Mosaic in Senna occidentalis in southern Brazil induced by a new strain of Soybean mosaic virus

Plants of Senna occidentalis (sin. Cassia occidentalis) with mosaic symptoms were collected near a soybean (Glycine max) field where some plants exhibited symptoms of mosaic and blistering. A preliminary examination of leaf tissue from diseased S. occidentalis by electron microscopy revealed the presence of pinwheel inclusions as well as long flexuous particles, indicating the presence of a potyvirus. Host range, serology, and amino acid sequence from this potyvirus were similar to those from other Brazilian isolates of Soybean mosaic virus (SMV). The 3'- terminal region of the genomic RNA was cloned and a cDNA sequence of 1.9 kb upstream of the poly (A) tract was determined. The sequence contains a single open reading frame and a 3'- non-translated region (NTR) of 259 bp. The nucleotide sequence of the CP gene of SMV-Soc was 98% identical to that of Brazilian isolates SMV-B, SMV-L, and SMV-FT10. The percentage of nucleotide identity of their 3'-NTR's was 91, 98, and 99% in relation to SMV-L, SMV-B, and SMV-FT10, respectively. In contrast to other Brazilian SMV isolates studied, SMV-Soc was able to infect sunflower (Helianthus annuus). Based on these results, the S. occidentalis isolate was identified as a new strain of SMV belonging to the SMV strain, group G5 and was named SMV-Soc. This is the first report of naturaly occurring SMV infecting plants of S. occidentalis in Brazil, adding this weed as a new source of SMV in the field.

Reação de folhas de mandioca ao Microcyclus ulei, agente causal do mal-das-folhas da seringueira

Folhas jovens de mandioca (Manihot esculenta) inoculadas com uma suspensão de conídios viáveis ou autoclavados de Microcyclus ulei, um patógeno de diversas espécies do gênero Hevea, reagiram fortemente com indução de compostos azuis fluorescentes nas áreas de contato, com a morte das células locais e a formação irregular dos tecidos, distorção das folhas e, ocasionalmente, com a abscisão da folha. Também ocorreu crescimento restrito das hifas, mas sem produção de novos conídios. A reação das plantas foi mais semelhante a uma reação de resistência complexa a um patógeno biotrófico do que uma reação típica de defesa de uma planta não hospedeira.

Biological and molecular characterization of an isolate of Tobacco streak virus obtained from soybeans in Brazil

A virus was isolated from soybean (Glycine max) plants with symptoms of dwarfing and bud blight in Wenceslau Braz County, Paraná, Brazil. The host range and properties resembled those of Tobacco streak virus (TSV). The purified virus showed three peaks in a frozen sucrose gradient. Antiserum was produced and the virus was serologically related to TSV. Electron microscopy detected 28 nm spherical particles. Coat protein (CP) had a Mr of 29.880 Da. A fragment of 1028 nt was amplified, cloned and sequenced. One open reading frame with 717 nt was identified and associated to the CP. The CP gene shared 83% identity with the sequence of TSV CP from white clover (Trifolium repens) (GenBank CAA25133). This is the first report of the biological and molecular characterization of TSV isolated from soybeans. It is proposed that this isolate be considered a strain of TSV named TSV-BR.

Powdery mildew of ornamental species caused by Oidiopsis haplophylli in Brazil

Oidiopsis haplophylli (syn. Oidiopsis sicula) was identified as the causal agent of powdery mildew diseases occurring on five ornamental species in Brazil. This disease was observed in plastic house-grown lisianthus (Eustoma grandiflorum: Gentianaceae), in nasturtium (Tropaeolum majus: Tropaeolaceae) cultivated under open field conditions and in greenhouse-grown calla lily (Zantedeschia aethiopica: Araceae), impatiens (Impatiens balsamina: Balsaminaceae) and balloon plant (Asclepias physocarpa: Asclepiadaceae). Typical disease symptoms consisted of chlorotic areas on the upper leaf surface corresponding to a fungal colony in the abaxial surface. With the disease progression, these chlorotic areas eventually turned to necrotic (brown) lesions. Fungi morphology on all hosts was similar to that described for the imperfect stage of Leveillula taurica (O. haplophylli). The Koch's postulates were fulfilled by inoculating symptom-free plants via leaf-to-leaf contact with fungal colonies. Additional inoculations using an isolate of O. haplophylli from sweet pepper (Capsicum annuum) demonstrated that it is pathogenic to all five species belonging to distinct botanical families, indicating lack of host specialization. This is the first formal report of a powdery mildew disease on lisianthus, calla lilly, impatiens and nasturtium in Brazil. It is, to our knowledge, the first report of O. haplophyllii infecting A. physocarpa, extending the host range of this atypical powdery mildew-inducing fungus. This disease might become important on these ornamental crops especially in protected cultivation and also under field conditions in hot and dry areas of Brazil.

New thermal inducible Streptomyces phages isolated from tropical soils

Two new Streptomyces phages, øBP1 and øBP2, were isolated from tropical soil samples. These phages presented a large host range and developed both lytic and lysogenic responses in different Streptomyces species tested. Variations in the incubation temperature showed to be important in the development of the replication cycle. Increasing incubation temperature from 30oC to 42oC induced the lytic response of øBP2 and lysogenic of øBP1 in the host strain Streptomyces sp. WL6. øBP1 and øBP2 have icosahedral heads with long tails and were characterized in relation to morphology, G + C content, genome size and adsorption curve

The use of non-human primates as animal models for the study of hepatitis viruses

Hepatitis viruses belong to different families and have in common a striking hepatotropism and restrictions for propagation in cell culture. The transmissibility of hepatitis is in great part limited to non-human primates. Enterically transmitted hepatitis viruses (hepatitis A virus and hepatitis E virus) can induce hepatitis in a number of Old World and New World monkey species, while the host range of non-human primates susceptible to hepatitis viruses transmitted by the parenteral route (hepatitis B virus, hepatitis C virus and hepatitis delta virus) is restricted to few species of Old World monkeys, especially the chimpanzee. Experimental studies on non-human primates have provided an invaluable source of information regarding the biology and pathogenesis of these viruses, and represent a still indispensable tool for vaccine and drug testing.

Coevolution of hosts and microorganisms: an analysis of the involvment of cytokines in host-parasite interactions

Parasites may employ particular strategies of eluding an immune response by taking advantage of those mechanisms that normally guarantee immunological self-tolerance. Much in the way as it occurs during the establishment of self-tolerance, live pathogens may induce clonal deletion, functional inactivation(anergy) and immunosupression. At this latter level, it appears that certain pathogens produce immunosupresive cytokine-like mediators or provoke like host the secrete cytokines that will compromise the anti-parasite immune response. It appears that immune responses that preferentially involve T helper l cells (secretors of interleukin-2-and interferon-y) tend to be protective, whereas T helper 2 cells (secretors of IL-4, IL5, IL-6, and IL-10), a population that antagonizes T helper cells, mediate disease susceptibility and are immunopathological reactions. Cytokines produced by T helper 2 cells mediate many symptoms of infection, including eosinophilia, mastocytosis, hyperimmunoglobulinemia, and elevated IgE levels. Administration of IL-2 and IFN-y has beneficial effects in many infections mediated by viruses, bacteria, and protozoa. The use of live vaccinia virus might be an avenue for the treatment of or vaccination against infection. We have found that a vaccinia virus expressing the gene for human IL-2, though attenuated, precipitates autoimmune disease in immunodeficient athymic mice. Thus, although T helper l cytokines may have desired immunostimulatory properties, they also may lead to unwarranted autoaggressive responses.

The stabilizing effects of the acquired immunity on the schistosomiasis transmission modeling - the sensitivity Analysis

A mathematical model is proposed to analyze the effects of acquired immunity on the transmission of schistosomiasis in the human host. From this model the prevalence curve dependent on four parameters can be obtained. These parameters were estimated fitting the data by the maximum likelihood method. The model showed a good retrieving capacity of real data from two endemic areas of schistosomiasis: Touros, Brazil (Schistosoma mansoni) and Misungwi, Tanzania (S. haematobium). Also, the average worm burden per person and the dispersion of parasite per person in the community can be obtained from the model. In this paper, the stabilizing effects of the acquired immunity assumption in the model are assessed in terms of the epidemiological variables as follows. Regarded to the prevalence curve, we calculate the confidence interval, and related to the average worm burden and the worm dispersion in the community, the sensitivity analysis (the range of the variation) of both variables with respect to their parameters is performed.

Thermal preferences and limits of Triatoma brasiliensis in its natural environment - Field observations while host searching

The goal of this work was to explore the thermal relationship between foraging Triatoma brasiliensis and its natural habitat during the hottest season in the state of Ceará, Brazil. The thermal profiles were determined using infrared analysis. Although the daily temperature of rock surfaces varied in a wide range, T. brasiliensisselected to walk through areas with temperatures between 31.7-40.5ºC. The temperature of T. brasiliensisbody surface ranged from 32.8-34.4ºC, being higher in legs than the abdomen. A strong relationship was found between the temperature of the insect and the temperature of rock crevices where they were hidden (r: 0.96, p < 0.05). The species was active at full sunlight being a clear example of how the light-dark rhythm may be altered, even under predation risk. Our results strongly suggest a thermal borderline for T. brasiliensisforaging activity near 40ºC. The simultaneous determination of insect body and rock temperatures here presented are the only obtained in natural habitats for this or other triatomines.

Genetic variation between susceptible and non-susceptible snails to Schistosoma infection using random amplified polymorphic DNA analysis (RAPDs)

Susceptibility of snails to infection by certain trematodes and their suitability as hosts for continued development has been a bewildering problem in host-parasite relationships. The present work emphasizes our interest in snail genetics to determine what genes or gene products are specifically responsible for susceptibility of snails to infection. High molecular weight DNA was extracted from both susceptible and non-susceptible snails within the same species Biomphalaria tenagophila. RAPD was undertaken to distinguish between the two types of snails. Random primers (10 mers) were used to amplify the extracted DNA by the polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis (PAGE) and silver staining. The results suggest that RAPD represents an efficient means of genome comparison, since many molecular markers were detected as genetic variations between susceptible and non-susceptible snails.

Rat hepatocyte invasion by Listeria monocytogenes and analysis of TNF-alpha role in apoptosis

Listeria monocytogenes, etiological agent of severe human foodborne infection, uses sophisticated mechanisms of entry into host cytoplasm and manipulation of the cellular cytoskeleton, resulting in cell death. The host cells and bacteria interaction may result in cytokine production as Tumor Necrosis Factor (TNF) alpha. Hepatocytes have potential to produce pro-inflammatory cytokines as TNF-alpha when invaded by bacteria. In the present work we showed the behavior of hepatocytes invaded by L. monocytogenes by microscopic analysis, determination of TNF-alpha production by bioassay and analysis of the apoptosis through TUNEL technique. The presence of bacterium, in ratios that ranged from 5 to 50,000 bacteria per cell, induced the rupture of cellular monolayers. We observed the presence of internalized bacteria in the first hour of incubation by electronic microscopy. The levels of TNF-alpha increased from first hour of incubation to sixth hour, ranging from 0 to 3749 pg/mL. After seven and eight hours of incubation non-significant TNF-alpha levels decrease occurred, indicating possible saturation of cellular receptors. Thus, the quantity of TNF-alpha produced by hepatocytes was dependent of the incubation time, as well as of the proportion between bacteria and cells. The apoptosis rate increased in direct form with the incubation time (1 h to 8 + 24 h), ranging from 0 to 43%, as well as with the bacteria : cells ratio. These results show the ability of hepatocyte invasion by non-hemolytic L. monocytogenes, and the main consequences of this phenomenon were the release of TNF-alpha by hepatocytes and the induction of apoptosis. We speculate that hepatocytes use apoptosis induced by TNF-alpha for release bacteria to extracellular medium. This phenomenon may facilitate the bacteria destruction by the immune system.

Detection and molecular analysis of Toxoplasma gondii and Neospora caninum from dogs with neurological disorders

INTRODUCTION: Toxoplasma gondii and Neospora caninum are related Apicomplexa parasites responsible for systemic diseases in many species of animals, including dogs. METHODS: This study aimed to determine the occurrence of T. gondii and N. caninum infections in 50 dogs with neurological signs that were admitted to the Veterinary Hospital of Universidade Estadual Paulista, City of Botucatu, Brazil. All animals were screened for antibodies using an immunofluorescent antibody test for both parasites. Tissues of positive animals were bioassayed in mice (T. gondii) and gerbils (N. caninum), and DNA was analyzed using the polymerase chain reaction (PCR). Positive samples for T. gondii by PCR were typed using restriction fragment length polymorphism-PCR for 11 markers: SAG1, SAG2 (5′-3′-SAG2 and alt.SAG2), SAG3, Btub, GRA6, L358, c22-8, c29-6, PK1 and Apico, and CS3 marker for virulence analysis. RESULTS: Specific antibodies were detected in 11/50 (22%; 95% confidence interval (CI95%), 12.8-35.3%) animals for T. gondii and 7/50 (14%; CI95%, 7.02-26.3%) for N. caninum. In the bioassay and PCR, 7/11 (63.6%; CI95%, 34.9-84.8%) samples were positive for T. gondii and 3/7 (42.9%; CI95%I, 15.7-75.5%) samples were positive for N. caninum. Three different genotypes were identified, but only 1 was unique. CONCLUSIONS: These data confirm the presence of T. gondii and N. caninum in dogs from Brazil, indicating the importance of this host as a sentinel of T. gondii for human beings, and the genotypic variation of this parasite in Brazil.

Spatio-temporal patterns of tuberculosis incidence in Ribeirão Preto, State of São Paulo, southeast Brazil, and their relationship with social vulnerability: a Bayesian analysis

INTRODUCTION: The purpose of this ecological study was to evaluate the urban spatial and temporal distribution of tuberculosis (TB) in Ribeirão Preto, State of São Paulo, southeast Brazil, between 2006 and 2009 and to evaluate its relationship with factors of social vulnerability such as income and education level. METHODS: We evaluated data from TBWeb, an electronic notification system for TB cases. Measures of social vulnerability were obtained from the SEADE Foundation, and information about the number of inhabitants, education and income of the households were obtained from Brazilian Institute of Geography and Statistics. Statistical analyses were conducted by a Bayesian regression model assuming a Poisson distribution for the observed new cases of TB in each area. A conditional autoregressive structure was used for the spatial covariance structure. RESULTS: The Bayesian model confirmed the spatial heterogeneity of TB distribution in Ribeirão Preto, identifying areas with elevated risk and the effects of social vulnerability on the disease. We demonstrated that the rate of TB was correlated with the measures of income, education and social vulnerability. However, we observed areas with low vulnerability and high education and income, but with high estimated TB rates. CONCLUSIONS: The study identified areas with different risks for TB, given that the public health system deals with the characteristics of each region individually and prioritizes those that present a higher propensity to risk of TB. Complex relationships may exist between TB incidence and a wide range of environmental and intrinsic factors, which need to be studied in future research.

Analysis of the chemical components of hydatid fluid from Echinococcus granulosus

Introduction The aim of this study was to explore the environment of Echinococcus granulosus (E. granulosus) protoscolices and their relationship with their host. Methods Proteins from the hydatid-cyst fluid (HCF) from E. granulosus were identified by proteomics. An inductively coupled plasma atomic emission spectrometer (ICP-AES) was used to determine the elements, an automatic biochemical analyzer was used to detect the types and levels of biochemical indices, and an automatic amino acid analyzer was used to detect the types and levels of amino acids in the E. granulosus HCF. Results I) Approximately 30 protein spots and 21 peptide mass fingerprints (PMF) were acquired in the two-dimensional gel electrophoresis (2-DE) pattern of hydatid fluid; II) We detected 10 chemical elements in the cyst fluid, including sodium, potassium, calcium, magnesium, copper, and zinc; III) We measured 19 biochemical metabolites in the cyst fluid, and the amount of most of these metabolites was lower than that in normal human serum; IV) We detected 17 free amino acids and measured some of these, including alanine, glycine, and valine. Conclusions We identified and measured many chemical components of the cyst fluid, providing a theoretical basis for developing new drugs to prevent and treat hydatid disease by inhibiting or blocking nutrition, metabolism, and other functions of the pathogen.

The use of a modular titanium endoprosthesis in skeletal reconstructions after bone tumor resections: method presentation and analysis of 37 cases

We analyzed 37 patients who underwent segmental wide resection of bone tumors and reconstruction with a modular titanium endoprosthesis at the Orthopaedic Oncology Group, between 1992 and 1998. Twelve patients were male and 25 were female, with a mean age of 30 years (9 - 81). The mean follow-up was 14 months (2 - 48). The diagnoses were: osteosarcoma (14 cases), metastatic carcinoma (10), Ewing's sarcoma (4), giant cell tumor (4), malignant fibrous histiocytoma (3), chondrosarcoma (1), and aneurysmal bone cyst (1). Eleven articulated total knee, 8 partial proximal femur with bipolar acetabulum, 8 partial proximal humerus, 3 total femur, 2 partial proximal tibia, 2 diaphyseal femur, 2 diaphyseal humerus, and 1 total proximal femur with cementless acetabulum endoprosthesis implant procedures were done. The complications related to the procedure included: infection (5 cases), dislocation (3), module loosening (1), and ulnar nerve paresthesia (1). We used the following criteria for the clinical evaluation: presence of pain, range of motion, reconstruction stability, surgical and oncologic complications, and patient acceptance. The results were good in 56.8% of the cases, regular in 32.4% and poor in 10.8%.