Biology subjects

Cunha, M. S.

Publications and source records attributed to Cunha, M. S..

3 recordsLinked to original sources

bioRxiv2024

Unique RNA replication characteristics and nucleocapsid protein expression may explain differences in the replication capacity of SARS-COV-2 lineages.

COVID-19 pandemic in Brazil was characterized by the sequential circulation of the SARS-CoV-2 lineages B.1.1.33, and variants Zeta (P.2), Gamma (P.1/P.1.*), Delta (B.1.617.2/AY.*), and Omicron (BA.*). Our research aimed to compare the biological traits of these lineages and variants by analyzing aspects of viral replication including binding, entry, RNA replication, and viral protein production. We demonstrated that the replication capacity of these variants varies depending on the cell type, with Omicron BA.1 exhibiting the lowest replication in the human pulmonary cells. Additionally, the nucleocapsid proteoforms generated during infection exhibit distinct patterns across variants. Our findings suggest that factors beyond the initial stages of virus entry influence the efficiency of viral replication among different SARS-CoV-2 variants. Thus, our study underscores the significance of RNA replication and the role of nucleocapsid proteins in shaping the replicative characteristics of SARS-CoV-2 variants. Author summaryThe COVID-19 pandemic was characterized by the emergence of different viral variants that presents specific properties such as response to antibodies, pathogenicity and detection by diagnostic tests. The circulation of these variants presented a particular pattern depending on the global geographic regions. Despite the cessation of the pandemic, as officially declared by the World Health Organization in 2023, new viral variants continue to emerge while aspects of the virus-cell interaction that contribute to the replication of these variants have not yet been completely understood. In our study, we compared the biological characteristics of SARS-CoV-2 variants that circulated in Brazil during the pandemic, verifying aspects of entry, viral replication and production of viral RNA and proteins. Our results indicate that Omicron BA.1 variant has reduced replication and protein production in human lung cells. We also observed that the viral nucleocapsid protein presents proteoforms that vary according to the variant. These differences could help to explain the differences observed in viral replication in human pulmonary cells.

microbiology↗

bioRxiv2019

Zika and dengue viruses infecting wild-caught mosquitoes in an environmental protection area in Brazil

Species of the genus Flavivirus are widespread in Brazil and are a major public health concern. The city of Sao Paulo is in a highly urbanized area with some green spaces which are used for recreation and where potential vertebrate hosts and mosquito vectors of these arboviruses can be found, a scenario that can contribute to the transmission of flaviviruses to humans. This study therefore sought to investigate natural flavivirus infection in mosquitoes collected in the Capivari-Monos Environmental Protection Area (EPA) in the south of the city. Monthly mosquito collections were carried out from March 2016 to April 2017 with CO2-baited CDC light traps. Specimens were identified morphologically and grouped in pools. A total of 260 pools of non-engorged females were inoculated into the C6/36 cell lineage after analysis by indirect immunofluorescence assay (IFA). IFA-positive specimens were tested by qRT-PCR with genus-specific primers targeting a region of ~260 nucleotides in the flavivirus NS5 gene, and the PCR products were sequenced to confirm and identify the flavivirus species. Anopheles (Kerteszia) cruzii and Wyeomyia (Prosopolepis) confusa were the most frequent species collected. Zika virus (ZIKV) nucleotide sequences were detected in three mosquito species, An. cruzii, Limatus durhami and Wy. confusa, and dengue virus 2 (DENV-2) sequences in Culex. spp. and Culex. (Mel.) vaxus. To our knowledge, this is the first report of natural isolation of DENV-2 and ZIKV in sylvatic species of mosquitoes in the Capivari-Monos EPA. Our findings suggest that DENV-2 is present in Culex mosquitoes, and ZIKV in Anopheles, Wyeomyia and Limatus. The flavivirus species identified here are of medical importance; surveillance is therefore recommended in this EPA, where vertebrates and mosquitoes can act as flavivirus hosts and vectors.

zoology↗

bioRxiv2019

Genomic Surveillance of Yellow Fever Virus Epidemic Waves in Sao Paulo, Brazil, 2017 - 2018

Sao Paulo (SP), a densely inhabited state in southeast Brazil that contains the fourth most populated city in the world, recently experienced its largest yellow fever virus (YFV) outbreak in decades. YFV does not normally circulate extensively in SP, so most people were unvaccinated when the outbreak began. Surveillance in non-human primates (NHPs) is important for determining the magnitude and geographic extent of an epizootic, thereby helping to evaluate the risk of YFV spillover to humans. Data from infected NHPs can give more accurate insights into YFV spread than when using data from human cases alone. To contextualise human cases, identify epizootic foci and uncover the rate and direction of YFV spread in SP, we generated and analysed virus genomic data and epizootic case data from NHP in SP. We report the occurrence of three spatiotemporally distinct phases of the outbreak in SP prior to February 2018. We generated 51 new virus genomes from YFV positive cases identified in 23 different municipalities in SP, mostly sampled from non-human primates between October 2016 and January 2018. Although we observe substantial heterogeneity in lineage dispersal velocities between phylogenetic branches, continuous phylogeographic analyses of generated YFV genomes suggest that YFV lineages spread in Sao Paulo state at a mean rate of approximately 1km per day during all phases of the outbreak. Viral lineages from the first epizootic phase in northern Sao Paulo subsequently dispersed towards the south of the state to cause the second and third epizootic phases there. This alters our understanding of how YFV was introduced into the densely populated south of SP state. Our results shed light on the sylvatic transmission of yellow fever in highly fragmented forested regions in SP state and highlight the importance of continued surveillance of zoonotic pathogens in sentinel species. Authors SummarySince July 2016, the southeast region of Brazil has experienced the largest yellow fever virus (YFV) outbreak in decades. Sao Paulo is the most densely populated state in southeast Brazil. The outbreak has caused serious public health concern in the state, as YFV does not normally circulate widely there and most of the 21 million inhabitants were correspondingly unvaccinated against YFV when the outbreak began. In Brazil, YFV typically circulates among non-human primates, and human cases represent isolated spillover events from this predominantly sylvatic cycle. Understanding the epidemiological dynamics and spread of YFV in non-human primates is therefore critical for contextualising human cases, and guiding vaccination strategies that can better protect local human populations. Here, we aim to contextualise human cases, identify epizootic foci and uncover the rate and direction of YFV spread in SP. We analyse the geographic and temporal distribution of observed cases of YFV in non-human primates in Sao Paulo state, and identify three distinct phases of the epizootic. We generate sequence data from 51 YFV-positive cases and perform phylogenetic and phylogeographic analyses aimed at understanding the spatial spread of YFV in Sao Paulo state. Analyses of these data indicate that YFV spread from the north of Sao Paulo state into more densely populated southern regions. Although we observe substantial heterogeneity in the rate at which different sampled YFV lineages spread, the typical rate of spread was low with a mean rate of ~1 km per day. This is consistent with a scenario in which the majority of transmission events occurred between non-human primates and sylvatic vectors across forested patches. Article Summary LineGenomic surveillance of yellow fever in Sao Paulo during the 2016-2018 epizootic

epidemiology↗