RESUMO
In this work, we determined the diversity and dynamics of the gut virome of infants during the first year of life. Fecal samples were collected monthly, from birth to one year of age, from three healthy children living in a semi-rural village in Mexico. Most of the viral reads were classified into six families of bacteriophages including five dsDNA virus families of the order Caudovirales, with Siphoviridae and Podoviridae being the most abundant. Eukaryotic viruses were detected as early as two weeks after birth and remained present all along the first year of life. Thirty-four different eukaryotic virus families were found, where eight of these families accounted for 98% of all eukaryotic viral reads: Anelloviridae, Astroviridae, Caliciviridae, Genomoviridae, Parvoviridae, Picornaviridae, Reoviridae and the plant-infecting viruses of the Virgaviridae family. Some viruses in these families are known human pathogens, and it is surprising that they were found during the first year of life in infants without gastrointestinal symptoms. The eukaryotic virus species richness found in this work was higher than that observed in previous studies; on average between 7 and 24 virus species were identified per sample. The richness and abundance of the eukaryotic virome significantly increased during the second semester of life, probably because of an increased environmental exposure of infants with age. Our findings suggest an early and permanent contact of infants with a diverse array of bacteriophages and eukaryotic viruses, whose composition changes over time. The bacteriophages and eukaryotic viruses found in these children could represent a metastable virome, whose potential influence on the development of the infant's immune system or on the health of the infants later in life, remains to be investigated.
Assuntos
Vírus de DNA/isolamento & purificação , Trato Gastrointestinal/virologia , Viroma/genética , Bacteriófagos/genética , Bacteriófagos/isolamento & purificação , Vírus de DNA/genética , Fezes/virologia , Gastroenteropatias/virologia , Humanos , Lactente , Recém-Nascido , MéxicoRESUMO
Chikungunya virus (CHIKV) is a reemerging and rapidly spreading pathogen transmitted by mosquitoes. The emergence of new epidemic variants of the virus is associated with genetic evolutionary traits, including duplication of repeated RNA elements in the 3' untranslated region (UTR) that seemingly favor transmission by mosquitoes. The transmission potential of a given variant results from a complex interplay between virus populations and anatomical tissue barriers in the mosquito. Here, we used the wild-type CHIKV Caribbean strain and an engineered mutant harboring a deletion in the 3' UTR to dissect the interactions of virus variants with the anatomical barriers that impede transmission during the replication cycle of the virus in Aedes mosquitoes. Compared to the 3'-UTR mutant, we observed that the wild-type virus had a short extrinsic incubation period (EIP) after an infectious blood meal and was expectorated into mosquito saliva much more efficiently. We found that high viral titers in the midgut are not sufficient to escape the midgut escape barrier. Rather, viral replication kinetics play a crucial role in determining midgut escape and the transmission ability of CHIKV. Finally, competition tests in mosquitoes coinfected with wild-type and mutant viruses revealed that both viruses successfully colonized the midgut, but wild-type viruses effectively displaced mutant viruses during systemic infection due to their greater efficiency of escaping from the midgut into secondary tissues. Overall, our results uncover a link between CHIKV replication kinetics and the effect of bottlenecks on population diversity, as slowly replicating variants are less able to overcome the midgut escape barrier.IMPORTANCE It is well established that selective pressures in mosquito vectors impose population bottlenecks for arboviruses. Here, we used a CHIKV Caribbean lineage mutant carrying a deletion in the 3' UTR to study host-virus interactions in vivo in the epidemic mosquito vector Aedes aegypti We found that the mutant virus had a delayed replication rate in mosquitoes, which lengthened the extrinsic incubation period (EIP) and reduced fitness relative to the wild-type virus. As a result, the mutant virus displayed a reduced capacity to cross anatomical barriers during the infection cycle in mosquitoes, thus reducing the virus transmission rate. Our findings show how selective pressures act on CHIKV noncoding regions to select variants with shorter EIPs that are preferentially transmitted by the mosquito vector.
Assuntos
Aedes/virologia , Febre de Chikungunya/transmissão , Vírus Chikungunya/patogenicidade , Trato Gastrointestinal/virologia , Interações Hospedeiro-Patógeno , Mosquitos Vetores/virologia , Replicação Viral , Animais , Vírus Chikungunya/genética , Feminino , Humanos , Mutação , Carga ViralRESUMO
Recently, a new coronavirus (SARS-CoV-2) was discovered in China. Due to its high level of contagion, it has already reached most countries, quickly becoming a pandemic. Although the most common symptoms are related to breathing problems, SARS-CoV-2 infections also affect the gastrointestinal tract culminating in inflammation and diarrhea. However, the mechanisms related to these enteric manifestations are still not well understood. Evidence shows that the SARS-CoV-2 binds to the angiotensin-converting enzyme receptor 2 (ACE2) in host cells as a viral invasion mechanism and can infect the lungs and the gut. Other viruses have already been linked to intestinal symptoms through binding to ACE2. In turn, this medical hypothesis article conjectures that the ACE2 downregulation caused by the SARS-CoV-2 internalization could lead to decreased activation of the mechanistic target of mTOR with increased autophagy and lead to intestinal dysbiosis, resulting in diarrhea. Besides that, dysbiosis can directly affect the respiratory system through the lungs. Although there are clues to other viruses that modulate the ACE2/gut/lungs axis, including the participation of autophagy and dysbiosis in the development of gastrointestinal symptoms, there is still no evidence of the ACE2/mTOR/autophagy pathway in SARS-CoV-2 infections. Thus, we propose that the new coronavirus causes a change in the intestinal microbiota, which culminates in a diarrheal process through the ACE2/mTOR/autophagy pathway into enterocytes. Our assumption is supported by premises that unregulated intestinal microbiota increases the susceptibility to other diseases and extra-intestinal manifestations, which can even cause remote damage in lungs. These putative connections lead us to suggest and encourage future studies aiming at assessing the aforementioned hypothesis and regulating dysbiosis caused by SARS-CoV-2 infection, in order to confirm the decrease in lung injuries and the improvement in the prognosis of the disease.
Assuntos
Enzima de Conversão de Angiotensina 2/metabolismo , Autofagia , COVID-19/metabolismo , Diarreia/complicações , Disbiose/complicações , SARS-CoV-2 , Serina-Treonina Quinases TOR/metabolismo , COVID-19/complicações , Enterócitos/virologia , Microbioma Gastrointestinal , Trato Gastrointestinal/virologia , Humanos , Intestinos/virologia , Modelos Teóricos , Pandemias , Sistema Renina-AngiotensinaRESUMO
The new coronavirus disease pandemic is defining 2020, with almost 17.5 million infected individuals and 700 thousand deaths up to beginning of August. It is caused by SARS-CoV-2 and the transmission is through the respiratory tract. Those infected may be asymptomatic, present typical symptoms (fever, dry cough and dyspnea), gastrointestinal symptoms (diarrhea, nausea, vomiting and abdominal pain) and viral RNA in stools. The objective of this work was to review the literature related to the prevalence of gastrointestinal symptoms, and to check the possibility of fecal-oral transmission. We searched PubMed® database on COVID-19 and gastrointestinal tract and selected articles using the PRISMA method. We eliminated articles based on titles and abstracts, small number of patients and the mechanism of infection, leaving 14 studies. Comorbidities and laboratory alterations (elevation of hepatic aminotransferases and bilirubin) were related to worsening of the disease. The prevalence of gastrointestinal symptoms ranged from 6.8% to 61.3%, including diarrhea (8.14% to 33.7%), nausea/vomiting (1.53% to 26.4%), anorexia (12.1% to 40.0%) and abdominal pain (0% to 14.5%). The presence of viral RNA in stools was rarely tested, but positive in 0% to 48.1%. The gastrointestinal tract is affected by COVID-19, causing specific symptoms, laboratory alterations and viral presence in the feces. However, the results of prevalence and possibility of fecal-oral transmission were varied, requiring further studies for more assertive conclusions. It is important that healthcare professionals draw attention to this fact, since these changes can help make diagnosis and initiate early treatment.
Assuntos
Infecções por Coronavirus/fisiopatologia , Trato Gastrointestinal/virologia , Pneumonia Viral/fisiopatologia , Betacoronavirus , COVID-19 , Infecções por Coronavirus/transmissão , Fezes/virologia , Trato Gastrointestinal/fisiopatologia , Humanos , Pandemias , Pneumonia Viral/transmissão , SARS-CoV-2RESUMO
Plant viruses have been reported to be common in the gut of human adults, presumably as result of food ingestion. In this work, we report that plant viruses can also be found frequently in the gut and oropharynx of children during their first year of life, even when they are exclusively breast-fed. Fecal and oropharynx samples were collected monthly, from birth to 1 year of age, from three apparently healthy children in a semi-rural community and analyzed by next generation sequencing. In 100% of the fecal samples and 65% of the oropharynx samples at least one plant virus was identified. Tobamoviruses in the Virgaviridae family were by far the most frequently detected, with tropical soda apple mosaic virus, pepper mild mottle virus, and opuntia tobamovirus 2 being the most common species. Seventeen complete virus genomes could be assembled, and phylogenetic analyses showed a large diversity of virus strains circulating in the population. These results suggest that children are continuously exposed to an extensive and highly diverse collection of tobamoviruses. Whether the common presence of plant viruses at an early age influences the infant's immune system, either directly or through interaction with other members of the microbiota, remains to be investigated.
Assuntos
Trato Gastrointestinal/virologia , Orofaringe/virologia , Vírus de Plantas/isolamento & purificação , Tobamovirus/isolamento & purificação , Fezes/virologia , Feminino , Variação Genética , Genoma Viral/genética , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Recém-Nascido , Masculino , Filogenia , Vírus de Plantas/classificação , Vírus de Plantas/genética , Tobamovirus/classificação , Tobamovirus/genéticaRESUMO
ABSTRACT The new coronavirus disease pandemic is defining 2020, with almost 17.5 million infected individuals and 700 thousand deaths up to beginning of August. It is caused by SARS-CoV-2 and the transmission is through the respiratory tract. Those infected may be asymptomatic, present typical symptoms (fever, dry cough and dyspnea), gastrointestinal symptoms (diarrhea, nausea, vomiting and abdominal pain) and viral RNA in stools. The objective of this work was to review the literature related to the prevalence of gastrointestinal symptoms, and to check the possibility of fecal-oral transmission. We searched PubMed® database on COVID-19 and gastrointestinal tract and selected articles using the PRISMA method. We eliminated articles based on titles and abstracts, small number of patients and the mechanism of infection, leaving 14 studies. Comorbidities and laboratory alterations (elevation of hepatic aminotransferases and bilirubin) were related to worsening of the disease. The prevalence of gastrointestinal symptoms ranged from 6.8% to 61.3%, including diarrhea (8.14% to 33.7%), nausea/vomiting (1.53% to 26.4%), anorexia (12.1% to 40.0%) and abdominal pain (0% to 14.5%). The presence of viral RNA in stools was rarely tested, but positive in 0% to 48.1%. The gastrointestinal tract is affected by COVID-19, causing specific symptoms, laboratory alterations and viral presence in the feces. However, the results of prevalence and possibility of fecal-oral transmission were varied, requiring further studies for more assertive conclusions. It is important that healthcare professionals draw attention to this fact, since these changes can help make diagnosis and initiate early treatment.
RESUMO Com quase 17,5 milhões de infectados e 700 mil mortos até o início de agosto no mundo, a pandemia do novo coronavírus está marcando o ano de 2020. O agente causador da doença é o vírus SARS-CoV-2, e a transmissão é por via respiratória. Os infectados podem ser assintomáticos, apresentar sintomas típicos (febre, tosse seca e dispneia), sintomas gastrintestinais (diarreia, náusea, vômito e dor abdominal) e RNA viral nas fezes. O objetivo deste trabalho foi revisar a literatura relacionada com a prevalência dos sintomas gastrintestinais, e verificar se é possível a transmissão fecal-oral da doença. Fizemos uma pesquisa na base de dados PubMed® sobre a COVID-19 e o trato gastrintestinal, selecionando artigos pelo método PRISMA. Eliminamos artigos com base em títulos e resumos, quantidade pequena de pacientes e sobre mecanismo de infecção, restando 14 estudos. Comorbidades e alterações laboratoriais (elevação de aminotransferases hepáticas e bilirrubina) foram relacionadas com piora da doença. A prevalência de sintomas gastrintestinais variou entre 6,8% e 61,3%, sendo eles diarreia (8,14% a 33,7%), náusea/vômito (1,53% a 26,4%), anorexia (12,1% a 40,0%) e dor abdominal (0% a 14,5%). A presença do RNA viral foi pouco testada, mas foi positiva entre 0% a 48,1%. O trato gastrintestinal é muito acometido pela COVID-19, provocando sintomas específicos, alterações laboratoriais e presença viral nas fezes. Contudo, os resultados de prevalência e a possibilidade de transmissão fecal-oral foram variados, necessitando de estudos maiores para conclusões mais assertivas. É importante a atenção de profissionais da saúde a isso, visto que essas alterações podem ajudar no diagnóstico e a iniciar tratamento precoce.
Assuntos
Humanos , Pneumonia Viral/fisiopatologia , Infecções por Coronavirus/fisiopatologia , Trato Gastrointestinal/virologia , Pneumonia Viral/transmissão , Infecções por Coronavirus/transmissão , Trato Gastrointestinal/fisiopatologia , Fezes/virologia , Pandemias , Betacoronavirus , SARS-CoV-2 , COVID-19RESUMO
Multiplex polymerase chain reaction (PCR) platforms have enhanced understanding of intestinal pathogens in low- and middle-income countries (LMICs). However, few such studies have been performed in Latin America, where poverty, poor sanitation, and undernutrition persist. Multiplex PCR (BioFire, Salt Lake City, UT) was used to identify viral, bacterial, and parasitic pathogens in stool collected on day 1 and 31 from children aged 6 to 35 months with acute, non-bloody diarrhea in two locations (rural and urban) in Guatemala. We analyzed correlation between pathogens and clinical, demographic, and socioeconomic variables; described patterns of pathogen acquisition, persistence, and clearance over the 30-day period; and calculated population attributable fractions (PAFs) for diarrheal causation for individual pathogens. We analyzed 316 subjects (144 urban; 172 rural) enrolled between March 2015 and January 2016. Rural subjects had significantly more malnutrition, animal exposure, and unimproved water/sanitation infrastructure. The majority of subjects had multiple pathogens/sample (4.8 rural and 2.7 urban). Few meaningful correlates were identified between individual pathogens and clinical, demographic, or environmental variables. Escherichia coli pathotypes, Shigella, Campylobacter, and Giardia had high rates of persistence between initial and 30-day follow-up. Statistically significant adjusted PAFs were identified for Campylobacter (14.9%, 95% CI: 3.2-23.1), norovirus (10.2%, 95% CI: 0.4-17.1), sapovirus (7.6%, 95% CI: 2.3-10.9), and adenovirus 40/41 (5.6%, 95% CI: 0.3-8.7). These observations further characterize the diversity and complexity of enteric pathogens in children in LMICs. Patterns of chronic symptomatic and asymptomatic infection among Latin American children are similar to those observed in other LMIC regions. Findings have direct implications for practitioners treating individuals with acute infectious diarrhea and should inform regional public health strategies.
Assuntos
Diarreia/diagnóstico , Reação em Cadeia da Polimerase Multiplex , População Rural , População Urbana , Doença Aguda , Animais , Bactérias/genética , Bactérias/patogenicidade , Pré-Escolar , Coinfecção/diagnóstico , Coinfecção/microbiologia , Coinfecção/parasitologia , Coinfecção/virologia , Diarreia/microbiologia , Diarreia/parasitologia , Diarreia/virologia , Feminino , Trato Gastrointestinal/microbiologia , Trato Gastrointestinal/parasitologia , Trato Gastrointestinal/virologia , Humanos , Lactente , Masculino , Parasitos/genética , Parasitos/patogenicidade , Vírus/genética , Vírus/patogenicidadeRESUMO
Dengue virus (DENV) is an arbovirus transmitted to humans by Aedes mosquitoes1. In the insect vector, the small interfering RNA (siRNA) pathway is an important antiviral mechanism against DENV2-5. However, it remains unclear when and where the siRNA pathway acts during the virus cycle. Here, we show that the siRNA pathway fails to efficiently silence DENV in the midgut of Aedes aegypti although it is essential to restrict systemic replication. Accumulation of DENV-derived siRNAs in the midgut reveals that impaired silencing results from a defect downstream of small RNA biogenesis. Notably, silencing triggered by endogenous and exogenous dsRNAs remained effective in the midgut where known components of the siRNA pathway, including the double-stranded RNA (dsRNA)-binding proteins Loquacious and r2d2, had normal expression levels. We identified an Aedes-specific paralogue of loquacious and r2d2, hereafter named loqs2, which is not expressed in the midgut. Loqs2 interacts with Loquacious and r2d2 and is required to control systemic replication of DENV and also Zika virus. Furthermore, ectopic expression of Loqs2 in the midgut of transgenic mosquitoes is sufficient to restrict DENV replication and dissemination. Together, our data reveal a mechanism of tissue-specific regulation of the mosquito siRNA pathway controlled by Loqs2.
Assuntos
Aedes/metabolismo , Proteínas de Transporte/metabolismo , Vírus da Dengue/metabolismo , Expressão Ectópica do Gene , RNA de Cadeia Dupla/metabolismo , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/metabolismo , Aedes/genética , Aedes/virologia , Animais , Animais Geneticamente Modificados , Antivirais/metabolismo , Antivirais/farmacologia , Proteínas de Transporte/genética , Replicação do DNA , Dengue/virologia , Vírus da Dengue/efeitos dos fármacos , Vírus da Dengue/genética , Vírus da Dengue/patogenicidade , Proteínas de Drosophila , Feminino , Trato Gastrointestinal/virologia , Inativação Gênica , Interações Hospedeiro-Patógeno , Mosquitos Vetores/virologia , RNA Viral/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/farmacologia , Replicação Viral , Zika virus/metabolismoRESUMO
BACKGROUND: Digestion of blood in the midgut of Aedes aegypti results in the release of pro-oxidant molecules that can be toxic to the mosquito. We hypothesized that after a blood meal, the antioxidant capacity of the midgut is increased to protect cells against oxidative stress. Concomitantly, pathogens present in the blood ingested by mosquitoes, such as the arboviruses Dengue and Zika, also have to overcome the same oxidative challenge, and the antioxidant program induced by the insect is likely to influence infection status of the mosquito and its vectorial competence. METHODOLOGY/PRINCIPAL FINDINGS: We found that blood-induced catalase mRNA and activity in the midgut peaked 24 h after feeding and returned to basal levels after the completion of digestion. RNAi-mediated silencing of catalase (AAEL013407-RB) reduced enzyme activity in the midgut epithelia, increased H2O2 leakage and decreased fecundity and lifespan when mosquitoes were fed H2O2. When infected with Dengue 4 and Zika virus, catalase-silenced mosquitoes showed no alteration in infection intensity (number of plaque forming units/midgut) 7 days after the infectious meal. However, catalase knockdown reduced Dengue 4, but not Zika, infection prevalence (percent of infected midguts). CONCLUSION/SIGNIFICANCE: Here, we showed that blood ingestion triggers an antioxidant response in the midgut through the induction of catalase. This protection facilitates the establishment of Dengue virus in the midgut. Importantly, this mechanism appears to be specific for Dengue because catalase silencing did not change Zika virus prevalence. In summary, our data suggest that redox balance in the midgut modulates mosquito vectorial competence to arboviral infections.
Assuntos
Aedes/enzimologia , Catalase/metabolismo , Vírus da Dengue/fisiologia , Dengue/transmissão , Insetos Vetores/enzimologia , Zika virus/fisiologia , Aedes/fisiologia , Aedes/virologia , Animais , Sangue , Catalase/genética , Feminino , Trato Gastrointestinal/enzimologia , Trato Gastrointestinal/virologia , Peróxido de Hidrogênio/análise , Peróxido de Hidrogênio/metabolismo , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Insetos Vetores/fisiologia , Insetos Vetores/virologia , Estresse Oxidativo , Interferência de RNA , Coelhos , Infecção por Zika virus/transmissãoRESUMO
HIV infection induces alterations in almost all immune cell populations, mainly in CD4+ T cells, leading to the development of opportunistic infections. The gut-associated lymphoid tissue (GALT) constitutes the most important site for viral replication, because the main target cells, memory T-cells, reside in this tissue. It is currently known that alterations in GALT are critical during the course of the infection, as HIV-1 induces loss of tissue integrity and promotes translocation of microbial products from the intestinal lumen to the systemic circulation, leading to a persistent immune activation state and immune exhaustion. Although antiretroviral treatment decreases viral load and substantially improves the prognosis of the infection, the alterations in GALT remains, having a great impact on the ability to establish effective immune responses. This emphasizes the importance of developing new therapeutic alternatives that may promote structural and functional integrity of this tissue. In this regard, therapy with probiotics/prebiotics has beneficial effects in GALT, mainly in syndromes characterized by intestinal dysbiosis, including the HIV-1 infection. In these patients, the consumption of probiotics/prebiotics decreased microbial products in plasma and CD4+ T cell activation, increased CD4+ T cell frequency, in particular Th17, and improved the intestinal flora. In this review, the most important findings on the potential impact of the probiotics/prebiotics therapy are discussed.