In the last decade, Flaviviruses such as yellow fever (YFV) and Zika (ZIKV) have expanded their transmission areas. These viruses originated in Africa, where they exhibit both sylvatic and interhuman transmission cycles. In Brazil, the risk of YFV urbanization has grown, with the sylvatic transmission approaching the most densely populated metropolis, while concern about ZIKV spillback to a sylvatic cycle has risen. To investigate these health threats, we carried out extensive collections and arbovirus screening of 144 free-living, non-human primates (NHPs) and 5219 mosquitoes before, during, and after ZIKV and YFV outbreaks (2015–2018) in southeast Brazil. ZIKV infection was not detected in any NHP collected at any time. In contrast, current and previous YFV infections were detected in NHPs sampled between 2017 and 2018, but not before the onset of the YFV outbreak. Mosquito pools screened by high-throughput PCR were positive for YFV when captured in the wild and during the YFV outbreak, but were negative for 94 other arboviruses, including ZIKV, regardless of the time of collection. In conclusion, there was no evidence of YFV transmission in coastal southeast Brazil before the current outbreak, nor the spread or establishment of an independent sylvatic cycle of ZIKV or urban Aedes aegypti transmission of YFV in the region. In view of the region’s receptivity and vulnerability to arbovirus transmission, surveillance of NHPs and mosquitoes should be strengthened and continuous.
Zika virus (ZIKV) was first discovered in 1947 in Uganda but was not considered a public health threat until 2007 when it found to be the source of epidemic activity in Asia. Epidemic activity spread to Brazil in 2014 and continued to spread throughout the tropical and subtropical regions of the Americas. Despite ZIKV being zoonotic in origin, information about transmission, or even exposure of non-human vertebrates and mosquitoes to ZIKV in the Americas, is lacking. Accordingly, from February 2017 to March 2018, we sought evidence of sylvatic ZIKV transmission by sampling whole blood from approximately 2000 domestic and wild vertebrates of over 100 species in West-Central Brazil within the active human ZIKV transmission area. In addition, we collected over 24,300 mosquitoes of at least 17 genera and 62 species. We screened whole blood samples and mosquito pools for ZIKV RNA using pan-flavivirus primers in a real-time reverse-transcription polymerase chain reaction (RT-PCR) in a SYBR Green platform. Positives were confirmed using ZIKV-specific envelope gene real-time RT-PCR and nucleotide sequencing. Of the 2068 vertebrates tested, none were ZIKV positive. Of the 23,315 non-engorged mosquitoes consolidated into 1503 pools tested, 22 (1.5%) with full data available showed some degree of homology to insect-specific flaviviruses. To identify previous exposure to ZIKV, 1498 plasma samples representing 62 species of domestic and sylvatic Viruses 2019, 11, 11643 of 18 vertebrates were tested for ZIKV-neutralizing antibodies by plaque reduction neutralization test (PRNT 90 ). From these, 23 (1.5%) of seven species were seropositive for ZIKV and negative for dengue virus serotype 2, yellow fever virus, and West Nile virus, suggesting potential monotypic reaction for ZIKV. Results presented here suggest no active transmission of ZIKV in non-human vertebrate populations or in alternative vector candidates, but suggest that vertebrates around human populations have indeed been exposed to ZIKV in West-Central Brazil.
The cellular immune response plays an important role in COVID-19, caused by SARS-CoV-2. This feature makes use of in vitro models’ useful tools to evaluate vaccines and biopharmaceutical effects. Here, we developed a two-step model to evaluate the cellular immune response after SARS-CoV-2 infection-induced or spike protein stimulation in peripheral blood mononuclear cells (PBMC) from both unexposed and COVID-19 (primo-infected) individuals (Step1). Moreover, the supernatants of these cultures were used to evaluate its effects on lung cell lines (A549) (Step2). When PBMC from the unexposed were infected by SARS-CoV-2, cytotoxic natural killer and nonclassical monocytes expressing inflammatory cytokines genes were raised. The supernatant of these cells can induce apoptosis of A549 cells (mock vs. Step2 [mean]: 6.4% × 17.7%). Meanwhile, PBMCs from primo-infected presented their memory CD4+ T cells activated with a high production of IFNG and antiviral genes. Supernatant from past COVID-19 subjects contributed to reduce apoptosis (mock vs. Step2 [ratio]: 7.2 × 1.4) and to elevate the antiviral activity (iNOS) of A549 cells (mock vs. Step2 [mean]: 31.5% × 55.7%). Our findings showed features of immune primary cells and lung cell lines response after SARS-CoV-2 or spike protein stimulation that can be used as an in vitro model to study the immunity effects after SARS-CoV-2 antigen exposure.
Background Alouatta spp. are highly susceptible to yellow fever (YF) infection and develop an often fatal disease. The threat posed by an outbreak started in 2016 leads us to investigate vaccination as a potential tool in preventing YF in non‐human primates (NHP). Methods Susceptible howler monkeys were immunized with three different concentrations of the human Brazilian commercial YF17DD vaccine. Post‐vaccination viremia/RNAemia, immunogenicity, and safety were characterized. Results The vaccine did not produce YF clinical manifestations in any of the NHPs. After immunization, all animals seroconverted demonstrating the ability of the YF vaccine to induce humoral response in Alouatta species. Conclusions The present work has demonstrated the safe and immunogenic profile of the existing YF 17DD vaccine in howler monkeys. This knowledge may support further studies with other susceptible monkey species and provide a possible solution for controlling epizootics and preventing the devastation of endangered species.
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