Navegando por Autor "Abrahão, Jônatas Santos"

Agora exibindo 1 - 3 de 3

Nanoparticles as vaccines to prevent arbovirus infection : a long road ahead.
(2021) Souza, Gabriel Augusto Pires de; Rocha, Raíssa Prado; Gonçalves, Ricardo Lemes; Ferreira, Cyntia Silva; Silva, Breno de Mello; Castro, Renato Fróes Goulart de; Rodrigues, João Francisco Vitório; Vieira Júnior, João Carlos Vilela; Malaquias, Luiz Cosme Cotta; Abrahão, Jônatas Santos; Coelho, Luiz Felipe Leomil
Arthropod-borne viruses (arboviruses) are a significant public health problem worldwide. Vaccination is considered one of the most effective ways to control arbovirus diseases in the human population. Nanoparticles have been widely explored as new vaccine platforms. Although nanoparticles’ potential to act as new vaccines against infectious diseases has been identified, nanotechnology’s impact on developing new vaccines to prevent arboviruses is unclear. Thus, we used a comprehensive bibliographic survey to integrate data concerning the use of diverse nanoparticles as vaccines against medically important arboviruses. Our analysis showed that considerable research had been conducted to develop and evaluate nanovaccines against Chikungunya virus, Dengue virus, Zika virus, Japanese encephalitis virus, and West Nile virus. The main findings indicate that nanoparticles have great potential for use as a new vaccine system against arboviruses. Most of the studies showed an increase in neutralizing antibody production after mouse immunization. Nevertheless, even with significant advances in this field, further efforts are necessary to address the nanoparticles’ potential to act as a vaccine against these arboviruses. To promote advances in the field, we proposed a roadmap to help researchers better characterize and evaluate nanovaccines against medically important arboviruses.
Pristimerin isolated from Salacia crassifolia (Mart. Ex. Schult.) G. Don. (Celastraceae) roots as a potential antibacterial agent against Staphylococcus aureus.
(2021) Nizer, Waleska Stephanie da Cruz; Ferraz, Ariane Coelho; Moraes, Thaís de Fátima Silva; Lima, William Gustavo de; Santos, Josana Pereira dos; Duarte, Lucienir Pains; Ferreira, Jaqueline Maria Siqueira; Magalhães, Cíntia Lopes de Brito; Vieira Filho, Sidney Augusto; Andrade, Ana Cláudia dos Santos Pereira; Rodrigues, Rodrigo Araújo Lima; Abrahão, Jônatas Santos; Magalhães, José Carlos de
Ethnopharmacological relevance: Pristimerin is a triterpenoid considered the main component of Salacia crassifolia extracts. This terpene has shown promising antitumor, anti-inflammatory, and antimicrobial effects. Likewise, S. crassifolia has been used in traditional medicine to treat cancer and as an antimicrobial and anti-inflammatory agent. Aim of the study: This study aimed to evaluate the antibacterial activity of the hexane extract of Salacia crassifolia roots (HER) and its isolate, pristimerin, against pathogenic bacteria. Materials and methods: First, we evaluated the spectrum of action of HER and pristimerin by the determination of the minimum inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC). Subsequently, we analyzed the time-kill curve of these plant-derived compounds against Staphylococcus aureus. Then, we examined their mode of action by three different assays: the crystal violet methodology, the release of intracellular material, and transmission electron microscopy methods (TEM). Finally, we evaluated the effect of HER and pristimerin on the pre-formed biofilm of S. aureus by the crystal violet assay, the synergistic effect by the checkerboard method, the cytotoxicity against Vero cells, and the in silico activity using the online software PASS. Results: HER and pristimerin presented a narrow spectrum of action against Gram-positive bacteria (MIC 0.195–25 μg/mL), and their primary mode of action is the alteration of membrane permeability of S. aureus. Our results show that the compounds disrupted the pre-formed biofilm of S. aureus in a dose-dependent manner. Furthermore, HER and pristimerin presented a significant synergic effect after the combination with well-known antibiotics, which was associated with the ability of these phytomedicines to change membrane permeability. Regarding the cytotoxic effect, the selective index (SI) of HER ranged from 0.37 to 11.86, and the SI of pristimerin varied from 0.24 to 30.87, according to the bacteria tested. Conclusions: Overall, HER and pristimerin showed a promising antibacterial effect in vitro through the alteration of membrane permeability of S. aureus.
Virulence in murine model shows the existence of two distinct populations of Brazilian vaccinia virus strains.
(2008) Ferreira, Jaqueline Maria Siqueira; Drumond, Betânia Paiva; Guedes, Maria Isabel Maldonado Coelho; Xavier, Marcelo Antônio Pascoal; Leite, Camila Megale Almeida; Arantes, Rosa Maria Esteves; Mota, Bruno Eduardo Fernandes; Abrahão, Jônatas Santos; Alves, Pedro Augusto; Oliveira, Fernando Meireles; Ferreira, Paulo César Peregrino; Bonjardim, Cláudio Antônio; Lobato, Zélia Inês Portela; Kroon, Erna Geessien
Brazilian Vaccinia virus had been isolated from sentinel mice, rodents and recently from humans, cows and calves during outbreaks on dairy farms in several rural areas in Brazil, leading to high economic and social impact. Some phylogenetic studies have demonstrated the existence of two different populations of Brazilian Vaccinia virus strains circulating in nature, but little is known about their biological characteristics. Therefore, our goal was to study the virulence pattern of seven Brazilian Vaccinia virus strains. Infected BALB/c mice were monitored for morbidity, mortality and viral replication in organs as trachea, lungs, heart, kidneys, liver, brain and spleen. Based on the virulence potential, the Brazilian Vaccinia virus strains were grouped into two groups. One group contained GP1V, VBH, SAV and BAV which caused disease and death in infected mice and the second one included ARAV, GP2V and PSTV which did not cause any clinical signals or death in infected BALB/ c mice. The subdivision of Brazilian Vaccinia virus strains into two groups is in agreement with previous genetic studies. Those data reinforce the existence of different populations circulating in Brazil regarding the genetic and virulence characteristics.