RESUMEN

BACKGROUND: Toxoplasma gondii is an intracellular opportunistic pathogenic protozoan that poses serious threats, particularly in immunocompromised individuals. In the absence of a robust prophylactic measure, the mitigation and management of toxoplasmosis present formidable challenges to public health. We recently found that GRA72 plays an important role in parasitophorous vacuole (PV) morphology, growth and virulence of T. gondii. However, whether gra72-deficient strain can be used as a vaccine remains unknown. METHODS: We first examined the attenuated virulence of gra72 gene knockout strain (PruΔgra72) and the parasite load in organs of the infected mice. Subsequently, we evaluated the immune-protective effects of the PruΔgra72 vaccination against challenge with various types of T. gondii tachyzoites and Pru cysts. Furthermore, levels of antibodies and cytokines induced by PruΔgra72 vaccination were examined. Statistical analysis was conducted by Student's t-test or Mantel-Cox log-rank test based on data obtained from three independent experiments with GraphPad Prism 8.0. RESULTS: We found that PruΔgra72 strain exhibited a significantly attenuated virulence even at the highest dose of 5 × 107 tachyzoites in Kunming mice model. The significant decrease of brain cyst burden and parasite load in the organs of the PruΔgra72-infected mice suggested its potentiality as a live-attenuated vaccine. Hence, we explored the protective immunity of PruΔgra72 vaccination against toxoplasmosis. Results showed that vaccination with 5 × 106 PruΔgra72 tachyzoites triggered a strong and sustained Th1-biased immune response, marked by significantly increased levels of anti-T. gondii IgG antibodies, and significantly higher levels of Th1 type cytokines (IL-2, IL-12 and IFN-γ) compared to that of Th2 type (IL-4 and IL-10). Vaccination with 5 × 106 PruΔgra72 tachyzoites in mice conferred long-term protection against T. gondii infection by less virulent tachyzoites (ToxoDB#9 PYS and Pru strains) and Pru cysts, provided partial protection against acute infection by high virulent Type I RH tachyzoites and significantly decreased brain cyst burden of chronically infected mice. CONCLUSIONS: The avirulent PruΔgra72 induced strong protective immunity against acute and chronic T. gondii infection and is a promising candidate for developing a safe and effective live-attenuated vaccine against T. gondii infection.

Asunto(s)

Anticuerpos Antiprotozoarios , Proteínas Protozoarias , Vacunas Antiprotozoos , Toxoplasma , Toxoplasmosis Animal , Vacunas Atenuadas , Animales , Toxoplasma/inmunología , Toxoplasma/genética , Ratones , Vacunas Antiprotozoos/inmunología , Vacunas Antiprotozoos/administración & dosificación , Vacunas Atenuadas/inmunología , Vacunas Atenuadas/administración & dosificación , Proteínas Protozoarias/inmunología , Proteínas Protozoarias/genética , Anticuerpos Antiprotozoarios/sangre , Femenino , Toxoplasmosis Animal/prevención & control , Toxoplasmosis Animal/inmunología , Citocinas/metabolismo , Virulencia , Carga de Parásitos , Modelos Animales de Enfermedad , Enfermedad Crónica , Toxoplasmosis/prevención & control , Toxoplasmosis/inmunología , Toxoplasmosis/parasitología

RESUMEN

Hepatitis E virus (HEV) is a single-stranded positive-sense RNA virus that belongs to Hepeviridae family. HEV is the most common cause of acute viral hepatitis worldwide. According to the World Health Organization (WHO), there are estimated 20 million HEV infections worldwide every year, leading to estimated 3.3 million symptomatic cases of HEV infection. The WHO estimates that HEV infection caused approximately 44,000 deaths in 2015, which represents 3.3% of mortality rates due to viral hepatitis. In low-income (LI) countries and lower-middle-income (LMI) countries, HEV is a waterborne infection induced by HEV genotype (gt) 1 and HEV gt 2 that cause large outbreaks and affect young individuals with a high mortality rate in pregnant women from South Asian countries and patients with liver diseases. HEV gt 3, HEV gt 4, and HEV gt 7 are responsible for sporadic infections with zoonotic transmission mainly through the consumption of raw or undercooked meat from different animals. Acute HEV infection is relatively asymptomatic or mild clinical form, in rare cases the disease can be moderate/severe clinical forms and result in fulminant hepatitis or acute liver failure (ALF). Furthermore, HEV infection is associated with extrahepatic manifestations, including renal and neurological clinical signs and symptoms. Pregnant women, infants, older people, immunocompromised individuals, patients with comorbidities, and workers who come into close contact with HEV-infected animals are recognized as major risk groups for severe clinical form of HEV infection and fatal outcome. Chronic HEV infection can occur in immunocompromised individuals with the possibility of progression to cirrhosis.

RESUMEN

Toxoplasma gondii (T. gondii) is an obligate intracellular parasitic protozoan that can cause toxoplasmosis in humans and other endotherms. T. gondii can manipulate the host gene expression profile by interfering with miRNA expression, which is closely associated with the molecular mechanisms of T. gondii-induced brain injury. However, it is unclear how T. gondii manipulates the gene expression of central nervous system (CNS) cells through modulation of miRNA expression in vivo during acute and chronic infection. Therefore, high-throughput sequencing was used to investigate expression profiles of brain miRNAs at 10, 25, and 50 days post-infection (DPI) in pigs infected with the Chinese I genotype T. gondii strain in this study. Compared with the control group 87, 68, and 135 differentially expressed miRNAs (DEMs) were identified in the infected porcine brains at 10, 25, and 50 DPI, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that a large number significantly enriched GO terms and KEGG pathways were found, and were mostly associated with stimulus or immune response, signal transduction, cell death or apoptosis, metabolic processes, immune system or diseases, and cancers. miRNA-gene network analysis revealed that the crucial connecting nodes, including DEMs and their target genes, might have key roles in the interactions between porcine brain and T. gondii. These results suggest that the regulatory strategies of T. gondii are involved in the modulation of a variety of host cell signaling pathways and cellular processes, containing unfolded protein response (UPR), oxidative stress (OS), autophagy, apoptosis, tumorigenesis, and inflammatory responses, by interfering with the global miRNA expression profile of CNS cells, allowing parasites to persist in the host CNS cells and contribute to pathological damage of porcine brain. To our knowledge, this is the first report on miRNA expression profile in porcine brains during acute and chronic T. gondii infection in vivo. Our results provide new insights into the mechanisms underlying T. gondii-induced brain injury during different infection stages and novel targets for developing therapeutic agents against T. gondii.

RESUMEN

BACKGROUND: Toxoplasma gondii is an obligate intracellular protozoan parasite that can cause a geographically widespread zoonosis. Our previous splenocyte microRNA profile analyses of pig infected with T. gondii revealed that the coordination of a large number of miRNAs regulates the host immune response during infection. However, the functions of other miRNAs involved in the immune regulation during T. gondii infection are not yet known. METHODS: Clustering analysis was performed by K-means, self-organizing map (SOM), and hierarchical clustering to obtain miRNA groups with the similar expression patterns. Then, the target genes of the miRNA group in each subcluster were further analyzed for functional enrichment by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Reactome pathway to recognize the key signaling molecules and the regulatory signatures of the innate and adaptive immune responses of the host during T. gondii infection. RESULTS: A total of 252 miRNAs were successfully divided into 22 subclusters by K-means clustering (designated as K1-K22), 29 subclusters by SOM clustering (designated as SOM1-SOM29), and six subclusters by hierarchical clustering (designated as H1-H6) based on their dynamic expression levels in the different infection stages. A total of 634, 660, and 477 GO terms, 15, 26, and 14 KEGG pathways, and 16, 15, and 7 Reactome pathways were significantly enriched by K-means, SOM, and hierarchical clustering, respectively. Of note, up to 22 miRNAs mainly showing downregulated expression at 50 days post-infection (dpi) were grouped into one subcluster (namely subcluster H3-K17-SOM1) through the three algorithms. Functional analysis revealed that a large group of immunomodulatory signaling molecules were controlled by the different miRNA groups to regulate multiple immune processes, for instance, IL-1-mediated cellular response and Th1/Th2 cell differentiation partly depending on Notch signaling transduction for subclusters K1 and K2, innate immune response involved in neutrophil degranulation and TLR4 cascade signaling for subcluster K15, B cell activation for subclusters SOM17, SOM1, and SOM25, leukocyte migration, and chemokine activity for subcluster SOM9, cytokine-cytokine receptor interaction for subcluster H2, and interleukin production, chemotaxis of immune cells, chemokine signaling pathway, and C-type lectin receptor signaling pathway for subcluster H3-K17-SOM1. CONCLUSIONS: Cluster analysis of splenocyte microRNAs in the pig revealed key regulatory properties of subcluster miRNA molecules and important features in the immune regulation induced by acute and chronic T. gondii infection. These results contribute new insight into the identification of physiological immune responses and maintenance of tolerance in pig spleen tissues during T. gondii infection.

Asunto(s)

MicroARNs , Toxoplasma , Toxoplasmosis , Animales , Análisis por Conglomerados , Inmunidad Innata , Inmunomodulación , MicroARNs/genética , Bazo/parasitología , Porcinos , Toxoplasmosis/genética

RESUMEN

Biomarkers (coming from host or parasite) to monitor Chagas disease (CD) progression as well as the therapeutic response in chronic CD are critically needed, since seronegativization, which may be considered the best indicator of therapeutic cure, takes several years to be observed in adults. Several molecules have been suggested as biomarkers for CD, however, they have to be validated. Taking advantage of mouse models of Trypanosoma cruzi infection, we investigated changes in the degradation profile of fibronectin in plasma. The degradation profile of fibronectin was different in the acute phase compared to the chronic phase of the infection. Fibronectin fragments of approximately 150, 100, 40 and 30 kDa were identified. Furthermore, those degradation profiles correlated with acute parasitaemia as well as with cardiac parasite burden and tissue damage during the infection. The usefulness of fibronectin degradation as a biomarker for therapeutic response following drug treatment and immunotherapeutic vaccination also was evaluated and a decreased fibronectin degradation profile was observed upon benznidazole or a vaccine candidate treatment.

Asunto(s)

Enfermedad de Chagas/diagnóstico , Fibronectinas/sangre , Trypanosoma cruzi/aislamiento & purificación , Animales , Enfermedad de Chagas/parasitología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos ICR , Parasitemia/diagnóstico , Parasitemia/parasitología

RESUMEN

The strategies by which intracellular pathogenic bacteria manipulate innate immunity to establish chronicity are poorly understood. Here, we show that Brucella abortus outer membrane protein Omp25 specifically binds the immune cell receptor SLAMF1 in vitro. The Omp25-dependent engagement of SLAMF1 by B. abortus limits NF-κB translocation in dendritic cells (DCs) with no impact on Brucella intracellular trafficking and replication. This in turn decreases pro-inflammatory cytokine secretion and impairs DC activation. The Omp25-SLAMF1 axis also dampens the immune response without affecting bacterial replication in vivo during the acute phase of Brucella infection in a mouse model. In contrast, at the chronic stage of infection, the Omp25/SLAMF1 engagement is essential for Brucella persistence. Interaction of a specific bacterial protein with an immune cell receptor expressed on the DC surface at the acute stage of infection is thus a powerful mechanism to support microbe settling in its replicative niche and progression to chronicity.

Asunto(s)

Proteínas de la Membrana Bacteriana Externa/metabolismo , Brucella abortus/inmunología , Células Dendríticas/microbiología , Interacciones Huésped-Patógeno/inmunología , Inflamación , Miembro 1 de la Familia de Moléculas Señalizadoras de la Activación Linfocitaria/metabolismo , Animales , Proteínas de la Membrana Bacteriana Externa/genética , Brucella abortus/genética , Brucella abortus/patogenicidad , Células Dendríticas/inmunología , Femenino , Inmunidad Innata , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación , Unión Proteica , Miembro 1 de la Familia de Moléculas Señalizadoras de la Activación Linfocitaria/genética

RESUMEN

OBJECTIVE: To evaluate the efficacy of different methods of antivirus therapy of tick-borne encephalitis (TBE) in children in the acute period and during chronic infections. MATERIAL AND METHODS: During 1 year, 130 children, aged 7-17 years, with TBEV received therapy in the acute period (an average in 3.5±1.3 days) in groups 1 (n=84) and 2 (n=20), and in the chronic infection in groups 3 (n=15) and 4 (n=11). Ribavirin orally, recombinant interferon-α2 (IFN-α2) i/m or in suppositories and anaferon orally were prescribed to children of groups 1 and 3. Children of groups 2 and 4 received tick-borne immunoglobulin (IgG)i/m and ribonuclease i/m. At admission, all patients received infusions of cytoflavin in the drip at the rate of 0.6 ml/kg per day. Etiological diagnosis included ELISA (IgM, G, viral antigen), and virus RNA by PCR in the blood and CSF. MRI of the brain and cervical spinal cord using standard programs was performed. All studies were performed prior to and in the course of treatment. RESULTS AND CONCLUSION: In patients of group 1, the period of increase in symptoms was reduced by ~ 4 days, and the duration of impairment of consciousness and pleocytosis in CSF ~ by 5 days, which was accompanied by a faster clearance of the virus in CSF, compared with group 2. In group 1, recovery without neurological deficit was observed in 83.3% (n=70), all patients had no progression of infection. In group 2, 30% of children (n=6) acquired TBEV chronic infection, and in 55% (n=11) there was a neurological deficit without progression. In patients of group 3 with chronic TBEV, the improvement was observed in 86.7% of cases, and complete regression of symptoms occurred in 1 patient, and replication of the virus was arrested in all of them. In group 4, symptoms increased in 72.7%, while virus replication was preserved and atrophic changes in the CNS increased on MRI. Antiviral therapy (ribavirin, IFN-α2 and release of active antibodies to gamma interferon -anaferon children) has the highest efficacy when prescribed for the first 5 days, while IgG and ribonuclease have insufficient efficacy in TBEV.

Asunto(s)

Antivirales , Virus de la Encefalitis Transmitidos por Garrapatas , Encefalitis Transmitida por Garrapatas , Inmunización Pasiva , Adolescente , Antivirales/uso terapéutico , Niño , Encefalitis Transmitida por Garrapatas/tratamiento farmacológico , Ensayo de Inmunoadsorción Enzimática , Humanos , Ribavirina/uso terapéutico

RESUMEN

BACKGROUND: Toxoplasma gondii is an obligate intracellular parasite that infects humans and other warm-blooded animals. Previous quantitative proteomic analyses of infected host cells revealed that the expression of many host proteins is modulated by T. gondii infection. However, at present limited data are available on the differentially expressed miRNAs (DEMs) associated with the pathology and host immune responses induced by acute and chronic infection with T. gondii in pigs in vivo. In this study, high-throughput sequencing was used to investigate expression profiles of spleen miRNAs at 10, 25 and 50 days post-infection (DPI) in pigs infected with Chinese I genotype strain T. gondii isolated from a dead pig. RESULTS: When compared to the control group, 34, 6 and 86 DEMs were found in spleens of infected pigs at 10, 25 and 50 DPI, respectively. Gene Ontology (GO) enrichment analysis of the target genes of DEMs showed that no GO terms were enriched at 25 DPI, whereas 28 and 241 GO terms, of which two and 215 were sample-specific, were significantly enriched at 10 and 50 DPI, respectively. The top 20 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of the target genes of DEMs included signal transduction, immune system, metabolism and diseases. miRNA-gene network analysis revealed that the DEMs played important roles in the host immune response to T. gondii infection by modulating expression levels of cellular immunity-related cytokines and immune-related C-type lectins. CONCLUSION: Our results not only showed that host miRNA expression is altered by T. gondii but also revealed differences in the regulation of key biological processes and pathways involved in host responses to acute versus chronic T. gondii infection. This will aid future research into miRNA-target interactions during T. gondii infection in pigs and the development of novel therapies against T. gondii.

Asunto(s)

Perfilación de la Expresión Génica/métodos , Redes Reguladoras de Genes , Interacciones Huésped-Parásitos , MicroARNs/genética , Bazo/metabolismo , Toxoplasma/genética , Toxoplasmosis Animal/genética , Enfermedad Aguda , Animales , Enfermedad Crónica , Regulación de la Expresión Génica , Análisis de Secuencia de ARN , Transducción de Señal , Bazo/parasitología , Porcinos , Toxoplasmosis Animal/parasitología