Recombinant viruses as tools to induce protective cellular immunity against infectious diseases

Infections by intracellular pathogens such as viruses, some bacteria and many parasites, are cleared in most cases after activation of specific T cellular immune responses that recognize foreign antigens and eliminate infected cells. Vaccines against those infectious organisms have been traditionally developed by administration of whole live attenuated or inactivated microorganisms. Nowadays, research is focused on the development of subunit vaccines, containing the most immunogenic antigens from the particular pathogen. However, when purified subunit vaccines are administered using traditional immunization protocols, the levels of cellular immunity induced are mostly low and not capable of eliciting complete protection against diseases caused by intracellular microbes. In this review, we present a promising alternative to those traditional protocols, which is the use of recombinant viruses encoding subunit vaccines as immunization tools. Recombinant viruses have several interesting features that make them extremely efficient at inducing immune responses mediated by T-lymphocytes. This cellular immunity has recently been demonstrated to be of key importance for protection against malaria and AIDS, both of which are major targets of the World Health Organization for vaccine development. Thus, this review will focus in particular on the development of new vaccination protocols against these diseases. [Int Microbiol 2004; 7(2):83–94

MyD88-dependent protective immunity elicited by adenovirus 5 expressing the surface antigen 1 from Toxoplasma gondii is mediated by CD8(+) T lymphocytes

Submitted by Nuzia Santos ([email protected]) on 2014-11-24T17:14:22Z No. of bitstreams: 1 MyD88-dependent protective immunity elicited by adenovirus 5 expressing the surface antigen 1 from Toxoplasma gondii is mediated by CD8(+) T lymphocytes.pdf: 1057989 bytes, checksum: 77f8f8b0d8b766903ef8408045500fd5 (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2014-11-24T17:49:07Z (GMT) No. of bitstreams: 1 MyD88-dependent protective immunity elicited by adenovirus 5 expressing the surface antigen 1 from Toxoplasma gondii is mediated by CD8(+) T lymphocytes.pdf: 1057989 bytes, checksum: 77f8f8b0d8b766903ef8408045500fd5 (MD5)Made available in DSpace on 2014-11-24T17:49:07Z (GMT). No. of bitstreams: 1 MyD88-dependent protective immunity elicited by adenovirus 5 expressing the surface antigen 1 from Toxoplasma gondii is mediated by CD8(+) T lymphocytes.pdf: 1057989 bytes, checksum: 77f8f8b0d8b766903ef8408045500fd5 (MD5) Previous issue date: 2011Universidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Bioquímica e Imunologia. Belo Horizonte, MG, BrazilUniversity of Massachusetts Medical School. Division of Infectious Disease and Immunology. Worcester, MA, USAUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Bioquímica e Imunologia. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Microbiologia. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Instituto de Ciências Biológicas. Departamento de Bioquímica e Imunologia. Belo Horizonte, MG, Brazil/University of Massachusetts Medical School. Division of Infectious Disease and Immunology. Worcester, MA, USA/Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrasilToxoplasma gondii is an intracellular parasite widely spread around the world. The Surface Antigens (SAG) 1, 2 and 3 are the main proteins expressed on the surface of T. gondii tachyzoites. Replication-defective adenovirus serotype 5 (rAd5) is one of the most potent recombinant viral vectors for eliciting T cell-mediated immunity in mice and humans. Here we show that vaccination with rAd5 expressing SAG1 (AdSAG1), but neither SAG2 nor SAG3, induces protective immunity in the highly susceptible C57BL/6 mice challenged with T. gondii. Furthermore, we evaluated different immunological components involved on viral induced protective immunity. We observed that host protection elicited by AdSAG1 is highly dependent on IL-12, IFN-γ and CD8+ T lymphocytes. Importantly, the induction of protective immunity (T cell-derived IFN-γ) was also dependent on Myeloid Differentiation Factor 88 (MyD88), and thus, likely to involve Toll-Like receptors. We conclude that protective parasite specific-CD8+ T cells are elicited by a mechanism that involves MyD88-dependent induction of IL-12

. Recombinant Vaccines against T. gondii: Comparison between Homologous and Heterologous Vaccination Protocols Using Two Viral Vectors Expressing SAG1

Submitted by Nuzia Santos ([email protected]) on 2018-10-29T14:15:32Z No. of bitstreams: 1 Recombinant Vaccines against T. gondii.pdf: 988495 bytes, checksum: 621257a469a6ac4cfb34dd968e44fef1 (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2018-10-29T14:21:22Z (GMT) No. of bitstreams: 1 Recombinant Vaccines against T. gondii.pdf: 988495 bytes, checksum: 621257a469a6ac4cfb34dd968e44fef1 (MD5)Made available in DSpace on 2018-10-29T14:21:22Z (GMT). No. of bitstreams: 1 Recombinant Vaccines against T. gondii.pdf: 988495 bytes, checksum: 621257a469a6ac4cfb34dd968e44fef1 (MD5) Previous issue date: 2013Universidade Federal de Minas Gerais. Instituto de Ciencias Biologicas. Departamento de Bioquimica e Imunologia. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Instituto de Ciencias Biologicas. Departamento de Microbiologia. Belo Horizonte, MG, Brazil/Fundacao Oswaldo Cruz. Centro de Pesquisas Rene Rachou. Belo Horizonte, MG, BrazilFundacao Oswaldo Cruz. Centro de Pesquisas Rene Rachou. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Instituto de Ciencias Biologicas. Departamento de Bioquimica e Imunologia. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Instituto de Ciencias Biologicas. Departamento de Bioquimica e Imunologia. Belo Horizonte, MG, Brazil/Fundacao Oswaldo Cruz. Centro de Pesquisas ReneRachou. Belo Horizonte, MG, Brazil/Division of Infectious Disease and Immunology. University of Massachusetts Medical School. Worcester, MA, United States of AmericaDivision of Infectious Disease and Immunology. University of Massachusetts Medical School. Worcester, MA, United States of AmericaThe 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

Phylogenetic analyses of influenza A (H1N1)pdm09 hemagglutinin gene during and after the pandemic event in Brazil

International audiencePandemic influenza A H1N1 [A(H1N1)pdm09] was first detected in Brazil in May 2009, and spread extensively throughout the country causing a peak of infection during June to August 2009. Since then, it has continued to circulate with a seasonal pattern, causing high rates of morbidity and mortality. Over this period, the virus has continually evolved with the accumulation of new mutations. In this study we analyze the phylogenetic relationship in a collection of 220 A(H1N1)pdm09 hemagglutinin (HA) gene sequences collected during and after the pandemic period (2009 to 2014) in Brazil. In addition, we have looked for evidence of viral polymorphisms associated with severe disease and compared the range of viral variants with the vaccine strain (A/California/7/2009) used throughout this period. The phylogenetic analyses in this study revealed the circulation of at least eight genetic groups in Brazil. Two (G6-pdm and G7-pdm) co-circulated during the pandemic period, showing an early pattern of viral diversification with a low genetic distance from vaccine strain. Other phylogenetic groups, G5, G6 (including 6B, 6C and 6D subgroups), and G7 were found in the subsequent epidemic seasons from 2011 to 2014. These viruses exhibited more amino acid differences from the vaccine strain with several substitutions at the antigenic sites. This is associated with a theoretical decrease in the vaccine efficacy. Furthermore, we observed that the presence of any polymorphism at residue 222 of the HA gene was significantly associated with severe/fatal cases, reinforcing previous reports that described this residue as a potential virulence marker. This study provides new information about the circulation of some viral variants in Brazil, follows up potential genetic markers associated with virulence and allows infer if the efficacy of the current vaccine against more recent A(H1N1)pdm09 strains may be reduced

Experimental reinfection of BALB/c mice with different recombinant type I/III strains of Toxoplasma gondii : involvement of IFN-γ and IL-10

To assess reinfection of BALB/c mice with different Toxoplasma gondii strains, the animals were prime infected with the non-virulent D8 strain and challenged with virulent recombinant strains. Thirty days after challenge, brain cysts were obtained from surviving BALB/c mice and inoculated in Swiss mice to obtain tachyzoites for DNA extraction and PCR-RFLP analysis to distinguish the different T. gondii strains present in possible co-infections. Anti- Toxoplasma immune responses were evaluated in D8-primed BALB/c mice by detecting IFN-γ and IL-10 produced by T cells and measuring immunoglobulin levels in serum samples. PCR-RFLP demonstrated that BALB/c mice were reinfected with the EGS strain at 45 days post prime infection (dpi) and with the EGS and CH3 strains at 180 dpi. High levels of IFN-γ were detected after D8 infection, with no significant difference between 45 and 180-day intervals. However, higher IL-10 levels and higher plasmatic IgG1 and IgA were detected from samples obtained 180 days after infection. BALB/c mice were susceptible to reinfection with different recombinant T. gondii strains and this susceptibility correlated with enhancement of IL-10 production

Clinical impact of respiratory virus in pulmonary exacerbations of children with Cystic Fibrosis.

BackgroundsCystic Fibrosis (CF) is a genetic, multisystemic, progressive illness that causes chronic suppurative lung disease. A major cause of morbimortality in this condition are pulmonary exacerbations. Although classically attributed to bacterial infections, respiratory virus have been increasingly recognized in its ethiopathogeny.MethodsNasopharyngeal swab samples were collected from children ResultsOut of 70 samples collected from 48 patients, 35.7% were positive for respiratory viruses. Rhinovirus were the most common (28% of all positive samples), followed by RSV. The virus positive group was associated with change in sinus discharge (p = 0.03). Considering only patients younger than five years old, positive virus detection was also associated with fever (p = 0.01). There was no significant difference in clinical severity or in bacterial colonization between virus positive and negative groups.ConclusionsProspective studies are still needed to assess the long term impact of viral infections in patients with CF, and their interaction with the bacterial microbiome in these patients

Requirement of UNC93B1 reveals a critical role for TLR7 in host resistance to primary infection with Trypanosoma cruzi

Submitted by Nuzia Santos ([email protected]) on 2014-08-04T18:55:42Z No. of bitstreams: 1 Requirement of UNC93B1 reveals a critical role for TLR7 in host resistance to primary infection with Trypanosoma cruzi.pdf: 3284582 bytes, checksum: 67620ec691076cf2c5ad46a02c597c03 (MD5)Made available in DSpace on 2014-08-04T18:55:42Z (GMT). No. of bitstreams: 1 Requirement of UNC93B1 reveals a critical role for TLR7 in host resistance to primary infection with Trypanosoma cruzi.pdf: 3284582 bytes, checksum: 67620ec691076cf2c5ad46a02c597c03 (MD5) Previous issue date: 2011University of Massachusetts. Medical School. Division of Infectious Disease and Immunology.Worcester, MA, USAUniversity of Massachusetts. Medical School. Division of Infectious Disease and Immunology.Worcester, MA, USAUniversity of Massachusetts. Medical School. Division of Infectious Disease and Immunology.Worcester, MA, USAUniversity of Massachusetts. Medical School. Division of Infectious Disease and Immunology.Worcester, MA, USAUniversidade Federal de Minas Gerais. Departamento de Bioquímica e Imunologia e Departamento de Parasitologia. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Departamento de Bioquímica e Imunologia e Departamento de Parasitologia. Belo Horizonte, MG, BrazilUniversity of Massachusetts. Medical School. Division of Infectious Disease and Immunology.Worcester, MA, USAUniversity of Massachusetts. Medical School. Division of Infectious Disease and Immunology.Worcester, MA, USA/Fundação Oswaldo Cruz. Centro de Pesquisa René Rachou. Belo Horizonte, MG, BrasilUNC93B1 associates with Toll-Like Receptor (TLR) 3, 7 and 9, mediating their translocation from the endoplasmic reticulum to the endolysosome, thus allowing proper activation by microbial nucleic acids. We found that the triple deficient ‘3d’ mice, which lack functional UNC93B1 as well as functional endossomal TLRs, are highly susceptible to infection with Trypanosoma cruzi. The enhanced parasitemia and mortality in 3d animals were associated with impaired pro-inflammatory response, including reduced levels of IL-12p40 and IFN-γ. Importantly, the phenotype of 3d mice was intermediary between MyD88−/−(highly susceptible) and TLR9−/−(less susceptible), indicating the involvement of an additional UN93B1-dependent-TLR(s) on host resistance to T. cruzi. Hence, our experiments also revealed that TLR7 is a ritical innate immune receptor involved in recognition of parasite RNA, induction of IL-12p40 by dendritic cells, and consequent IFN-γby T lymphocytes. Furthermore, we show that upon T. cruzi infection triple TLR3/7/9−/−mice had similar phenotype than 3d mice. These data imply hat the nucleic acid-sensing TLRs are critical determinants of host resistance to primary infection with T. cruzi

Whole-Genome Characterization of a Novel Human Influenza A(H1N2) Virus Variant, Brazil

We report the characterization of a novel reassortant influenza A(H1N2) virus not previously reported in humans. Recovered from a a pig farm worker in southeast Brazil who had influenza-like illness, this virus is a triple reassortant containing gene segments from subtypes H1N2 (hemagglutinin), H3N2 (neuraminidase), and pandemic H1N1 (remaining genes)