Papers by Gilberto Santiago
Ciência e Agrotecnologia, 2008
Page 1. SANTIAGO, GP et al. 792 Ciênc. agrotec., Lavras, v. 32, n. 3, p. 792-796, maio/jun., 2008... more Page 1. SANTIAGO, GP et al. 792 Ciênc. agrotec., Lavras, v. 32, n. 3, p. 792-796, maio/jun., 2008 ... Gilberto Pedreira Santiago1, Luiz Evaldo de Moura Pádua2, Paulo Roberto Ramalho Silva3, Eulália Maria Sousa Carvalho4, Cláudio Belmino Maia5 ...
Ruta graveolens L.), folhas e ramos de melão- de-são-caetano (Momordica charantia L.), folhas do ... more Ruta graveolens L.), folhas e ramos de melão- de-são-caetano (Momordica charantia L.), folhas do alecrim-pimenta ( Lippia sidoides Cham.) e fruto verde de mamona (Ricinus communis L.), sobre a biologia da lagarta-do-cartucho do milho ( Spodoptera frugiperda ), mantida em dieta artificial. Os parâmetros avaliados foram duração e viabilidade das fases larval e pupal, peso de pupa, fecundidade, fertilidade e
PLOS Neglected Tropical Diseases, 2015
In vitro studies have shown that dengue virus (DENV) can thwart the actions of interferon (IFN)-α... more In vitro studies have shown that dengue virus (DENV) can thwart the actions of interferon (IFN)-α/β and prevent the development of an antiviral state in infected cells. Clinical studies looking at gene expression in patients with severe dengue show a reduced expression of interferon stimulated genes compared to patients with dengue fever. Interestingly, there are conflicting reports as to the ability of DENV or other flaviviruses to inhibit IFN-α/β signaling. In order to determine the relative inhibition of IFN-α/β signaling by DENVs, a method combining flow cytometry and a four-parameter logistic regression model was established. A representative isolate from DENV-1, -3 and -4 and seventeen representative isolates encompassing all DENV-2 genotypes were evaluated. All of the DENVs evaluated in this study were capable of inhibiting IFN-α/β signaling. Most of the strains were able to inhibit IFN-α/β to a degree similar to DENV strain 16681; however, DENV-2 sylvatic strains demonstrated an increased inhibition of phosphorylated signal transducer and activator of transcription (pSTAT1). Surprisingly, we were unable to observe inhibition of pSTAT1 by DENV-2 sylvatic strains or the Asian strain 16681 in non-human primate (NHP) cell lines. Analysis in primary Rhesus macaque dendritic cells suggests that DENVs are capable of inhibiting IFN signaling in these cells. However, contrary to human dendritic cells, production of IFN-α was detected in the supernatant of DENV-infected Rhesus macaque dendritic cells. The ability of DENVs to inhibit IFN-α/β signaling is conserved. Although some variation in the inhibition was observed, the moderate differences may be difficult to correlate with clinical outcomes. DENVs were unable to inhibit pSTAT1 in NHP cell lines, but their ability to inhibit pSTAT1 in primary Rhesus macaque dendritic cells suggests that this may be a cell specific phenomena or due to the transformed nature of the cell lines.
PLoS ONE, 2014
Dengue is a potentially fatal acute febrile illness caused by four mosquito-transmitted dengue vi... more Dengue is a potentially fatal acute febrile illness caused by four mosquito-transmitted dengue viruses (DENV-1-4). Although dengue outbreaks regularly occur in many regions of the Pacific, little is known about dengue in the Republic of the Marshall Islands (RMI). To better understand dengue in RMI, we investigated an explosive outbreak that began in October 2011. Suspected cases were reported to the Ministry of Health, serum specimens were tested with a dengue rapid diagnostic test (RDT), and confirmatory testing was performed using RT-PCR and IgM ELISA. Laboratory-positive cases were defined by detection of DENV nonstructural protein 1 by RDT, DENV nucleic acid by RT-PCR, or anti-DENV IgM antibody by RDT or ELISA. Secondary infection was defined by detection of anti-DENV IgG antibody by ELISA in a laboratory-positive acute specimen. During the four months of the outbreak, 1,603 suspected dengue cases (3% of the RMI population) were reported. Of 867 (54%) laboratory-positive cases, 209 (24%) had dengue with warning signs, six (0.7%) had severe dengue, and none died. Dengue incidence was highest in residents of Majuro and individuals aged 10-29 years, and ,95% of dengue cases were experiencing secondary infection. Only DENV-4 was detected by RT-PCR, which phylogenetic analysis demonstrated was most closely related to a virus previously identified in Southeast Asia. Cases of vertical DENV transmission, and DENV/Salmonella Typhi and DENV/Mycobacterium leprae co-infection were identified. Entomological surveys implicated water storage containers and discarded tires as the most important development sites for Aedes aegypti and Ae. albopictus, respectively. Although this is the first documented dengue outbreak in RMI, the age groups of cases and high prevalence of secondary infection demonstrate prior DENV circulation. Dengue surveillance should continue to be strengthened in RMI and throughout the Pacific to identify and rapidly respond to future outbreaks.
PLoS Neglected Tropical Diseases, 2013
Dengue is an acute illness caused by the positive-strand RNA dengue virus (DENV). There are four ... more Dengue is an acute illness caused by the positive-strand RNA dengue virus (DENV). There are four genetically distinct DENVs (DENV-1-4) that cause disease in tropical and subtropical countries. Most patients are viremic when they present with symptoms; therefore, RT-PCR has been increasingly used in dengue diagnosis. The CDC DENV-1-4 RT-PCR Assay has been developed as an in-vitro diagnostic platform and was recently approved by the US Food and Drug Administration (FDA) for detection of dengue in patients with signs or symptoms of mild or severe dengue. The primers and probes of this test have been designed to detect currently circulating strains of DENV-1-4 from around the world at comparable sensitivity. In a retrospective study with 102 dengue cases confirmed by IgM anti-DENV seroconversion in the convalescent sample, the RT-PCR Assay detected DENV RNA in 98.04% of the paired acute samples. Using sequencing as a positive indicator, the RT-PCR Assay had a 97.92% positive agreement in 86 suspected dengue patients with a single acute serum sample. After extensive validations, the RT-PCR Assay performance was highly reproducible when evaluated across three independent testing sites, did not produce false positive results for etiologic agents of other febrile illnesses, and was not affected by pathological levels of potentially interfering biomolecules. These results indicate that the CDC DENV-1-4 RT-PCR Assay provides a reliable diagnostic platform capable for confirming dengue in suspected cases.
Current Protocols in Microbiology, 2005
Dengue is a disease caused by infection with one of the four dengue virus serotypes . The virus i... more Dengue is a disease caused by infection with one of the four dengue virus serotypes . The virus is transmitted to humans by Aedes sp. mosquitoes. This enveloped virus contains a positive single-stranded RNA genome. Clinical manifestations of dengue can have a wide range of outcomes varying from a mild febrile illness to a life-threatening condition. New techniques have largely replaced the use of DENV isolation in disease diagnosis. However, virus isolation still serves as the gold standard for detection and serotyping of DENV and is common practice in research and reference laboratories where clinical isolates of the virus are characterized and sequenced, or used for a variety of research experiments. Isolation of DENV from clinical samples can be achieved in mammalian and mosquito cells or by inoculation of mosquitoes. The experimental methods presented here describe the most common procedures used for the isolation, serotyping, propagation, and quantification of DENV. Curr. Protoc. Microbiol. 27:15D.2.1-15D.2.24. C 2012 by John Wiley & Sons, Inc.
Virology, 2012
The objective of the study was to evaluate if the antibodies elicited after immunization with a t... more The objective of the study was to evaluate if the antibodies elicited after immunization with a tetravalent dengue vaccine, based on chimeric yellow fever 17D/dengue viruses, can neutralize a large range of dengue viruses (DENV). A panel of 82 DENVs was developed from viruses collected primarily during the last decade in 30 countries and included the four serotypes and the majority of existing genotypes. Viruses were isolated and minimally amplified before evaluation against a tetravalent polyclonal serum generated during vaccine preclinical evaluation in monkey, a model in which protection efficacy of this vaccine has been previously demonstrated . Neutralization was observed across all the DENV serotypes, genotypes, geographical origins and isolation years. These data indicate that antibodies elicited after immunization with this dengue vaccine candidate should widely protect against infection with contemporary DENV lineages circulating in endemic countries.
Transfusion, 2012
In 2007, a total of 10,508 suspected dengue cases were reported in Puerto Rico. Blood donations w... more In 2007, a total of 10,508 suspected dengue cases were reported in Puerto Rico. Blood donations were tested for dengue virus (DENV) RNA and recipients of RNA-positive donations traced to assess transfusion transmission. Blood donation samples from 2007 were maintained in a repository and tested individually for DENV RNA by transcription-mediated amplification (TMA); a subset was further tested by an enhanced TMA (eTMA) assay. TMA-reactive samples were considered confirmed if TMA (including eTMA) was repeat reactive (RR). All TMA-RR samples were tested by quantitative, DENV type-specific reverse transcriptase-polymerase chain reaction (RT-PCR) and for anti-DENV immunoglobulin (Ig)M by enzyme-linked immunosorbent assay. Samples positive by RT-PCR were further tested for infectivity in mosquito cell culture. Patients receiving components from TMA-RR donations were followed. Of 15,350 donation samples tested, 29 were TMA-RR for a prevalence of 1 per 529 (0.19%). DENV Types 1, 2, and 3 with viral titers of 10(5) to 10(9) copies/mL were detected by RT-PCR in 12 samples of which all were infectious in mosquito culture. Six TMA-RR samples were IgM positive. Three of the 29 recipients receiving TMA-RR donations were tested. One recipient in Puerto Rico transfused with red blood cells containing 10(8) copies/mL DENV-2 became febrile 3 days posttransfusion and developed dengue hemorrhagic fever. The recipient was DENV-2 RNA positive by RT-PCR; both the donor and the recipient viruses had identical envelope sequences. High rates of viremia were detected in blood donors in Puerto Rico coupled with the first documented transfusion transmission of severe dengue disease, suggesting that further research on interventions is needed.
PLoS Neglected Tropical Diseases, 2013
Background: Dengue is a potentially fatal acute febrile illness (AFI) caused by four mosquito-tra... more Background: Dengue is a potentially fatal acute febrile illness (AFI) caused by four mosquito-transmitted dengue viruses (DENV-1-4) that are endemic in Puerto Rico. In January 2010, the number of suspected dengue cases reported to the passive dengue surveillance system exceeded the epidemic threshold and an epidemic was declared soon after.
PLoS Neglected Tropical Diseases, 2013
Dengue is an acute illness caused by the positive-strand RNA dengue virus (DENV). There are four ... more Dengue is an acute illness caused by the positive-strand RNA dengue virus (DENV). There are four genetically distinct DENVs (DENV-1-4) that cause disease in tropical and subtropical countries. Most patients are viremic when they present with symptoms; therefore, RT-PCR has been increasingly used in dengue diagnosis. The CDC DENV-1-4 RT-PCR Assay has been developed as an in-vitro diagnostic platform and was recently approved by the US Food and Drug Administration (FDA) for detection of dengue in patients with signs or symptoms of mild or severe dengue. The primers and probes of this test have been designed to detect currently circulating strains of DENV-1-4 from around the world at comparable sensitivity. In a retrospective study with 102 dengue cases confirmed by IgM anti-DENV seroconversion in the convalescent sample, the RT-PCR Assay detected DENV RNA in 98.04% of the paired acute samples. Using sequencing as a positive indicator, the RT-PCR Assay had a 97.92% positive agreement in 86 suspected dengue patients with a single acute serum sample. After extensive validations, the RT-PCR Assay performance was highly reproducible when evaluated across three independent testing sites, did not produce false positive results for etiologic agents of other febrile illnesses, and was not affected by pathological levels of potentially interfering biomolecules. These results indicate that the CDC DENV-1-4 RT-PCR Assay provides a reliable diagnostic platform capable for confirming dengue in suspected cases.
Journal of Infectious Diseases, 2012
Background. The dengue virus serotype 3 (DENV-3) Indian subcontinent strain emerged in Puerto Ric... more Background. The dengue virus serotype 3 (DENV-3) Indian subcontinent strain emerged in Puerto Rico in 1998 after a 21-year absence. The rapid expansion of DENV-3 on the island correlated with the withdrawal of the other serotypes for 7 years. The DENV-3 prevalence declined in 2008 and remains undetected.
Emerging Infectious Diseases, 2011
To study the evolution of dengue virus (DENV) serotype 2 in Puerto Rico, we examined the genetic ... more To study the evolution of dengue virus (DENV) serotype 2 in Puerto Rico, we examined the genetic composition and diversity of 160 DENV-2 genomes obtained through 22 consecutive years of sampling. A clade replacement took place in 1994-1997 during a period of high incidence of autochthonous DENV-2 and frequent, short-lived reintroductions of foreign DENV-2. This unique clade replacement was complete just before DENV-3 emerged. By temporally and geographically defi ning DENV-2 lineages, we describe a refuge of this virus through 4 years of low genome diversity. Our analyses may explain the long-term endurance of DENV-2 despite great epidemiologic changes in disease incidence and serotype distribution. E pidemic dengue fever (DF) and the emergence of dengue hemorrhagic fever (DHF) in the Americas are associated with increased endemicity and cocirculation of the 4 dengue virus (DENV) serotypes, 1-4 (1). These increases have been particularly evident in Puerto Rico, where transmission increased during the past 25 years (2-4). The fi rst DHF epidemics in the Americas occurred in the 1980s and were caused by the Asian/American genotype of DENV-2, then new to the region, which rapidly replaced the American genotype (5-7). This replacement has been linked to a potential to cause higher viremia and severe illness (8-10). Introduction of DENV-3 in the mid 1990s and increased human population and travel further fostered larger and more frequent DF and DHF epidemics in the region (11-13).
Emerging Infectious Diseases, 2013
Sequencing of dengue virus type 1 (DENV-1) strains isolated in Key West/Monroe County, Florida, i... more Sequencing of dengue virus type 1 (DENV-1) strains isolated in Key West/Monroe County, Florida, indicate endemic transmission for >2 years of a distinct and predominant sublineage of the American-African genotype. DENV-1 strains isolated elsewhere in Florida grouped within a separate Central American lineage. Findings indicate endemic transmission of DENV into the continental United States.
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Papers by Gilberto Santiago