasma gondii isolates from a dead human fetus and dead pigs in Jiangsu province, Eastern China

Toxoplasma gondii is an obligate intracellular parasite with worldwide distribution. Virulence of T. gondii is a multigenic trait. Genetic and virulence data for T. gondii isolates from humans and animals in China have been reported. However, almost all biological materials used for genotyping of T. gondii from humans and pigs were DNA samples prepared from tissues, and T. gondii strains used for virulence analysis were isolated mainly from cats. In this study, one isolate from a dead human fetus was identified as type I (ToxoDB #10) while the two isolates from dead pigs were type Chinese I (ToxoDB #9) with PCR-restriction fragment length polymorphism using 10 markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico). Three isolates were comfirmed as virulent strains in mice. By cloning and sequences analysis, all isolates contained a Pvu II restriction site (572-577 bp) in the KHB fragment and five tandem repeats in the 5' UTR region of SAG1, which were associated with T. gondii virulence. The type Chinese I isolates contained two deletions of 15 and 3 bp at positions 635 to 649 and 658 to 660 in the GRA6, which were correlated with genotype, but not with virulence. To our knowledge, this is the first report on the systematic analysis of murine virulence of type Chinese I strain from pigs, and the associations of sequences of the KHB fragment and SAG1 with virulence of type Chinese I strain. The Chinese I genotype was more closely related to type II strains.

Isolation and Genotyping of Toxoplasma gondii in Brazilian Dogs

Strains of Toxoplasma gondii in Brazil are highly genetically diverse compared to strains from North America and Europe. Dogs are epidemiologically important because they act as sentinels for T. gondii infections in humans and are good indicators of environmental contamination. The aim of this study was to isolate and genetically characterize T. gondii strains from tissues of naturally infected Brazilian dogs. For this study, 21 blood samples were collected from dogs at the Zoonosis Control Centers of Ilhéus and Itabuna cities, Bahia, Brazil. The sera were examined for T. gondii antibodies using the indirect hemagglutination test. Brains and hearts of seropositive dogs were bioassayed in mice to isolate and characterize T. gondii parasites by PCR-RFLP using 10 genetic markers (SAG1, newSAG2, SAG3, BTUB, c22-8, c29-2, GRA6, PK1, APICO, and L358). However, T. gondii was isolated from only 4 (57.1%) dogs, designated TgDgBr6, 13, 17, and 21. All strains were virulent, causing clinical changes (rough hair coat, lethargy, and abdominal distention) and the death of all mice within 8-20 days after inoculation. Genetic analysis of these 4 T. gondii isolates revealed 4 distinct genotypes with different clonal lineage combinations (types I, II, and III) and 2 atypical alleles. Using PCR-RFLP with several markers, this study contributes to evaluations of the genetic diversity of strains circulating in Brazil.

Toxoplasma gondii in backyard pigs: seroepidemiology and mouse bioassay

The aim of this study was to evaluate the occurrence of Toxoplasma gondii in backyard pigs destined for human consumption in Pernambuco state, Brazil. Blood and tissue samples (liver, heart, brain, lung and diaphragm) were collected from 224 pigs from legal slaughterhouses and tested for T. gondii infection. Antibodies to T. gondii were found in the sera of 37.9% (85/224) by using the immunofluorescence antibody test (cut-off - 1:64). Tissue samples from seropositive pigs were bioassayed in mice. Tissue samples from seropositive pigs and from mice of the bioassay were submitted to histopathology, immunohistochemistry, polymerase chain reaction (PCR) and sequencing; 14.1% of pig tissue samples and 27.7% of bioassayed mouse samples were positive for T. gondii DNA, but all pig and mouse tissues were negative in histopathology analysis and immunochemistry. By using a risk assessment questionnaire, there was significant difference (p<0.001) in seroprevalence of 21.2% (reproducer) and 3.1% (finishing pig). These data serve as indicative of the sanitary conditions and risk of T. gondii infection for backyard pigs. Preventive measures must be implemented by health services to avoid toxoplasmosis human cases due to ingestion of pig meat.

Lifelong Persistence of Toxoplasma Cysts: A Questionable Dogma?

It is believed that infection by Toxoplasma gondii triggers a lifelong protective immunity due to the persistence of parasitic cysts which induce immunoprotection against reinfection. A review of the scientific literature since the 1950s did not yield any definitive data regarding the duration of cysts in the host or the presence of lifelong protective immunity, which led us to question this dogma. We put forward the hypothesis that sustained immunity to T. gondii requires repeated antigenic stimulations. The decline of seroprevalence recently observed in many countries might contribute to explain the loss of immunity. We address the potential consequences of this phenomenon, should it persist and worsen.

Toxoplasma gondii infection in pork produced in France

The aim of this study was to assess the seroprevalence of the Toxoplasma gondii parasite in pork produced in France, and to determine infection risk factors. An innovative survey was designed based on annual numbers of slaughtered pigs from intensive and outdoor farms in France. A total of 1549 samples of cardiac fluids were collected from pig hearts to determine seroprevalence using a Modified Agglutination Test. Of those, 160 hearts were bio-assayed in mice to isolate live parasites. The overall seroprevalence among fattening pigs was 2·9%. The adjusted seroprevalence in pigs from intensive farms was 3·0%; the highest in sows (13·4%); 2·9% in fattening pigs and 2·6% in piglets. Adjusted seroprevalence in fattening animals from outdoor farms was 6·3%. Strains were isolated from 41 animals and all were genotyped by Restriction Fragment Length Polymorphism as type II. Risk-factor analysis showed that the risk of infection was more than three times higher for outdoor pigs, and that sows' risk was almost five times higher than that of fattening animals. This study provides further evidence of extensive pork infection with T. gondii regardless of breeding systems, indicating that farm conditions are still insufficient to guarantee 'Toxoplasma-free pork'.

First report of genotype #65 of Toxoplasma gondii in pigs

The aim of the present study was to isolate and genotype Toxoplasma gondii from pigs slaughtered for human consumption in northeastern Brazil. Indirect immunofluorescence antibody test (IFAT) was used to screen positive pigs. Tissues samples of animals with antibody titers ≥64 were submitted to bioassay in mice. One isolate of T. gondii was obtained, and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique, using 11 markers (SAG1, SAG2, altSAG2, SAG3, BTUB, GRA6, c228, c292, L358, PK1, and APICO), was applied to evaluate the genetic variability. DNA from reference strains was used as a positive control. By means of genetic analysis, genotype ToxoDB #65 was identified, which is considered an atypical strain. This is the first record of genotype #65 in pigs. Thus, further studies in this region are necessary to determine the genetic variability of T. gondii in pigs and possible impact on public health.

Identification and genetic characterization of Toxoplasma gondii in free-ranging bristle-spined porcupine (Chaetomys subspinosus), a threatened arboreal mammal from the Brazilian Atlantic Forest

Background

Strains of Toxoplasma gondii in Brazil have high genetic diversity compared to North America and Europe. The bristle-spined porcupine, Chaetomys subspinosus, is often subject to hunting for human food, but it is not known whether it can be a reservoir of this parasite. The aim of this study was to verify the occurrence of T. gondii in C. subspinosus from southern Bahia, Brazil, and genetically characterize and compare the strains found with those isolated in previous studies of the same region to quantify their genetic diversity by multilocus PCR-RFLP and PCR sequencing.

Findings

Twelve free-ranging C. subspinosus captured in forest fragments of the Una Biological Reserve and adjacent areas were evaluated. Three isolates of T. gondii (TgCsBr01-03) were detected. Two different genotypes were identified by applying multilocus PCR-RFLP with six molecular markers (SAG1, SAG2, SAG3, c22-8, PK1, and Apico). The isolates TgCsBr02 and TgCsBr03 were indistinguishable by this technique. However, the three isolates differed from all the reference strains and from the samples from the same region. Nevertheless, when the six genetic markers were used in multilocus PCR sequencing, all three isolates of T. gondii were different. The phylogenetic analysis revealed a greater genetic distance for TgCsBr01, which was closer to isolates from pigs from the same region, while TgCsBr02-03 was classified in the same lineage and was closer to isolates from sheep from this region.

Conclusions

All the isolates differed from the clonal genotypes of types I, II, and III using both genotyping techniques.

Prevalence and risk factors for Toxoplasma gondii infection in meat animals and meat products destined for human consumption

Toxoplasma gondii is a protozoan parasite that is responsible for approximately 24% of all estimated deaths attributed to foodborne pathogens in the United States. Human infection results from accidental ingestion of oocysts from the environment, in water, or on insufficiently washed produce or from consumption of raw or undercooked meat products that contain T. gondii tissue cysts. This review focused on studies of T. gondii in meat because many human T. gondii infections are acquired through consumption of raw or undercooked meat. Prevalence of T. gondii is higher in conventionally reared pigs, sheep, and poultry than in cattle and is greater in meat products from organic than from conventionally reared meat animals because of outdoor access, which poses substantially greater opportunities for exposure to infected rodents, wildlife, and oocyst-contaminated feed, water, or environmental surfaces. Risk factors related to T. gondii exposure for livestock include farm type, feed source, presence of cats, methods of rodent and bird control, methods of carcass handling, and water quality. This review serves as a useful resource and information repository for informing quantitative risk assessment studies for T. gondii infection in humans through meat consumption.