Seroprevalence and genetic characterization of Toxoplasma gondii in three species of pet birds in China

Genetic diversity of Toxoplasma gondii isolates from birds in the world: A systematic review

Toxoplasma gondii (T. gondii) is one of the most important foodborne pathogens that infects a large number of vertebrate species and has a cosmopolitan distribution. Birds as intermediate hosts are very important in the life cycle of T. gondii and they can be a main source of infection for humans and felids, as well as other animals. Most species of birds feed from the ground and are the best indicator for soil contamination with T. gondii oocysts. Hence, T. gondii strains isolated from birds can represent different genotypes circulating in the environment and their main predators and consumers. The recent systematic review tries to represent the population structure of T. gondii in birds around the world. Six English language databases were searched from 1990 to 2020 to find the related studies and overall, 1275 isolates of T. gondii were separated from the analyzed samples in birds. The results of our study revealed that atypical genotypes were predominant (58.8%, 750 out of 1275). Types II, III, and I had less frequency with prevalence rates of 23.4%, 13.8%, and 2%, respectively. No isolates of Type I were reported from Africa. Summarizing ToxoDB genotypes circulating in birds around the world manifested that ToxoDB #2 was the most common (101/875), followed by ToxoDB #1 (80/875), and #3 (63/875). Totally, the results of our review represented the high genetic diversity of T. gondii with circulating non-clonal strains in birds from South and North America, while clonal parasites with low genetic diversity were predominant in Europe, Asia, and Africa.

Global proteomic profiling of multiple organs of cats (Felis catus) and proteome-transcriptome correlation during acute Toxoplasma gondii infection

Background

Toxoplasma gondii is a protozoan parasite which can infect almost all warm-blooded animals and humans. Understanding the differential expression of proteins and transcripts associated with T. gondii infection in its definitive host (cat) may improve our knowledge of how the parasite manipulates the molecular microenvironment of its definitive host. The aim of this study was to explore the global proteomic alterations in the major organs of cats during acute T. gondii infection.

Methods

iTRAQ-based quantitative proteomic profiling was performed on six organs (brain, liver, lung, spleen, heart and small intestine) of cats on day 7 post-infection by cysts of T. gondii PRU strain (Genotype II). Mascot software was used to conduct the student’s t-test. Proteins with P values < 0.05 and fold change > 1.2 or < 0.83 were considered as differentially expressed proteins (DEPs).

Results

A total of 32,657 proteins were identified in the six organs, including 2556 DEPs; of which 1325 were up-regulated and 1231 were down-regulated. The brain, liver, lung, spleen, heart and small intestine exhibited 125 DEPs, 463 DEPs, 255 DEPs, 283 DEPs, 855 DEPs and 575 DEPs, respectively. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of all proteins and DEPs in all organs showed that many proteins were enriched in binding, cell part, cell growth and death, signal transduction, translation, sorting and degradation, extracellular matrix remodeling, tryptophan catabolism, and immune system. Correlations between differentially expressed proteins and transcripts were detected in the liver (n = 19), small intestine (n = 17), heart (n = 9), lung (n = 9) and spleen (n = 3).

Conclusions

The present study identified 2556 DEPs in six cat tissues on day 7 after infection by T. gondii PRU strain, and functional enrichment analyses showed that these DEPs were associated with various cellular and metabolic processes. These findings provide a solid base for further in-depth investigation of the complex proteotranscriptomic reprogramming that mediates the dynamic interplays between T. gondii and the different feline tissues.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-022-01022-7.

Molecular detection of Toxoplasma gondii and Neospora caninum in rock pigeons (Columba livia) in Punjab, Pakistan

Rock pigeons are synanthropic birds and live in close association within human settlements. Synanthropic birds are considered potential carriers of diseases and pose a subsequent risk of their transmission to humans. Neospora caninum and Toxoplasma gondii are intracellular protozoans infecting a wide range of hosts, as well as birds. Data related to the incidence of these protozoans in rock pigeons in Pakistan are scant. The aims of the study were to detect T. gondii and N. caninum DNA in tissue samples from rock pigeons (Columba livia) and to identify possible risk factors associated with infection. To accomplish this, pectoral muscle and brain samples were carefully collected from rock pigeons (n = 120) belonging to three zones located in ten districts of Punjab during a 4-month sampling span (July 2018 to October 2018). Data related to sex, age, sampling site, districts, seasonality, and ecological zones were recorded. DNA from brain and pectoral muscle samples was screened for both T. gondii and N. caninum by PCR assays. Chi-square analysis was used to check the association between positive samples and risk factors. The level of significance was p ≤ 0.05. T. gondii was detected in 46 (38.3%) brain samples, while 24 pectoral muscle samples (20%) were positive for N. caninum. Agroecological zones were statistically associated with the detection of N. caninum DNA. The outcomes of this study provide an understanding of the epidemiological pattern of N. caninum and T. gondii infection in rock pigeons in different regions of Punjab, Pakistan.

Epidemiologic significance of Toxoplasma gondii infections in turkeys, ducks, ratites and other wild birds: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Wild and domestic avian species are important in the epidemiology of T. gondii infections because felids prey on them and excrete millions of oocysts in the environment, disseminating the infection. Herbivorous birds are also excellent sentinels of environmental contamination with T. gondii oocysts because they feed on the ground. Toxoplasma gondii infections in birds of prey reflect infections in intermediate hosts. Humans can become infected by consuming undercooked avian tissues. Here, the authors reviewed prevalence, persistence of infection, clinical disease, epidemiology and genetic diversity of T. gondii strains isolated from turkeys, geese, ducks, ratites and avian species (excluding chickens) worldwide 2009-2020. Genetic diversity of 102 T. gondii DNA samples isolated worldwide is discussed. The role of migratory birds in dissemination of T. gondii infection is discussed.

Serological evidence of Toxoplasma gondii and Neospora caninum infection in black-boned sheep and goats in southwest China

Toxoplasma gondii and Neospora caninum are two closely related protozoan parasites which can cause abortion and significant economic losses in sheep and goats. However, it is yet to know whether black-bone sheep and goats are infected with T. gondii and N. caninum in China. In the present investigation, the seroprevalence and risk factors of T. gondii and N. caninum infections in black-boned sheep and goats were investigated in Yunnan Province, subtropical southwest China between July and August of 2017. A total of 481 serum samples were tested for T. gondii antibodies using the Modified Agglutination Test (MAT), and 468 serum samples were examined for N. caninum antibodies by indirect Enzyme-Linked Immunosorbent Assay (iELISA). The overall seroprevalence of T. gondii in black-boned sheep and goats was 36.80% (177/481, 95% CI 32.49-41.11), and 40 out of 468 serum samples were N. caninum-seropositive (8.55%, 95% CI 6.02-11.08). There was significant difference in the seroprevalence of T. gondii infection in different regions (χ² = 19.869, df = 2, P<0.01). As for the seroprevalence of N. caninum infection, region (χ² = 8.558, df = 2, P<0.05), age (χ² = 16.631, df = 3, P < 0.01), gender (χ² = 11.219, df = 1, P < 0.01) and species (χ² = 8.673, df = 1, P < 0.01) were the risk factors. In addition, the seroprevalence of coinfection of T. gondii and N. caninum in black-boned sheep and goats was 3.63% (17/468, 95% CI 1.94-5.32). To our knowledge, this is the first report of T. gondii and N. caninum seroprevalence in black-boned sheep and goats in China, which provided base-line data for the execution of control strategies and measures against T. gondii and N. caninum infection in black-boned sheep and goats.

Seroprevalence and risk assessment of Toxoplasma gondii in Java sparrows (Lonchura oryzivora) in China

BACKGROUND

Toxoplasma gondii, an intracellular zoonotic parasite, infects all mammalian and birds. Understanding the prevalence of Toxoplasma in bird is important for evaluating the transmission of this parasite. No information about the seroprevalence of T. gondii in Java sparrows (Lonchura oryzivora) is available.

RESULTS

In this study, from 2014 to 2015, 350 serum samples from Java sparrows were collected in Beijing and Shangqiu, Henan province, and the antibodies against T. gondii were evaluated with MAT. The seroprevalence in Java sparrows was 34.29% (CI_95% 29.31-39.26). A phenomenon of seropositivity tended to increase with age were observed, but the difference is not significant. The prevalence was significant different in gender and color, which could be risk factors.

CONCLUSIONS

This study firstly reported T. gondii seroprevalence in Java sparrows, which extended the host range of T. gondii. Java sparrows may pose significant transmission medium, accelerating the spread of T. gondii diffusion.

Acute Toxoplasma Gondii Infection in Cats Induced Tissue-Specific Transcriptional Response Dominated by Immune Signatures

RNA-sequencing was used to detect transcriptional changes in six tissues of cats, seven days after T. gondii infection. A total of 737 genes were differentially expressed (DEGs), of which 410 were up-regulated and 327 were down-regulated. The liver exhibited 151 DEGs, lung (149 DEGs), small intestine (130 DEGs), heart (123 DEGs), brain (104 DEGs), and spleen (80 DEGs)-suggesting tissue-specific transcriptional patterns. Gene ontology and KEGG analyses identified DEGs enriched in immune pathways, such as cytokine-cytokine receptor interaction, Jak-STAT signaling pathway, NOD-like receptor signaling pathway, NF-kappa B signaling pathway, MAPK signaling pathway, T cell receptor signaling pathway, and the cytosolic DNA sensing pathway. C-X-C motif chemokine 10 (CXCL10) was involved in most of the immune-related pathways. PI3K/Akt expression was down-regulated in all tissues, except the spleen. The genes for phosphatase, indoleamine 2,3-dioxygenase, Hes Family BHLH Transcription Factor 1, and guanylate-binding protein 5, playing various roles in immune defense, were co-expressed across various feline tissues. Multivariate K-means clustering analysis produced seven gene clusters featuring similar gene expression patterns specific to individual tissues, with lung tissue cluster having the largest number of DEGs. These findings suggest the presence of a broad immune defense mechanism across various tissues in cats against acute T. gondii infection.

Toxoplasma gondii and Neospora caninum in Tolai Hares (Lepus tolai) Intended for Human Consumption in China: Seroprevalence, DNA Detection, and Genotyping

Currently, there is no information available on the detection of Toxoplasma gondii and Neospora caninum in the tissues of Tolai hares in China. This study aimed to investigate the prevalence of these protozoan parasites in Tolai hares obtained from Shandong province, eastern China, between January 2016 and June 2017. Serum and brain tissue samples of 358 Tolai hares were obtained and detected for the presence of antibody and parasite DNAs by serodiagnosis and polymerase chain reaction (PCR), respectively. The seroprevalence of T. gondii and N. caninum infection in Tolai hares was 8.10% (29/358) and 0.84% (3/358), respectively. However, all the 358 tested Tolai hares were negative for N. caninum by PCR and T. gondii DNA was detected in 23 Tolai hares (6.42%, 23/358). The positive T. gondii DNA was genotyped at 11 genetic markers using multilocus PCR-restriction fragment length polymorphism technology. Of the 23 positive samples, only 2 of them produced complete genotyping results, and were identified as ToxoDB Genotype #9. This is the first report to detect T. gondii in the tissues of Tolai hares from China and the first study to focus on N. caninum in Tolai hares from China.

Sixty Years (1957-2017) of Research on Toxoplasmosis in China-An Overview

Toxoplasma gondii is a ubiquitous zoonotic pathogen belonging to apicomplexan parasites. Infection in humans and animals may cause abortion and other severe symptoms under certain circumstances, leading to great economical losses and public health problems. T. gondii was first discovered in China in 1955 and the corresponding work was published in 1957. Since then, a lot of work has been done on this parasite and the diseases it causes. This review summarizes the major progress made by Chinese scientists over the last 60 years, and gives our perspectives on what should be done in the near future. A wide variety of diagnostic approaches were designed, including the ones to detect T. gondii specific antibodies in host sera, and T. gondii specific antigens or DNA in tissue and environmental samples. Further work will be needed to translate some of the laboratory assays into reliable products for clinic uses. Epidemiological studies were extensively done in China and the sero-prevalence in humans increased over the years, but is still below the world average, likely due to the unique eating and cooking habits. Infection rates were shown to be fairly high in meat producing animals such as, pigs, sheep, and chickens, as well as in the definitive host cats. Numerous subunit vaccines in the form of recombinant proteins or DNA vaccines were developed, but none of them is satisfactory in the current form. Live attenuated parasites using genetically modified strains may be a better option for vaccine design. The strains isolated from China are dominated by the ToxoDB #9 genotype, but it likely contains multiple subtypes since different ToxoDB #9 strains exhibited phenotypic differences. Further studies are needed to understand the general biology, as well as the unique features of strains prevalent in China.

Molecular detection and genetic characterization of Toxoplasma gondii in farmed raccoon dogs (Nyctereutes procyonoides) in Shandong province, eastern China

Toxoplasma gondii is a successful opportunistic parasite, affecting a wide range of vertebrate animals and humans. Genetic diversity of T. gondii in raccoon dogs (Nyctereutes procyonoides) is of great importance to understand the transmission of T. gondii in the environment. However, no information is available about the distribution of genetic diversity of T. gondii infection in raccoon dogs. This study was conducted to estimate the prevalence and genetic characterization of T. gondii from raccoon dogs in Shandong province, eastern China. A total of 314 brain tissue samples of raccoon dogs were collected and genomic DNA was extracted and assayed for T. gondii infection using semi-nested PCR targeting B1 gene. The positive DNA samples were typed at 10 genetic markers (SAG1, SAG2(5'+3' SAG2, alter.SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) by multiplex multilocus nested polymerase chain reaction-restriction fragment length polymorphism (Mn- PCR-RFLP) technology. Thirty-five (11.15%) of 314 DNA samples were detected positive. Only six samples were completely typed at all genetic loci, and these samples represented ToxoDB genotype#9. Two sample were typed at 9 genetic loci and one was typed at 8 genetic loci, all of them represented Type I. To our knowledge, this is the first report of genetic characterization of T. gondii in raccoon dogs in China. These results revealed the existence of genetic diversity of T. gondii in raccoon dogs in China. These data provided base-line information for controlling T. gondii infection in raccoon dogs.

Geographical distribution of Toxoplasma gondii genotypes in Asia: A link with neighboring continents

Defining the pattern of genetic diversity of Toxoplasma gondii is important to understand its worldwide distribution. During the last decades, a large number of studies have been published on Toxoplasma genotypes circulating in Europe, in North and South America. Two continents are still largely unexplored, Africa and, to a less extent, Asia. In this last continent, an increasing number of publications reported genotypes circulating in diverse provinces of China, but very few data are available for other Asian countries. After a systematic database search, 47 papers related to T. gondii genotypes in Asia were analyzed. Genetic characterization of DNA was performed by microsatellite markers, or more usually by a multiplex PCR using 11 PCR-RFLP markers, allowing data comparison to draw a first global picture of the population structure of this parasite throughout Asia. Overall, 390 isolates or DNA extracts were completely typed by PCR-RFLP and/or microsatellite marker methods, revealing 36 different PCR-RFLP or equivalent microsatellite genotypes: 15 genotypes identified by a ToxoDB number and 21 atypical or unique genotypes. The most common genotype found in Asia is the genotype ToxoDB#9 (Chinese 1). The clonal types I, II and II variant, and III were also commonly found in Asia. The geographical distribution of these genotypes across Asia may reflect either a continuum with Europe for the western part of Asia (presence of Type II), or the circulation of strains through animal migration or human activities between Africa and the Southwestern part of Asia (Africa 1 genotype in Turkey or ToxoDB#20 both I Sri-Lanka and in Ethiopia or Egypt). Although there are some indications of a genetic population structure in Southeast Asian countries different from the rest of Asia, more studies in this tropical part of Asia will be necessary for a region which represent as well as Africa one of the missing links of the T. gondii genetic diversity.

Diagnosis of Swine Toxoplasmosis by PCR and Genotyping of Toxoplasma gondii from pigs in Henan, Central China

Background

Toxoplasma gondii, a widely prevalent protozoan parasite, causes serious toxoplasmosis infections in humans and other animals. Among livestock, pigs are susceptible to T. gondii infection. Despite Henan being one of the biggest pig-raising provinces in China, little information exists on the epidemiology of toxoplasmosis in this location. Therefore, we molecularly characterized DNA samples from pigs in Henan. A total of 1647 samples, including 952 from dead piglets, 478 from seriously sick fattening pigs and 217 from abortion sows, were collected from different animal hospitals or pig farms from 10 different cities in Henan (2006–2008). Each pig corresponded to a separate pig farm. DNA was extracted from 3 to 5 g of the most severely affected pig tissue (liver, spleen, lung, hilar lymph nodes and amniotic fluid) after postmortem examination. The presence of the T. gondii B1 gene was detected using nested polymerase chain reactions (PCR). Genotyping was performed directly on DNA from the PCR-positive tissue samples using 11 PCR restriction fragment length polymorphism markers (SAG1, 5′- and 3′-SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, c22–8, c29–2, and Apico).

Results

Of all samples, thirty-four were positive for the T. gondii B1 gene (2.06%, 95% CI: 1.86%–2.26%) from four cities, including 31 from NanYang city, one (PgXY 1) from Xinyang City, one (PgZZ 1) from Zhengzhou City and one (PgZK1) from Zhoukou City. The prevalence was found to be highest in piglets than in fattening pigs and sows. And the difference was statistically significant (P<0.01). The following 32 samples were genotyped with complete data: 13 hilar lymph node tissue samples, seven liver tissue samples, seven lung tissue samples, four spleen tissue samples, and one amniotic fluid sample. Only one genotype, belonging to ToxoDB Genotype #9, was identified.

Conclusions

This is the first large-scale survey molecularly characterizing T. gondii from pigs in Henan. The results of the present study revealed that T. gondii infection is present in swine in Henan and is a potential source of foodborne toxoplasmosis in the investigated areas. Implementation of effective control measures for T. gondii to reduce the chance of zoonotic toxoplasmosis spreading from pig farms may be warranted. The results show that the ToxoDB #9 genotype may be the dominant T. gondii lineage in mainland China. These findings strengthen the limited Chinese T. gondii epidemiology database.

Molecular Detection and Genetic Characterization of Toxoplasma gondii in Farmed Minks (Neovison vison) in Northern China by PCR-RFLP

Toxoplasma gondii is a worldwide prevalent parasite, affecting a wide range of mammals and human beings. Little information is available about the distribution of genetic diversity of T. gondii infection in minks (Neovison vison). This study was conducted to estimate the prevalence and genetic characterization of T. gondii isolates from minks in China. A total of 418 minks brain tissue samples were collected from Jilin and Hebei provinces, northern China. Genomic DNA were extracted and assayed for T. gondii infection by semi-nested PCR of B1 gene. The positive DNA samples were typed at 10 genetic markers (SAG1, SAG2 (5'+3' SAG2, alter.SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology. 36 (8.6%) of 418 DNA samples were overall positive for T. gondii. Among them, 5 samples were genotyped at all loci, and 1 sample was genotyped for 9 loci. In total, five samples belong to ToxoDB PCR-RFLP genotype#9, one belong to ToxoDB genotye#3. To our knowledge, this is the first report of genetic characterization of T. gondii in minks in China. Meanwhile, these results revealed a distribution of T. gondii infection in minks in China. These data provided base-line information for controlling T. gondii infection in minks.

Seroprevalence and genotypes of Toxoplasma gondii isolated from pigs intended for human consumption in Liaoning province, northeastern China

Background

Genetic information for Toxoplasma gondii isolates from pigs in eastern, south, and southwestern regions of China has been reported previously. However, there are no data from pigs in the northeastern area of the country. To better understand the epidemiology of T. gondii, we determined the seroprevalence and genotypes of T. gondii from pigs slaughtered for human consumption in Liaoning province, northeastern China.

Findings

Out of 2063 pigs examined, 233 (11.26 %) were seropositive for T. gondii by the modified agglutination test (MAT), and viable parasites were isolated by bioassay in mice from 23 (9.87 %) of the 233 seropositive pigs. Fifteen out of 23 isolates were genotyped using 10 PCR-restriction fragment length polymorphism (RFLP) genetic markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico. One isolate was identified as ToxoDB genotype #3 (type II-variant), and one was genotype #1 or #3. The other 13 isolates were ToxoDB #9 (type Chinese 1).

Conclusions

To our knowledge, this is the first report of T. gondii isolation and genotyping from pigs in northeastern China. This study indicates that pigs are a potential source for transmission of T. gondii to humans, therefore poses a potential public health concern. The genotyping results revealed the presence of genotype Chinese 1 in northeastern China, enriching the scope of T. gondii genotypes distribution in eastern Asia.

Toxoplasmosis in a Pet Peach-Faced Lovebird (Agapornis roseicollis)

Toxoplasma gondii atypical type II genotype was diagnosed in a pet peach-faced lovebird (Agapornis roseicollis) based on histopathology, immunohistochemistry, and multilocus DNA typing. The bird presented with severe neurological signs, and hematology was suggestive of chronic granulomatous disease. Gross post-mortem examination revealed cerebral hemorrhage, splenomegaly, hepatitis, and thickening of the right ventricular free wall. Histologic sections of the most significant lesions in the brain revealed intralesional protozoan organisms associated with malacia, spongiform changes, and a mild histiocytic response, indicative of diffuse, non-suppurative encephalitis. Immunohistochemistry confirmed the causative organisms to be T. gondii. DNA isolated from the brain was used to confirm the presence of T. gondii DNA. Multilocus genotyping based on SAG1, altSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico markers demonstrated the presence of ToxoDB PCR-RFLP genotype #3 and B1 gene as atypical T. gondii type II. The atypical type II strain has been previously documented in Australian wildlife, indicating an environmental transmission route.

Prevalence and genetic characterization of Toxoplasma gondii in pet dogs in Central China

The prevalence and genotype of Toxoplasma gondii infection in dogs in Henan Province, Central China was investigated. A total of 125 blood samples were collected from pet dogs during April to June 2013, and all samples were examined by indirect hemagglutination antibody test (IHA) and nested PCR. The overall T. gondii prevalence in pet dogs was 24.0% (30/125), with 20.8% (26/125) in IHA and 10.4% (13/125) in PCR, respectively. No statistical associations were found between animal gender and age and the prevalence of T. gondii infection. Thirteen positive DNA samples were genotyped using 11 PCR-RFLP markers, including SAG1, (3'+5') SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico. Of these, only 2 samples were genotyped with complete data for all loci, and a novel genotype (type III at SAG3 and GRA6 loci, and type I at other loci) was identified. This is the first report of genetic characterization of T. gondii infection in dogs in China.

Molecular detection and genotypic characterization of Toxoplasma gondii infection in bats in four provinces of China

Background

Toxoplasma gondii is an intracellular protozoan parasite that infects a wide variety of warm-blooded hosts, including humans. Limited information about T. gondii infection in bats is available in China. The objective of the present study was to determine prevalence and genetic characterization of T. gondii infection in bats in Jilin, Liaoning, Jiangxi and Guangdong provinces, China.

Methods

During May 2005 to August 2013, bats were sampled from Jilin, Liaoning, Jiangxi, and Guangdong provinces, China, and liver tissues were collected for the detection of T. gondii by a nested PCR targeting the B1 gene. The positive samples were genotyped at 11 genetic markers (SAG1, 5′-and 3′-SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and Apico) using multilocus polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

Results

A total of 626 bats representing 10 species were examined for T. gondii infection, 38 (6.1%) were tested positive with by PCR, 8 positive DNA samples were completely genotyped, of which 3 samples (2 from Cynopterus sphinx, and 1 from Murina leucogaster) represented ToxoDB#10, and 5 samples (2 from Murina leucogaster, 2 from Myotis chinensis, and 1 from Rhinolophus ferrumequinum) belonged to ToxoDB#9 (http://toxodb.org/toxo/).

Conclusions

The present study revealed an overall T. gondii prevalence of 6.1% in bats from Jilin, Liaoning, Jiangxi and Guangdong provinces in China, and reported two T. gondii genotypes (ToxoDB#9 and #10) having a wide geographical distribution in China. These results provide new genetic information about T. gondii infection in bats, and have implications for better understanding of the genetic diversity of T. gondii in China and elsewhere.

Identification of host proteins interacting with the integrin-like A domain of Toxoplasma gondii micronemal protein MIC2 by yeast-two-hybrid screening

Background

Toxoplasma gondii is an obligate intracellular protozoan, causing the important zoonosis toxoplasmosis. This parasite utilizes a unique form of locomotion called gliding motility to find and invade host cells. The micronemal adhesin MIC2 plays critical roles in these processes by binding to substrates and host cell receptors using its extracellular adhesive domains. Although MIC2 is known to mediate important interactions between parasites and host cells during invasion, the specific host proteins interacting with MIC2 have not been clearly identified. In this study, we used a yeast-two-hybrid system to search for host proteins that interact with MIC2.

Methods

Different adhesive domains of MIC2 were cloned into the pGBKT7 vector and expressed in fusion with the GAL4 DNA-binding domain as baits. Expression of bait proteins in yeast cells was analyzed by immuno-blotting and their autoactivation was tested via comparison with the pGBKT7 empty vector, which expressed the GAL4 DNA binding-domain only. To identify host proteins interacting with MIC2, a mouse cDNA library cloned into a GAL4 activation-domain expressing vector was screened by yeast-two-hybrid using the integrin-like A domain of MIC2 (residues 74–270) as bait. After initial screening and exclusion of false positive hits, positive preys were sequenced and analyzed using BLAST analysis and Gene Ontology Classifications.

Results

Two host proteins that had not previously been reported to interact with T. gondii MIC2 were identified: they are LAMTOR1 (late endosomal/lysosomal adaptor, MAPK and mTOR activator 1) and RNaseH2B (ribonuclease H2 subunit B). Gene Ontology analysis indicated that these two proteins are associated with many cellular processes, such as lysosome maturation, signaling transduction, and RNA catabolism.

Conclusion

This study is the first one to report interactions between Toxoplasma gondii MIC2 and two host proteins, LAMTOR1 and RNaseH2B. The data will help us to gain a better understanding of the function of MIC2 and suggest that MIC2 may play roles in modulating host signal transduction and other biological processes in addition to binding host cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-014-0543-1) contains supplementary material, which is available to authorized users.

Seroprevalence, risk factors and genotyping of Toxoplasma gondii in domestic geese (Anser domestica) in tropical China

BACKGROUND

Little information is available about the seroprevalence of Toxoplasma gondii infection in geese (Anser domestica) in China. In the present investigation, the seroprevalence, risk factors and genotyping of T. gondii in geese were investigated in Hainan province, tropical China.

FINDINGS

A total of 600 serum samples and 150 brain tissue samples were collected from six administrative regions in tropical China, and assayed for T. gondii antibodies by Indirect Haemagglutination (IHA) test. Genomic DNA was extracted from the 30 brain tissues of seropositive geese and T. gondii B1 gene was amplified using a semi-nested PCR. DNA samples giving positive B1 amplification were then genetically characterized using multi-locus PCR-RFLP. Overall, 17% (95% CI: 14-20) of the animals were positive for T. gondii antibodies. Presence of cats in the household (odds ratio, OR 3), hygiene (OR 2.3) and presence of stray cat around the house (OR 2.3) were considered as main risk factors associated with T. gondii infection. Of 30 DNA samples, three were positive for the T. gondii B1 gene, two showed complete genotyping results. Only one genotype (type II) was identified.

CONCLUSIONS

The results of the present survey indicated the presence of T. gondii infection in geese in tropical China. Therefore, it is imperative that improved integrated measures be carried out to prevent and control T. gondii infection in geese in this province. This is the first report documenting the occurrence of T. gondii genotype in geese in China.