RESUMO
Viruses with encephalitogenic potential can cause neurological conditions of clinical and epidemiological importance, such as Saint Louis encephalitis virus, Venezuelan equine encephalitis virus, Eastern equine encephalitis virus, Western equine encephalitis virus, Dengue virus, Zika virus, Chikungunya virus, Mayaro virus and West Nile virus. The objective of the present study was to determine the number of arboviruses with neuroinvasive potential isolated in Brazil that corresponds to the collection of viral samples belonging to the Department of Arbovirology and Hemorrhagic Fevers, Evandro Chagas Institute (SAARB/IEC) of the Laboratory Network of National Reference for Arbovirus Diagnosis from 1954 to 2022. In the analyzed period, a total of 1,347 arbovirus samples with encephalitogenic potential were isolated from mice; 5,065 human samples were isolated exclusively by cell culture; and 676 viruses were isolated from mosquitoes. The emergence of new arboviruses may be responsible for diseases still unknown to humans, making the Amazon region a hotspot for infectious diseases due to its fauna and flora species characteristics. The detection of circulating arboviruses with the potential to cause neuroinvasive diseases is constant, which justifies the continuation of active epidemiological surveillance work that offers adequate support to the public health system regarding the virological diagnosis of circulating arboviruses in Brazil.
Assuntos
Arbovírus , Vírus Chikungunya , Flavivirus , Infecção por Zika virus , Zika virus , Animais , Humanos , Camundongos , Brasil/epidemiologia , Vírus da Encefalite de St. LouisRESUMO
Zika virus (ZIKV; Flaviviridae, Flavivirus) was discovered in 1947 in Uganda, Africa, from the serum of a sentinel Rhesus monkey (Macaca mulatta). It is an enveloped, positive-sense, single-stranded RNA virus, which encodes a single polyprotein that is cleaved into 10 individual proteins. In 2015, the Zika-epidemic in Brazil was marked mainly by the exponential growth of microcephaly cases and other congenital defects. With regard to host-pathogen relationships, understanding the role of the immune response in the pathogenesis ZIKV infection is challenging. The innate immune response is the first-line immunological defence, in which pathogen-associated molecular patterns are recognized by pattern-recognition receptors that trigger macrophages, dendritic cells, natural killer cells and endothelial cells to produce several mediators, which modulate viral replication and immune evasion. In this review, we have summarized current knowledge on the innate immune response against ZIKV.
Assuntos
Imunidade Inata , Infecção por Zika virus , Zika virus , África , Citocinas , Células Endoteliais , HumanosRESUMO
Zika virus (ZIKV) is an arbovirus that is transmitted by Aedes mosquitos. Its prototype was isolated in 1947 from serum of a sentinel Rhesus monkey (Macaca mulatta) in the Zika forest of Uganda. As a member of the genus Flavivirus, family Flaviviridae, ZIKV is enveloped and icosahedral and possesses a single-stranded, positive-sense RNA genome of approximately 10.7 kb. Epidemiologically, infection by ZIKV has become a global health concern in recent years because of the occurrence of epidemics, its speed of dissemination, routes of transmission, and the sequelae it can cause especially in newborns. At the neural level, there are still many gaps in our understanding of the mechanisms that induce ZIKV infection-associated microcephaly. However, some studies already demonstrated that underlying cell death is determinant to induce the congenital malformation. In this report, we reviewed the various mechanisms of cell injury involved in the immunopathogenesis of ZIKV infection and discussed its relationship with the death of neuronal and glial cells development and microcephaly.
RESUMO
Triniti virus (TNTV) has been isolated in Trinidad and Tobago and in Brazil. To date little is known about this virus, which is classified as an ungrouped virus within the family Togaviridae. Here, three isolates of TNTV were characterized both genetically and antigenically. The genome was shown to contain three RNA segments: small (S), medium (M) and large (L). Genome organization, protein sizes and protein motifs were similar to those of viruses in the genus Orthobunyavirus, family Peribunyaviridae. Antigenic reactivity revealed the three TNTV isolates to be closely related, but no serologic cross-reaction with other orthobunyaviruses. Morphological observation by transmission electron microscopy indicated that virus size and symmetry were compatible with those of viruses in the family Peribunyaviridae. Our serological, morphological and molecular results support the taxonomic reclassification of TNTV as a member of the genus Orthobunyavirus, family Peribunyaviridae.
Assuntos
Antígenos Virais/imunologia , Orthobunyavirus/classificação , Orthobunyavirus/isolamento & purificação , RNA Viral/genética , Ordem dos Genes , Genoma Viral , Microscopia Eletrônica de Transmissão , Orthobunyavirus/genética , Orthobunyavirus/imunologia , Sorotipagem , Proteínas Virais/análise , Vírion/ultraestruturaRESUMO
This study showed that laboratory markers of recent infection by dengue, Zika or chikungunya arboviruses were detected in the biological samples of approximately one-third of patients with encephalitis, myelitis, encephalomyelitis or Guillain-Barré syndrome, in a surveillance programme in Piauí state, Brazil, between 2015-2016. Fever and myalgia had been associated with these cases. Since in non-tropical countries most infections or parainfectious diseases associated with the nervous system are attributed to herpesviruses, enteroviruses, and Campylobacter jejuni, the present findings indicate that in tropical countries, arboviruses may now play a more important role and reinforce the need for their surveillance and systematic investigation in the tropics.
Assuntos
Vírus Chikungunya , Vírus da Dengue , Doenças do Sistema Nervoso/virologia , Zika virus , Doença Aguda , Vírus Chikungunya/genética , Vírus Chikungunya/imunologia , Vírus da Dengue/genética , Vírus da Dengue/imunologia , Encefalite/diagnóstico , Encefalite/virologia , Encefalomielite Aguda Disseminada/diagnóstico , Encefalomielite Aguda Disseminada/virologia , ELISPOT , Síndrome de Guillain-Barré/diagnóstico , Síndrome de Guillain-Barré/virologia , Humanos , Mielite Transversa/diagnóstico , Mielite Transversa/virologia , Doenças do Sistema Nervoso/diagnóstico , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Zika virus/genética , Zika virus/imunologiaRESUMO
Zika virus (ZIKV) has caused substantial concern worldwide owing to its association with severe birth defects, such as microcephaly and other congenital malformations. Inflammasomes, i.e., multi-protein complexes that induce inflammation and pyroptosis, are predicted to contribute to the immune response to this flavivirus. Accordingly, in this study, the in situ inflammasome response was evaluated in fatal cases of ZIKV-linked microcephaly. Brain tissue samples were collected from eight babies, including four ZIKV-positive microcephalic neonates who died after birth and four flavivirus-negative neonatal controls who died of other causes and whose central nervous system (CNS) architecture was preserved. In the ZIKV-positive newborn/stillbirth babies, the major histopathological alterations included atrophy of the cortical layer, a predominance of mononuclear cell infiltration in the Virchow-Robin space, neuronal necrosis, vacuolization and neuronal degeneration, neuronophagy, and gliosis. An immunohistochemical analysis of tissues in the neural parenchyma showed significantly higher expression of the receptors NLRP1, NLRP3, and AIM2, cytokines IL-1ß, IL-18, and IL-33, and enzymes caspase 1, iNOS, and arginase 1 in ZIKV-positive microcephaly cases than in flavivirus-negative controls. These results suggest that inflammasome activation can aggravate the neuroinflammatory response and consequently increase CNS damage in neonates with fetal neural ZIKV infection and microcephaly.
Assuntos
Sistema Nervoso Central/patologia , Sistema Nervoso Central/virologia , Inflamassomos/fisiologia , Microcefalia/patologia , Microcefalia/virologia , Infecção por Zika virus/patologia , Zika virus/patogenicidade , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/virologia , Sistema Nervoso Central/metabolismo , Citocinas/metabolismo , Feminino , Feto/metabolismo , Feto/virologia , Humanos , Recém-Nascido , Inflamassomos/metabolismo , Masculino , Microcefalia/metabolismo , Gravidez , Complicações Infecciosas na Gravidez/metabolismo , Complicações Infecciosas na Gravidez/patologia , Complicações Infecciosas na Gravidez/virologia , Infecção por Zika virus/metabolismo , Infecção por Zika virus/virologiaRESUMO
We report a case of encephalitis associated with Zika virus infection and reactivation of varicella-zoster virus in the central nervous system of a Brazilian child. This case raises the possibility that reactivation of the latent varicella-zoster virus may be a mechanism of neurological impairment induced by acquired Zika virus infection.
Assuntos
Líquido Cefalorraquidiano/virologia , Encefalite por Varicela Zoster/complicações , Herpesvirus Humano 3/isolamento & purificação , Infecção por Zika virus/complicações , Zika virus/isolamento & purificação , Criança , DNA Viral/líquido cefalorraquidiano , Eletroencefalografia , Encefalite por Varicela Zoster/diagnóstico , Humanos , Masculino , Ativação Viral , Infecção por Zika virus/diagnósticoRESUMO
Abstract We report a case of encephalitis associated with Zika virus infection and reactivation of varicella-zoster virus in the central nervous system of a Brazilian child. This case raises the possibility that reactivation of the latent varicella-zoster virus may be a mechanism of neurological impairment induced by acquired Zika virus infection.
Assuntos
Humanos , Masculino , Criança , Herpesvirus Humano 3/isolamento & purificação , Encefalite por Varicela Zoster/complicações , Zika virus/isolamento & purificação , Infecção por Zika virus/complicações , Ativação Viral , DNA Viral/líquido cefalorraquidiano , Líquido Cefalorraquidiano/virologia , Encefalite por Varicela Zoster/diagnóstico , Eletroencefalografia , Infecção por Zika virus/diagnósticoRESUMO
This study showed that laboratory markers of recent infection by dengue, Zika or chikungunya arboviruses were detected in the biological samples of approximately one-third of patients with encephalitis, myelitis, encephalomyelitis or Guillain-Barré syndrome, in a surveillance programme in Piauí state, Brazil, between 2015-2016. Fever and myalgia had been associated with these cases. Since in non-tropical countries most infections or parainfectious diseases associated with the nervous system are attributed to herpesviruses, enteroviruses, and Campylobacter jejuni, the present findings indicate that in tropical countries, arboviruses may now play a more important role and reinforce the need for their surveillance and systematic investigation in the tropics.