Flávio Guimarães da Fonseca

Federal University of Minas Gerais, Cidade de Minas, Minas Gerais, Brazil

Are you Flávio Guimarães da Fonseca?

Claim your profile

Publications (55)153.36 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: CD8(+) T cells that recognize virus-derived peptides presented on MHC class I are vital antiviral effectors. Such peptides presented by any given virus vary greatly in immunogenicity, allowing them to be ranked in an immunodominance hierarchy. However, the full range of parameters that determine immunodominance and the underlying mechanisms remain unknown. In this study, we show across a range of vaccinia virus strains, including the current clonal smallpox vaccine, that the ability of a strain to spread systemically correlated with reduced immunodominance. Reduction in immunodominance was observed both in the lymphoid system and at the primary site of infection. Mechanistically, reduced immunodominance was associated with more robust priming and especially priming in the spleen. Finally, we show this is not just a property of vaccine and laboratory strains of virus, because an association between virulence and immunodominance was also observed in isolates from an outbreak of zoonotic vaccinia virus that occurred in Brazil. Copyright © 2015 by The American Association of Immunologists, Inc.
    The Journal of Immunology 07/2015; DOI:10.4049/jimmunol.1402508 · 5.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The complexity of giant virus genomes is intriguing, especially the presence of genes encoding components of the protein translation machinery such as transfer RNAs and aminoacyl-tRNA-synthetases; these features are uncommon among other viruses. Although orthologs of these genes are codified by their hosts, one can hypothesize that having these translation-related genes might represent a gain of fitness during infection. Therefore, the aim of this study was to evaluate the expression of translation-related genes by mimivirus during infection of Acanthamoeba castellanii under different nutritional conditions. In silico analysis of amino acid usage revealed remarkable differences between the mimivirus isolates and the A. castellanii host. Relative expression analysis by quantitative PCR revealed that mimivirus was able to modulate the expression of eight viral translation-related genes according to the amoebal growth condition, with a higher induction of gene expression under starvation. Some mimivirus isolates presented differences in translation-related gene expression; notably, polymorphisms in the promoter regions correlated with these differences. Two mimivirus isolates did not encode the tryptophanyl-tRNA synthetase in their genomes, which may be linked with low conservation pressure based on amino acid usage analysis. Taken together, our data suggest that mimivirus can modulate the expression of translation-related genes in response to nutrient availability in the host cell, allowing the mimivirus to adapt to different hosts growing under different nutritional conditions.
    Frontiers in Microbiology 06/2015; 06. DOI:10.3389/fmicb.2015.00539 · 3.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In 2010, a vaccinia virus isolate caused an atypically severe outbreak that affected humans and cattle in Brazil. Of 26 rural workers affected, 12 were hospitalized. Our data raise questions about the risk factors related to the increasing number and severity of vaccinia virus infections.
    Emerging Infectious Diseases 04/2015; 21(4):695-698. DOI:10.3201/eid2104.140351 · 7.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Human T-lymphotropic virus 1 (HTLV-1) has been associated with leukemia/lymphoma (ATL) and myelopathy/tropical spastic paraparesis (HAM/TSP), in addition to other inflammatory diseases as well as infection complications. Therapeutic approaches for HTLV-1-related pathologies are limited. The labdane diterpene myriadenolide (AMY) is a natural product that exhibit biological activities, such as anti-inflammatory and antiviral activity as reported for HIV and herpesvirus.ResultsWe demonstrated that this natural product was able to inhibit the expression of gag-pol mRNA and substantially reduced the expression of the structural proteins p19 and gp46. Comparison of treated and untreated cells shows that AMY alters both the morphology and the release of viral particles. The Atomic Force Microscopy assay showed that the AMY treatment reduced the number of particles on the cell surface by 47%.Conclusion We demonstrated that the labdane diterpene myriadenolide reduced the expression of the structural proteins and the budding of viral particles, besides induces altered morphogenesis of HTLV-1, conferring on AMY a new antiviral activity that may be useful for the development of new compounds with specific anti-HTLV-1 activity.
    BMC Microbiology 12/2014; 14(1):3. DOI:10.1186/s12866-014-0331-2 · 2.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Introduction Hantavirus infections have been described in several regions in Brazil through seroepidemiological studies. Usually, populations are associated with rural and wild environment mainly due to close contact to species of Sigmodontinae rodents, considered hantavirus reservoirs. Methods A retrospective serosurvey was conducted to access the hantavirus seroprevalence in people living in regions affected by bovine vaccinia outbreaks. Results Sera from 53 patients were analyzed and none of them presented anti-hantavirus IgG antibodies. Conclusions This study presents an opportunity to analyze seronegativity despite close and recurrent contact with known hantavirus reservoirs. Aspects of hantavirus and bovine vaccinia emergence are also discussed.
    Revista da Sociedade Brasileira de Medicina Tropical 12/2014; 47(6):778-82. DOI:10.1590/0037-8682-0033-2014 · 0.94 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The present study compares the profile of NK cells in an in vitro re-exposure by Vaccinia virus (VACV), in groups that have had a previous vaccination or natural infection. Our data suggests that stimulation with VACV triggers a cytotoxic response by NK cells marked by an increase of NCRs: NKp30, NKp44, and NKp46 in infected (vaccinated and unvaccinated) subjects and in non-infected vaccinated patients, when compared with non-infected unvaccinated individuals. However, the degranulation and secretion processes are inhibited in infected (vaccinated and unvaccinated) subjects and in the non-infected vaccinated patients, when compared with non-infected unvaccinated individuals. We demonstrated that stimulation with VACV downregulates the percentage of expression of perforin, granzyme A, and CD107a, but upregulate CD94 in infected (vaccinated and unvaccinated) subjects and in non-infected vaccinated patients, when compared with non-infected unvaccinated individuals. Furthermore, the percentage of IFN-γ+ NK cells was significantly lower in non-infected unvaccinated subjects, when compared with infected (vaccinated and unvaccinated) and non-infected vaccinated individuals. Our results also show that the percentage of TNF-α+ NK cells was significantly higher in infected (vaccinated and unvaccinated) subjects and in non-infected vaccinated patients, when compared with non-infected unvaccinated individuals, after in vitro stimulation with UV-inactivated VACV. Our data suggest that the expression of NCRs NKp30, NKp44, NKp46 and cytokines by NK cells are important in the innate response against VACV.
    Virus Research 05/2014; 184. DOI:10.1016/j.virusres.2014.02.001 · 2.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dengue is a global public health concern and this is aggravated by a lack of vaccines or antiviral therapies. Despite the well-known role of CD8(+) T cells in the immunopathogenesis of Dengue virus (DENV), only recent studies have highlighted the importance of this arm of the immune response in protection against the disease. Thus, the majority of DENV vaccine candidates are designed to achieve protective titers of neutralizing antibodies, with less regard for cellular responses. Here, we used a mouse model to investigate CD8(+) T cell and humoral responses to a set of potential DENV vaccines based on recombinant modified vaccinia virus Ankara (rMVA). To enable this study, we identified two CD8(+) T cell epitopes in the DENV-3 E protein in C57BL/6 mice. Using these we found that all the rMVA vaccines elicited DENV-specific CD8(+) T cells that were cytotoxic in vivo and polyfunctional in vitro. Moreover, vaccines expressing the E protein with an intact signal peptide sequence elicited more DENV-specific CD8(+) T cells than those expressing E proteins in the cytoplasm. Significantly, it was these same ER-targeted E protein vaccines that elicited antibody responses. Our results support the further development of rMVA vaccines expressing DENV E proteins and add to the tools available for dengue vaccine development.
    Vaccine 04/2014; 32(25). DOI:10.1016/j.vaccine.2014.03.093 · 3.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bovine anaplasmosis is a disease caused by the intraerythrocytic rickettsia Anaplasma marginale. Surface proteins (MSPs) of A. marginale are important in the interaction of the pathogen with the host and constitute potential vaccine targets against this pathogen. Currently, there is no commercial inactivated vaccine against bovine anaplasmosis that can generate a protective immune response that effectively prevents the development of clinical disease. The objective of this study was to evaluate the humoral and cellular immune responses of BALB/c mice immunized with the recombinant fragment of rMSP1a from A. marginale using carbon nanotubes as a carrier molecule. The fragment of rMSP1a comprising the N-terminal region of the protein was expressed in Escherichia coli BL21, purified by nickel affinity chromatography and covalently linked to multiwalled carbon nanotubes (MWNTs). After this functionalization, thirty BALB/c mice were divided into five groups, G1 (rMSP1a), G2 (MWNT+rMSP1a), G3 (MWNT), G4 (adjuvant) and G5 (unimmunized). The mice were immunized subcutaneously at days 0, 21 and 42. Blood samples were collected on day 11 after immunization. The spleens were collected, and the splenocytes were cultured for cell proliferation assays and cell immunophenotyping. Mice immunized with rMSP1a (G1 and G2) produced high levels of anti-rMSP1a IgG, demonstrating that the functionalization to carbon nanotubes did not interfere with protein immunogenicity. Immunization with MWNT+rMSP1a significantly induced higher percentages of CD4(+)CD44(+) and CD4(+)CD62L(+) lymphocytes, high levels of TNF-α, and a higher proliferative rate of splenocytes compared to mice immunized with rMSP1a alone (G1 group). Therefore, additional experiments using cattle should be performed to determine the efficacy, safety, immunogenicity and protection induced by rMSP1a associated with MWNT.
    Vaccine 03/2014; 32(19). DOI:10.1016/j.vaccine.2014.02.062 · 3.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Disease prevention through vaccination is one of the most important achievements of medicine. Today, we have a substantial number of vaccines against a variety of pathogens. In this context, poxviruses and vaccinology are closely related, as the birth of modern vaccinology was marked by the use of poxviruses as immunogens and so was the eradication of smallpox, one of the world’s most feared diseases ever. Nowadays, poxviruses continue to notoriously contribute to vaccinology since their use as vaccine vectors has become popular and widespread. One of the most promising vectors is the modified vaccinia ankara. In this review we provide an overview of the contribution of poxvirus to vaccine immunology, particularly focusing on modified vaccinia ankara-based vaccines developed to date.
    Future Virology 02/2014; 9(2):173-187. DOI:10.2217/fvl.13.129 · 1.00 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The present study evaluates the immune response of memory CD4+ and CD8+ T cells from patients following a natural Vaccinia virus (VACV) infection. A total of 42 individuals were involved in the study being: 22 previously infected individuals (vaccinated or not against smallpox) and 20 non-infected individuals (vaccinated or not). A short-term in vitro stimulation with UV-inactivated VACV of whole blood cells was performed. Our study showed that previously infected individuals have a lower percentage of CD4+ T cells expressing lymph-node homing receptors (CD4+CD62L+CCR7+) and higher percentage of memory CD4+ T cells subsets (CD4+CD45ROHigh) when compared with non-infected subjects, after in vitro viral stimulation. We also showed that infected individuals presented higher percentages of CD4+ and CD8+ memory T lymphocytes expressing IFN-γ when compared to non-infected individuals. We verified that the percentage of CD4+ and CD8+ T memory cells expressing TNF-α was higher in infected and non-infected vaccinated subjects when compared with non-infected unvaccinated individual. We also observed that previously infected individuals have higher percentages of CD8+ T cells expressing lymph-node homing receptors (CCR7+ and CD62L+) and that the memory T cells expressing IFN-γ and TNF-α were at higher percentages in the whole blood cells from infected and non-infected vaccinated individuals, when compared to unvaccinated non-infected subjects. Thus, our findings suggest that CD4+ and CD8+ T cells are involved in the immune memory response against Vaccinia virus natural infection.
    12/2013; 3:104–113. DOI:10.1016/j.rinim.2013.10.002
  • Flávio Guimarães da Fonseca · Daniel Mendes Ribeiro · Nara Pereira Carvalho · Brunello Stancioli
    Journal of medical ethics 08/2013; 40(11). DOI:10.1136/medethics-2013-101674 · 1.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The use of recombinant viral vectors expressing T. gondii antigens is a safe and efficient approach to induce immune response against the parasite and a valuable tool for vaccine development. We have previously protected mice from toxoplasmosis by immunizing the animals with an adenovirus expressing the protein SAG1 (AdSAG1) of T. gondii. We are now looking for ways to improve the vaccination strategy and enhance protection. One limitation of homologous vaccinations (sequential doses of the same vector) is induction of anti-vector immune response that blocks cell transduction, restricts transgene expression and, consequently, compromises the overall outcome of vaccination. One way to avert the effects of anti-vector response is to use different viruses in prime and boost (heterologous vaccination). Bearing this in mind, we generated a modified Vaccinia Virus Ankara encoding SAG1 (MVASAG1), to be tested as boost agent after prime with AdSAG1. Although minor differences were observed in the magnitude of the anti-SAG1 immune response induced by each vaccination protocol, the heterologous immunization with AdSAG1 followed by MVASAG1 resulted in improved capacity to control brain cyst formation in a model of chronic toxoplasmosis in C57BL/6 mice.
    PLoS ONE 05/2013; 8(5):e63201. DOI:10.1371/journal.pone.0063201 · 3.23 Impact Factor
  • Source
  • Source
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this article, we examine the ethical implications of human transgenesis by considering the phenomenon in its larger evolutionary context. After clarifying the concept of transgenesis, we show that rather than unprecedented or unnatural, transgenesis is a common aspect of the evolutionary process that has likely affected all extant living animals, humans included. Additionally, we demonstrate that human transgenesis is technically feasible and that the moral barriers to it are mostly based on irrational fears premised on distorted and unrealistic views of “human nature”. Furthermore, we suggest that transgenically modifying persons might be morally preferable to relying blindly on the “natural lottery”, and that it is possible to do so in an ethical and responsible manner.
    12/2012; 25(4). DOI:10.1007/s13347-012-0074-7
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Since 1999, several Vaccinia virus (VACV) isolates, the etiological agents of bovine vaccinia (BV), have been frequently isolated and characterized with various biological and molecular methods. The results from these approaches have grouped these VACV isolates into two different clusters. This dichotomy has elicited debates surrounding the origin of the Brazilian VACV and its epidemiological significance. To ascertain vital information to settle these debates, we and other research groups have made efforts to identify molecular markers to discriminate VACV from other viruses of the genus Orthopoxvirus (OPV) and other VACV-BR groups. In this way, some genes have been identified as useful markers to discriminate between the VACV-BR groups. However, new markers are needed to infer ancestry and to correlate each sample or group with its unique epidemiological and biological features. The aims of this work were to characterize a new VACV isolate (VACV DMTV-2005) molecularly and biologically using conserved and non-conserved gene analyses for phylogenetic inference and to search for new genes that would elucidate the VACV-BR dichotomy. The VACV DMTV-2005 isolate reported in this study is biologically and phylogenetically clustered with other strains of Group 1 VACV-BR, the most prevalent VACV group that was isolated during the bovine vaccinia outbreaks in Brazil. Sequence analysis of C23L, the gene that encodes for the CC-chemokine-binding protein, revealed a ten-nucleotide deletion, which is a new Group 1 Brazilian VACV genetic marker. This deletion in the C23L open reading frame produces a premature stop-codon that is shared by all Group 1 VACV-BR strains and may also reflect the VACV-BR dichotomy; the deletion can also be considered to be a putative genetic marker for non-virulent Brazilian VACV isolates and may be used for the detection and molecular characterization of new isolates.
    PLoS ONE 11/2012; 7(11):e50413. DOI:10.1371/journal.pone.0050413 · 3.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Dengue virus (DENV) is the most prevalent arbovirus in the world, found mainly in tropical regions. As clinical manifestations present frequently as nonspecific febrile illness, laboratory diagnosis is essential to confirm DENV infections and for epidemiological studies. Recombinant envelope (E) antigens of four serotypes of DENV were used to develop an immunoglobulin G enzyme-linked immunosorbent assay (IgG-ELISA). To evaluate the IgG-ELISA, a panel of serum samples that had been tested previously by a plaque reduction neutralization test (PRNT) was investigated for the presence of anti-E antibodies against the four DENV serotypes. IgG-ELISA was found to have a sensitivity (91%) and specificity (98%) at a receiver-operating characteristic (ROC) optimized cutoff and demonstrated high performance as well as good indexes. A concordance of 97% was achieved between both assays, and only 21/704 (3%) samples were not concordant. The results of the present study demonstrate a moderate correlation between neutralizing antibody titers and IgG-ELISA values. These findings indicate that the recombinant protein-based IgG-ELISA is a suitable method for routine serodiagnosis, monitoring and seroepidemiological studies of DENV infections.
    Journal of virological methods 09/2012; 187(1). DOI:10.1016/j.jviromet.2012.09.012 · 1.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In 2010, the WHO celebrated the 30th anniversary of the smallpox eradication. Ironically, infections caused by viruses related to smallpox are being increasingly reported worldwide, including Monkeypox , Cowpox, and Vaccinia virus (VACV). Little is known about the human immunological responses elicited during acute infections caused by orthopoxviruses. We have followed VACV zoonotic outbreaks taking place in Brazil and analyzed cellular immune responses in patients acutely infected by VACV. Results indicated that these patients show a biased immune modulation when compared to noninfected controls. Amounts of B cells are low and less activated in infected patients. Although present, T CD4 + cells are also less activated when compared to noninfected individuals, and so are monocytes/macrophages. Similar results were obtained when Balb/C mice were experimentally infected with a VACV sample isolated during the zoonotic outbreaks. Taking together, the data suggest that zoonotic VACVs modulate specific immune cell compartments during an acute infection in humans.
    Clinical and Developmental Immunology 01/2012; 2012(2):974067. DOI:10.1155/2012/974067 · 2.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Vaccinia virus (VACV), the prototype species of the Orthopoxvirus (OPV) genus, causes an occupational zoonotic disease in Brazil that is primarily associated with the handling of infected dairy cattle. Cattle and human outbreaks have been described in southeastern Brazil since 1999 and have now occurred in almost half of the territory. Phylogenetic studies have shown high levels of polymorphisms among isolated VACVs, which indicate the existence of at least two genetically divergent clades; this has also been proven in virulence assays in a mouse model system. In humans, VACV infection is characterized by skin lesions, primarily on the hands, accompanied by systemic symptoms such as fever, myalgia, headache and lymphadenopathy. In this review, we will discuss the virological, epidemiological, ecological and clinical aspects of VACV infection, its diagnosis and compounds that potentially could be used for the treatment of severe cases.
    Antiviral research 08/2011; 92(2):150-63. DOI:10.1016/j.antiviral.2011.08.018 · 3.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Human herpesvirus type 1 (HHV-1) is widely dispersed among the human population. Although infection is often asymptomatic in humans, nonhuman primates develop a severe and often fatal infection. In August 2006, 13 black-tufted marmosets (Callithrix penincillata) from a group of 14 presented with clinical apathy, anorexia, and ataxia. Physical examination revealed conjunctivitis, erosive or ulcerative lesions on the skin, and swollen lymph nodes. Of the 14 animals captured, 10 died. Grossly, ulcers and erosions were observed on the skin of face, nasal planum, lips, and oral mucosa. Histologically, superficial vesicular and erosive stomatitis with associated basophilic intranuclear inclusion bodies in the squamous epithelium were observed. Swabs from oral lesions and tissue samples from necropsied animals were positive for HHV-1 by nested polymerase chain reaction for eight animals.
    Journal of wildlife diseases 07/2011; 47(3):690-3. DOI:10.7589/0090-3558-47.3.690 · 1.31 Impact Factor

Publication Stats

591 Citations
153.36 Total Impact Points

Institutions

  • 1998–2015
    • Federal University of Minas Gerais
      • Departamento de Microbiologia
      Cidade de Minas, Minas Gerais, Brazil
  • 2009–2011
    • Unimed Belo Horizonte
      Cidade de Minas, Minas Gerais, Brazil
  • 2006–2011
    • Fundação Oswaldo Cruz
      Rio de Janeiro, Rio de Janeiro, Brazil
  • 2007
    • Faculdade de Medicina de São José do Rio Preto
      Rio Preto, São Paulo, Brazil
  • 2004
    • CEP America
      Emeryville, California, United States
  • 2003
    • National Institutes of Health
      베서스다, Maryland, United States