RESUMO
The venom of Antarctic octopus remains completely unstudied. Here, a preliminary investigation was conducted into the properties of posterior salivary gland (PSG) extracts from four Antarctica eledonine (Incirrata; Octopodidae) species (Adelieledone polymorpha, Megaleledone setebos, Pareledone aequipapillae, and Pareledone turqueti) collected from the coast off George V's Land, Antarctica. Specimens were assayed for alkaline phosphatase (ALP), acetylcholinesterase (AChE), proteolytic, phospholipase A(2) (PLA(2)), and haemolytic activities. For comparison, stomach tissue from Cirroctopus sp. (Cirrata; Cirroctopodidae) was also assayed for ALP, AChE, proteolytic and haemolytic activities. Dietary and morphological data were collected from the literature to explore the ecological importance of venom, taking an adaptive evolutionary approach. Of the incirrate species, three showed activities in all assays, while P. turqueti did not exhibit any haemolytic activity. There was evidence for cold-adaptation of ALP in all incirrates, while proteolytic activity in all except P. turqueti. Cirroctopus sp. stomach tissue extract showed ALP, AChE and some proteolytic activity. It was concluded that the AChE activity seen in the PSG extracts was possibly due to a release of household proteins, and not one of the secreted salivary toxins. Although venom undoubtedly plays an important part in prey capture and processing by Antarctica eledonines, no obvious adaptations to differences in diet or morphology were apparent from the enzymatic and haemolytic assays. However, several morphological features including enlarged PSG, small buccal mass, and small beak suggest such adaptations are present. Future studies should be conducted on several levels: Venomic, providing more detailed information on the venom compositions as well as the venom components themselves; ecological, for example application of serological or genetic methods in identifying stomach contents; and behavioural, including observations on capture of different types of prey.
Assuntos
Adaptação Fisiológica , Temperatura Baixa , Meio Ambiente , Venenos de Moluscos/análise , Octopodiformes/fisiologia , Fosfatase Alcalina/metabolismo , Animais , Regiões Antárticas , Inibidores da Colinesterase/metabolismo , Eritrócitos/efeitos dos fármacos , Feminino , Hemólise , Masculino , Venenos de Moluscos/enzimologia , Venenos de Moluscos/farmacologia , Octopodiformes/anatomia & histologia , Octopodiformes/classificação , Fenótipo , Filogenia , Glândulas Salivares/química , Glândulas Salivares/metabolismoRESUMO
The origin and evolution of venom in many animal orders remain controversial or almost entirely uninvestigated. Here we use cDNA studies of cephalopod posterior and anterior glands to reveal a single early origin of the associated secreted proteins. Protein types recovered were CAP (CRISP, Antigen 5 [Ag5] and Pathogenesis-related [PR-1]), chitinase, peptidase S1, PLA(2) (phospholipase A(2)), and six novel peptide types. CAP, chitinase, and PLA(2) were each recovered from a single species (Hapalochlaena maculosa, Octopus kaurna, and Sepia latimanus, respectively), while peptidase S1 transcripts were found in large numbers in all three posterior gland libraries. In addition, peptidase S1 transcripts were recovered from the anterior gland of H. maculata. We compare their molecular evolution to that of related proteins found in invertebrate and vertebrate venoms, revealing striking similarities in the types of proteins selected for toxic mutation and thus shedding light on what makes a protein amenable for use as a toxin.
Assuntos
Cefalópodes/anatomia & histologia , Evolução Molecular , Venenos de Moluscos/genética , Peçonhas/genética , Sequência de Aminoácidos , Animais , Teorema de Bayes , Quitinases/genética , Dados de Sequência Molecular , Venenos de Moluscos/metabolismo , Fosfolipases A2/genética , Alinhamento de Sequência , Taquicininas/genéticaRESUMO
Mitochondrial ND2 sequences were used to investigate the phylogenetic relationships amongst 31 diprotodontid marsupials (kangaroos, wombats, koala, possums, and allies). ND2 sequences were analyzed separately and in conjunction with available 12S rDNA sequences for 22 diprotodontid taxa. Phylogenetic analyses consistently identified monophyly for the Burramyoidea, Phalangeroidea, Petauroidea, Tarsipedoidea, Macropodoidea, and the Vombatiformes. Like previous molecular and morphological studies, relationships between the super-families were less well resolved. Inconsistency between taxonomic rank and genetic distance was identified amongst the diprotodontids.
Assuntos
DNA Mitocondrial , Evolução Molecular , Marsupiais/genética , Filogenia , Animais , RNA RibossômicoRESUMO
Molecular analysis of two Australo-Papuan rainforest birds exhibiting correlated 'leapfrog' patterns were used to elucidate the evolutionary origin of this unusual pattern of geographical differentiation. In both sooty owls (Tyto) and logrunners (Orthonyx), phenotypically similar populations occupy widely disjunct areas (central-eastern Australia and upland New Guinea) with a third, highly distinctive population, occurring between them in northeastern Queensland. Two mechanisms have been proposed to explain the origin of leapfrog patterns in avian distributions: recent shared ancestry of terminal populations and unequal rates or phenotypic change among populations. As the former should generate correlated patterns of phenotypic and genetic differentiation, we tested for a sister relationship between populations from New Guinea and central-eastern Australia using nuclear and mitochondrial DNA sequences. The resulting phylogenies not only refute recent ancestry as an explanation for the leapfrog pattern, but provide evidence of vastly different spatio-temporal histories for sooty owls and logrunners within the Australo-Papuan rainforests. This incongruence indicates that the evolutionary processes responsible for generating leapfrog patterns in these co-distributed taxa are complex, possibly involving a combination of selection and drift in sooty owls and convergence or retention of ancestral characteristics in logrunners.
Assuntos
DNA Mitocondrial/genética , Ecossistema , Aves Canoras/genética , Estrigiformes/genética , Adenosina Trifosfatases/genética , Animais , Austrália , Sequência de Bases , Evolução Biológica , Grupo dos Citocromos b/genética , DNA Mitocondrial/química , Demografia , Geografia , Dados de Sequência Molecular , Papua Nova Guiné , Filogenia , Dinâmica Populacional , Análise de Sequência , Aves Canoras/classificação , Estrigiformes/classificaçãoRESUMO
MuStDO 5 is a multivalent plasmid DNA vaccine for malaria comprised of five plasmid DNAs encoding five proteins from Plasmodium falciparum and one plasmid DNA encoding human GM-CSF. To evaluate the safety of MuStDO 5, a series of pre-clinical studies were conducted in mice and rabbits. In pharmacology studies in mice, GM-CSF could not be detected in the serum following either intramuscular or a combined intramuscular/intradermal administration of the vaccine, but was readily detected in the muscle following intramuscular administration. In a tissue distribution study in mice, MuStDO 5 plasmid DNA was detected by PCR initially in highly vascularized tissues, while at later time-points the plasmid DNA was detected primarily at the site(s) of injection. In GLP safety studies in mice and rabbits, repeated intramuscular/intradermal administration of the MuStDO 5 vaccine was found to be safe and well tolerated without any evidence of autoimmune pathology.
Assuntos
Adjuvantes Imunológicos/toxicidade , Fator Estimulador de Colônias de Granulócitos e Macrófagos/toxicidade , Vacinas Antimaláricas/toxicidade , Vacinas de DNA/toxicidade , Adjuvantes Imunológicos/farmacocinética , Animais , Anticorpos Antinucleares/sangue , Feminino , Fator Estimulador de Colônias de Granulócitos e Macrófagos/genética , Fator Estimulador de Colônias de Granulócitos e Macrófagos/farmacocinética , Injeções Intradérmicas , Injeções Intramusculares , Vacinas Antimaláricas/imunologia , Vacinas Antimaláricas/farmacocinética , Masculino , Camundongos , Camundongos Endogâmicos , Músculo Esquelético/metabolismo , Plasmídeos , Reação em Cadeia da Polimerase , Coelhos , Distribuição Tecidual , Vacinas de DNA/imunologia , Vacinas de DNA/farmacocinéticaRESUMO
The mountain pygmy-possum, Burramys parvus, exists in isolated and fragmented populations in the Australian alps. To examine the degree of interpopulation divergence, mitochondrial cytochrome b and NADH dehydrogenase subunit 2 (NADH2) sequences were obtained from samples representing all populations of B. parvus. Three divergent mitochondrial DNA (mtDNA) lineages were identified which exhibited strong phylogeographical structure. This indicates the presence of three maternal clades corresponding to populations in the northern, central and southern Australian alps. Molecular clock estimates suggest that the mtDNA lineages diverged from one another 420-680 thousand years ago. On this basis it is argued that B. parvus populations have probably been isolated since the mid-Pleistocene, and that management should focus on maintaining viable B. parvus populations in each of the three regional localities.
Assuntos
DNA Mitocondrial/genética , Variação Genética , Haplótipos , Marsupiais/genética , Animais , Austrália , Conservação dos Recursos Naturais , Grupo dos Citocromos b/genética , Genética Populacional , Marsupiais/classificação , NADH Desidrogenase/genética , FilogeniaRESUMO
The freezing characteristics of genetically modified lymphocytes obtained from a donor with mucopolysaccharidosis type II (MPS II) were determined using cryomicroscopy and controlled rate freezing studies to determine postthaw viability. The cells from a donor with MPS II used in this investigation were cultured and transduced with a retroviral vector for the iduronate-2-sulfatase (IDS) enzyme for clinical studies for human gene therapy. The water transport and intracellular ice formation (IIF) characteristics of the cells were determined after completion of the culture and transduction protocol. The water transport parameters, I(pg) and E(lp), for the cultured and transduced cells were determined to be 4.4 +/- 1.3 x 10(-14) m3/Ns and 173 +/- 25 kJ/mol, respectively. The IIF nucleation parameters, kappa and omega, were 5.5 x 10(10) K5 and 3.5 x 10(11) (l/m2 s), respectively. The postthaw viability of the genetically modified cells was less than the viability of the freshly isolated cells from the same donor. The postthaw viability of the cultured and transduced cells from a donor with MPS II was also less than that observed with cells from a normal donor that were frozen and thawed under the same conditions. These studies are essential in understanding the biophysical changes resulting from the ex vivo culture of cells and the manner in which these changes influence the ability of the cells to be cryopreserved.
Assuntos
Criopreservação , Iduronato Sulfatase/genética , Transfusão de Linfócitos , Linfócitos/citologia , Mucopolissacaridose II/terapia , Transplante Autólogo , Transporte Biológico , Tamanho Celular , Sobrevivência Celular , Congelamento , Técnicas de Transferência de Genes , Terapia Genética , Humanos , Iduronato Sulfatase/metabolismo , Linfócitos/fisiologiaRESUMO
To evaluate the safety of a plasmid DNA vaccine, tissue distribution studies in mice and safety studies in mice and rabbits were conducted with VCL-2510, a plasmid DNA encoding the gene for the malaria circumsporozoite protein from Plasmodium falciparum (PfCSP). After intramuscular administration, VCL-2510 plasmid DNA was detected initially in all of the highly vascularized tissues, but at later time points was found primarily in the muscle at the site of injection, where it persisted for up to 8 weeks. After intravenous administration, plasmid DNA initially distributed at a relatively low frequency to all the tissues examined except the gonads and brain. However, plasmid DNA rapidly cleared, and by 4 weeks postadministration could be detected only in the lung of one of six animals evaluated. In a safety study in mice, eight repeated intramuscular injections of VCL-2510 at plasmid DNA doses of 1, 10, and 100 microg had no adverse effects on clinical chemistry or hematology, and did not result in any organ pathology or systemic toxicity. In a safety study in rabbits, six repeated intramuscular injections of VCL-2510 at plasmid DNA doses of 0.15 and 0.45 mg had no discernible effects on clinical chemistry, hematology, or histopathology. No evidence of autoimmune-mediated pathology, anti-nuclear antibodies (ANA), or antibodies to dsDNA were observed in the mouse or rabbit studies.
Assuntos
Malária/prevenção & controle , Plasmídeos/metabolismo , Plasmodium falciparum/imunologia , Proteínas de Protozoários/imunologia , Vacinas de DNA/uso terapêutico , Fatores Etários , Animais , Relação Dose-Resposta a Droga , Eletroforese em Gel de Ágar , Estudos de Avaliação como Assunto , Feminino , Vetores Genéticos/administração & dosagem , Vetores Genéticos/metabolismo , Histocitoquímica , Injeções Intramusculares , Masculino , Camundongos , Camundongos Endogâmicos ICR , Reação em Cadeia da Polimerase , Coelhos , Fatores Sexuais , Fatores de Tempo , Distribuição TecidualRESUMO
A cancer treatment is described in which i.m. injection of plasmid DNA (pDNA) encoding murine interferon alpha (mIFN-alpha) leads to potent antitumor effects on primary and metastatic tumors in mice. Mice bearing s.c. B16F10 melanoma, Cloudman melanoma, or glioma 261 tumors were injected i.m. with mIFN-alpha pDNA. In all three tumor models, a significant reduction in tumor volume and enhancement of survival was found after IFN pDNA therapy. The mIFN-alpha pDNA could be injected as infrequently as once every other week and still produce a significant antitumor effect, and, in a metastatic tumor model, the therapy markedly reduced the number of lung tumor metastases. Depletion of immune cell subsets indicated that CD8(+) T cells were required for the antitumor response. These studies demonstrate that primary and metastatic tumors can be treated systemically by i.m. injection of a plasmid encoding a cytokine gene.
Assuntos
Terapia Genética/métodos , Glioma/terapia , Interferon-alfa/genética , Melanoma Experimental/terapia , Animais , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Divisão Celular , Glioma/patologia , Injeções Intramusculares , Interferon-alfa/biossíntese , Células L , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/secundário , Neoplasias Pulmonares/terapia , Depleção Linfocítica , Melanoma Experimental/patologia , Melanoma Experimental/secundário , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Nus , Plasmídeos/administração & dosagem , Subpopulações de Linfócitos T/imunologia , Células Tumorais CultivadasRESUMO
Intratumoral (i.t.) injection of a plasmid DNA vector encoding the murine interleukin-2 (IL-2) gene was used to treat established renal cell carcinoma (Renca) tumors in BALB/c mice. Tumor regression was observed in 60-90% of mice that were injected i.t. for 4 days with IL-2 plasmid DNA complexed with the cationic lipid DMRIE/DOPE ((+/-)-N-(2-hydroxyethyl)-N,N-dimethyl-2,3-bis(tetradecyloxy)-1-propa naminium bromide/dioleoylphosphatidylethanolamine). The mice remained tumor-free until the conclusion of the study, which was 4 months after tumor challenge. In a rechallenge experiment, mice that were rendered tumor-free for 6 months by IL-2 plasmid DNA treatment rejected a subsequent challenge of Renca cells but could not reject a challenge with the unrelated, syngeneic CT-26 tumor. Spleen cells from cured mice contained Renca-specific cytotoxic T lymphocytes, and adoptive transfer of mixed lymphocyte cultures into naive mice at 2 days after challenge with Renca cells prevented tumor growth. In vivo depletion of T-cell subsets at the time of i.t. injection with IL-2 plasmid DNA demonstrated that CD8+ T cells, but not CD4+ T cells, were the primary effectors of the antitumor response.
Assuntos
Carcinoma de Células Renais/imunologia , Carcinoma de Células Renais/terapia , Imunoterapia/métodos , Interleucina-2/genética , Plasmídeos/farmacologia , Animais , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/efeitos dos fármacos , Linfócitos T CD8-Positivos/imunologia , Testes de Carcinogenicidade , Relação Dose-Resposta a Droga , Portadores de Fármacos/farmacologia , Injeções Intralesionais , Interleucina-2/farmacologia , Neoplasias Renais/imunologia , Neoplasias Renais/terapia , Lipídeos/química , Lipídeos/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias Experimentais/imunologia , Neoplasias Experimentais/terapia , Fosfatidiletanolaminas/química , Fosfatidiletanolaminas/farmacologia , Plasmídeos/genética , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/farmacologiaRESUMO
CD8+ cytotoxic T lymphocytes (CTLs) are critical for protection against intracellular pathogens but often have been difficult to induce by subunit vaccines in animals. DNA vaccines elicit protective CD8+ T cell responses. Malaria-naïve volunteers who were vaccinated with plasmid DNA encoding a malaria protein developed antigen-specific, genetically restricted, CD8+ T cell-dependent CTLs. Responses were directed against all 10 peptides tested and were restricted by six human lymphocyte antigen (HLA) class I alleles. This first demonstration in healthy naïve humans of the induction of CD8+ CTLs by DNA vaccines, including CTLs that were restricted by multiple HLA alleles in the same individual, provides a foundation for further human testing of this potentially revolutionary vaccine technology.
Assuntos
Vacinas Antimaláricas/imunologia , Plasmodium falciparum/imunologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Linfócitos T Citotóxicos/imunologia , Vacinas de DNA/imunologia , Adulto , Animais , Antígenos de Protozoários/genética , Antígenos de Protozoários/imunologia , Feminino , Genes MHC Classe I , Antígenos HLA/genética , Humanos , Esquemas de Imunização , Vacinas Antimaláricas/genética , Masculino , Plasmodium falciparum/genética , VacinaçãoRESUMO
The first clinical trial of a DNA vaccine designed to protect against malaria has just commenced. This vaccine has been designed to induce protective CD8+ T cell responses against Plasmodium falciparum infected hepatocytes. Herein, we review the rationale behind the development of vaccines that induce protective CD8+ T cells, the strategy for the development of a DNA vaccine designed to protect against falciparum malaria, and the experimental data in rodent models and nonhuman primates which has provided the foundation for trials of DNA vaccines against P. falciparum malaria in humans.
Assuntos
Vacinas Antimaláricas , Malária Falciparum/prevenção & controle , Plasmodium falciparum , Vacinas de DNA , Animais , Previsões , HumanosRESUMO
In mid 1997 the first malaria DNA vaccine will enter clinical trials. This single gene DNA vaccine encoding the Plasmodium falciparum circumsporozoite protein (PfCSP) will be studied for safety and immunogenicity. If these criteria are met, a multi-gene DNA vaccine designed to induce protective CD8+ T cell responses against P. falciparum infected hepatocytes will be subsequently assessed for safety, immunogenicity and capacity to protect immunized volunteers against experimental challenge with P. falciparum sporozoites. Our perspectives on malaria vaccine development in general, and on a multi-gene DNA vaccine in particular, have been recently reviewed. Herein, we review the rationale and experimental foundation for the anticipated P. falciparum DNA vaccine trials.
Assuntos
Antígenos de Protozoários/imunologia , Malária/prevenção & controle , Vacinação/métodos , Vacinas de DNA/uso terapêutico , Animais , Linfócitos T CD8-Positivos/imunologia , Ensaios Clínicos como Assunto , Imunidade Ativa , Hepatopatias/imunologia , Hepatopatias/microbiologia , Hepatopatias/prevenção & controle , Macaca mulatta , Camundongos , Plasmodium falciparum/genética , Plasmodium falciparum/imunologiaRESUMO
Recent studies of mitochondrial DNA (mtDNA) variation among marine turtle populations are consistent with the hypothesis that females return to beaches in their natal region to nest as adults. In contrast, less is known about breeding migrations of male marine turtles and whether they too are philopatric to natal regions. Studies of geographic structuring of restriction fragment and microsatellite polymorphisms at anonymous nuclear loci in green turtle (Chelonia mydas) populations indicate that nuclear gene flow is higher than estimates from mtDNA analyses. Regional populations from the northern and southern Great Barrier Reef were distinct for mtDNA but indistinguishable at nuclear loci, whereas the Gulf of Carpentaria (northern Australia) population was distinct for both types of marker. To assess whether this result was due to reduced philopatry of males across the Great Barrier Reef, we determined the mtDNA haplotypes of breeding males at courtship areas for comparison with breeding females from the same three locations. We used a PCR-restriction fragment length polymorphism approach to determine control region haplotypes and designed mismatch primers for the identification of specific haplotypes. The mtDNA haplotype frequencies were not significantly different between males and females at any of the three areas and estimates of Fst among the regions were similar for males and females (Fst = 0.78 and 0.73, respectively). We conclude that breeding males, like females, are philopatric to courtship areas within their natal region. Nuclear gene flow between populations is most likely occurring through matings during migrations of both males and females through nonnatal courtship areas.
Assuntos
DNA Mitocondrial/genética , Genética Populacional , Tartarugas/genética , Animais , Feminino , Masculino , Polimorfismo GenéticoRESUMO
Optimizing gene expression and delivery are necessary steps in the production of vectors for DNA-based immunization as well as for other gene therapy applications. A mouse muscle/reporter gene assay system was used to systematically improve a plasmid DNA vector. The optimized vector VR1255 contained: (1) CMV promoter and enhancer; (2) CMV IE Intron A; (3) kanamycin resistance gene; (4) deleted SV40 origin of replication; (5) optimized lux coding region; and (6) a minimal synthetic terminator from the rabbit beta globin gene, mRBG. The vector VR1255 expressed 137 times greater than an earlier prototype RSV-based vector. For plasmid vector delivery into nonmuscle tissues, a recently synthesized cationic lipid, GAP-DLRIE, was found to greatly enhance the uptake and expression of plasmid DNA by 100-fold when instilled into the mouse lung. The time-course of CAT expression with GAP-DLRIE indicated that peak expression occurs 2-5 days after intranasal administration and expression diminished to about one-third the peak value by day 21. This cationic lipid may be useful for immunization by pulmonary and perhaps other nonmuscle routes.
Assuntos
Terapia Genética/métodos , Vetores Genéticos , Vacinação/métodos , Vacinas de DNA , Vacinas Virais , Animais , Citomegalovirus/genética , Humanos , Camundongos , Plasmídeos/genética , Coelhos , Vacinas de DNA/administração & dosagem , Vacinas Virais/administração & dosagemRESUMO
Data generated in the Plasmodium yoelii rodent model indicated that plasmid DNA vaccines encoding the P.yoelii circumsporozoite protein (PyCSP) or 17 kDa hepatocyte erythrocyte protein (PyHEP17) were potent inducers of protective CD8+ T cell responses directed against infected hepatocytes. Immunization with a mixture of these plasmids circumvented the genetic restriction of protective immunity and induced additive protection. A third DNA vaccine encoding the P. yoelii sporozoite surface protein 2 (PySSP2) also induced protection. The P. falciparum genes encoding the homologues of these three protective P. yoelii antigens as well as another P. falciparum gene encoding a protein that is expressed in infected hepatocytes have been chosen for the development of a human vaccine. The optimal plasmid constructs for human use will be selected on the basis of immunogenicity data generated in mice and nonhuman primates. We anticipate that optimization of multi-gene P. falciparum DNA vaccines designed to protect against malaria by inducing CD8+ T cells that target infected hepatocytes will require extensive clinical trials during the coming years.
Assuntos
Vacinas Antimaláricas , Malária Falciparum/prevenção & controle , Plasmodium falciparum/genética , Vacinas de DNA , Animais , Antígenos de Protozoários/genética , Antígenos de Protozoários/imunologia , DNA de Protozoário/imunologia , Modelos Animais de Doenças , Eritrócitos/parasitologia , Humanos , Malária/imunologia , Malária/prevenção & controle , Vacinas Antimaláricas/genética , Vacinas Antimaláricas/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Plasmodium falciparum/imunologia , Plasmodium yoelii/genética , Plasmodium yoelii/imunologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologiaRESUMO
Sulfur heterocycles are common constituents of petroleum and liquids derived from coal, and they are found in some secondary metabolites of microorganisms and plants. They exist primarily as saturated rings and thiophenes. There are two major objectives driving investigations of the microbial metabolism of organosulfur compounds. One is the quest to develop a process for biodesulfurization of fossil fuels, and the other is to understand the fates of organosulfur compounds in petroleum- or creosote-contaminated environments which is important in assessing bioremediation processes. For these processes to be successful, cleavage of different types of sulfur heterocyclic rings is paramount. This paper reviews the evidence for microbial ring cleavage of a variety of organosulfur compounds and discusses the few well-studied cases which have shown that the C-S bond is most susceptible to breakage leading to disruption of the ring. In most cases, the introduction of one or more oxygen atom(s) onto the adjacent C atom and/or onto the S atom weakens the C-S bond, facilitating its cleavage. Although much is known about the thiophene ring cleavage in dibenzothiophene, there is still a great deal to be learned about the cleavage of other sulfur heterocycles.
Assuntos
Compostos Heterocíclicos/química , Compostos Heterocíclicos/metabolismo , Compostos de Enxofre/química , Compostos de Enxofre/metabolismo , Bactérias/metabolismo , Biodegradação Ambiental , Cefalosporinas/química , Penicilinas/química , Tiofenos/químicaAssuntos
Antígenos de Protozoários/genética , Vacinas Antimaláricas , Malária Falciparum/prevenção & controle , Plasmodium falciparum/imunologia , Vacinas de DNA , Animais , Antígenos de Protozoários/imunologia , Linfócitos T CD8-Positivos/imunologia , Ensaios Clínicos como Assunto , Previsões , Saúde Global , Fígado/parasitologia , Macaca mulatta , Malária/imunologia , Malária/prevenção & controle , Vacinas Antimaláricas/imunologia , Malária Falciparum/epidemiologia , Malária Falciparum/imunologia , Camundongos , Plasmodium falciparum/genética , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium yoelii/genética , Plasmodium yoelii/imunologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Vacinação , Vacinas Combinadas/imunologia , Vacinas de DNA/imunologiaRESUMO
The number, type, and location of cytokine- and Ab-secreting cells activated in mice immunized and boosted with plasmid DNA encoding the circumsporozoite protein of the malarial parasite Plasmodium yoelii (PyCSP) were monitored. The initial humoral response was localized to the draining lymph nodes and was characterized by production of IgG1 anti-PyCSP Abs and the Th2 cytokine IL-4. In contrast, the secondary response was dominated by IFN-gamma production (a Th1 cytokine) and the secretion of IgG2a anti-PyCSP Abs in the spleen. PyCSP DNA and mRNA were detected only in the quadriceps muscles (sites of plasmid injection), yet these sites lacked either cytokine- or Ab-secreting cells. These findings indicate that circulating lymphocytes encounter plasmid-encoded Ag in the muscle bed, initiate a humoral response in the draining lymph nodes, and then seed distal lymphoid organs. Profound differences were observed between the primary and secondary immune responses induced by plasmid immunization, which may influence vaccine efficacy.