Toxoplasma gondii (T. gondii) is an obligate intracellular, zoonotic protozoan parasite of interest to physicians and veterinarians with its highly complex structure. It is known to infect about one-third of the world\'s population. Since it is a zoonotic disease, it is necessary to keep the animal population under control in order to prevent human exposure. Many studies have been conducted on the detection of T. gondii and it has been determined that there are three clonal groups consisting of types 1, 2, 3. Developments in molecular studies have led to changes in the taxonomy and new developments in parasitic diseases. It has helped in diagnosis, treatment, development of antiparasitic drugs and research on resistance. They also provided research on vaccine studies, genetic typing and phylogenetics of parasitic diseases. Conventional polymerase chain reaction (PCR), real-time PCR and genotyping studies conducted today increase our knowledge about T. gondii. Methods such as B1, SAG1, SAG2, GRA1, 529-bp repeat element, OWP genes and 18S rRNAs are mostly used in PCR, and methods such as MS, MLST, PCR-RFLP, RAPD-PCR and HRM are used in genotyping. Toxoplasmosis is a disease that is within the framework of the concept of one health and must attract attention, has not yet been eradicated in the world and needs joint studies for humans, animals and ecosystems to be eradicated. This can only be possible by establishing interdisciplinary groups, conducting surveys and training.
Toxoplasma gondii (T. gondii) oldukça karışık olan yapısı ile hekimleri ve veteriner hekimleri ilgilendiren, zorunlu hücre içinde bulunan, zoonotik protozoan bir parazittir. Dünya nüfusunun yaklaşık üçte birini enfekte ettiği bilinmektedir. Zoonoz bir hastalık olması nedeniyle insan maruziyetini önlemek için, hayvan popülasyonunu da kontrol altında tutmak gerekir. T. gondii tespiti ile ilgili birçok çalışma yapılmış ve tip 1, 2, 3’ten oluşan üç klonal grubu olduğu tespit edilmiştir. Moleküler çalışmalarda oluşan gelişmeler paraziter hastalıklarda da taksonominin değişmesini ve yeni gelişmelerin oluşumunu sağlamıştır. Tanı, tedavi, antiparaziter ilaçların geliştirilmesi ve direncinin araştırılmasına yardımcı olmuştur. Ayrıca paraziter hastalıkların aşı çalışmalarının, genetik tiplendirmesinin ve filogenetiğin araştırılmasını da sağlamıştır. Bugün yapılan konvasiyonel polimeraz zincir reaksiyonu (PZR), gerçek zamanlı PZR ve genotiplendirme çalışmaları T. gondii hakkındaki bilgimizi artırmaktadır. PZR’de en fazla B1, SAG1, SAG2, GRA1, 529-bp repeat element, OWP genleri ve 18S rRNA’lar ve genotiplendirmede ise MS, MLST, PZR-RFLP, RAPD-PZR ve HRM gibi yöntemler kullanılmaktadır. Toxoplasmosis tek sağlık kavramı çerçevesinde yer alan ve ilgi çekmesi zorunlu, Dünya’da halen eradike edilememiş ve edilmesi için insan, hayvan ve ekosistem için ortak çalışmalara ihtiyaç duyan bir hastalıktır. Bu ancak disiplinlerarası gruplar kurup, sürveyans ve eğitim çalışmaları yaparak mümkün olabilir.

OBJECTIVE: To investigate the development and dynamic changes of cysts in the brain of mice following infection with different forms of Toxoplasma gondii, so as to provide insights into for toxoplasmosis prevention and control.
METHODS: ICR mice at ages of 6 to 8 weeks, each weighing 20 to 25 g, were intraperitoneally injected with tachyzoites of the T. gondii PRU strain at a dose of 1 × 105 tachyzoites per mouse, orally administered with cysts at a dose of 20 oocysts per mouse or oocysts at a dose of 200 oocysts per mouse for modeling chronic T. gondii infection in mice, and the clinical symptoms and survival of mice were observed post-infection. Mice were orally infected with T. gondii cysts at doses of 10 (low-dose group), 20 (medium-dose group), 40 cysts per mouse (high-dose group), and the effect of different doses of T. gondii infections on the number of cysts was examined in the mouse brain. Mice were orally administered with T. gondii cysts at a dose of 20 cysts per mouse, and grouped according to gender (female and male) and time points of infections (20, 30, 60, 90, 120, 150, 180 days post-infection), and the effects of gender and time points of infections on the number of cysts was examined in the mouse brain. In addition, mice were divided into the tachyzoite group (Group T), the first-generation cyst group (Group C1), the second-generation cyst group (Group C2), the third-generation cyst (Group C3) and the fourth-generation cyst group (Group C4). Mice in the Group T were intraperitoneally injected with T. gondii tachyzoites at a dose of 1 × 105 tachyzoites per mouse, and the cysts were collected from the mouse brain tissues 30 days post-infection, while mice in the Group C1 were orally infected with the collected cysts at a dose of 30 cysts per mouse. Continuous passage was performed by oral administration with cysts produced by the previous generation in mice, and the effect of continuous passage on the number of cysts was examined in the mouse brain.
RESULTS: Following infection with T. gondii tachyzoites, cysts and oocysts in mice, obvious clinical symptoms were observed on days 6 to 13 and mice frequently died on days 7 to 12. The survival rates of mice were 67.0%, 87.0% and 53.0%, and the mean numbers of cysts were (516.0 ± 257.2), (1 203.0 ± 502.0) and (581.0 ± 183.1) in the mouse brain (F = 11.94, P < 0.01) on day 30 post-infection with T. gondii tachyzoites, cysts and oocysts, respectively, and the numbers of cysts in the brain tissues were significantly lower in mice infected with T. gondii tachyzoites and oocysts than in those infected with cysts (all P values < 0.01). The survival rates of mice were 87.0%, 87.0% and 60.0%, and the mean numbers of cysts were (953.0 ± 355.5), (1 084.0 ± 474.3) and (1 113.0 ± 546.0) in the mouse brain in the low-, medium- and high-dose groups on day 30 post-infection, respectively (F = 0.42, P > 0.05). The survival rates of male and female mice were 73.0% and 80.0%, and the mean numbers of cysts were (946.4 ± 411.4) and (932.1 ± 322.4) in the brain tissues of male and female mice, respectively (F = 1.63, P > 0.05). Following continuous passage, the mean numbers of cysts were (516.0 ± 257.2), (1 203.0 ± 502.0), (896.8 ± 332.3), (782.5 ± 423.9) and (829.2 ± 306.0) in the brain tissues of mice in the T, C1, C2, C3 and C4 groups, respectively (F = 4.82, P < 0.01), and the number of cysts was higher in the mouse brain in Group 1 than in Group T (P < 0.01). Following oral administration of 20 T. gondii cysts in mice, cysts were found in the moues brain for the first time on day 20 post-infection, and the number of cysts gradually increased over time, peaked on days 30 and 90 post-infection and then gradually decreased; however, the cysts were still found in the mouse brain on day 180 post-infection.
CONCLUSIONS: There is a higher possibility of developing chronic T. gondii infection in mice following infection with cysts than with oocysts or tachyzoites and the most severe chronic infection is seen following infection with cysts. The number of cysts does not correlate with the severity of chronic T. gondii infection, and the number of cysts peaks in the mouse brain on days 30 and 90 post-infection.
［摘要］ 目的 观察不同形态刚地弓形虫感染后小鼠脑内包囊形成及其动态变化, 为弓形虫病防控提供依据。方法 取 6~8周龄ICR小鼠 (20~25 g) 建立慢性弓形虫感染模型, 其中弓形虫PRU株速殖子按1 × 105个/只剂量腹腔注射感染小鼠, 包囊和卵囊分别按20、200个/只剂量通过灌胃针口服感染小鼠, 观察感染后小鼠临床症状和存活情况。分别以10 (低剂 量组) 、20 (中剂量组) 、40个包囊/只 (高剂量组) 剂量感染小鼠, 观察弓形虫不同感染剂量对小鼠脑内包囊数量的影响。 将小鼠按性别 (雌、雄性) 、感染时间 (感染后20、30、60、90、120、150、180 d) 分组, 按20个/只剂量口服弓形虫包囊后, 分别 观察性别和感染时间对小鼠脑内包囊数量的影响。将小鼠分成速殖子组 (T组) 、包囊1代组 (C1组) 、包囊2代组 (C2 组) 、包囊3代组 (C3组) 、包囊4代组 (C4组); T组小鼠按1 × 105个/只剂量腹腔注射弓形虫速殖子, 感染后第30天处死小 鼠并收集其脑组织内包囊, 再按20个/只感染C1组小鼠。此后每一代小鼠均采用上一代所产生包囊进行口服连续传代, 观察连续传代对小鼠脑内弓形虫包囊数量的影响。结果 以弓形虫速殖子、包囊、卵囊分别感染小鼠, 感染第6~13天 小鼠出现明显临床症状、感染第 7~12 天小鼠出现集中死亡。感染第 30 天时, 感染速殖子、包囊、卵囊的小鼠存活率分 别为67.0%、87.0%、53.0%, 平均脑内包囊数量分别为 (516.0 ± 257.2) 、 (1 203.0 ± 502.0) 、 (581.0 ± 183.1) 个, 差异有统计 学意义 (F = 11.94, P < 0.01), 感染速殖子、卵囊的小鼠脑内包囊数低于感染包囊的小鼠 (P 均< 0.01) 。感染后第30天, 低、中、高剂量组小鼠存活率分别为87.0%、87.0%、60.0%, 平均脑内包囊数量分别为 (953.0 ± 355.5) 、 (1 084.0 ± 474.3) 、 (1 113.0 ± 546.0) 个, 差异无统计学意义 (F = 0.42, P > 0.05); 雄、雌性组小鼠存活率分别为73.0%和80.0%, 平均脑内包 囊数量分别为 (946.4 ± 411.4) 、 (932.1 ± 322.4) 个, 差异无统计学意义 (F = 1.63, P > 0.05) 。通过连续传代感染后, T、C1、 C2、C3、C4组小鼠平均脑内包囊数量分别为 (516.0 ± 257.2) 、 (1 203.0 ± 502.0) 、 (896.8 ± 332.3) 、 (782.5 ± 423.9) 、 (829.2 ± 306.0) 个, 差异有统计学意义 (F = 4.82, P < 0.01); C1组小鼠脑内包囊数高于速殖子组, 差异有统计学意义 (P < 0.01) 。 小鼠口服20个包囊后, 感染第20天首次查见脑内弓形虫包囊, 随感染时间延长脑内包囊数量逐渐增加; 至感染第30、90 天时, 脑内包囊数量分别达峰值, 此后逐步下降, 至感染第180天时仍能查见脑内包囊。结论 刚地弓形虫包囊较速殖 子、卵囊感染后形成慢性感染的可能性更高, 且慢性感染程度亦最严重; 感染弓形虫包囊数量与慢性感染严重程度无关; 脑内包囊形成数量于感染第30天和90天时达高峰。.

Co-infections are a common reality but understanding how the immune system responds in this context is complex and can be unpredictable. Heligmosomoides bakeri (parasitic roundworm, previously Heligmosomoides polygyrus) and Toxoplasma gondii (protozoan parasite) are well studied organisms that stimulate a characteristic Th2 and Th1 response, respectively. Several studies have demonstrated reduced inflammatory cytokine responses in animals co-infected with such organisms. However, while general cytokine signatures have been examined, the impact of the different cytokine producing lymphocytes on parasite control/clearance is not fully understood. We investigated five different lymphocyte populations (NK, NKT, γδ T, CD4+ T and CD8+ T cells), five organs (small intestine, Peyer\'s patches, mesenteric lymph nodes, spleen and liver), and 4 cytokines (IFN©, IL-4, IL-10 and IL-13) at two different time points (days 5 and 10 post T. gondii infection). We found that co-infected animals had significantly higher mortality than either single infection. This was accompanied by transient and local changes in parasite loads and cytokine profiles. Despite the early changes in lymphocyte and cytokine profiles, severe intestinal pathology in co-infected mice likely contributed to early mortality due to significant damage by both parasites in the small intestine. Our work demonstrates the importance of taking a broad view during infection research, studying multiple cell types, organs/tissues and time points to link and/or uncouple immunological from pathological findings. Our results provide insights into how co-infection with parasites stimulating different arms of the immune system can lead to drastic changes in infection dynamics.

BACKGROUND: Toxoplasma gondii is a widely prevalent zoonotic protozoan parasite in humans and warm-blooded animals worldwide. Infection of humans by this parasite can result in severe clinical symptoms, particularly in individuals with congenital toxoplasmosis or immunocompromised patients. Contamination mainly occurs through foodborne routes, especially the consumption of raw or undercooked meat from animals.
OBJECTIVE: The aim of this study was to use PCR to detect T. gondii in tissues and organs of buffaloes and cattle slaughtered at Tabriz slaughterhouse, in Iran.
METHODS: Fifty grams of heart, thigh, diaphragm and tongue from 50 buffaloes and 100 cattle slaughtered at the Tabriz industrial slaughterhouse were selected for sampling using a combination of convenience sampling. The samples were tested using a previously published PCR method.
RESULTS: Out of the 150 animal samples, T. gondii was detected in 10 (6.7%, 95%CI: 3.2-11.9), including one buffalo (2%, 95%CI: 0.1-10.6) and nine cattle (9%, 95%CI: 4.2-16.4). There was no statistically significant difference in the rate of T. gondii infection among cattle based on age and sex (p > 0.05).
CONCLUSIONS: The results indicated a potential risk of T. gondii transmission to humans through the consumption of infected meat. Therefore, appropriate and effective preventive measures should be taken to limit the transmission of this parasite to humans, and the consumption of raw and undercooked meat should be discouraged.

UNASSIGNED: Toxoplasma gondii is an intracellular parasite of importance to human and veterinary health. The structure and diversity of the genotype population of T. gondii varies considerably with respect to geography, but three lineages, type I, II and III, are distributed globally. Lineage III genotypes are the least well characterized in terms of biology, host immunity and virulence. Once a host is infected with T.gondii, innate immune mechanisms are engaged to reduce the parasite burden in tissues and create a pro-inflammatory environment in which the TH1 response develops to ensure survival. This study investigated the early cellular immune response of Swiss-Webster mice post intraperitoneal infection with 10 tachyzoites of four distinct non-clonal genotypes of lineage III and a local isolate of ToxoDB#1. The virulence phenotype, cumulative mortality (CM) and allele profiles of ROP5, ROP16, ROP18 and GRA15 were published previously.
UNASSIGNED: Parasite dissemination in different tissues was analyzed by real-time PCR and relative expression levels of IFNγ, IL12-p40, IL-10 and TBX21 in the cervical lymph nodes (CLN), brain and spleen were calculated using the ΔΔCt method. Stage conversion was determined by detection of the BAG1 transcript in the brain.
UNASSIGNED: Tissue dissemination depends on the virulence phenotype but not CM, while the TBX21 and cytokine levels and kinetics correlate better with CM than virulence phenotype. The earliest detection of BAG1 was seven days post infection. Only infection with the genotype of high CM (69.4%) was associated with high T-bet levels in the CLN 24 h and high systemic IFNγ expression which was sustained over the first week, while infection with genotypes of lower CM (38.8%, 10.7% and 6.8%) is characterized by down-regulation and/or low systemic levels of IFNγ. The response intensity, as assessed by cytokine levels, to the genotype of high CM wanes over time, while it increases gradually to genotypes of lower CM.
UNASSIGNED: The results point to the conclusion that the immune response is not correlated with the virulence phenotype and/or allele profile, but an early onset, intense pro-inflammatory response is characteristic of genotypes with high CM. Additionally, high IFNγ level in the brain may hamper stage conversion.

BACKGROUND: Pathogens can impact host RNA modification machinery to establish a favorable cellular environment for their replication. In the present study, we investigated the effect of Toxoplasma gondii infection on host RNA modification profiles and explored how these modifications may influence the host-parasite interaction.
RESULTS: We analyzed the modification levels of ∼ 80 nt tRNA and 17-50 nt sncRNAs in mouse liver, spleen, and serum using liquid chromatography and tandem mass spectrometry analysis. The results revealed alterations in RNA modification profiles, particularly during acute infection. The liver exhibited more differentially abundant RNA modifications than the spleen. RNA modification levels in serum were mostly downregulated during acute infection compared to control mice. Correlations were detected between different RNA modifications in the liver and spleen during infection and between several RNA modifications and many cytokines. Alterations in RNA modifications affected tRNA stability and protein translation.
CONCLUSIONS: These findings provide new insight into the role of RNA modifications in mediating the murine host response to T. gondii infection.

Toxoplasmosis is a foodborne disease caused by the protozoan Toxoplasma gondii, and transmitted to humans by eating raw or undercooked meat, mainly. Poultry, beef, and pork are the main meats consumed in Peru; despite this, guinea pig meat is also widely consumed. For this reason, the objective of this study was to molecularly detect T. gondii in domestic and wild guinea pigs from the Marangani district in Cuzco, Peru, and identify some risk factors associated with this pathogen. DNA was extracted from the brain tissue samples of guinea pigs (30 domestic and 30 wild), and PCR protocols were used to amplify the internal transcribed spacer (ITS-1) region and a 529 bp fragment from the T. gondii genome. T. gondii DNA was detected in 14 (23.3%) guinea pigs. T. gondii frequency was 33.3% in domestic guinea pigs and 13.3% in wild guinea pigs. Our results demonstrated that guinea pigs represent an important source for T. gondii infection in human populations in this locality.

BACKGROUND: Toxoplasma gondii is an intracellular protozoan parasite that is widely distributed in humans and warm-blooded animals. T. gondii chronic infections can cause toxoplasmic encephalopathy, adverse pregnancy, and male reproductive disorders. In male reproduction, the main function of the testis is to provide a stable place for spermatogenesis and immunological protection. The disorders affecting testis tissue encompass abnormalities in the germ cell cycle, spermatogenic retardation, or complete cessation of sperm development. However, the mechanisms of interaction between T. gondii and the reproductive system is unclear. The aims were to study the expression levels of genes related to spermatogenesis, following T. gondii infection, in mouse testicular tissue.
METHODS: RNA-seq sequencing was carried out on mouse testicular tissues from mice infected or uninfected with the T. gondii type II Prugniaud (PRU) strain and validated in combination with real-time quantitative PCR and immunofluorescence assays.
RESULTS: The results showed that there were 250 significant differentially expressed genes (DEGs) (P < 0.05, |log2fold change| ≧ 1). Bioinformatics analysis showed that 101 DEGs were annotated to the 1696 gene ontology (GO) term. While there was a higher number of DEGs in the biological process classification as a whole, the GO enrichment revealed a significant presence of DEGs in the cellular component classification. The Arhgap18 and Syne1 genes undergo regulatory changes following T. gondii infection, and both were involved in shaping the cytoskeleton of the blood-testis barrier (BTB). The number of DEGs enriched in the MAPK signaling pathway, the ERK1/2 signaling pathway, and the JNK signaling pathway were significant. The PTGDS gene is located in the Arachidonic acid metabolism pathway, which plays an important role in the formation and maintenance of BTB in the testis. The expression of PTGDS is downregulated subsequent to T. gondii infection, potentially exerting deleterious effects on the integrity of the BTB and the spermatogenic microenvironment within the testes.
CONCLUSIONS: Overall, our research provides in-depth insights into how chronic T. gondii infection might affect testicular tissue and potentially impact male fertility. These findings offer a new perspective on the impact of T. gondii infection on the male reproductive system.

As Toxoplasma gondii disseminates through its host, the parasite must sense and adapt to its environment and scavenge nutrients. Oxygen (O2) is one such environmental factor and cytoplasmic prolyl 4-hydroxylases (PHDs) are evolutionarily conserved O2 cellular sensing proteins that regulate responses to changes in O2 availability. Toxoplasma expresses 2 PHDs. One of them, TgPHYa hydroxylates SKP1, a subunit of the SCF-E3 ubiquitin ligase complex. In vitro, TgPHYa is important for growth at low O2 levels. However, studies have yet to examine the role that TgPHYa or any other pathogen-encoded PHD plays in virulence and disease. Using a type II ME49 Toxoplasma TgPHYa knockout, we report that TgPHYa is important for Toxoplasma virulence and brain cyst formation in mice. We further find that while TgPHYa mutant parasites can establish an infection in the gut, they are unable to efficiently disseminate to peripheral tissues because the mutant parasites are unable to survive within recruited immune cells. Since this phenotype was abrogated in IFNγ knockout mice, we studied how TgPHYa mediates survival in IFNγ-treated cells. We find that TgPHYa is not required for release of parasite-encoded effectors into host cells that neutralize anti-parasitic processes induced by IFNγ. In contrast, we find that TgPHYa is required for the parasite to scavenge tryptophan, which is an amino acid whose levels are decreased after IFNγ up-regulates the tryptophan-catabolizing enzyme, indoleamine dioxygenase (IDO). We further find, relative to wild-type mice, that IDO knockout mice display increased morbidity when infected with TgPHYa knockout parasites. Together, these data identify the first parasite mechanism for evading IFNγ-induced nutritional immunity and highlight a novel role that oxygen-sensing proteins play in pathogen growth and virulence.

This study investigates the molecular prevalence and phylogenetic characteristics of two prominent blood-borne pathogens, Toxoplasma gondii (T. gondii) and Plasmodium spp., in common quails (Coturnix coturnix) sampled from both wild (N = 236) and farmed (N = 197) populations across four districts (Layyah, Dera Ghazi Khan, Lahore, and Multan) in Punjab, Pakistan, during the hunting seasons from 2021 to 2023. Additionally, the impact of these pathogens on the complete blood count (CBC) of the hosts is examined. Out of 433 quails tested, 25 (5.8%) exhibited amplification of the internal transcribed spacer (ITS-1) gene for T. gondii, while 15 (3.5%) showed amplification of the Cytochrome b gene for Plasmodium spp. A risk factor analysis indicated that the prevalence of both pathogens was not confined to specific sampling sites or bird sexes (P > 0.05). District-wise analysis highlighted that hens were more susceptible to both T. gondii and Plasmodium spp. infections than cocks. Wild quails exhibited a higher susceptibility to T. gondii compared to farmed birds. Significant CBC variations were recorded in infected birds as compared to uninfected ones. BLAST analysis of generated sequences has confirmed the identity of recovered PCR amplicons as T. gondii and Plasmodium relictum. Phylogenetic analysis revealed that Pakistani isolates clustered with those reported from various countries globally. This study provides the first documentation of T. gondii and Plasmodium sp. infections in Pakistani quails, underscoring the need for detailed investigations across different regions to enhance our understanding of infection rates and the zoonotic potential of these parasites.