Surveillance of viruses transmitted by insects (arboviruses), such as dengue, Zika and yellow fever, is one of the main strategies for monitoring the spread of viral strains that may have greater potential for infection. The measure also makes it possible to assess the impact of circulating viruses in the event of possible outbreaks. Biologist Fernanda de Bruycker Nogueira, recent doctor of the Graduate Program Strict sensu in Parasitic Biology at Instituto Oswaldo Cruz (IOC/Fiocruz), developed a broad study that contributes to the surveillance of the dengue virus.
Guided by researcher Flavia Barreto dos Santos, from the Viral Immunology Laboratory of IOC, the thesis presents an overview of the routes of introduction and dispersion of the virus in Brazil and the Americas, and brings together genetic discoveries obtained through molecular characterization analyses. The work entitled 'Evolutionary history, characterization and molecular surveillance of the different strains of the dengue virus type 1 in Brazil' was awarded an honorable mention by the 2019 Capes de Thesis Award, in the Biological Sciences III category.
“I feel very honored to have been a part of it and to have been able to contribute with a deeper understanding of the variants of the dengue virus, an arbovirus that has been circulating in the country for over 30 years. It is the appreciation of a work developed as a team”, celebrated Fernanda. “Capes recognition is unique, not only for the student but also for the advisor. Faced with the difficulties we always encounter, it is rewarding and shows how encouraging science makes a difference, especially if applied effectively and judiciously”, added Flavia.
Analysis of genetic sequences of 48 samples, representing strains isolated between 1986 and 2011 in Brazil, allowed the molecular characterization of serotype 1 of the circulating dengue virus in the country. The investigation revealed that all the analyzed viruses belonged to the V genotype, however grouped in different lineages. The data showed greater proximity between two strains (named 1a and 1b in the study) with DENV-1 of Latin American origin, and the same for strain 2 in relation to viruses of Asian origin. Differentiation between the strains was associated with observed amino acid substitutions in the E protein of the virus.
According to the study, changes in this protein may be related to changes in immunogenicity – the ability to stimulate the production of antibodies, in addition to influencing viral replication, disease pathogenicity and determining the characteristics of the host-pathogen interaction.
“The molecular and genetic characterization of arboviruses is of paramount importance. Point mutations in the genome are sufficient for greater virulence, for example, or even for the virus to adapt to a particular vector. In addition, the circulation of different genotypes of the dengue virus can have different impacts on the population”, emphasized Flavia.
In a second step, the thesis deepens the knowledge of the dynamics of DENV-1 genotype V, the most prevalent in the American continent. The reconstruction of the evolutionary history of this genotype in the Americas was performed using phylogenetic and phylogeographic approaches. Data from more than 800 genetic sequences, originating from 46 countries, covering an approximate period of 50 years were considered.
The study pointed out that the genetic diversity of the DENV-1 genotype V resulted from two independent introductions to the American continent from India, around the beginning of the 1970s and beginning of the 1980s. The analyzes estimate that the first strain was introduced in the Lesser Antilles, in the Caribbean. The region became a source of several strains of DENV-1, which spread throughout the Americas during the 1970s and 1980s. “It is of great importance to investigate the role of countries in maintaining and spreading this virus to the rest of the American continent. This knowledge is crucial for understanding the occurrence of epidemics and establishing control strategies”, points out Flavia.
According to the investigation, most of these lineages seem to have become extinct during the 1990s, except for one that persisted in Venezuela and spread to other American countries. A second strain of genotype V, also of Indian origin, was probably introduced in the Lesser Antilles in the early 1980s and remained almost undetected for about 15 years, until it was introduced in the mid-1990s in the northern region of Brazil. , from where it spread to other regions of the country.
“The results demonstrate that different geographic regions played roles in the maintenance and dissemination of the DENV-1 genotype V in the Americas over time”, explains Fernanda. “Lineages originated, spread and disappeared on the continent with different dynamics. The phenomenon of lineage replacement through successive epidemic outbreaks of dengue virus type 1 has been a common feature in most American countries,” she adds.
The research continued with continued molecular surveillance in the post-reemergence period, between 2012 and 2016. Phylogenetic analyzes confirmed the continued presence of genotype V and the co-circulation of three distinct lineages. The phylogeographic analyzes highlighted two regional patterns: one of them relates lineages from the Southeast, Midwest and Northeast regions of Brazil to ancestors from Argentina, while the other suggests an introduction route in the North region of the country from Venezuela.
The thesis also highlights the importance of studying co-infection by different serotypes of the dengue virus. The work describes the detection and molecular characterization of a case of co-infection with dengue viruses type 1 and type 4, from a sample isolated in Rio de Janeiro, during the 2012 epidemic. During the period, DENV-1 and DENV-4 co-circulated in the country, causing a high number of cases. The study emphasizes that, although the consequences of a co-infection in the course of the disease for the patient are still unknown, the characterization of co-infection reinforces the role of virological and entomological surveillance.
Surveillance of viruses transmitted by insects (arboviruses), such as dengue, Zika and yellow fever, is one of the main strategies for monitoring the spread of viral strains that may have greater potential for infection. The measure also makes it possible to assess the impact of circulating viruses in the event of possible outbreaks. Biologist Fernanda de Bruycker Nogueira, recent doctor of the Graduate Program Strict sensu in Parasitic Biology at Instituto Oswaldo Cruz (IOC/Fiocruz), developed a broad study that contributes to the surveillance of the dengue virus.
Guided by researcher Flavia Barreto dos Santos, from the Viral Immunology Laboratory of IOC, the thesis presents an overview of the routes of introduction and dispersion of the virus in Brazil and the Americas, and brings together genetic discoveries obtained through molecular characterization analyses. The work entitled 'Evolutionary history, characterization and molecular surveillance of the different strains of the dengue virus type 1 in Brazil' was awarded an honorable mention by the 2019 Capes de Thesis Award, in the Biological Sciences III category.
“I feel very honored to have been a part of it and to have been able to contribute with a deeper understanding of the variants of the dengue virus, an arbovirus that has been circulating in the country for over 30 years. It is the appreciation of a work developed as a team”, celebrated Fernanda. “Capes recognition is unique, not only for the student but also for the advisor. Faced with the difficulties we always encounter, it is rewarding and shows how encouraging science makes a difference, especially if applied effectively and judiciously”, added Flavia.
Analysis of genetic sequences of 48 samples, representing strains isolated between 1986 and 2011 in Brazil, allowed the molecular characterization of serotype 1 of the circulating dengue virus in the country. The investigation revealed that all the analyzed viruses belonged to the V genotype, however grouped in different lineages. The data showed greater proximity between two strains (named 1a and 1b in the study) with DENV-1 of Latin American origin, and the same for strain 2 in relation to viruses of Asian origin. Differentiation between the strains was associated with observed amino acid substitutions in the E protein of the virus.
According to the study, changes in this protein may be related to changes in immunogenicity – the ability to stimulate the production of antibodies, in addition to influencing viral replication, disease pathogenicity and determining the characteristics of the host-pathogen interaction.
“The molecular and genetic characterization of arboviruses is of paramount importance. Point mutations in the genome are sufficient for greater virulence, for example, or even for the virus to adapt to a particular vector. In addition, the circulation of different genotypes of the dengue virus can have different impacts on the population”, emphasized Flavia.
In a second step, the thesis deepens the knowledge of the dynamics of DENV-1 genotype V, the most prevalent in the American continent. The reconstruction of the evolutionary history of this genotype in the Americas was performed using phylogenetic and phylogeographic approaches. Data from more than 800 genetic sequences, originating from 46 countries, covering an approximate period of 50 years were considered.
The study pointed out that the genetic diversity of the DENV-1 genotype V resulted from two independent introductions to the American continent from India, around the beginning of the 1970s and beginning of the 1980s. The analyzes estimate that the first strain was introduced in the Lesser Antilles, in the Caribbean. The region became a source of several strains of DENV-1, which spread throughout the Americas during the 1970s and 1980s. “It is of great importance to investigate the role of countries in maintaining and spreading this virus to the rest of the American continent. This knowledge is crucial for understanding the occurrence of epidemics and establishing control strategies”, points out Flavia.
According to the investigation, most of these lineages seem to have become extinct during the 1990s, except for one that persisted in Venezuela and spread to other American countries. A second strain of genotype V, also of Indian origin, was probably introduced in the Lesser Antilles in the early 1980s and remained almost undetected for about 15 years, until it was introduced in the mid-1990s in the northern region of Brazil. , from where it spread to other regions of the country.
“The results demonstrate that different geographic regions played roles in the maintenance and dissemination of the DENV-1 genotype V in the Americas over time”, explains Fernanda. “Lineages originated, spread and disappeared on the continent with different dynamics. The phenomenon of lineage replacement through successive epidemic outbreaks of dengue virus type 1 has been a common feature in most American countries,” she adds.
The research continued with continued molecular surveillance in the post-reemergence period, between 2012 and 2016. Phylogenetic analyzes confirmed the continued presence of genotype V and the co-circulation of three distinct lineages. The phylogeographic analyzes highlighted two regional patterns: one of them relates lineages from the Southeast, Midwest and Northeast regions of Brazil to ancestors from Argentina, while the other suggests an introduction route in the North region of the country from Venezuela.
The thesis also highlights the importance of studying co-infection by different serotypes of the dengue virus. The work describes the detection and molecular characterization of a case of co-infection with dengue viruses type 1 and type 4, from a sample isolated in Rio de Janeiro, during the 2012 epidemic. During the period, DENV-1 and DENV-4 co-circulated in the country, causing a high number of cases. The study emphasizes that, although the consequences of a co-infection in the course of the disease for the patient are still unknown, the characterization of co-infection reinforces the role of virological and entomological surveillance.
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