Airway epithelial cells and macrophages trigger IL-6-CD95/CD95L axis and mediate initial immunopathology of COVID-19.

Airway epithelial cells (AEC) infected with SARS-CoV-2 may drive the dysfunction of macrophages during COVID-19. We hypothesized that the direct interaction of AEC with macrophages mediated by CD95/CD95L or indirect interaction mediated by IL-6 signaling are key steps for the COVID-19 severe acute inflammation. The interaction of macrophages with apoptotic and infected AEC increased CD95 and CD163 expression, and induced macrophage death. Macrophages exposed to tracheal aspirate with high IL-6 levels from intubated patients with COVID-19 or to recombinant human IL-6 exhibited decreased HLA-DR expression, increased CD95 and CD163 expression and IL-1ß production. IL-6 effects on macrophages were prevented by both CD95/CD95L antagonist and by IL-6 receptor antagonist and IL-6 or CD95 deficient mice showed significant reduction of acute pulmonary inflammation post-infection. Our findings show a non-canonical CD95L-CD95 pathway that simultaneously drives both macrophage activation and dysfunction and point to CD95/CD95L axis as therapeutic target.

Serological evidence of hantavirus infection in neotropical bats in an urban area of São Paulo State, Brazil.

BACKGROUND: Although hantaviruses have long been associated with rodents, they are also described in other mammalian hosts, such as shrews, moles and bats. Hantaviruses associated with bats have been described in Asian, European and Brazilian species of bats. As these mammals represent the second major mammalian order, and they are the major mammals that inhabit urban areas, it is extremely important to maintain a viral surveillance in these animals. Our aim was to conduct serosurveillance in bats in an urban area in the city of Ribeirão Preto, São Paulo State, Brazil, to contribute to the information about hantaviruses circulation in bats. METHODS: We analyzed samples from 778 neotropical bat specimens classified into 21 bat species and four different families collected in the urban area of Ribeirão Preto city, from 2014 to 2019 by an ELISA for the detection of IgG antibodies against orthohantavirus. RESULTS: We detected IgG-specific antibodies against the nucleoprotein of orthohantavirus in 0.9% (7/778) bats tested, including four Molossus molossus (Pallas' Free-tailed Bat), two Glossophaga soricina (Pallas's Long-tongued Bat) and one Eumops glaucinus (Wagner's mastiff bat). CONCLUSIONS: Overall, our results show the first serological evidence of hantavirus infection in three common bat species in urban areas.

HIV-1 Gag and Vpr impair the inflammasome activation and contribute to the establishment of chronic infection in human primary macrophages.

The successful establishment of HIV-1 infection is related to inflammasome blocking or inactivation, which can result in the viral evasion of the immune responses and formation of reservoirs in several tissues. In this sense, we aimed to evaluate the viral and cellular mechanisms activated during HIV-1 infection in human primary macrophages that allow an effective viral replication in these cells. We found that resting HIV-1-infected macrophages, but not those activated in classical or alternative patterns, released IL-1ß and other pro-inflammatory cytokines, and showed increased CXCL10 expression, without changes in the NLRP3, AIM2 or RIG-I inflammasome pathways. Also, similar levels of Casp-1, phosphorylated NF-κB (p65) and NLRP3 proteins were found in uninfected and HIV-1-infected macrophages. Likewise, no alterations were detected in ASC specks released in the culture supernatant after HIV-1 infection, suggesting that macrophages remain viable after infection. Using in silico prediction studies, we found that the HIV-1 proteins Gag and Vpr interact with several host proteins. Comparable levels of trans-LTB4 were found in the supernatants of uninfected and HIV-1-infected macrophages, whereas ROS production was impaired in infected cells, which was not reversed after the PMA stimulus. Immunofluorescence analysis showed structural alterations in the mitochondrial architecture and an increase of BIM in the cytoplasm of infected cells. Our data suggest that HIV-1 proteins Gag and Vpr, through interacting with cellular proteins in the early steps of infection, preclude the inflammasome activation and the development of effective immune responses, thus allowing the establishment of the infection.

CCR2 Plays a Protective Role in Rocio Virus-Induced Encephalitis by Promoting Macrophage Infiltration Into the Brain.

Rocio virus (ROCV) is a highly neuropathogenic mosquito-transmitted flavivirus responsible for an unprecedented outbreak of human encephalitis during 1975-1976 in Sao Paulo State, Brazil. Previous studies have shown an increased number of inflammatory macrophages in the central nervous system (CNS) of ROCV-infected mice, implying a role for macrophages in the pathogenesis of ROCV. Here, we show that ROCV infection results in increased expression of CCL2 in the blood and in infiltration of macrophages into the brain. Moreover, we show, using CCR2 knockout mice, that CCR2 expression is essential for macrophage infiltration in the brain during ROCV infection and that the lack of CCR2 results in increased disease severity and mortality. Thus, our findings show the protective role of CCR2-mediated infiltration of macrophages in the brain during ROCV infection.

Neutrophil Extracellular Traps Effectively Control Acute Chikungunya Virus Infection.

The Chikungunya virus (CHIKV) is a re-emerging arbovirus, in which its infection causes a febrile illness also commonly associated with severe joint pain and myalgia. Although the immune response to CHIKV has been studied, a better understanding of the virus-host interaction mechanisms may lead to more effective therapeutic interventions. In this context, neutrophil extracellular traps (NETs) have been described as a key mediator involved in the control of many pathogens, including several bacteria and viruses, but no reports of this important protective mechanism were documented during CHIKV infection. Here we demonstrate that the experimental infection of mouse-isolated neutrophils with CHIKV resulted in NETosis (NETs release) through a mechanism dependent on TLR7 activation and reactive oxygen species generation. In vitro, mouse-isolated neutrophils stimulated with phorbol 12-myristate 13-acetate release NETs that once incubated with CHIKV, resulting in further virus capture and neutralization. In vivo, NETs inhibition by the treatment of the mice with DNase resulted in the enhanced susceptibility of IFNAR-/- mice to CHIKV experimental acute infection. Lastly, by accessing the levels of MPO-DNA complex on the acutely CHIKV-infected patients, we found a correlation between the levels of NETs and the viral load in the blood, suggesting that NETs are also released in natural human infection cases. Altogether our findings characterize NETosis as a contributing natural process to control CHIKV acute infection, presenting an antiviral effect that helps to control systemic virus levels.

Full genome sequence of Rocio virus reveal substantial variations from the prototype Rocio virus SPH 34675 sequence.

Rocio virus (ROCV) is an arbovirus belonging to the genus Flavivirus, family Flaviviridae. We present an updated sequence of ROCV strain SPH 34675 (GenBank: AY632542.4), the only available full genome sequence prior to this study. Using next-generation sequencing of the entire genome, we reveal substantial sequence variation from the prototype sequence, with 30 nucleotide differences amounting to 14 amino acid changes, as well as significant changes to predicted 3'UTR RNA structures. Our results present an updated and corrected sequence of a potential emerging human-virulent flavivirus uniquely indigenous to Brazil (GenBank: MF461639).

Congenital Zika Virus Infection Induces Severe Spinal Cord Injury.

We report 2 fatal cases of congenital Zika virus (ZIKV) infection. Brain anomalies, including atrophy of the cerebral cortex and brainstem, and cerebellar aplasia were observed. The spinal cord showed architectural distortion, severe neuronal loss, and microcalcifications. The ZIKV proteins and flavivirus-like particles were detected in cytoplasm of spinal neurons, and spinal cord samples were positive for ZIKV RNA.

Zika Virus Meningoencephalitis in an Immunocompromised Patient.

The World Health Organization considers the Zika virus (ZIKV) outbreak in the Americas a global public health emergency. The neurologic complications due to ZIKV infection comprise microcephaly, meningoencephalitis, and Guillain-Barré syndrome. We describe a fatal case of an adult patient receiving an immunosuppressive regimen following heart transplant. The patient was admitted with acute neurologic impairment and experienced progressive hemodynamic instability and mental deterioration that finally culminated in death. At autopsy, a pseudotumoral form of ZIKV meningoencephalitis was confirmed. Zika virus infection was documented by reverse trancriptase-polymerase chain reaction, immunohistochemistry, and immunofluorescence and electron microscopy of the brain parenchyma and cerebral spinal fluid. The sequencing of the viral genome in this patient confirmed a Brazilian ZIKV strain. In this case, central nervous system involvement and ZIKV propagation to other organs in a disseminated pattern is quite similar to that observed in other fatal Flaviviridae viral infections.

Chimeric viruses between Rocio and West Nile: the role for Rocio prM-E proteins in virulence and inhibition of interferon-α/ß signaling.

Mosquito-transmitted flavivirus Rocio (ROCV) was responsible for an outbreak of encephalitis in the Ribeira Valley, located in the south coast of Sao Paulo State, Brazil, in 1975-1976. ROCV also causes fatal encephalitis in adult mice. Seroprevalence studies in humans, horses and water buffaloes in different regions of Brazil have suggested that ROCV is still circulating in the country, indicating the risk of re-emergence of this virus. West Nile virus (WNV) is also a mosquito-transmitted encephalitic flavivirus, however, WNV strains circulating in Australia have not been associated with outbreaks of disease in humans and exhibit low virulence in adult mice. To identify viral determinants of ROCV virulence, we have generated reciprocal chimeric viruses between ROCV and the Australian strain of WNV by swapping structural prM and E genes. Chimeric WNV containing ROCV prM-E genes replicated more efficiently than WNV or chimeric ROCV containing WNV prM-E genes in mammalian cells, was as virulent as ROCV in adult mice, and inhibited type I IFN signaling as efficiently as ROCV. The results show that ROCV prM and E proteins are major virulence determinants and identify unexpected function of these proteins in inhibition of type I interferon response.

Epidemiological surveillance of herpes viral encephalitis in Cordoba, Colombia / Vigilancia epidemiológica de encefalitis por herpes virus en Córdoba, Colombia

Objective To establish an epidemiological surveillance of viral herpes encephalitis in major hospitals of Monteria, Cordoba. Methods From September 2009 to December 2011, a descriptive study of cases of viral encephalitis was made in three hospitals in the city of Monteria. Cerebrospinal fluid (CSF) samples from 118 patients were included in the study. Clinical aspects, as well as cytochemical and microbiological analysis (Gram stain and culture) of CSF, were used for selecting the patients. Virus detection was performed by using multiplex nested PCR for Herpes simplex virus 1 and 2, Epstein Barr virus, Cytomegalovirus and Varicella zoster virus. Results Viral DNA of herpesvirus was detected in the CSFs of 30 (25.4 %) participants, as follows: 22 (18.6 %) Herpes simplex 1 and 2 viruses, 4 (3.3 %) Cytomegalovirus and 1 (0.8 %) Varicella zoster virus. Co-infections were observed in 3 patients (2.5 %), 1 case by HSV-VZV and 2 cases by CMV/HSV. The clinical manifestations of the patients included: headache (18.6 %), fever (14.4 %), asthenia (10.1 %), seizures (9.3 %), vomiting (8.4 %), and stiff neck (5.9 %). Thirty percent of the patients also had HIV-AIDS. A case fatality rate of 20 % was observed for the patients. Conclusions This paper shows that herpesvirus is a cause of infection of the CNS in patients from Cordoba. This study contributes to the epidemiology of encephalitis, as well as to patient management.(AU)

Objetivo Establecer una vigilancia epidemiológica de la encefalitis viral herpética en los principales hospitales de Montería, Córdoba. Materiales y Métodos Se realizó un estudio descriptivo de los casos de encefalitis viral entre septiembre de 2009 diciembre de 2011 en tres hospitales en la ciudad de Montería. Las muestras líquido cefalorraquídeo (LCR) de 118 pacientes fueron incluidos en el estudio. Los aspectos clínicos como el análisis citoquímico y microbiológico (tinción de Gram y cultivo) de LCR fueron utilizados para la selección de los pacientes. La detección de virus se realizó por PCR anidada multiplex para Herpes simplex virus 1 y 2, virus de Epstein Barr, virus zoster de la varicela y el citomegalovirus. Resultados Se detectó ADN viral del virus del herpes en 30 (25,4 %) muestras de LCR en los pacientes de la siguiente manera: 22 (18,6 %) Herpes simplex virus 1 y 2, 4 (3,3 %) Citomegalovirus y 1 (0,8 %) del virus de la varicela zóster. Se observaron Co-infecciones en 3 pacientes (2,5 %), 1 caso por el VHS-VZV y 2 casos por CMV / HSV. Las manifestaciones clínicas de los pacientes fueron: cefalea (18,6 %), fiebre (14,4 %), astenia (10,1 %), convulsiones (9,3 %), vómitos (8,4 %), y rigidez de nuca (5,9 %). El treinta por ciento de los pacientes también tenía VIH-SIDA. Se observó una tasa de letalidad del 20 % de los pacientes. Conclusiones Se demuestra que el herpesvirus es causa de infección del SNC en pacientes en Córdoba. Este estudio contribuye a la caracterización serológica viral epidemiológica de la encefalitis viral, así como en el manejo del paciente ya que se describen hallazgos clínicos importante en la población adulta estudiada.(AU)

Epidemiological surveillance of herpes viral encephalitis in Cordoba, Colombia.

Objective To establish an epidemiological surveillance of viral herpes encephalitis in major hospitals of Monteria, Cordoba. Methods From September 2009 to December 2011, a descriptive study of cases of viral encephalitis was made in three hospitals in the city of Monteria. Cerebrospinal fluid (CSF) samples from 118 patients were included in the study. Clinical aspects, as well as cytochemical and microbiological analysis (Gram stain and culture) of CSF, were used for selecting the patients. Virus detection was performed by using multiplex nested PCR for Herpes simplex virus 1 and 2, Epstein Barr virus, Cytomegalovirus and Varicella zoster virus. Results Viral DNA of herpesvirus was detected in the CSFs of 30 (25.4 %) participants, as follows: 22 (18.6 %) Herpes simplex 1 and 2 viruses, 4 (3.3 %) Cytomegalovirus and 1 (0.8 %) Varicella zoster virus. Co-infections were observed in 3 patients (2.5 %), 1 case by HSV-VZV and 2 cases by CMV/HSV. The clinical manifestations of the patients included: headache (18.6 %), fever (14.4 %), asthenia (10.1 %), seizures (9.3 %), vomiting (8.4 %), and stiff neck (5.9 %). Thirty percent of the patients also had HIV-AIDS. A case fatality rate of 20 % was observed for the patients. Conclusions This paper shows that herpesvirus is a cause of infection of the CNS in patients from Cordoba. This study contributes to the epidemiology of encephalitis, as well as to patient management.

Influence of the CCR-5/MIP-1 α axis in the pathogenesis of Rocio virus encephalitis in a mouse model.

Rocio virus (ROCV) caused an outbreak of human encephalitis during the 1970s in Brazil and its immunopathogenesis remains poorly understood. CC-chemokine receptor 5 (CCR5) is a chemokine receptor that binds to macrophage inflammatory protein (MIP-1 α). Both molecules are associated with inflammatory cells migration during infections. In this study, we demonstrated the importance of the CCR5 and MIP-1 α, in the outcome of viral encephalitis of ROCV-infected mice. CCR5 and MIP-1 α knockout mice survived longer than wild-type (WT) ROCV-infected animals. In addition, knockout mice had reduced inflammation in the brain. Assessment of brain viral load showed mice virus detection five days post-infection in wild-type and CCR5-/- mice, while MIP-1 α-/- mice had lower viral loads seven days post-infection. Knockout mice required a higher lethal dose than wild-type mice as well. The CCR5/MIP-1 α axis may contribute to migration of infected cells to the brain and consequently affect the pathogenesis during ROCV infection.

Mayaro virus infection in amazonia: a multimodel inference approach to risk factor assessment.

BACKGROUND: Arboviral diseases are major global public health threats. Yet, our understanding of infection risk factors is, with a few exceptions, considerably limited. A crucial shortcoming is the widespread use of analytical methods generally not suited for observational data--particularly null hypothesis-testing (NHT) and step-wise regression (SWR). Using Mayaro virus (MAYV) as a case study, here we compare information theory-based multimodel inference (MMI) with conventional analyses for arboviral infection risk factor assessment. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional survey of anti-MAYV antibodies revealed 44% prevalence (n = 270 subjects) in a central Amazon rural settlement. NHT suggested that residents of village-like household clusters and those using closed toilet/latrines were at higher risk, while living in non-village-like areas, using bednets, and owning fowl, pigs or dogs were protective. The "minimum adequate" SWR model retained only residence area and bednet use. Using MMI, we identified relevant covariates, quantified their relative importance, and estimated effect-sizes (ß ± SE) on which to base inference. Residence area (ß(Village)  =  2.93 ± 0.41; ß(Upland) = -0.56 ± 0.33, ß(Riverbanks)  =  -2.37 ± 0.55) and bednet use (ß = -0.95 ± 0.28) were the most important factors, followed by crop-plot ownership (ß  =  0.39 ± 0.22) and regular use of a closed toilet/latrine (ß = 0.19 ± 0.13); domestic animals had insignificant protective effects and were relatively unimportant. The SWR model ranked fifth among the 128 models in the final MMI set. CONCLUSIONS/SIGNIFICANCE: Our analyses illustrate how MMI can enhance inference on infection risk factors when compared with NHT or SWR. MMI indicates that forest crop-plot workers are likely exposed to typical MAYV cycles maintained by diurnal, forest dwelling vectors; however, MAYV might also be circulating in nocturnal, domestic-peridomestic cycles in village-like areas. This suggests either a vector shift (synanthropic mosquitoes vectoring MAYV) or a habitat/habits shift (classical MAYV vectors adapting to densely populated landscapes and nocturnal biting); any such ecological/adaptive novelty could increase the likelihood of MAYV emergence in Amazonia.

Expression of recombinant Araraquara Hantavirus nucleoprotein in insect cells and its use as an antigen for immunodetection compared to the same antigen expressed in Escherichia coli.

BACKGROUND: Antigens for Hantavirus serological tests have been produced using DNA recombinant technology for more than twenty years. Several different strategies have been used for that purpose. All of them avoid the risks and difficulties involved in multiplying Hantavirus in the laboratory. In Brazil, the Araraquara virus is one of the main causes of Hantavirus Cardio-Pulmonary Syndrome (HCPS). METHODS: In this investigation, we report the expression of the N protein of the Araraquara Hantavirus in a Baculovirus Expression System, the use of this protein in IgM and IgG ELISA and comparison with the same antigen generated in E. coli. RESULTS: The protein obtained, and purified in a nickel column, was effectively recognized by antibodies from confirmed HCPS patients. Comparison of the baculovirus generated antigen with the N protein produced in E. coli showed that both were equally effective in terms of sensitivity and specificity. CONCLUSIONS: Our results therefore indicate that either of these proteins can be used in serological tests in Brazil.

Mosquitoes infected with dengue viruses in Brazil.

Dengue epidemics have been reported in Brazil since 1985. The scenery has worsened in the last decade because several serotypes are circulating and producing a hyper-endemic situation, with an increase of DHF/DSS cases as well as the number of fatalities. Herein, we report dengue virus surveillance in mosquitoes using a Flavivirus genus-specific RT-Hemi-Nested-PCR assay. The mosquitoes (Culicidae, n = 1700) collected in the Northeast, Southeast and South of Brazil, between 1999 and 2005, were grouped into 154 pools. Putative genomes of DENV-1, -2 and -3 were detected in 6 mosquito pools (3.8%). One amplicon of putative DENV-1 was detected in a pool of Haemagogus leucocelaenus suggesting that this virus could be involved in a sylvatic cycle. DENV-3 was found infecting 3 pools of larvae of Aedes albopictus and the nucleotide sequence of one of these viruses was identified as DENV-3 of genotype III, phylogenetically related to other DENV-3 isolated in Brazil. This is the first report of a nucleotide sequence of DENV-3 from larvae of Aedes albopictus.

Detection of dengue virus in saliva and urine by real time RT-PCR.

Early diagnosis of dengue virus (DENV) infection is important for patient management and control of dengue outbreaks. The objective of this study was to analyze the usefulness of urine and saliva samples for early diagnosis of DENV infection by real time RT-PCR. Two febrile patients, who have been attended at the General Hospital of the School of Medicine of Ribeirao Preto, Sao Paulo University were included in the study. Serum, urine and saliva samples collected from both patients were subjected to real time RT-PCR for DENV detection and quantification. Dengue RNA was detected in serum, urine and saliva samples of both patients. Patient 1 was infected with DENV-2 and patient 2 with DENV-3. Data presented in this study suggest that urine and saliva could be used as alternative samples for early diagnosis of dengue virus infection when blood samples are difficult to obtain, e.g., in newborns and patients with hemorrhagic syndromes.

Genetic diversity of the E protein of dengue type 3 virus.

BACKGROUND: Dengue is the most important arbovirus disease in tropical and subtropical countries. The viral envelope (E) protein is responsible for cell receptor binding and is the main target of neutralizing antibodies. The aim of this study was to analyze the diversity of the E protein gene of DENV-3. E protein gene sequences of 20 new viruses isolated in Ribeirao Preto, Brazil, and 427 sequences retrieved from GenBank were aligned for diversity and phylogenetic analysis. RESULTS: Comparison of the E protein gene sequences revealed the presence of 47 variable sites distributed in the protein; most of those amino acids changes are located on the viral surface. The phylogenetic analysis showed the distribution of DENV-3 in four genotypes. Genotypes I, II and III revealed internal groups that we have called lineages and sub-lineages. All amino acids that characterize a group (genotype, lineage, or sub-lineage) are located in the 47 variable sites of the E protein. CONCLUSION: Our results provide information about the most frequent amino acid changes and diversity of the E protein of DENV-3.

Hantavirus pulmonary syndrome, central plateau, southeastern, and southern Brazil.

Hantavirus pulmonary syndrome (HPS) is an increasing health problem in Brazil because of encroachment of sprawling urban, agricultural, and cattle-raising areas into habitats of subfamily Sigmodontinae rodents, which serve as hantavirus reservoirs. From 1993 through June 2007, a total of 884 cases of HPS were reported in Brazil (case-fatality rate 39%). To better understand this emerging disease, we collected 89 human serum samples and 68 rodent lung samples containing antibodies to hantavirus from a 2,500-km-wide area in Brazil. RNA was isolated from human samples and rodent tissues and subjected to reverse transcription-PCR. Partial sequences of nucleocapsid protein and glycoprotein genes from 22 human and 16 rodent sources indicated only Araraquara virus and Juquitiba virus lineages. The case-fatality rate of HPS was higher in the area with Araraquara virus. This virus, which may be the most virulent hantavirus in Brazil, was associated with areas that have had greater anthropogenic changes.

In vitro and in vivo studies of ribavirin action on Brazilian Orthobunyavirus.

Oropouche, Caraparu, Guama, Guaroa, and Tacaiuma are viruses (genus Orthobunyavirus) that cause human febrile illnesses and encephalitis. The goal of this study was to evaluate the antiviral action of ribavirin on these orthobunyaviruses to achieve a therapeutical agent to treat the diseases caused by these viruses. In vitro results showed that ribavirin (50 microg/mL) had antiviral activity only on the Tacaiuma virus. Addition of guanosine in the culture reversed the antiviral effect of ribavirin on Tacaiuma virus, suggesting that ribavirin inhibited this virus by reducing the intra-cellular guanosine pool. Moreover, ribavirin was not an effective drug in vivo because it was unable to inhibit the death of the mice or virus replication in the brain. The results suggest that ribavirin has no antiviral activity on the Oropouche, Caraparu, Guama, Guaroa, or Tacaiuma viruses; consequently, ribavirin would not be a good therapeutical agent to treat these arboviruses.

Molecular epidemiology of dengue type 3 virus in Brazil and Paraguay, 2002-2004.

We studied the molecular epidemiology of dengue virus type 3 (DENV-3) in Brazil and Paraguay by analyzing the 5' and 3' untranslated regions (5' and 3'UTRs) and the E protein gene of viruses isolated between 2002 and 2004. Both 5' and 3'UTRs were highly conserved. However, the 3'UTR of two isolates from Brazil contained eight nucleotide deletions compared with the remaining 26 viruses. Phylogenetic analyses suggested that DENV-3 was introduced into Brazil from the Caribbean Islands at least twice and into Paraguay from Brazil at least three times.