Navegando por Palavras-chave "protozoan parasites"
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- ItemSomente MetadadadosA DNA-priming protein-boosting regimen significantly improves type 1 immune response but not protective immunity to Trypanosoma cruzi infection in a highly susceptible mouse strain(Blackwell Publishing Asia, 2003-04-01) Vasconcelos, Jose Ronnie Carvalho de [UNIFESP]; Boscardin, Silvia Beatriz [UNIFESP]; Hiyane, Meire Ioshie [UNIFESP]; Kinoshita, Sheila Sayumi [UNIFESP]; Fujimura, Adriana Erika [UNIFESP]; Rodrigues, Mauricio Martins [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)BALB/c or C57Bl/6 mice immunized with plasmids containing Trypanosoma cruzi genes developed specific immune responses and protective immunity against lethal parasitic infection. in contrast, in the highly susceptible mouse strain A/Sn, DNA vaccination reduced the peak parasitemia but promoted limited mouse survival after challenge. in the present study, we tested whether the immunogenicity and protective efficacy of vaccination could be improved by combining DNA and recombinant protein immunization regimens. A/Sn mice immunized with plasmid p154/13 which harbours the gene encoding Trypanosoma cruzi trans -sialidase developed a predominant type 1 immune response. in contrast, immunization with the recombinant Trypanosoma cruzi trans -sialidase protein adsorbed to alum generated a typical type 2 immune response. Simultaneous administration of both p154/13 and recombinant Trypanosoma cruzi trans -sialidase protein also led to a predominant type 2 immune response. Sequential immunization consisting of two priming doses of p154/13 followed by booster injections with recombinant Trypanosoma cruzi trans -sialidase protein significantly improved specific type 1 immune response, as revealed by a drastic reduction of the serum IgG1/IgG2a ratio and by an increase in the in vitro interferon-gamma secretion by CD4 T cells. Our observations confirm and extend previous data showing that a DNA-priming protein-boosting regimen might be a general strategy to enhance type 1 immune response to DNA vaccines. Upon challenge with Trypanosoma cruzi , no improvement in protective immunity was observed in mice immunized with the DNA-priming protein-boosting regimen when compared to animals that received DNA only. Therefore, our results suggest that in this experimental model there is no correlation between the magnitude of type 1 immune response and protective immunity against Trypanosoma cruzi infection.
- ItemAcesso aberto (Open Access)Infection Strategies of Intestinal Parasite Pathogens and Host Cell Responses(Frontiers Media Sa, 2016) Di Genova, Bruno M. [UNIFESP]; Tonelli, Renata R. [UNIFESP]Giardia lamblia, Cryptosporidium sp., and Entamoeba histolytica are important pathogenic intestinal parasites and are amongst the leading causes worldwide of diarrheal illness in humans. Diseases caused by these organisms, giardiasis, cryptosporidiosis, and amoebiasis, respectively, are characterized by self -limited diarrhea but can evolve to long-term complications. The cellular and molecular mechanisms underlying the pathogenesis of diarrhea associated with these three pathogens are being unraveled, with knowledge of both the strategies explored by the parasites to establish infection and the methods evolved by hosts to avoid it. Special attention is being given to molecules participating in parasite host interaction and in the mechanisms implicated in the diseases' pathophysiologic processes. This review focuses on cell mechanisms that are modulated during infection, including gene transcription, cytoskeleton rearrangements, signal transduction pathways, and cell death.
- ItemAcesso aberto (Open Access)Non-coding RNAs in Host-Pathogen Interactions: Subversion of Mammalian Cell Functions by Protozoan Parasites(Frontiers Media Sa, 2017) Bayer-Santos, Ethel; Marini, Marjorie M. [UNIFESP]; da Silveira, Jose F. [UNIFESP]Pathogens have evolved mechanisms to modulate host cell functions and avoid recognition and destruction by the host damage response. For many years, researchers have focused on proteins as the main effectors used by pathogens to hijack host cell pathways, but only recently with the development of deep RNA sequencing these molecules were brought to light as key players in infectious diseases. Protozoan parasites such as those from the genera Plasmodium, Toxoplasma, Leishmania, and Trypanosoma cause life-threatening diseases and are responsible for 1000s of deaths worldwide every year. Some of these parasites replicate intracellularly when infecting mammalian hosts, whereas others can survive and replicate extracellularly in the bloodstream. Each of these parasites uses specific evasion mechanisms to avoid being killed by the host defense system. An increasing number of studies have shown that these pathogens can transfer non-coding RNA molecules to the host cells to modulate their functions. This transference usually happens via extracellular vesicles, which are small membrane vesicles secreted by the microorganism. In this mini-review we will combine published work regarding several protozoan parasites that were shown to use non-coding RNAs in inter-kingdom communication and briefly discuss future perspectives in the field.