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      Establishment of a murine model of congenital toxoplasmosis and validation of a qPCR assay to assess the parasite load in maternal and fetal tissues


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          Toxoplasma gondii is the causative agent of toxoplasmosis, a disease that affects warm-blooded animals and one third of the human population worldwide. Pregnant women who have never been exposed to the parasite constitute an important risk group, as infection during pregnancy often leads to congenital toxoplasmosis, the most severe form of the disease. Current therapy for toxoplasmosis is the same as it was 50 years ago and has little or no effect when vertical transmission occurs. Therefore, it is urgent to develop new strategies to prevent mother-to-fetus transmission. The implementation of experimental animal models of congenital toxoplasmosis that reproduces the transmission rates and clinical signs in humans opens an avenue of possibilities to interfere in the progression of the disease. In addition, knowing the parasite load in maternal and fetal tissues after infection, which may be related to organ abnormalities and disease outcome, is another important step in designing a promising intervention strategy. Therefore, we implemented here a murine model of congenital toxoplasmosis with outbred Swiss Webster mice infected intravenously with tachyzoites of the ME49 strain of T. gondii that mimics the frequency of transmission of the parasite, as well as important clinical signs of human congenital toxoplasmosis, such as macrocephaly, in addition to providing a highly sensitive quantitative real-time PCR assay to assess parasite load in mouse tissues. As the disease is not restricted to humans, also affecting several domestic animals, including companion animals and livestock, they can also benefit from the model presented in this study.

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          Most cited references64

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          Persistence of SARS-CoV-2 in Water and Wastewater

          Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA is frequently detected in the feces of infected individuals. While infectious SARS-CoV-2 has not previously been identified in wastewater, infectious SARS-CoV-2 has been isolated from the feces of at least one patient, raising concerns about the presence of infectious SARS-CoV-2 in wastewater. The fate and inactivation characteristics of SARS-CoV-2 in water and wastewater are unknown, with current inactivation estimates based on surrogate models. In this study, the persistence of SARS-CoV-2 infectivity and RNA signal was determined in water and wastewater. The times for 90% reduction (T 90) of viable SARS-CoV-2 in wastewater and tap water at room temperature were 1.5 and 1.7 days, respectively. In high-starting titer (105 TCID50 mL–1) experiments, infectious virus persisted for the entire 7-day sampling time course. In wastewater at 50 and 70 °C, the observed T 90 values for infectious SARS-CoV-2 were decreased to 15 and 2 min, respectively. SARS-CoV-2 RNA was found to be significantly more persistent than infectious SARS-CoV-2, indicating that the environmental detection of RNA alone does not substantiate risk of infection.
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            Epidemiology of and diagnostic strategies for toxoplasmosis.

            The apicomplexan parasite Toxoplasma gondii was discovered a little over 100 years ago, but knowledge of its biological life cycle and its medical importance has grown in the last 40 years. This obligate intracellular parasite was identified early as a pathogen responsible for congenital infection, but its clinical expression and the importance of reactivations of infections in immunocompromised patients were recognized later, in the era of organ transplantation and HIV infection. Recent knowledge of host cell-parasite interactions and of parasite virulence has brought new insights into the comprehension of the pathophysiology of infection. In this review, we focus on epidemiological and diagnostic aspects, putting them in perspective with current knowledge of parasite genotypes. In particular, we provide critical information on diagnostic methods according to the patient's background and discuss the implementation of screening tools for congenital toxoplasmosis according to health policies.
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              Management of Toxoplasma gondii infection during pregnancy.

              Acute infection with Toxoplasma gondii during pregnancy and its potentially tragic outcome for the fetus and newborn continue to occur in the United States, as well as worldwide, despite the fact that it can be prevented. The infection can be acquired through ingestion of infected, undercooked meat or contaminated food or water. Transmission to the fetus occurs almost solely in women who acquire their primary infection during gestation and can result in visual and hearing loss, mental and psychomotor retardation, seizures, hematological abnormalities, hepatosplenomegaly, or death. Systematic education and serological screening of pregnant women are the most reliable and currently available strategies for the prevention, diagnosis, and early treatment of the infection in the offspring; this is largely because toxoplasmosis in pregnant women most often goes unrecognized. Treatment of the infection in the fetus and infant during the first year of life has been demonstrated to significantly improve the clinical outcome.

                Author and article information

                Front Microbiol
                Front Microbiol
                Front. Microbiol.
                Frontiers in Microbiology
                Frontiers Media S.A.
                27 February 2023
                : 14
                : 1124378
                [1] 1Laboratório de Biologia Estrutural, Instituto Oswaldo Cruz , Fiocruz, Rio de Janeiro, Brazil
                [2] 2Plataforma de PCR em Tempo Real RPT09A, Laboratório de Virologia Molecular, Instituto Oswaldo Cruz , Fiocruz, Rio de Janeiro, Brazil
                [3] 3Department of Biological Science, Border Biomedical Research Center, The University of Texas at El Paso , El Paso, TX, United States
                [4] 4Laboratório de Biologia Celular, Instituto Oswaldo Cruz , Fiocruz, Rio de Janeiro, Brazil
                Author notes

                Edited by: Julie M. Moore, University of Florida, United States

                Reviewed by: Ruojun Wang, Princeton University, United States; Mário Cézar Oliveira, Federal University of Uberlândia, Brazil; Murilo Vieira Silva, Federal University of Uberlândia, Brazil

                *Correspondence: Otacilio C. Moreira, otacilio@ 123456ioc.fiocruz.br

                These authors have contributed equally to this work

                This article was submitted to Infectious Agents and Disease, a section of the journal Frontiers in Microbiology

                Copyright © 2023 Souza, Farani, Ferreira, Barbosa, Menna-Barreto, Moreira and Mariante.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

                : 15 December 2022
                : 06 February 2023
                Page count
                Figures: 7, Tables: 1, Equations: 0, References: 64, Pages: 12, Words: 9198
                This research was funded by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) – ARC E-26/211.466/2019, Apoio a Projetos Temáticos no Estado do Rio de Janeiro SEI-260003/001351/2020, and Programa Redes de Pesquisa em Saúde no Estado do Rio de Janeiro E-26/010.002419/2019; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) – Finance Code 001; and Instituto Oswaldo Cruz – Fundação Oswaldo Cruz (IOC-Fiocruz).
                Original Research

                Microbiology & Virology
                toxoplasma gondii,congenital toxoplasmosis,vertical transmission,outbred murine model,swiss webster,parasite load,quantitative real-time pcr


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