Role of the Microbiome in Aedes spp. Vector Competence: What Do We Know?

Aedes aegypti and Aedes albopictus are the vectors of important arboviruses: dengue fever, chikungunya, Zika, and yellow fever. Female mosquitoes acquire arboviruses by feeding on the infected host blood, thus being able to transmit it to their offspring. The intrinsic ability of a vector to infect itself and transmit a pathogen is known as vector competence. Several factors influence the susceptibility of these females to be infected by these arboviruses, such as the activation of the innate immune system through the Toll, immunodeficiency (Imd), JAK-STAT pathways, and the interference of specific antiviral response pathways of RNAi. It is also believed that the presence of non-pathogenic microorganisms in the microbiota of these arthropods could influence this immune response, as it provides a baseline activation of the innate immune system, which may generate resistance against arboviruses. In addition, this microbiome has direct action against arboviruses, mainly due to the ability of Wolbachia spp. to block viral genome replication, added to the competition for resources within the mosquito organism. Despite major advances in the area, studies are still needed to evaluate the microbiota profiles of Aedes spp. and their vector competence, as well as further exploration of the individual roles of microbiome components in activating the innate immune system.

Natural vertical cotransmission of Dengue virus and Chikungunya virus from Aedes aegypti in Brumado, Bahia, Brazil.

BACKGROUND: Arthropod-borne viruses have recently emerged and are pathogens of various human diseases, including dengue, zika, and chikungunya viruses. METHODS: We collectedAedes aegyptilarvae (N = 20) from Brumado, Bahia, Brazil, and treated and individually preserved the specimens. We analyzed the samples for dengue, zika, and chikungunya viruses using molecular biology methods. RESULTS: We found that 25% (N = 5) and 15% (N = 3) were positive exclusively for dengue and chikungunya viruses, respectively; 15% (N = 3) were coinfected with both. CONCLUSIONS: This is the first report of dengue and chikungunya virus coinfection in A. aegypti larvae.

COVID-19 gastrointestinal manifestations: a systematic review.

INTRODUCTION: The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has greatly challenged public health worldwide. A growing number of studies have reported gastrointestinal (GI) symptoms. We performed a systematic review of GI symptoms associated with coronavirus disease 2019 (COVID-19) as well as of the serum levels of biomarkers related to liver function and lesion in SARS-CoV-2-infected individuals. METHODS: We surveyed relevant articles published in English, Spanish, and Portuguese up to July, 2020 in the PubMed, MEDLINE, SciELO, LILACS, and BVS databases. Moreover, we surveyed potentially important articles in journals such as the NEJM, JAMA, BMJ, Gut, and AJG. RESULTS: This systematic review included 43 studies, including 18,246 patients. Diarrhea was the most common GI symptom, affecting 11.5% of the patients, followed by nausea and vomiting (6.3%) and abdominal pain (2.3%). With regard to clinical severity, 17.5% of the patients were classified as severely ill, whereas 9.8% of them were considered to have a non-severe disease. Some studies showed increased aspartate transaminase and alanine aminotransferase levels in a portion of the 209 analyzed patients and two studies. CONCLUSIONS: Our results suggest that digestive symptoms are common in COVID-19 patients. In addition, alterations in cytolysis biomarkers could also be observed in a lesser proportion, calling attention to the possibility of hepatic involvement in SARS-CoV-2-infected individuals.

Vertical Transmission of Zika Virus (Flaviviridae, Flavivirus) in Amazonian Aedes aegypti (Diptera: Culicidae) Delays Egg Hatching and Larval Development of Progeny.

Zika virus (ZIKV) has emerged as a globally important arbovirus and has been reported from all states of Brazil. The virus is primarily transmitted to humans through the bite of an infective Aedes aegypti (Linnaeus, 1762) or Aedes albopictus (Skuse, 1895). However, it is important to know if ZIKV transmission also occurs from Ae. aegypti through infected eggs to her offspring. Therefore, a ZIKV and dengue virus (DENV) free colony was established from eggs collected in Manaus and maintained until the third-fourth generation in order to conduct ZIKV vertical transmission (VT) experiments which used an infectious bloodmeal as the route of virus exposure. The eggs from ZIKV-infected females were allowed to hatch. The resulting F1 progeny (larvae, pupae, and adults) were quantitative polymerase chain reaction (qPCR) assayed for ZIKV. The viability of ZIKV vertically transmitted to F1 progeny was evaluated by cultivation in C6/36 cells. The effects of ZIKV on immature development of Ae. aegypti was assessed and compared with noninfected mosquitoes. AmazonianAe. aegypti were highly susceptible to ZIKV infection (96.7%), and viable virus passed to their progeny via VT. Moreover, eggs from the ZIKV-infected mosquitoes had a significantly lower hatch rate and the slowest hatching. In addition, the larval development period was slower when compared to noninfected, control mosquitoes. This is the first study to illustrate VT initiated by oral infection of the parental population by using mosquitoes, which originated from the field and a ZIKV strain that is naturally circulating in-country. Additionally, this study suggests that ZIKV present in the Ae. aegypti can modify the mosquito life cycle. The data reported here suggest that VT of ZIKV to progeny from naturally infected females may have a critical epidemiological role in the dissemination and maintenance of the virus circulating in the vector.

Natural vertical cotransmission of Dengue virus and Chikungunya virus from Aedes aegypti in Brumado, Bahia, Brazil

ABSTRACT Background: Arthropod-borne viruses have recently emerged and are pathogens of various human diseases, including dengue, zika, and chikungunya viruses. Methods: We collectedAedes aegyptilarvae (N = 20) from Brumado, Bahia, Brazil, and treated and individually preserved the specimens. We analyzed the samples for dengue, zika, and chikungunya viruses using molecular biology methods. Results: We found that 25% (N = 5) and 15% (N = 3) were positive exclusively for dengue and chikungunya viruses, respectively; 15% (N = 3) were coinfected with both. Conclusions: This is the first report of dengue and chikungunya virus coinfection in A. aegypti larvae.

COVID-19 gastrointestinal manifestations: a systematic review

Abstract INTRODUCTION: The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has greatly challenged public health worldwide. A growing number of studies have reported gastrointestinal (GI) symptoms. We performed a systematic review of GI symptoms associated with coronavirus disease 2019 (COVID-19) as well as of the serum levels of biomarkers related to liver function and lesion in SARS-CoV-2-infected individuals. METHODS: We surveyed relevant articles published in English, Spanish, and Portuguese up to July, 2020 in the PubMed, MEDLINE, SciELO, LILACS, and BVS databases. Moreover, we surveyed potentially important articles in journals such as the NEJM, JAMA, BMJ, Gut, and AJG. RESULTS: This systematic review included 43 studies, including 18,246 patients. Diarrhea was the most common GI symptom, affecting 11.5% of the patients, followed by nausea and vomiting (6.3%) and abdominal pain (2.3%). With regard to clinical severity, 17.5% of the patients were classified as severely ill, whereas 9.8% of them were considered to have a non-severe disease. Some studies showed increased aspartate transaminase and alanine aminotransferase levels in a portion of the 209 analyzed patients and two studies. CONCLUSIONS: Our results suggest that digestive symptoms are common in COVID-19 patients. In addition, alterations in cytolysis biomarkers could also be observed in a lesser proportion, calling attention to the possibility of hepatic involvement in SARS-CoV-2-infected individuals.

The presence of Helicobacter pylori in the liver depends on the Th1, Th17 and Treg cytokine profile of the patient

The hypothesis that Helicobactermight be a risk factor for human liver diseases has arisen after the detection of Helicobacter DNA in hepatic tissue of patients with hepatobiliary diseases. Nevertheless, no explanation that justifies the presence of the bacterium in the human liver has been proposed. We evaluated the presence of Helicobacterin the liver of patients with hepatic diseases of different aetiologies. We prospectively evaluated 147 patients (106 with primary hepatic diseases and 41 with hepatic metastatic tumours) and 20 liver donors as controls. Helicobacter species were investigated in the liver by culture and specific 16S rDNA nested-polymerase chain reaction followed by sequencing. Serum and hepatic levels of representative cytokines of T regulatory cell, T helper (Th)1 and Th17 cell lineages were determined using enzyme linked immunosorbent assay. The data were evaluated using logistic models. Detection of Helicobacter pylori DNA in the liver was independently associated with hepatitis B virus/hepatitis C virus, pancreatic carcinoma and a cytokine pattern characterised by high interleukin (IL)-10, low/absent interferon-γ and decreased IL-17A concentrations (p < 10-3). The bacterial DNA was never detected in the liver of patients with alcoholic cirrhosis and autoimmune hepatitis that are associated with Th1/Th17 polarisation. H. pylori may be observed in the liver of patients with certain hepatic and pancreatic diseases, but this might depend on the patient cytokine profile.