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1.
PLoS Pathog ; 17(10): e1009970, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34597344

RESUMO

Toxoplasma gondii is an orally acquired pathogen that induces strong IFN-γ based immunity conferring protection but that can also be the cause of immunopathology. The response in mice is driven in part by well-characterized MyD88-dependent signaling pathways. Here we focus on induction of less well understood immune responses that do not involve this Toll-like receptor (TLR)/IL-1 family receptor adaptor molecule, in particular as they occur in the intestinal mucosa. Using eYFP-IL-12p40 reporter mice on an MyD88-/- background, we identified dendritic cells, macrophages, and neutrophils as cellular sources of MyD88-independent IL-12 after peroral T. gondii infection. Infection-induced IL-12 was lower in the absence of MyD88, but was still clearly above noninfected levels. Overall, this carried through to the IFN-γ response, which while generally decreased was still remarkably robust in the absence of MyD88. In the latter mice, IL-12 was strictly required to induce type I immunity. Type 1 and type 3 innate lymphoid cells (ILC), CD4+ T cells, and CD8+ T cells each contributed to the IFN-γ pool. We report that ILC3 were expanded in infected MyD88-/- mice relative to their MyD88+/+ counterparts, suggesting a compensatory response triggered by loss of MyD88. Furthermore, bacterial flagellin and Toxoplasma specific CD4+ T cell populations in the lamina propria expanded in response to infection in both WT and KO mice. Finally, we show that My88-independent IL-12 and T cell mediated IFN-γ production require the presence of the intestinal microbiota. Our results identify MyD88-independent intestinal immune pathways induced by T. gondii including myeloid cell derived IL-12 production, downstream type I immunity and IFN-γ production by ILC1, ILC3, and T lymphocytes. Collectively, our data reveal an underlying network of immune responses that do not involve signaling through MyD88.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Microbioma Gastrointestinal/imunologia , Imunidade nas Mucosas/imunologia , Subunidade p40 da Interleucina-12/imunologia , Toxoplasmose Animal/imunologia , Animais , Mucosa Intestinal/imunologia , Camundongos , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/deficiência , Fator 88 de Diferenciação Mieloide/imunologia , Transdução de Sinais/imunologia , Receptores Toll-Like/deficiência , Receptores Toll-Like/imunologia , Toxoplasma/imunologia
2.
Avian Dis ; 65(1): 138-148, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-34339133

RESUMO

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is an important foodborne zoonosis affecting a wide range of hosts, including birds. This study investigated the seroconversion, feed conversion rate, weight gain, and parasite tissue tropism as a function of parasite dose and virulence in turkeys. Twenty-five 4-wk-old female domestic turkeys (Meleagris gallapavo) were intraperitoneally infected with two different strains and two doses (105 and 108 tachyzoites/ml) of T. gondii tachyzoites, resulting in four treatment groups. A fifth group of 10 additional birds was intraperitoneally injected with sterile phosphate-buffered saline as a negative control. All birds remained subclinical except for three birds in the two high-dose groups (108 tachyzoites/ml). Survival rate was 88% (22/25). A 92% seroconversion rate was detected in T. gondii-infected birds using a modified agglutination test. Antibody titers as well as weight gain were related to the dose and strain of T. gondii used. Feed conversion rate was higher in the high-dose groups compared with low-dose and control groups, while weight gain was significantly lower at 14 days postinfection in the group infected with 108 tachyzoites/ml of virulent T. gondii strain. Gross lesions were detected in the pancreas and lungs of only one bird, and histopathologic findings varied depending on strain and dose. The organs that most frequently contained T. gondii DNA as detected by quantitative PCR were the brain and the heart, followed by the bursa of Fabricius and the lungs. This study confirmed that turkeys can be infected with T. gondii, and turkeys can show signs of infection when exposed to high doses. Given the increased practice of outdoor-raised livestock and wildlife consumption, continual experimental infection of T. gondii in wild and domestic animals should be pursued.


Assuntos
Anticorpos Antiprotozoários/imunologia , Formação de Anticorpos , Peso Corporal , Metabolismo Energético , Doenças das Aves Domésticas/parasitologia , Toxoplasma/fisiologia , Toxoplasmose Animal/parasitologia , Perus , Ração Animal , Animais , Feminino , Doenças das Aves Domésticas/imunologia , Toxoplasmose Animal/imunologia
3.
J Immunol ; 207(6): 1507-1512, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34400524

RESUMO

Resistance and tolerance are vital for survivability of the host-pathogen relationship. Virulence during Toxoplasma infection in mice is mediated by parasite kinase-dependent antagonism of IFN-γ-induced host resistance. Whether avirulence requires expression of parasite factors that induce host tolerance mechanisms or is a default status reflecting the absence of resistance-interfering factors is not known. In this study, we present evidence that avirulence in Toxoplasma requires parasite engagement of the scavenger receptor CD36. CD36 promotes macrophage tropism but is dispensable for the development of resistance mechanisms. Instead CD36 is critical for re-establishing tissue homeostasis and survival following the acute phase of infection. The CD36-binding capacity of T. gondii strains is negatively controlled by the virulence factor, ROP18. Thus, the absence of resistance-interfering virulence factors and the presence of tolerance-inducing avirulence factors are both required for long-term host-pathogen survival.


Assuntos
Antígenos CD36/deficiência , Antígenos CD36/metabolismo , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/parasitologia , Toxoplasma/metabolismo , Toxoplasma/patogenicidade , Toxoplasmose Animal/imunologia , Animais , Antígenos CD36/genética , Células CHO , Cricetulus , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Tolerância Imunológica/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Protozoários/metabolismo , Células RAW 264.7 , Toxoplasmose Animal/metabolismo , Toxoplasmose Animal/parasitologia , Virulência/genética , Fatores de Virulência/metabolismo
4.
Nat Commun ; 12(1): 3842, 2021 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-34158487

RESUMO

Toxoplasma gondii is hypothesized to manipulate the behavior of warm-blooded hosts to promote trophic transmission into the parasite's definitive feline hosts. A key prediction of this hypothesis is that T. gondii infections of non-feline hosts are associated with costly behavior toward T. gondii's definitive hosts; however, this effect has not been documented in any of the parasite's diverse wild hosts during naturally occurring interactions with felines. Here, three decades of field observations reveal that T. gondii-infected hyena cubs approach lions more closely than uninfected peers and have higher rates of lion mortality. We discuss these results in light of 1) the possibility that hyena boldness represents an extended phenotype of the parasite, and 2) alternative scenarios in which T. gondii has not undergone selection to manipulate behavior in host hyenas. Both cases remain plausible and have important ramifications for T. gondii's impacts on host behavior and fitness in the wild.


Assuntos
Anticorpos Antiprotozoários/imunologia , Gatos/imunologia , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Animais , Comportamento Animal , Gatos/parasitologia , Gatos/fisiologia , Feminino , Interações Hospedeiro-Parasita , Masculino , Toxoplasma/fisiologia , Toxoplasmose Animal/diagnóstico , Toxoplasmose Animal/parasitologia
5.
Parasitol Res ; 120(8): 2855-2861, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34185155

RESUMO

This study aimed to compare the immune response against Toxoplasma gondii (T. gondii) in BALB/c mice induced by excreted/secreted (E/S) antigens and mannose-modified nanoliposome of E/S antigens. Here, E/S antigens and mannose-modified nanoliposome of E/S antigens were firstly prepared, and then BALB/c female inbred mice were separately immunized. In the next step, anti-E/S antigen antibodies and the relative expression levels of IL-10 and IL-12 mRNA were detected by ELISA and real-time PCR, respectively. After immunization, mice were intraperitoneally challenged with 102 tachyzoites of T. gondii, and the survival rate was recorded. The ELISA analysis showed significant differences between the levels of anti-E/S antigen antibodies in the mice immunized by E/S antigens and those immunized by mannose-modified nanoliposome of E/S antigens at days 7, 10, 20, 25, and 30 (P < 0.05). Real-time PCR analysis showed that the relative expression of IL-10 was significantly decreased during 20 days. Yet, the relative expression of IL-12 was significantly increased during 20 days (P < 0.05). In T. gondii challenge test, significant differences were found between the survival rates of mice immunized by E/S antigens and mice immunized by mannose-modified nanoliposome with E/S antigens. This project evidenced that mannose-modified nanoliposome of E/S antigens induced a more powerful immune response against T. gondii in BALB/c mice when compared with excreted/secreted antigens alone.


Assuntos
Vacinas Protozoárias , Toxoplasma , Toxoplasmose Animal , Animais , Anticorpos Antiprotozoários , Antígenos de Protozoários/imunologia , Feminino , Imunidade Humoral , Interleucina-10 , Interleucina-12 , Lipossomos , Manose , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas , Proteínas de Protozoários , Vacinas Protozoárias/imunologia , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia
6.
mBio ; 12(3): e0133121, 2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34154412

RESUMO

Toxoplasmic encephalitis can develop in individuals infected with the protozoan parasite Toxoplasma gondii and is typified by parasite replication and inflammation within the brain. Patients often present with seizures, but the parasite genes and host pathways involved in seizure development and/or propagation are unknown. We previously reported that seizure induction in Toxoplasma-infected mice is parasite strain dependent. Using quantitative trait locus mapping, we identify four loci in the Toxoplasma genome that potentially correlate with seizure development. In one locus, we identify the polymorphic virulence factor, GRA15, as a Toxoplasma gene associated with onset of seizures. GRA15 was previously shown to regulate host NF-κB-dependent gene expression during acute infections, and we demonstrate a similar role for GRA15 in brains of toxoplasmic encephalitic mice. GRA15 is important for increased expression of interleukin 1 beta (IL-1ß) and other IL-1 pathway host genes, which is significant since IL-1 signaling is involved in onset of seizures. Inhibiting IL-1 receptor signaling reduced seizure severity in Toxoplasma-infected mice. These data reveal one mechanism by which seizures are induced during toxoplasmic encephalitis. IMPORTANCE Inflammation in the brain caused by infections lead to seizures and other neurological symptoms. But the microbial products that induce seizures as well as the host pathways downstream of these factors are largely unknown. Using a nonbiased genetic screening approach, we identify 4 loci in the Toxoplasma genome that correlate with the induction of seizures in Toxoplasma-infected mice. One of these loci contains the gene, GRA15, which we demonstrate is associated with seizure development in toxoplasmic encephalitic mice. GRA15 accomplishes this in part by activating host pathways that lead to increased IL-1 receptor signaling and that inhibition of this signaling inhibits Toxoplasma-induced seizures.


Assuntos
Encéfalo/imunologia , Interações Hospedeiro-Parasita/imunologia , Interleucina-1beta/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Transdução de Sinais/imunologia , Toxoplasma/genética , Animais , Encéfalo/parasitologia , Encéfalo/patologia , Feminino , Expressão Gênica , Genoma de Protozoário , Humanos , Interleucina-1beta/genética , Camundongos , Camundongos Endogâmicos C57BL , Convulsões/imunologia , Convulsões/parasitologia , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/parasitologia , Fatores de Virulência
7.
J Wildl Dis ; 57(2): 393-398, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33822151

RESUMO

Serum samples of 11 Bengal tigers (Panthera tigris tigris) from Chitwan National Park in Nepal, collected between 2011-17, were evaluated for the presence of antibodies to eight diseases commonly investigated in large felids. This initial serologic survey was done to establish baseline information to understand the exposure of Nepal's free-ranging tiger population to these diseases. Tiger serum samples collected opportunistically during encounters such as translocation, human conflict, and injury were placed in cold storage for later use. Frozen serum samples were assessed for feline coronavirus (FCoV), feline immunodeficiency virus, feline leukemia virus, feline herpesvirus (FHV), canine distemper virus, canine parvovirus-2 (CPV-2), leptospirosis (LEP; seven serovars), and toxoplasmosis (TOX). Six tigers were found to be positive for LEP, eight for CPV-2, five for FHV, one for FCoV, and 10 for TOX. Tigers, like other wild felids, have been exposed to these common pathogens, but further research is needed to determine the significance of these pathogens to the Nepali population.


Assuntos
Doenças Transmissíveis/veterinária , Tigres , Animais , Anticorpos Antibacterianos/sangue , Anticorpos Antiprotozoários/sangue , Anticorpos Antivirais/sangue , Doenças Transmissíveis/epidemiologia , Doenças Transmissíveis/imunologia , Feminino , Leptospirose/epidemiologia , Leptospirose/imunologia , Leptospirose/veterinária , Masculino , Nepal/epidemiologia , Toxoplasmose Animal/epidemiologia , Toxoplasmose Animal/imunologia , Viroses/epidemiologia , Viroses/imunologia , Viroses/veterinária
8.
Acta Trop ; 219: 105915, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33861971

RESUMO

This study investigated the participation extracellular vesicles (EVs) in Toxoplasma gondii-host interaction. EVs of three T. gondii strains (RH, ME-49 and VEG) were purified by chromatography and ELISA. Results of "nanoparticle tracking analysis" and scanning electron microscopy showed that RH strain released more EVs than other strains. Images of transmission electron microscopy showed that in beginning of incubation (culture medium), EVs were inside of tachyzoites preparing to be released. After 24 hours, they were largely produced inside tachyzoites and were released through plasma membrane. The parasite burden of mice infected with RH strain plus EVs was increased and with early death of 1-2 days compared of those that received only parasites. EV proteins of ME-49 and VEG strains were poorly reactive to sera of infected patients in imunoblot. However, those from RH strain were reactive against sera of patients with cerebral toxoplasmosis. EVs stimulated murine splenocytes caused similar production of IFN-γ and IL-10 levels. RH strain derived EVs stimulated more TNF-α than those stimulated by other strains. T. gondii and infected hosts can express the same miRNAs (miR-155-5p, miR-125b-5p, miR-423-3p). In conclusion, T. gondii derived EVs promote host-parasite interactions, modulate host immune responses, carry virulent factors and cause an imbalance in cellular immune response.


Assuntos
Vesículas Extracelulares/metabolismo , Toxoplasma/citologia , Animais , Humanos , Imunidade Celular , Interleucina-10/sangue , Camundongos , MicroRNAs/sangue , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Fator de Necrose Tumoral alfa/sangue
9.
Parasitol Res ; 120(5): 1851-1860, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33682048

RESUMO

The aims of the present study were to determine the Neospora caninum and Toxoplasma gondii seropositivity rates in farmed red deer hinds from Argentina and their relationship with reproductive losses. Over a 2-year period, 449 hinds from 4 commercial farms were serologically tested at late gestation for N. caninum and T. gondii by IFAT. During the first year, a sequential serological analysis was carried out at 3 different time points to analyze antibody dynamics from mating until the end of the gestation period. Fetal and postnatal mortality rates were estimated by 3 successive ultrasound scannings (us) annually and a breeding control carried out after the calving period. Ultrasound fetal measurements were used to estimate conception date and gestational age of abortions. The seropositivity rate for N. caninum was 25.5% (37/145) for the yearlings and 34.2% (104/304) for the adults, while for T. gondii was 64.3% (93/145) and 78.3% (238/304), respectively. Abortions detected at us1 and us2 were 13/21 (61.9%) with a range of gestational age of 30-87 days, while abortions detected at us3 were 8/21 (38.1%) with a range of gestational age of 49-209 days. The fetal mortality rate was 4% and 5.8%, while the postnatal mortality rate was 18.8% and 4.1% of 101 yearlings and 294 adult pregnant hinds, respectively. Most seropositive hinds to both protozoans showed a stable antibody titer pattern from mating to the end of gestation, and a lower proportion developed an increase in titers suggesting infection recrudescence. Seroconversion during the gestational period was demonstrated in 6 and 50 hinds for N. caninum and T. gondii, respectively. Hinds with fetal mortality were more likely to be seropositive to N. caninum (OR = 3.1) or have N. caninum titers ≥400 (OR = 27.4) than hinds that weaned a fawn. No statistical associations were detected for T. gondii seropositivity and reproductive losses. The pregnancy rate was not affected by N. caninum or T. gondii infection, while the serological evidence of N. caninum causing postnatal mortality was marginal. Based on serological evidence, N. caninum would be a potential abortigenic agent in red deer hinds.


Assuntos
Coccidiose/veterinária , Cervos/parasitologia , Neospora , Toxoplasma , Toxoplasmose Animal/fisiopatologia , Aborto Animal , Animais , Anticorpos Antiprotozoários , Argentina , Coccidiose/parasitologia , Feminino , Masculino , Neospora/imunologia , Gravidez , Complicações Parasitárias na Gravidez/veterinária , Reprodução , Estudos Soroepidemiológicos , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Desmame
10.
J Parasitol ; 107(2): 179-181, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33662116

RESUMO

Toxoplasma gondii is an obligate intracellular parasite that has a worldwide distribution and can infect almost all warm-blood animals. Serological tests are the main detection methods for T. gondii infection in animals and humans. Little is known of biological behavior, antibody responses, and virulence of T. gondii strains in mice from China. Here we document antibody responses, tissue cyst burden, and mouse virulence of T. gondii strains isolated from different hosts in China. All T. gondii strains formed tissue cysts in the brains of mice and positively correlated with the T. gondii antibody titer (R2 = 0.3345). These results should aid in the diagnosis and characterization of T. gondii isolates.


Assuntos
Anticorpos Antiprotozoários/biossíntese , Toxoplasma/imunologia , Toxoplasma/patogenicidade , Toxoplasmose Animal/parasitologia , Animais , Antiprotozoários/administração & dosagem , Encéfalo/parasitologia , China , Interações Hospedeiro-Parasita/imunologia , Camundongos , Sulfadiazina/administração & dosagem , Toxoplasma/efeitos dos fármacos , Toxoplasma/isolamento & purificação , Toxoplasmose Animal/diagnóstico , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/patologia , Virulência
11.
Parasitology ; 148(4): 464-476, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33315001

RESUMO

In most of the world Toxoplasma gondii is comprised of archetypal types (types I, II and III); however, South America displays several non-archetypal strains. This study used an experimental mouse model to characterize the immune response and parasite kinetics following infection with different parasite genotypes. An oral inoculation of 50 oocysts per mouse from T. gondii M4 type II (archetypal, avirulent), BrI or BrIII (non-archetypal, virulent and intermediate virulent, respectively) for groups (G)2, G3 and G4, respectively was used. The levels of mRNA expression of cytokines, immune compounds, cell surface markers and receptor adapters [interferon gamma (IFNγ), interleukin (IL)-12, CD8, CD4, CD25, CXCR3 and MyD88] were quantified by SYBR green reverse transcription-quantitative polymerase chain reaction. Lesions were characterized by histology and detection by immunohistochemistry established distribution of parasites. Infection in G2 mice was mild and characterized by an early MyD88-dependent pathway. In G3, there were high levels of expression of pro-inflammatory cytokines IFNγ and IL-12 in the mice showing severe clinical symptoms at 8­11 days post infection (dpi), combined with the upregulation of CD25, abundant tachyzoites and tissue lesions in livers, lungs and intestines. Significant longer expression of IFNγ and IL-12 genes, with other Th1-balanced immune responses, such as increased levels of CXCR3 and MyD88 in G4, resulted in survival of mice and chronic toxoplasmosis, with the occurrence of tissue cysts in brain and lungs, at 14 and 21 dpi. Different immune responses and kinetics of gene expression appear to be elicited by the different strains and non-archetypal parasites demonstrated higher virulence.


Assuntos
Toxoplasma/fisiologia , Toxoplasmose Animal/parasitologia , Animais , Antígenos CD/metabolismo , Gatos , Citocinas/metabolismo , DNA Complementar/biossíntese , DNA de Protozoário/isolamento & purificação , Feminino , Genótipo , Imuno-Histoquímica , Linfonodos/parasitologia , Linfonodos/patologia , Mesentério , Camundongos , Fator 88 de Diferenciação Mieloide/metabolismo , RNA de Protozoário/genética , RNA de Protozoário/isolamento & purificação , Distribuição Aleatória , Reação em Cadeia da Polimerase em Tempo Real , Receptores CXCR3/metabolismo , Baço/parasitologia , Baço/patologia , Toxoplasma/classificação , Toxoplasma/genética , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/patologia
12.
Emerg Microbes Infect ; 9(1): 2619-2621, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33215979

RESUMO

Toxoplasma gondii oocysts in the environment are a threat to humans and animals. This study is aimed to evaluate the prevalence of T. gondii in white spoonbills and isolate viable T. gondii from white spoonbills. In 28.6% (2/7) of white spoonbills, T. gondii antibodies were found in heart juice by the modified agglutination test (cut-off: 1:4). T. gondii DNA was detected in tissues of 42.9% (3/7) white spoonbills. One viable T. gondii strain, named TgSpoonbillCHn1, was isolated from the myocardium of a white spoonbill by bioassay in mice. DNA extracted from TgSpoonbillCHn1 tachyzoites was characterized by PCR-restriction fragment length polymorphism with ten markers and the virulence genes ROP5 and ROP18. The results revealed that it was ToxoDB#2 (Type III). The ROP18/ROP5 genotype combination predicts that this strain is avirulent for mice, which is supported by the infection experiments in mice. This is the first report of the isolation of viable T. gondii strain from white spoonbil. The prevalence of T. gondii in white spoonbills may be indicative of environmental contamination of oocysts. This report provides direct evidence of white spoonbill as an intermediate host of T. gondii.


Assuntos
Anticorpos Antiprotozoários/metabolismo , Aves/virologia , Toxoplasma/isolamento & purificação , Toxoplasmose Animal/diagnóstico , Animais , China , DNA de Protozoário/genética , Feminino , Coração/virologia , Masculino , Camundongos , Especificidade da Espécie , Toxoplasma/genética , Toxoplasma/imunologia , Toxoplasma/patogenicidade , Toxoplasmose Animal/imunologia , Virulência
13.
Korean J Parasitol ; 58(5): 487-492, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33202500

RESUMO

Toxoplasmosis is caused by an obligate intracellular protozoan parasite; Toxoplasma gondii, which is one of the most important zoonotic parasite worldwide. In dogs, the sexual reproductive cycle of T. gondii is lacking, and the animals are not widely consumed as food, but they are vital in the mechanical transmission of the parasite. However, there is no present data on the exposure of stray dogs to T. gondii in Malaysia. The objective of this serological survey was to determine the prevalence of T. gondii antibodies (IgG) and associated factors in stray dogs in East and West Malaysia. Antibodies to T. gondii were determined in serum samples from 222 stray dogs from 6 different states in East and West Malaysia (Peninsular Malaysia) using an Indirect ELISA. The seroprevalence for T. gondii was 23.4% (Confidence interval: CI 17.8-29.2%). Stray dogs from Selangor and Kuala Lumpur had the highest seroprevalence (32.4%; CI 13.2-45.5%) and lowest in those from Penang and Kedah (12.5%; CI 1.3-23.5%). Gender and breed were not associated with T. gondii seropositivity. However, adult dogs were more likely to be seropositive for T. gondii (OR=2.89; CI 1.1-7.7) compared with younger dogs. These results revealed that T. gondii is prevalent in stray dogs in the studied areas in Malaysia, and indicative of the level of environmental contamination of this parasite especially in urban areas.


Assuntos
Animais Selvagens , Anticorpos Antiprotozoários/análise , Doenças do Cão/epidemiologia , Doenças do Cão/parasitologia , Toxoplasma/imunologia , Toxoplasmose Animal/epidemiologia , Toxoplasmose Animal/parasitologia , Animais , Doenças do Cão/imunologia , Cães , Feminino , Malásia/epidemiologia , Masculino , Prevalência , Estudos Soroepidemiológicos , Toxoplasmose Animal/imunologia
14.
Front Immunol ; 11: 2183, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33013917

RESUMO

Toxoplasma gondii is a parasitic protozoan of worldwide distribution, able to infect all warm-blooded animals, but particularly sheep. Primary infection in pregnant sheep leads to millions of abortions and significant economic losses for the livestock industry. Moreover, infected animals constitute the main parasitic reservoir for humans. Therefore, the development of a One-health vaccine seems the best prevention strategy. Following earlier work, a vaccine constituted of total extract of Toxoplasma gondii proteins (TE) associated with maltodextrin nanoparticles (DGNP) was developed in rodents. In this study we evaluated the ability of this vaccine candidate to protect against latent and congenital toxoplasmosis in sheep. After two immunizations by either intranasal or intradermal route, DGNP/TE vaccine generated specific Th1-cellular immune response, mediated by APC-secretion of IFN-γ and IL-12. Secretion of IL-10 appeared to regulate this Th1 response for intradermally vaccinated sheep but was absent in intranasally-vaccinated animals. Finally, protection against latent toxoplasmosis and transplacental transmission were explored. Intranasal vaccination led to a marked decrease of brain cysts compared with the non-vaccinated group. This DGNP/TE vaccine administered intranasally conferred a high level of protection against latent toxoplasmosis and its transplacental transmission in sheep, highlighting the potential for development of such a vaccine for studies in other species.


Assuntos
Encéfalo/patologia , Infecção Latente/imunologia , Nanopartículas/administração & dosagem , Proteínas de Protozoários/imunologia , Vacinas Protozoárias/imunologia , Ovinos/fisiologia , Células Th1/imunologia , Toxoplasma/fisiologia , Toxoplasmose Animal/imunologia , Toxoplasmose Congênita/imunologia , Administração Intranasal , Animais , Transmissão Vertical de Doenças Infecciosas , Ativação Linfocitária , Camundongos , Nanopartículas/química , Polissacarídeos/química , Ratos , Vacinação
15.
Exp Parasitol ; 218: 108006, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32991867

RESUMO

This study aimed to elucidate the cellular immune response against Toxoplasma gondii in chronically infected mice reinfected with different strains of the parasite to elucidate the immunological basis for chronicity or virulence and to uncover the involvement of genes that encode virulence proteins and modulate the immune response. BALB/c mice were infected by oral gavage with non-virulent D8 strain and challenged 45 days post-infection with virulent EGS or CH3 strains. Cytokine measurement was performed 2 days post-challenge in cell extracts of the small intestine and 2, 7, and 14 days post-challenge in serum. Virulence gene allele type of these strains was analyzed. Challenged mice survived by avoiding exacerbated inflammation and inhibiting the overproduction of cytokines. Local and systemic cytokine response in challenged mice was similar to chronic controls and quite distinct in mice acutely infected with the EGS or CH3 strains. Allelic combinations of the virulence genes ROP5/ROP18 was predictive of virulence in mice when tested in these T. gondii strains. Other allelic combinations of rhoptries and dense granules genes showed discrepancies.


Assuntos
Citocinas/biossíntese , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Alelos , Animais , Doença Crônica , Citocinas/sangue , Citocinas/genética , Cães , Feminino , Íleo/imunologia , Imunidade Celular , Camundongos , Camundongos Endogâmicos BALB C , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Proteínas de Protozoários/genética , Toxoplasma/classificação , Toxoplasma/genética , Toxoplasma/patogenicidade , Toxoplasmose Animal/parasitologia , Virulência
16.
Front Immunol ; 11: 1397, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32733463

RESUMO

Toxoplasma gondii (T. gondii) is a parasite infecting animals and humans. In intermediate hosts, such as humans or rodents, rapidly replicating tachyzoites drive vigorous innate and adaptive immune responses resulting in bradyzoites that survive within tissue cysts. Activation of the innate immune system is critical during the early phase of infection to limit pathogen growth and to instruct parasite-specific adaptive immunity. In rodents, dendritic cells (DCs) sense T. gondii through TLR11/12, leading to IL-12 production, which activates NK cells to produce IFN-γ as an essential mechanism for early parasite control. Further, C3 can bind to T. gondii resulting in limited complement activation. Here, we determined the role of C5a/C5aR1 axis activation for the early innate immune response in a mouse model of peritoneal T. gondii infection. We found that C5ar1 -/- animals suffered from significantly higher weight loss, disease severity, mortality, and parasite burden in the brain than wild type control animals. Severe infection in C5ar1 -/- mice was associated with diminished serum concentrations of IL-12, IL-27, and IFN-γ. Importantly, the serum levels of pro-inflammatory cytokines, including IL-1α, IL-6, and TNF-α, as well as several CXC and CC chemokines, were decreased in comparison to wt animals, whereas anti-inflammatory IL-10 was elevated. The defect in IFN-γ production was associated with diminished Ifng mRNA expression in the spleen and the brain, reduced frequency of IFN-γ+ NK cells in the spleen, and decreased Nos2 expression in the brain of C5ar1 -/- mice. Mechanistically, DCs from the spleen of C5ar1 -/- mice produced significantly less IL-12 in response to soluble tachyzoite antigen (STAg) stimulation in vivo and in vitro. Our findings suggest a model in which the C5a/C5aR1 axis promotes IL-12 induction in splenic DCs that is critical for IFN-γ production from NK cells and subsequent iNOS expression in the brain as a critical mechanism to control acute T. gondii infection.


Assuntos
Ativação do Complemento/imunologia , Imunidade Inata/imunologia , Interferon gama/imunologia , Receptor da Anafilatoxina C5a/imunologia , Toxoplasmose Animal/imunologia , Animais , Células Dendríticas/imunologia , Modelos Animais de Doenças , Células Matadoras Naturais/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Baço/imunologia , Toxoplasma/imunologia
17.
PLoS Pathog ; 16(8): e1008327, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32853276

RESUMO

Host resistance to Toxoplasma gondii relies on CD8 T cell IFNγ responses, which if modulated by the host or parasite could influence chronic infection and parasite transmission between hosts. Since host-parasite interactions that govern this response are not fully elucidated, we investigated requirements for eliciting naïve CD8 T cell IFNγ responses to a vacuolar resident antigen of T. gondii, TGD057. Naïve TGD057 antigen-specific CD8 T cells (T57) were isolated from transnuclear mice and responded to parasite-infected bone marrow-derived macrophages (BMDMs) in an antigen-dependent manner, first by producing IL-2 and then IFNγ. T57 IFNγ responses to TGD057 were independent of the parasite's protein export machinery ASP5 and MYR1. Instead, host immunity pathways downstream of the regulatory Immunity-Related GTPases (IRG), including partial dependence on Guanylate-Binding Proteins, are required. Multiple T. gondii ROP5 isoforms and allele types, including 'avirulent' ROP5A from clade A and D parasite strains, were able to suppress CD8 T cell IFNγ responses to parasite-infected BMDMs. Phenotypic variance between clades B, C, D, F, and A strains suggest T57 IFNγ differentiation occurs independently of parasite virulence or any known IRG-ROP5 interaction. Consistent with this, removal of ROP5 is not enough to elicit maximal CD8 T cell IFNγ production to parasite-infected cells. Instead, macrophage expression of the pathogen sensors, NLRP3 and to a large extent NLRP1, were absolute requirements. Other members of the conventional inflammasome cascade are only partially required, as revealed by decreased but not abrogated T57 IFNγ responses to parasite-infected ASC, caspase-1/11, and gasdermin D deficient cells. Moreover, IFNγ production was only partially reduced in the absence of IL-12, IL-18 or IL-1R signaling. In summary, T. gondii effectors and host machinery that modulate parasitophorous vacuolar membranes, as well as NLR-dependent but inflammasome-independent pathways, determine the full commitment of CD8 T cells IFNγ responses to a vacuolar antigen.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Inflamassomos/imunologia , Interferon gama/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Proteínas de Protozoários/metabolismo , Transdução de Sinais , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Animais , Linfócitos T CD8-Positivos/parasitologia , Feminino , Macrófagos/imunologia , Macrófagos/parasitologia , Camundongos , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteínas de Protozoários/genética , Toxoplasmose Animal/parasitologia , Vacúolos/imunologia , Vacúolos/metabolismo , Vacúolos/parasitologia , Virulência/imunologia
18.
Int J Med Microbiol ; 310(5): 151432, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32654774

RESUMO

The extracellular signal-regulated kinases (ERKs) serve as important determinants of cellular signal transduction pathways, and hence may play important roles during infections. Previous work suggested that putative ERK7 of Toxoplasma gondii is required for efficient intracellular replication of the parasite. However, the antigenic and immunostimulatory properties of TgERK7 protein remain unknown. The objective of this study was to produce a recombinant TgERK7 protein in vitro and to evaluate its effect on the induction of humoral and T cell-mediated immune responses against T. gondii infection in BALB/c mice. Immunization using TgERK7 mixed with Freund's adjuvants significantly increased the ratio of CD3e+CD4+ T/CD3e+CD8a+ T lymphocytes in spleen and elevated serum cytokines (IFN-γ, IL-2, IL-4, IL-10, IL-12p70, IL-23, MCP-1, and TNF-α) in immunized mice compared to control mice. On the contrary, immunization did not induce high levels of serum IgG antibodies. Five predicted peptides of TgERK7 were synthesized and conjugated with KLH and used to analyze the antibody specificity in the sera of immunized mice. We detected a progressive increase in the antibody level only against TgERK7 peptide A (DEVDKHVLRKYD). Antibody raised against this peptide significantly decreased intracellular proliferation of T. gondii in vitro, suggesting that peptide A can potentially induce a protective antibody response. We also showed that immunization improved the survival rate of mice challenged with a virulent strain and significantly reduced the parasite cyst burden within the brains of chronically infected mice. Our data show that TgERK7-based immunization induced TgERK7 peptide A-specific immune responses that can impart protective immunity against T. gondii infection. The therapeutic potential of targeting ERK7 signaling pathway for future toxoplasmosis treatment is warranted.


Assuntos
Antígenos de Protozoários/imunologia , MAP Quinases Reguladas por Sinal Extracelular/imunologia , Toxoplasma/imunologia , Toxoplasmose Animal/imunologia , Animais , Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/genética , Citocinas/sangue , MAP Quinases Reguladas por Sinal Extracelular/genética , Feminino , Imunidade Celular , Imunidade Humoral , Imunização , Imunoglobulina G/sangue , Camundongos , Camundongos Endogâmicos BALB C , Peptídeos/química , Peptídeos/genética , Conformação Proteica , Vacinas Protozoárias/imunologia , Coelhos , Proteínas Recombinantes/imunologia , Toxoplasma/genética
19.
J Parasitol ; 106(3): 392-394, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32556162

RESUMO

The objective of the study was to identify the seroprevalence of anti-Toxoplasma gondii antibodies in sheep herds from 3 municipalities from Jalisco, Mexico, as well as estimate the association between seroprevalence and certain factors presents in the farms. In total, 12 sheep farms that maintain only hair breeds were included in the work. From these farms, 336 blood samples were collected, corresponding 324 to ewes and 12 rams. Serum samples were subjected to ELISA test, and the association between the frequency of antibodies and some potential risk factors was estimated. The overall seroprevalence to anti-T. gondii antibodies in the population studied was 17.8% (60/336; 95% confidence interval [C.I.] 14-22), all farms had positive animals, and the seroprevalence of antibodies ranged between 7 to 32%. Seroprevalence in specific municipalities was 18.7% in Lagos de Moreno, 17.8% in Encarnación de Díaz, and 16.9% in San Juan de los Lagos. Seroprevalence in ewes was 17.5% (57/324; 95% C.I. 13-22), and seroprevalence in rams was 25% (3/12; 95% C.I. 6-57), while among breeds it was 17.8% in Pelibuey (20/112; 95% C.I. 11-26), 16.6% in Kathadin (14/84; 95% C.I. 9-26), 15.4% in Blackbelly (13/84; 95% C.I. 8-25), and 23.2% in Dorper (13/56; 95% C.I. 13-36); no differences were observed among breeds (p < 0.05). The presence of cats on the farms was associated with seroprevalence (odds ratio [OR] 2.8; 95% C.I. 1.8-7.3, p < 0.001), as was the absence of a rodent-control program (OR 1.5; 95% C.I. 0.8-3.2, p < 0.05). No other factors were identified as associated with seroprevalence.


Assuntos
Anticorpos Antiprotozoários/sangue , Doenças dos Ovinos/parasitologia , Toxoplasma/imunologia , Toxoplasmose Animal/epidemiologia , Animais , Gatos , Feminino , Masculino , México/epidemiologia , Controle de Pragas/estatística & dados numéricos , Ratos , Estudos Soroepidemiológicos , Ovinos , Doenças dos Ovinos/epidemiologia , Doenças dos Ovinos/imunologia , Doenças dos Ovinos/transmissão , Inquéritos e Questionários , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/parasitologia , Toxoplasmose Animal/transmissão
20.
Dis Model Mech ; 13(7)2020 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-32461265

RESUMO

Toxoplasma gondii is an obligate intracellular parasite capable of invading any nucleated cell. Three main clonal lineages (type I, II, III) exist and murine models have driven the understanding of general and strain-specific immune mechanisms underlying Toxoplasma infection. However, murine models are limited for studying parasite-leukocyte interactions in vivo, and discrepancies exist between cellular immune responses observed in mouse versus human cells. Here, we developed a zebrafish infection model to study the innate immune response to Toxoplasma in vivo By infecting the zebrafish hindbrain ventricle, and using high-resolution microscopy techniques coupled with computer vision-driven automated image analysis, we reveal that Toxoplasma invades brain cells and replicates inside a parasitophorous vacuole to which type I and III parasites recruit host cell mitochondria. We also show that type II and III strains maintain a higher infectious burden than type I strains. To understand how parasites are cleared in vivo, we further analyzed Toxoplasma-macrophage interactions using time-lapse microscopy and three-dimensional correlative light and electron microscopy (3D CLEM). Time-lapse microscopy revealed that macrophages are recruited to the infection site and play a key role in Toxoplasma control. High-resolution 3D CLEM revealed parasitophorous vacuole breakage in brain cells and macrophages in vivo, suggesting that cell-intrinsic mechanisms may be used to destroy the intracellular niche of tachyzoites. Together, our results demonstrate in vivo control of Toxoplasma by macrophages, and highlight the possibility that zebrafish may be further exploited as a novel model system for discoveries within the field of parasite immunity.This article has an associated First Person interview with the first author of the paper.


Assuntos
Macrófagos/parasitologia , Rombencéfalo/microbiologia , Toxoplasma/crescimento & desenvolvimento , Toxoplasmose Animal/parasitologia , Toxoplasmose Cerebral/parasitologia , Peixe-Zebra/parasitologia , Animais , Modelos Animais de Doenças , Interações Hospedeiro-Parasita , Macrófagos/imunologia , Macrófagos/ultraestrutura , Microscopia Confocal , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência , Microscopia de Vídeo , Carga Parasitária , Rombencéfalo/imunologia , Rombencéfalo/ultraestrutura , Fatores de Tempo , Toxoplasma/imunologia , Toxoplasma/ultraestrutura , Toxoplasmose Animal/imunologia , Toxoplasmose Animal/patologia , Toxoplasmose Cerebral/imunologia , Toxoplasmose Cerebral/patologia
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