RESUMO
The incidence of chikungunya has dramatically surged worldwide in recent decades, imposing an expanding burden on public health. In recent years, South America, particularly Brazil, has experienced outbreaks that have ravaged populations following the rapid dissemination of the chikungunya virus (CHIKV), which was first detected in 2014. The primary vector for CHIKV transmission is the urban mosquito species Aedes aegypti, which is highly prevalent throughout Brazil. However, the impact of the locally circulating CHIKV genotypes and specific combinations of local mosquito populations on vector competence remains unexplored. Here, we experimentally analyzed and compared the infectivity and transmissibility of the CHIKV-ECSA lineage recently isolated in Brazil among four Ae. aegypti populations collected from different regions of the country. When exposed to CHIKV-infected AG129 mice for blood feeding, all the mosquito populations displayed high infection rates and dissemination efficiency. Furthermore, we observed that all the populations were highly efficient in transmitting CHIKV to a vertebrate host (naïve AG129 mice) as early as eight days post-infection. These results demonstrate the high capacity of Brazilian Ae. aegypti populations to transmit the locally circulating CHIKV-ECSA lineage. This observation could help to explain the high prevalence of the CHIKV-ECSA lineage over the Asian lineage, which was also detected in Brazil in 2014. However, further studies comparing both lineages are necessary to gain a better understanding of the vector's importance in the epidemiology of CHIKV in the Americas.
Assuntos
Aedes , Febre de Chikungunya , Vírus Chikungunya , Mosquitos Vetores , Animais , Aedes/virologia , Vírus Chikungunya/genética , Vírus Chikungunya/classificação , Vírus Chikungunya/fisiologia , Vírus Chikungunya/isolamento & purificação , Brasil/epidemiologia , Febre de Chikungunya/transmissão , Febre de Chikungunya/virologia , Febre de Chikungunya/epidemiologia , Camundongos , Mosquitos Vetores/virologia , Genótipo , Feminino , FilogeniaRESUMO
The global incidence of chikungunya has surged in recent decades, with South America, particularly Brazil, experiencing devastating outbreaks. The primary vector for transmitting CHIKV in urban areas is the mosquito species Aedes aegypti, which is very abundant in Brazil. However, little is known about the impact of locally circulating CHIKV genotypes and specific combinations of mosquito populations on vector competence. In this study, we analyzed and compared the infectivity and transmissibility of a recently isolated CHIKV-ECSA lineage from Brazil among four Ae. aegypti populations collected from different regions of the country. When exposed to CHIKV-infected mice for blood feeding, all mosquito populations showed high infection rates and dissemination efficiency. Moreover, using a mouse model to assess transmission rates in a manner that better mirrors natural cycles, we observed that these populations exhibit highly efficient transmission rates of CHIKV-ECSA. Our findings underscore the robust capability of Brazilian Ae. aegypti populations to transmit the locally circulating CHIKV-ECSA lineage, potentially explaining its higher prevalence compared to the Asian lineage also introduced in Brazil.
RESUMO
Arboviruses (an acronym for "arthropod-borne virus"), such as dengue, yellow fever, Zika, and Chikungunya, are important human pathogens transmitted by mosquitoes. These viruses impose a growing burden on public health. Despite laboratory mice having been used for decades for understanding the basic biological phenomena of these viruses, it was only recently that researchers started to develop immunocompromised animals to study the pathogenesis of arboviruses and their transmission in a way that parallels natural cycles. Here, we show that the AG129 mouse (IFN α/ß/γ R-/-) is a suitable and comprehensive vertebrate model for studying the mosquito vector competence for the major arboviruses of medical importance, namely the dengue virus (DENV), yellow fever virus (YFV), Zika virus (ZIKV), Mayaro virus (MAYV), and Chikungunya virus (CHIKV). We found that, after intraperitoneal injection, AG129 mice developed a transient viremia lasting several days, peaking on day two or three post infection, for all five arboviruses tested in this study. Furthermore, we found that the observed viremia was ample enough to infect Aedes aegypti during a blood meal from the AG129 infected mice. Finally, we demonstrated that infected mosquitoes could transmit each of the tested arboviruses back to naïve AG129 mice, completing a full transmission cycle of these vector-borne viruses. Together, our data show that A129 mice are a simple and comprehensive vertebrate model for studies of vector competence, as well as investigations into other aspects of mosquito biology that can affect virus-host interactions.
RESUMO
Diagnostic tests for brown spider accidents are unavailable and impact treatment decisions, increasing costs and patient risks. In this work, we used for the first time a fast, simple, and visual method based on the loop-mediated isothermal amplification assay (LAMP) to detect Loxosceles envenomation. Using the DNA from L. similis legs, we observed a high sensitivity using this test since as low as 0.32 pg of DNA could be detected. This pH-dependent colorimetric assay was 64 times more sensitive than PCR to detect spider DNA. The test was specific for Loxosceles once no cross-reaction was observed when testing DNA from different agents that cause similar dermonecrotic injuries. The test allowed the detection of Loxosceles intermedia DNA from hair, serum, and exudate samples obtained from experimentally-envenomed rabbit within 72 h. The method sensitivity varied according to the sample and the collection time, reaching 100% sensitivity in serum and hair, respectively, 1 h and 24 h after the experimental envenomation. Due to its ease of execution, speed, sensitivity, and specificity, LAMP presents an excellent potential for identifying Loxosceles spp. Envenomation. This can reduce the burden on the Health System and the morbidity for the patient by implementing the appropriate therapy immediately.In addition, this work opens up the perspective to other venomous animal accident identification using LAMP.
Assuntos
Venenos de Aranha , Aranhas , Animais , Colorimetria , Técnicas de Diagnóstico Molecular , Técnicas de Amplificação de Ácido Nucleico , Diester Fosfórico Hidrolases/genética , Coelhos , Sensibilidade e Especificidade , Venenos de Aranha/genética , Venenos de Aranha/toxicidade , Aranhas/genéticaRESUMO
Field release of Wolbachia-infected Aedes aegypti has emerged as a promising solution to manage the transmission of dengue, Zika and chikungunya in endemic areas across the globe. Through an efficient self-dispersing mechanism, and the ability to induce virus-blocking properties, Wolbachia offers an unmatched potential to gradually modify wild Ae. aegypti populations turning them unsuitable disease vectors. Here we describe a proof-of-concept field trial carried out in a small community of Niterói, greater Rio de Janeiro, Brazil. Following the release of Wolbachia-infected eggs, we report here a successful invasion and long-term establishment of the bacterium across the territory, as denoted by stable high-infection indexes (> 80%). We have also demonstrated that refractoriness to dengue and Zika viruses, either thorough oral-feeding or intra-thoracic saliva challenging assays, was maintained over the adaptation to the natural environment of Southeastern Brazil. These findings further support Wolbachia's ability to invade local Ae. aegypti populations and impair disease transmission, and will pave the way for future epidemiological and economic impact assessments.
Assuntos
Aedes/virologia , Arbovírus/fisiologia , Mosquitos Vetores/virologia , Controle Biológico de Vetores/estatística & dados numéricos , Wolbachia , Animais , Brasil , Vírus da Dengue/isolamento & purificação , Feminino , Controle Biológico de Vetores/métodos , Zika virus/isolamento & purificaçãoRESUMO
The emergence of new human viral pathogens and re-emergence of several diseases are of particular concern in the last decades. Oropouche orthobunyavirus (OROV) is an arbovirus endemic to South and Central America tropical regions, responsible to several epidemic events in the last decades. There is little information regarding the ability of OROV to be transmitted by urban/peri-urban mosquitoes, which has limited the predictability of the emergence of permanent urban transmission cycles. Here, we evaluated the ability of OROV to infect, replicate, and be transmitted by three anthropophilic and urban species of mosquitoes, Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus. We show that OROV is able to infect and efficiently replicate when systemically injected in all three species tested, but not when orally ingested. Moreover, we find that, once OROV replication has occurred in the mosquito body, all three species were able to transmit the virus to immunocompromised mice during blood feeding. These data provide evidence that OROV is restricted by the midgut barrier of three major urban mosquito species, but, if this restriction is overcome, could be efficiently transmitted to vertebrate hosts. This poses a great risk for the emergence of permanent urban cycles and geographic expansion of OROV to other continents.
Assuntos
Aedes/virologia , Culex/virologia , Mosquitos Vetores/virologia , Orthobunyavirus/fisiologia , Animais , Infecções por Bunyaviridae/transmissão , Infecções por Bunyaviridae/virologia , Modelos Animais de Doenças , Feminino , Especificidade de Hospedeiro , Interações Hospedeiro-Patógeno , Camundongos , Camundongos KnockoutRESUMO
Newly emerging or re-emerging arthropod-borne viruses (arboviruses) are important causes of human morbidity and mortality worldwide. Arboviruses such as Dengue (DENV), Zika (ZIKV), Chikungunya (CHIKV), and West Nile virus (WNV) have undergone extensive geographic expansion in the tropical and sub-tropical regions of the world. In the Americas the main vectors of DENV, ZIKV, and CHIKV are mosquito species adapted to urban environments, namely Aedes aegypti and Aedes albopictus, whereas the main vector of WNV is Culex quinquefasciatus. Given the widespread distribution in the Americas and high permissiveness to arbovirus infection, these mosquito species may play a key role in the epidemiology of other arboviruses normally associated with sylvatic vectors. Here, we test this hypothesis by determining the vector competence of Ae. aegypti, Ae. albopictus, and Cx. quinquefasciatus to Mayaro (MAYV) virus, a sylvatic arbovirus transmitted mainly by Haemagogus janthinomys that has been causing an increasing number of outbreaks in South America, namely in Brazil. Using field mosquitoes from Brazil, female mosquitoes were experimentally infected, and their competence for infection and transmission rates of MAYV was evaluated. We found consistent infection rate for MAYV in Ae. aegypti (57.5%) and Ae. albopictus (61.6%), whereas very low rates were obtained for Cx. quinquefasciatus (2.5%). Concordantly, we observed high potential transmission ability in Ae. aegypti and Ae. albopictus (69.5% and 71.1% respectively), in contrast to Cx. quinquefasciatus, which could not transmit the MAYV. Notably, we found that very low quantities of virus present in the saliva (undetectable by RT-qPCR) were sufficiently virulent to guarantee transmission. Although Ae. aegypti and Ae. albopictus mosquitoes are not the main vectors for MAYV, our studies suggest that these mosquitoes could play a significant role in the transmission of this arbovirus, since both species showed significant vector competence for MAYV (Genotype D), under laboratory conditions.
Assuntos
Aedes/virologia , Infecções por Alphavirus/virologia , Alphavirus/isolamento & purificação , Culex/virologia , Transmissão de Doença Infecciosa , Alphavirus/genética , Alphavirus/crescimento & desenvolvimento , Infecções por Alphavirus/transmissão , Animais , Brasil , Feminino , Reação em Cadeia da Polimerase em Tempo Real , Saliva/virologia , Carga ViralRESUMO
Background: Yellow fever outbreaks have re-emerged in Brazil during 2016-18, with mortality rates up to 30%. Although urban transmission has not been reported since 1942, the risk of re-urbanization of yellow fever is significant, as Aedes aegypti is present in most tropical and sub-tropical cities in the World and still remains the main vector of urban YFV. Although the YFV vaccine is safe and effective, it does not always reach populations at greatest risk of infection and there is an acknowledged global shortage of vaccine supply. The introgression of Wolbachia bacteria into Ae. aegypti mosquito populations is being trialed in several countries ( www.worldmosquito.org) as a biocontrol method against dengue, Zika and chikungunya. Here, we studied the ability of Wolbachia to reduce the transmission potential of Ae. aegypti mosquitoes for Yellow fever virus (YFV). Methods: Two recently isolated YFV (primate and human) were used to challenge field-derived wild-type and Wolbachia-infected ( wMel +) Ae. aegypti mosquitoes. The YFV infection status was followed for 7, 14 and 21 days post-oral feeding (dpf). The YFV transmission potential of mosquitoes was evaluated via nano-injection of saliva into uninfected mosquitoes or by inoculation in mice. Results: We found that Wolbachia was able to significantly reduce the prevalence of mosquitoes with YFV infected heads and thoraces for both viral isolates. Furthermore, analyses of mosquito saliva, through indirect injection into naïve mosquitoes or via interferon-deficient mouse model, indicated Wolbachia was associated with profound reduction in the YFV transmission potential of mosquitoes (14dpf). Conclusions: Our results suggest that Wolbachia introgression could be used as a complementary strategy for prevention of urban yellow fever transmission, along with the human vaccination program.
RESUMO
Brazil has experienced several arbovirus outbreaks in recent years, among which yellow fever stands out. The state of Minas Gerais faced outbreaks of sylvatic yellow fever in 2017 and 2018, with 1002 confirmed cases and 340 deaths. This work presents the results of survey efforts to detect the yellow fever virus in mosquitoes from two conservation areas in the metropolitan region of Belo Horizonte, Brazil. A total of 867 mosquitoes of 20 species were collected between September 2017 and May 2018, the most abundant being Psorophora (Janthinosoma) ferox (von Humboldt, 1819) (31.3%), Limatus durhamii Theobald, 1901 (19.1%) and Haemagogus (Haemagogus) janthinomys Dyar, 1921 (18.2%). Total RNA was extracted from the mosquitoes for real-time PCR analysis for yellow fever, chikungunya, mayaro, Zika and dengue viruses. The yellow fever infection rate was 8.2% for Hg. janthinomys (13 mosquitoes), which is the main vector of sylvatic yellow fever in Brazil. In addition to surveying the mosquito fauna of these conservation units, this work demonstrates the importance of monitoring the circulation of viruses near large urban centers.
RESUMO
BACKGROUND: Wolbachia's ability to restrict arbovirus transmission makes it a promising tool to combat mosquito-transmitted diseases. Wolbachia-infected Aedes aegypti are currently being released in locations such as Brazil, which regularly experience concurrent outbreaks of different arboviruses. A. aegypti can become co-infected with, and transmit multiple arboviruses with one bite, which can complicate patient diagnosis and treatment. METHODOLOGY/PRINCIPLE FINDINGS: Using experimental oral infection of A. aegypti and then RT-qPCR, we examined ZIKV/DENV-1 and ZIKV/DENV-3 co-infection in Wolbachia-infected A. aegypti and observed that Wolbachia-infected mosquitoes experienced lower prevalence of infection and viral load than wildtype mosquitoes, even with an extra infecting virus. Critically, ZIKV/DENV co-infection had no significant impact on Wolbachia's ability to reduce viral transmission. Wolbachia infection also strongly altered expression levels of key immune genes Defensin C and Transferrin 1, in a virus-dependent manner. CONCLUSIONS/SIGNIFICANCE: Our results suggest that pathogen interference in Wolbachia-infected A. aegypti is not adversely affected by ZIKV/DENV co-infection, which suggests that Wolbachia-infected A. aegypti will likely prove suitable for controlling mosquito-borne diseases in environments with complex patterns of arbovirus transmission.
Assuntos
Aedes/microbiologia , Aedes/virologia , Vírus da Dengue/fisiologia , Controle de Mosquitos/métodos , Mosquitos Vetores/microbiologia , Mosquitos Vetores/virologia , Wolbachia/fisiologia , Zika virus/fisiologia , Animais , Brasil , Vírus da Dengue/genética , Feminino , Masculino , Wolbachia/genética , Zika virus/genéticaRESUMO
BACKGROUND: The leishmaniases are important neglected diseases caused by Leishmania spp. which are transmitted by sand flies, Lutzomyia longipalpis being the main vector of visceral leishmaniasis in the Americas. The methodologies for leishmaniasis control are not efficient, causing 1.5 million reported cases annually worldwide, therefore showing the need for development of novel strategies and interventions to control transmission of the disease. The bacterium Wolbachia pipientis is being used to control viruses transmitted by mosquitoes, such as dengue and Zika, and its introduction in disease vectors has been effective against parasites such as Plasmodium. Here we show the first successful establishment of Wolbachia into two different embryonic cell lines from L. longipalpis, LL-5 and Lulo, and analysed its effects on the sand fly innate immune system, followed by in vitro Leishmania infantum interaction. RESULTS: Our results show that LL-5 cells respond to wMel and wMelPop-CLA strains within the first 72 h post-infection, through the expression of antimicrobial peptides and inducible nitric oxide synthase resulting in a decrease of Wolbachia detection in the early stages of infection. In subsequent passages, the wMel strain was not able to infect any of the sand fly cell lines while the wMelPop-CLA strain was able to stably infect Lulo cells and LL-5 at lower levels. In Wolbachia stably infected cells, the expression of immune-related genes involved with downregulation of the IMD, Toll and Jak-Stat innate immune pathways was significantly decreased, in comparison with the uninfected control, suggesting immune activation upon Wolbachia transinfection. Furthermore, Wolbachia transinfection did not promote a negative effect on parasite load in those cells. CONCLUSIONS: Initial strong immune responses of LL5 cells might explain the inefficiency of stable infections in these cells while we found that Lulo cells are more permissive to infection with Wolbachia causing an effect on the cell immune system, but not against in vitro L. infantum interaction. This establishes Lulo cells as a good system for the adaptation of Wolbachia in L. longipalpis.
Assuntos
Expressão Gênica , Imunidade Inata , Fatores Imunológicos/biossíntese , Leishmania infantum/crescimento & desenvolvimento , Interações Microbianas , Psychodidae/imunologia , Wolbachia/imunologia , Animais , Linhagem Celular , Carga Parasitária , Psychodidae/microbiologia , Wolbachia/crescimento & desenvolvimentoRESUMO
West Nile virus (WNV) is a neurovirulent mosquito-borne Flavivirus that is maintained in nature by a zoonotic transmissioncycle between avian hosts and ornithophilic mosquito vectors, mostly from the Culex genus. Until the 1990s, WNV wasconsidered to be an old-world arbovirus, but in 1999, WNV emerged in the United States (US) and spread rapidly, becoming amajor threat to public health. WNV adapted to the transmission cycle involving American mosquitoes and birds and reachedCentral and South America in subsequent years. In 2003, the National West Nile Fever Surveillance System was created in Brazilbased on serological screening of animals and sentinel vectors, as recommended by the Pan American Health Organization(PAHO) and the World Health Organization (WHO). Since 2008, serological evidence of WNV infection in Brazilian horseshas been reported, and the circulation of WNV has been monitored through the regular serological screening of sentinel horsesand reporting of encephalomyelitis cases. Horses are highly susceptible to WNV infection, and outbreaks of neurologicaldisease among horses often precede human cases. In this regard, equine surveillance has been essential in providing earlywarning to public and animal health authorities in several countries, including Brazil. This demonstrates the need for animaland public health intervention programs to allocate resources to make
O vírus do Nilo Ocidental (WNV) é um flavivírus neuropatogênico transmitido por mosquito, mantido na natureza emum ciclo de transmissão zoonótica entre as aves e os mosquitos ornitofílicos, principalmente do gênero Culex. Até a décadade 1990, o WNV era considerado um arbovírus do mundo antigo, mas em 1999 surgiu nos Estados Unidos da Américae se espalhou rapidamente, tornando-se uma grande ameaça à saúde pública. O WNV se adaptou ao ciclo envolvendomosquitos e pássaros americanos e chegou à América Central e do Sul nos anos subsequentes. Em 2003, o Sistema Nacionalde Vigilância da Febre do Nilo Ocidental no Brasil foi criado com base na triagem sorológica de animais sentinelas evetores, conforme recomendado pela Organização Pan-Americana da Saúde (OPAS) e pela Organização Mundial daSaúde (OMS). Desde 2008, evidências sorológicas de infecção por WNV em equinos brasileiros têm sido relatadas e acirculação do WNV monitorada por meio de triagem sorológica de cavalos sentinelas, além da notificação de casos deencefalomielite. Os equinos são altamente suscetíveis ao WNV e surtos de doenças neurológicas geralmente precedemcasos humanos. Nesse sentido, a vigilância equina tem sido essencial para fornecer um alerta precoce às autoridades desaúde pública e animal em vários países, incluindo o Brasil. Isso demonstra a necessidade de programas de intervençãoem saúde pública e animal para a
RESUMO
West Nile virus (WNV) is a neurovirulent mosquito-borne Flavivirus that is maintained in nature by a zoonotic transmissioncycle between avian hosts and ornithophilic mosquito vectors, mostly from the Culex genus. Until the 1990s, WNV wasconsidered to be an old-world arbovirus, but in 1999, WNV emerged in the United States (US) and spread rapidly, becoming amajor threat to public health. WNV adapted to the transmission cycle involving American mosquitoes and birds and reachedCentral and South America in subsequent years. In 2003, the National West Nile Fever Surveillance System was created in Brazilbased on serological screening of animals and sentinel vectors, as recommended by the Pan American Health Organization(PAHO) and the World Health Organization (WHO). Since 2008, serological evidence of WNV infection in Brazilian horseshas been reported, and the circulation of WNV has been monitored through the regular serological screening of sentinel horsesand reporting of encephalomyelitis cases. Horses are highly susceptible to WNV infection, and outbreaks of neurologicaldisease among horses often precede human cases. In this regard, equine surveillance has been essential in providing earlywarning to public and animal health authorities in several countries, including Brazil. This demonstrates the need for animaland public health intervention programs to allocate resources to make
O vírus do Nilo Ocidental (WNV) é um flavivírus neuropatogênico transmitido por mosquito, mantido na natureza emum ciclo de transmissão zoonótica entre as aves e os mosquitos ornitofílicos, principalmente do gênero Culex. Até a décadade 1990, o WNV era considerado um arbovírus do mundo antigo, mas em 1999 surgiu nos Estados Unidos da Américae se espalhou rapidamente, tornando-se uma grande ameaça à saúde pública. O WNV se adaptou ao ciclo envolvendomosquitos e pássaros americanos e chegou à América Central e do Sul nos anos subsequentes. Em 2003, o Sistema Nacionalde Vigilância da Febre do Nilo Ocidental no Brasil foi criado com base na triagem sorológica de animais sentinelas evetores, conforme recomendado pela Organização Pan-Americana da Saúde (OPAS) e pela Organização Mundial daSaúde (OMS). Desde 2008, evidências sorológicas de infecção por WNV em equinos brasileiros têm sido relatadas e acirculação do WNV monitorada por meio de triagem sorológica de cavalos sentinelas, além da notificação de casos deencefalomielite. Os equinos são altamente suscetíveis ao WNV e surtos de doenças neurológicas geralmente precedemcasos humanos. Nesse sentido, a vigilância equina tem sido essencial para fornecer um alerta precoce às autoridades desaúde pública e animal em vários países, incluindo o Brasil. Isso demonstra a necessidade de programas de intervençãoem saúde pública e animal para a
RESUMO
West Nile virus (WNV) is a neurovirulent mosquito-borne Flavivirus that is maintained in nature by a zoonotic transmissioncycle between avian hosts and ornithophilic mosquito vectors, mostly from the Culex genus. Until the 1990s, WNV wasconsidered to be an old-world arbovirus, but in 1999, WNV emerged in the United States (US) and spread rapidly, becoming amajor threat to public health. WNV adapted to the transmission cycle involving American mosquitoes and birds and reachedCentral and South America in subsequent years. In 2003, the National West Nile Fever Surveillance System was created in Brazilbased on serological screening of animals and sentinel vectors, as recommended by the Pan American Health Organization(PAHO) and the World Health Organization (WHO). Since 2008, serological evidence of WNV infection in Brazilian horseshas been reported, and the circulation of WNV has been monitored through the regular serological screening of sentinel horsesand reporting of encephalomyelitis cases. Horses are highly susceptible to WNV infection, and outbreaks of neurologicaldisease among horses often precede human cases. In this regard, equine surveillance has been essential in providing earlywarning to public and animal health authorities in several countries, including Brazil. This demonstrates the need for animaland public health intervention programs to allocate resources to make
O vírus do Nilo Ocidental (WNV) é um flavivírus neuropatogênico transmitido por mosquito, mantido na natureza emum ciclo de transmissão zoonótica entre as aves e os mosquitos ornitofílicos, principalmente do gênero Culex. Até a décadade 1990, o WNV era considerado um arbovírus do mundo antigo, mas em 1999 surgiu nos Estados Unidos da Américae se espalhou rapidamente, tornando-se uma grande ameaça à saúde pública. O WNV se adaptou ao ciclo envolvendomosquitos e pássaros americanos e chegou à América Central e do Sul nos anos subsequentes. Em 2003, o Sistema Nacionalde Vigilância da Febre do Nilo Ocidental no Brasil foi criado com base na triagem sorológica de animais sentinelas evetores, conforme recomendado pela Organização Pan-Americana da Saúde (OPAS) e pela Organização Mundial daSaúde (OMS). Desde 2008, evidências sorológicas de infecção por WNV em equinos brasileiros têm sido relatadas e acirculação do WNV monitorada por meio de triagem sorológica de cavalos sentinelas, além da notificação de casos deencefalomielite. Os equinos são altamente suscetíveis ao WNV e surtos de doenças neurológicas geralmente precedemcasos humanos. Nesse sentido, a vigilância equina tem sido essencial para fornecer um alerta precoce às autoridades desaúde pública e animal em vários países, incluindo o Brasil. Isso demonstra a necessidade de programas de intervençãoem saúde pública e animal para a
RESUMO
West Nile virus (WNV) is a neurovirulent mosquito-borne Flavivirus that is maintained in nature by a zoonotic transmissioncycle between avian hosts and ornithophilic mosquito vectors, mostly from the Culex genus. Until the 1990s, WNV wasconsidered to be an old-world arbovirus, but in 1999, WNV emerged in the United States (US) and spread rapidly, becoming amajor threat to public health. WNV adapted to the transmission cycle involving American mosquitoes and birds and reachedCentral and South America in subsequent years. In 2003, the National West Nile Fever Surveillance System was created in Brazilbased on serological screening of animals and sentinel vectors, as recommended by the Pan American Health Organization(PAHO) and the World Health Organization (WHO). Since 2008, serological evidence of WNV infection in Brazilian horseshas been reported, and the circulation of WNV has been monitored through the regular serological screening of sentinel horsesand reporting of encephalomyelitis cases. Horses are highly susceptible to WNV infection, and outbreaks of neurologicaldisease among horses often precede human cases. In this regard, equine surveillance has been essential in providing earlywarning to public and animal health authorities in several countries, including Brazil. This demonstrates the need for animaland public health intervention programs to allocate resources to make
O vírus do Nilo Ocidental (WNV) é um flavivírus neuropatogênico transmitido por mosquito, mantido na natureza emum ciclo de transmissão zoonótica entre as aves e os mosquitos ornitofílicos, principalmente do gênero Culex. Até a décadade 1990, o WNV era considerado um arbovírus do mundo antigo, mas em 1999 surgiu nos Estados Unidos da Américae se espalhou rapidamente, tornando-se uma grande ameaça à saúde pública. O WNV se adaptou ao ciclo envolvendomosquitos e pássaros americanos e chegou à América Central e do Sul nos anos subsequentes. Em 2003, o Sistema Nacionalde Vigilância da Febre do Nilo Ocidental no Brasil foi criado com base na triagem sorológica de animais sentinelas evetores, conforme recomendado pela Organização Pan-Americana da Saúde (OPAS) e pela Organização Mundial daSaúde (OMS). Desde 2008, evidências sorológicas de infecção por WNV em equinos brasileiros têm sido relatadas e acirculação do WNV monitorada por meio de triagem sorológica de cavalos sentinelas, além da notificação de casos deencefalomielite. Os equinos são altamente suscetíveis ao WNV e surtos de doenças neurológicas geralmente precedemcasos humanos. Nesse sentido, a vigilância equina tem sido essencial para fornecer um alerta precoce às autoridades desaúde pública e animal em vários países, incluindo o Brasil. Isso demonstra a necessidade de programas de intervençãoem saúde pública e animal para a
RESUMO
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
Wolbachia, an intracellular endosymbiont present in up to 70% of all insect species, has been suggested as a sustainable strategy for the control of arboviruses such as Dengue, Zika and Chikungunya. As Mayaro virus outbreaks have also been reported in Latin American countries, the objective of this study was to evaluate the vector competence of Brazilian field-collected Ae. aegypti and the impact of Wolbachia (wMel strain) upon this virus. Our in vitro studies with Aag2 cells showed that Mayaro virus can rapidly multiply, whereas in wMel-infected Aag2 cells, viral growth was significantly impaired. In addition, C6/36 cells seem to have alterations when infected by Mayaro virus. In vivo experiments showed that field-collected Ae. aegypti mosquitoes are highly permissive to Mayaro virus infection, and high viral prevalence was observed in the saliva. On the other hand, Wolbachia-harboring mosquitoes showed significantly impaired capability to transmit Mayaro virus. Our results suggest that the use of Wolbachia-harboring mosquitoes may represent an effective mechanism for the reduction of Mayaro virus transmission throughout Latin America.
Assuntos
Aedes/virologia , Mosquitos Vetores/virologia , Togaviridae/fisiologia , Replicação Viral , Wolbachia/patogenicidade , Aedes/microbiologia , Animais , Linhagem Celular , Células Cultivadas , Feminino , Humanos , Mosquitos Vetores/microbiologia , Simbiose , Togaviridae/patogenicidade , Infecções por Togaviridae/transmissãoRESUMO
The inflammatory process plays a major role in the prognosis of dengue. In this context, the eicosanoids may have considerable influence on the regulation of the Dengue virus-induced inflammatory process. To quantify the molecules involved in the cyclooxygenase and lipoxygenase pathways during Dengue virus infection, plasma levels of thromboxane A2, prostaglandin E2 and leukotriene B4; mRNA levels of thromboxane A2 synthase, prostaglandin E2 synthase, leukotriene A4 hydrolase, cyclooxygenase-2 and 5-lipoxygenase; and the levels of lipid bodies in peripheral blood leukocytes collected from IgM-positive and IgM-negative volunteers with mild dengue, and non-infected volunteers, were evaluated. Dengue virus infection increases the levels of thromboxane A2 in IgM-positive individuals as well as the amount of lipid bodies in monocytes in IgM-negative individuals. We suggest that increased levels of thromboxane A2 in IgM-positive individuals plays a protective role against the development of severe symptoms of dengue, such as vascular leakage.
Assuntos
Vírus da Dengue/imunologia , Dengue/sangue , Dengue/imunologia , Imunoglobulina M/imunologia , Tromboxano A2/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Ciclo-Oxigenase 2/sangue , Ciclo-Oxigenase 2/genética , Dengue/diagnóstico , Dengue/virologia , Feminino , Humanos , Imunoglobulina M/sangue , Leucócitos/imunologia , Leucócitos/metabolismo , Masculino , Pessoa de Meia-Idade , Monócitos/imunologia , Monócitos/metabolismo , Tromboxano A2/genética , Carga Viral , Adulto JovemRESUMO
The recent association of Zika virus with cases of microcephaly has sparked a global health crisis and highlighted the need for mechanisms to combat the Zika vector, Aedes aegypti mosquitoes. Wolbachia pipientis, a bacterial endosymbiont of insect, has recently garnered attention as a mechanism for arbovirus control. Here we report that Aedes aegypti harboring Wolbachia are highly resistant to infection with two currently circulating Zika virus isolates from the recent Brazilian epidemic. Wolbachia-harboring mosquitoes displayed lower viral prevalence and intensity and decreased disseminated infection and, critically, did not carry infectious virus in the saliva, suggesting that viral transmission was blocked. Our data indicate that the use of Wolbachia-harboring mosquitoes could represent an effective mechanism to reduce Zika virus transmission and should be included as part of Zika control strategies.
Assuntos
Aedes/microbiologia , Aedes/virologia , Wolbachia/fisiologia , Zika virus/fisiologia , Animais , Antibiose , Brasil , Transmissão de Doença Infecciosa/prevenção & controle , Feminino , Insetos Vetores/microbiologia , Insetos Vetores/virologia , Masculino , Saliva/microbiologia , Saliva/virologia , Simbiose , Zika virus/isolamento & purificação , Infecção por Zika virus/microbiologia , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologiaRESUMO
A series of N-acylhydrazonyl-thienyl derivatives (compounds 2 and 3), mainly of the type 2-(aryl-CH=N-NHCOCH2 )-thiene (2: aryl = substituted-phenyl; 3: aryl = heteroaryl) were evaluated against Mycobacterium tuberculosis. Particularly active compound was 3 (heteroaryl = 5-nitrothien-2-yl or 5-nitrofuran-2-yl) with MIC values of 8.5 and 9.0 µM, respectively. Moderately active compounds were compound 3 (heteroaryl = pyridin-2-yl) and compound 2 containing aryl = 2- or 4-hydroxyphenyl groups, with MIC values between 170 and 408 µM. Compound 2 containing OMe, H, F, Cl, Br, CN, and NO2 substituents and compound 3 (heteroaryl = furan-2-yl, thien-2-yl, pyrrol-2-yl, imidazol-2-yl, pyridin-3-yl, and pyridin-4-yl) were all inactive. Clearly, there is no correlation of activity with the electronic effects of the substituents. The activities suggest different modes of biological action of the compounds having nitro-heteroaryl groups, on the one hand, and the 2-hydroxyphenyl or pyridin-2-yl substituents, on the other hand. Compounds having 2- or 4-hydroxyphenyl, 2-hydroxy-5-nitrophenyl, or 4-hydroxy-3-chlorophenyl were less cytotoxic than ethambutol. It is important to notice that compound 3 (aryl = 5-NO2 -furan-2-yl) exhibited a promising therapeutic index (TI = 1093.90), with a value 4.4 less than that of ethambutol. Compounds 2 and 3 exist in DMSO or MeOD solutions as mixtures of EC(O)N /EC=N and ZC(O)N /EC=N conformers.