Gasdermin-D activation by SARS-CoV-2 triggers NET and mediate COVID-19 immunopathology.

BACKGROUND: The release of neutrophil extracellular traps (NETs) is associated with inflammation, coagulopathy, and organ damage found in severe cases of COVID-19. However, the molecular mechanisms underlying the release of NETs in COVID-19 remain unclear. OBJECTIVES: We aim to investigate the role of the Gasdermin-D (GSDMD) pathway on NETs release and the development of organ damage during COVID-19. METHODS: We performed a single-cell transcriptome analysis in public data of bronchoalveolar lavage. Then, we enrolled 63 hospitalized patients with moderate and severe COVID-19. We analyze in blood and lung tissue samples the expression of GSDMD, presence of NETs, and signaling pathways upstreaming. Furthermore, we analyzed the treatment with disulfiram in a mouse model of SARS-CoV-2 infection. RESULTS: We found that the SARS-CoV-2 virus directly activates the pore-forming protein GSDMD that triggers NET production and organ damage in COVID-19. Single-cell transcriptome analysis revealed that the expression of GSDMD and inflammasome-related genes were increased in COVID-19 patients. High expression of active GSDMD associated with NETs structures was found in the lung tissue of COVID-19 patients. Furthermore, we showed that activation of GSDMD in neutrophils requires active caspase1/4 and live SARS-CoV-2, which infects neutrophils. In a mouse model of SARS-CoV-2 infection, the treatment with disulfiram inhibited NETs release and reduced organ damage. CONCLUSION: These results demonstrated that GSDMD-dependent NETosis plays a critical role in COVID-19 immunopathology and suggests GSDMD as a novel potential target for improving the COVID-19 therapeutic strategy.

The Importance of Coordinated Actions in Preventing the Spread of Yellow Fever to Human Populations: The Experience from the 2016-2017 Yellow Fever Outbreak in the Northeastern Region of São Paulo State.

Yellow fever (YF) is a zoonotic arthropod-borne disease that is caused by the yellow fever virus (YFV) and characterized by a sylvatic and urban cycle. Its most severe presentation is manifested as a hemorrhagic disease, and it has been responsible for thousands of deaths in the last decades. This study describes the public health approaches taken to control the 2016-2017 YF outbreak in nonhuman primates (NHPs) that took place in the northeastern region of São Paulo state, Brazil. NHPs recovered from the field were necropsied, and YF diagnoses were made at the Laboratory of Molecular Virology, Ribeirão Preto Medical School and the Center of Pathology, Adolfo Lutz Institute of São Paulo. NHP samples were inoculated into Vero cells for YFV isolation. RNA extraction was performed directly from NHP tissues and tested by RT-qPCR. YFV-positive samples were confirmed by sequencing. Based on the rapid RT-qPCR results, surveillance actions were implemented in the entire region. Confirmatory histopathology and immunohistochemistry for YFV were also performed. Among nine NHPs, gross hepatic involvement was observed in six animals, five of which were YFV-RT-qPCR-positive. One YFV was isolated from the serum of an infant NHP. YFV RNA sequences diverged from the virus responsible for the last epizootic that occurred in São Paulo state, but it was similar to the current Brazilian epizootic. Public health actions included dissemination of information on YF transmission, investigation of the probable location of NHP infection, characterization of the environment, and subsequent creation of the blueprint from which prevention and control measures were implemented. The YFV sylvatic cycle occurred in the periurban areas of the northeastern region of São Paulo state, but no human cases were reported during this period, showing that integrated actions between human, animal, and environmental health professionals were critical to restrain the virus to the sylvatic cycle.

Enzyme-linked immunosorbent assay using recombinant envelope protein 2 antigen for diagnosis of Chikungunya virus.

BACKGROUND: Chikungunya (CHIKV) virus is an important mosquito-borne virus causing outbreaks of acute febrile illness with arthropathy. The detection of specific antibodies against CHIKV is used for diagnosis after the acute viremic phase of the disease. However, a major challenge for serologic diagnosis of CHIKV and other alphaviruses is the cross-reactivity of antibodies to common antigens among these viruses. In the present study, we have developed an enzyme-linked immunosorbend assay using a recombinant envelope protein 2 of CHIKV produced in Escherichia coli system, as a capture antigen. RESULTS: High titers (1600 to 12,800) of anti-CHIKV antibodies were detected in human sera analyzed by the CHIKV assay, suggesting it may detect low levels of the antibodies presence. On the other side, cross-reactivity was not observed in mouse hyperimmune sera to Mayaro virus and other alphaviruses analyzed by the CHIKV immunosorbend assay, suggesting it is a CHIKV-specific test. Fifty-nine human serum samples of CHIKV infection suspected cases were tested for immunoglobulin G (IgG) and M (IgM) antibodies detection using the CHIKV immunosorbend assay. A total of 44% (26/59) of samples were positive for IgG to CHIKV, determining 89.66% sensitivity and 100% specificity when the assay is compared to a CHIKV-specific neutralization assay. In addition, 40.6% (24/59) of samples were positive for IgM, determining 92.48% sensitivity and 79.04% specificity by a Bayesian method in the absence of a gold standard. Moreover, CHIKV immunosorbend assay showed similar sensibilities to a commercial immunochromatography assay (Lumiquick, USA) for CHIKV IgG and IgM detection. CONCLUSION: In short, we have developed a rapid, simple, specific and sensitive CHIKV immunosorbend assay for IgG and IgM detection and our results showed potential applicability on the diagnosis of infections by this virus.

Expression Profiles of Cytokine mRNAs in the Pleural Fluid Reveal Differences Among Tuberculosis, Malignancies, and Pneumonia-Exudative Pleural Effusions.

INTRODUCTION: Tuberculosis (TB) and malignant diseases are the most common causes of lymphocytic pleural effusion in adults. Serum and pleural fluid cytokine levels have been analyzed to help in the differential diagnosis, but with limited results. PURPOSE: This study investigates transcription levels of selected cytokine genes in pleural effusion of patients under investigation for TB. METHODS: This was a prospective study that included adult patients under investigation for pleural effusion in Brazil. The expression of 19 cytokine genes was analyzed by RT-qPCR. RESULTS: The majority of cytokine-related genes expressed in pleural fluid of TB patients were similar in non-TB patients, except for RORA and RORC genes, which showed a statistically higher level in TB. All cytokines in the Th17 pattern were induced in TB patients' pleural fluid. Patients with malignant pleural effusion expressed higher levels of IFN-α1, IFN-ß1, TNF-α, IL-4 and IL-6, and suppression of TGFß-1. CONCLUSION: There is still a lot to understand about the cytokine roles in the pro- and anti-inflammatory environment of exudative pleural effusions. The data presented here showed an increased expression of Th17 pattern cytokines genes in TB patients that could be used as markers to differentiate tuberculous pleuritis from other common causes of exudative pleural effusion.

Breastfeeding by chikungunya virus-infected dams confers resistance to challenge in the offspring.

Vertical transmission of Chikungunya virus (CHIKV) has been reported in humans, but the transmission routes have not been completely understood, and experimental animal models are needed to enable detailed investigation of the transmission and pathogenesis of congenital infections. The intertwining of immune response and virus components at the gestation/breastfeeding interfaces between mother and fetus/newborn may have effects during the offspring development. An experimental model of CHIKV was established by infecting pregnant BALB/c female mice that enabled confirmation that dams inoculated up to the 10th gestational day transmit CHIKV transplacentally to approximately 8.4% of the fetuses, resulting in severe teratogenic effects. CHIKV neutralizing antibodies were detected in sera from adult mice born to healthy females and breastfed by CHIKV-infected dams, while no neutralization was detected in sera from animals born to CHIKV-infected dams. Moreover, adult mice born to healthy dams and cross-fostered for breastfeeding by CHIKV-infected dams were resistant to challenge with CHIKV on the 90th day after birth. The animals also had reduced viral loads in brain and spleen as compared to controls. There was expression of fluorescent CHIKV non-structural protein, and detection of viral RNA by RT-PCR in breast tissue from infected dams. CHIKV RNA and proteins were also detected in breast milk retrieved from the stomachs of recently fed newborns. The experimental results were also complemented by the finding of CHIKV RNA in 6% of colostrum samples from healthy lactating women in a CHIKV-endemic area. Breastfeeding induces immune protection to challenge with CHIKV in mice.

Risk of Zika virus transmission by blood donations in Brazil.

BACKGROUND: Zika, a disease caused by Zika virus infections, has recently emerged and caused outbreaks in many parts of the world. The clinical manifestations of Zika are usually mild, mostly presenting as an exanthematic febrile disease, but on some occasions, it might be associated with microcephaly after intrauterine infection, and Guillain-Barré Syndrome. Zika virus is primarily transmitted by mosquito bites, but other means of transmission have been described, and potential risk for blood transmission has been reported in French Polynesia and Brazil. METHODS: To investigate the risk of Zika virus infection after a blood transfusion in an area of Brazil where a possible transmission by a platelet concentrate has been described. Using a mini-pool format, 1857 blood donations were evaluated by real-time reverse transcriptase polymerase chain reaction designed to detect Zika virus RNA. RESULTS: After testing samples individually from positive mini-pools, the prevalence of Zika virus RNA was only 0.16%, a result probably associated to the low circulation of this virus in the study area. In addition, it was evident that the implementation of post-surveillance programs is important to detect Zika virus infections in blood donors, as the post-donation surveillance program detected two blood donors with the disease in this study. CONCLUSION: This study shows that the risk for Zika virus transmission by blood transfusion is real, even in regions with a low circulation of the disease, but the combination of the detection of Zika virus RNA by polymerase chain reaction and post-donation surveillance might reduce the risk of transmission by blood transfusions.

Sensitivity and detection of chikungunya viral genetic material using several PCR-based approaches.

INTRODUCTION:: Chikungunya fever is a condition resulting from infection by chikungunya virus (CHIKV), an Aedes sp.-transmitted virus. This disease has been diagnosed in thousands of cases in the Americas, particularly in Brazil, in recent years, and there is an ongoing epidemic of chikungunya fever in Brazil that began in 2014. Clinical diagnosis is difficult; only a few cases have been confirmed by laboratory tests due to the low number of specific, efficient tests available for virus or antibody detection. Here, we aimed to evaluate different polymerase chain reaction (PCR) approaches for detection of CHIKV genetic material. METHODS:: Specific primers and probes within the viral capsid gene region were designed for this work. To evaluate the analytic sensitivity of detection, human sera were spiked with serial dilutions of the viral stock. Several PCR protocols were performed to investigate the sensitivity of CHIKV RNA detection in serum dilutions ranging from 106 to 1 PFU equivalents. RESULTS:: The technique showing the greatest sensitivity was a real-time PCR assay using specific probes that could detect the genetic material of the virus at all dilutions, followed by conventional PCR. Digital PCR showed low sensitivity and was much more expensive than other technologies. Digital PCR should be used for specific purposes other than clinical diagnosis. CONCLUSIONS:: Although quantitative PCR using probes was more expensive than the use of intercalating dyes or conventional PCR, it had the highest sensitivity out of all tested PCR approaches.

Will Mayaro virus be responsible for the next outbreak of an arthropod-borne virus in Brazil?

Mayaro virus is an alphavirus from the Togaviridae family and is transmitted mainly by Hemagogus mosquitoes. This virus circulates in high-density tropical forests or rural areas of Central and South America causing a disease characterized by high-grade fever, maculopapular skin rash and marked arthralgia that, in some patients, can persist for long periods after infection and may be misinterpreted as chikungunya. Although only a few outbreaks involving this virus have been reported, in the last years the number of Mayaro virus infections has increased in the central and northern regions of Brazil. In this review, we describe the reported prevalence of this infection over the years and discuss the circumstances that can contribute to the establishment of an urban mayaro virus epidemic in Brazil and the problems encountered with the specific diagnosis, especially the antigenic cross-reactivity of this pathogen with other viruses of the same family.

First Complete Genome Sequence of Zika Virus (Flaviviridae, Flavivirus) from an Autochthonous Transmission in Brazil.

We report here the genome sequence of Zika virus, strain ZikaSPH2015, containing all structural and nonstructural proteins flanked by the 5' and 3' untranslated region. It was isolated in São Paulo state, Brazil, in 2015, from a patient who received a blood transfusion from an asymptomatic donor at the time of donation.

Complete Genome Sequence of Mayaro Virus (Togaviridae, Alphavirus) Strain BeAr 20290 from Brazil.

We report here the complete genome sequence of Mayaro virus strain BeAr 20290 isolated from Haemagogus mosquitoes in 1960. The sequence presented here includes all nonstructural and structural proteins and the 5'- and 3'-untranslated (UTR) regions.

Dengue vaccines: what we know, what has been done, but what does the future hold?

Dengue, a disease caused by any of the four serotypes of dengue viruses, is the most important arthropod-borne viral disease in the world in terms of both morbidity and mortality. The infection by these viruses induces a plethora of clinical manifestations ranging from asymptomatic infections to severe diseases with involvement of several organs. Severe forms of the disease are more frequent in secondary infections by distinct serotypes and, consequently, a dengue vaccine must be tetravalent. Although several approaches have been used on the vaccine development, no vaccine is available against these viruses, especially because of problems on the development of a tetravalent vaccine. Here, we describe briefly the vaccine candidates available and their ability to elicit a protective immune response. We also discuss the problems and possibilities of any of the vaccines in final development stage reaching the market for human use.

The Attenuated Live Yellow Fever Virus 17D Infects the Thymus and Induces Thymic Transcriptional Modifications of Immunomodulatory Genes in C57BL/6 and BALB/C Mice.

Thymus is involved in induction of self-tolerance in T lymphocytes, particularly due to Aire activity. In peripheral tissues, Treg cells and immunomodulatory molecules, like the major histocompatibility complex (MHC) class Ib molecules, are essential for maintenance of autotolerance during immune responses. Viral infections can trigger autoimmunity and modify thymic function, and YFV17D immunization has been associated with the onset of autoimmunity, being contraindicated in patients with thymic disorders. Aiming to study the influence of YFV17D immunization on the transcriptional profiles of immunomodulatory genes in thymus, we evaluated the gene expression of AIRE, FOXP3, H2-Q7 (Qa-2/HLA-G), H2-T23 (Qa-1/HLA-E), H2-Q10, and H2-K1 following immunization with 10,000 LD50 of YFV17D in C57BL/6 and BALB/c mice. The YFV17D virus replicated in thymus and induced the expression of H2-Q7 (Qa-2/HLA-G) and H2-T23 (Qa-1/HLA-E) transcripts and repressed the expression of AIRE and FOXP3. Transcriptional expression varied according to tissue and mouse strain analyzed. Expression of H2-T23 (Qa-1/HLA-E) and FOXP3 was induced in thymus and liver of C57BL/6 mice, which exhibited defective control of viral load, suggesting a higher susceptibility to YFV17D infection. Since the immunization with YFV17D modulated thymus gene expression in genetically predisposed individuals, the vaccine may be related to the onset of autoimmunity disorders.

Risk of Zika virus transmission by blood donations in Brazil

ABSTRACT Background: Zika, a disease caused by Zika virus infections, has recently emerged and caused outbreaks in many parts of the world. The clinical manifestations of Zika are usually mild, mostly presenting as an exanthematic febrile disease, but on some occasions, it might be associated with microcephaly after intrauterine infection, and Guillain-Barré Syndrome. Zika virus is primarily transmitted by mosquito bites, but other means of transmission have been described, and potential risk for blood transmission has been reported in French Polynesia and Brazil. Methods: To investigate the risk of Zika virus infection after a blood transfusion in an area of Brazil where a possible transmission by a platelet concentrate has been described. Using a mini-pool format, 1857 blood donations were evaluated by real-time reverse transcriptase polymerase chain reaction designed to detect Zika virus RNA. Results: After testing samples individually from positive mini-pools, the prevalence of Zika virus RNA was only 0.16%, a result probably associated to the low circulation of this virus in the study area. In addition, it was evident that the implementation of post-surveillance programs is important to detect Zika virus infections in blood donors, as the post-donation surveillance program detected two blood donors with the disease in this study. Conclusion: This study shows that the risk for Zika virus transmission by blood transfusion is real, even in regions with a low circulation of the disease, but the combination of the detection of Zika virus RNA by polymerase chain reaction and post-donation surveillance might reduce the risk of transmission by blood transfusions.

Will Mayaro virus be responsible for the next outbreak of an arthropod-borne virus in Brazil?

Abstract Mayaro virus is an alphavirus from the Togaviridae family and is transmitted mainly by Hemagogus mosquitoes. This virus circulates in high-density tropical forests or rural areas of Central and South America causing a disease characterized by high-grade fever, maculopapular skin rash and marked arthralgia that, in some patients, can persist for long periods after infection and may be misinterpreted as chikungunya. Although only a few outbreaks involving this virus have been reported, in the last years the number of Mayaro virus infections has increased in the central and northern regions of Brazil. In this review, we describe the reported prevalence of this infection over the years and discuss the circumstances that can contribute to the establishment of an urban mayaro virus epidemic in Brazil and the problems encountered with the specific diagnosis, especially the antigenic cross-reactivity of this pathogen with other viruses of the same family.

Sensitivity and detection of chikungunya viral genetic material using several PCR-based approaches

Abstract INTRODUCTION: Chikungunya fever is a condition resulting from infection by chikungunya virus (CHIKV), an Aedes sp.-transmitted virus. This disease has been diagnosed in thousands of cases in the Americas, particularly in Brazil, in recent years, and there is an ongoing epidemic of chikungunya fever in Brazil that began in 2014. Clinical diagnosis is difficult; only a few cases have been confirmed by laboratory tests due to the low number of specific, efficient tests available for virus or antibody detection. Here, we aimed to evaluate different polymerase chain reaction (PCR) approaches for detection of CHIKV genetic material. METHODS: Specific primers and probes within the viral capsid gene region were designed for this work. To evaluate the analytic sensitivity of detection, human sera were spiked with serial dilutions of the viral stock. Several PCR protocols were performed to investigate the sensitivity of CHIKV RNA detection in serum dilutions ranging from 106 to 1 PFU equivalents. RESULTS: The technique showing the greatest sensitivity was a real-time PCR assay using specific probes that could detect the genetic material of the virus at all dilutions, followed by conventional PCR. Digital PCR showed low sensitivity and was much more expensive than other technologies. Digital PCR should be used for specific purposes other than clinical diagnosis. CONCLUSIONS: Although quantitative PCR using probes was more expensive than the use of intercalating dyes or conventional PCR, it had the highest sensitivity out of all tested PCR approaches.

First complete Genome Sequence of Zika Virus (Flaviviridae, Flavivirus) from an Autochthonous Transmission in Brazil

We report here the genome sequence of Zika virus, strain ZikaSPH2015, containing all structural and nonstructural proteins flanked by the 5' and 3' untranslated region. It was isolated in São Paulo state, Brazil, in 2015, from a patient who received a blood transfusion from an asymptomatic donor at the time of donation.