Skin test and tick immune status in susceptible and resistant cattle in Brazil

A cutaneous hypersensitivity test (CHT) was used to correlate host resistance to ticks and type of reaction elicited to unfed larval extract-ULE of the cattle tick Boophilus microplus in European and Indian cattle. Twenty calves were separated into four groups of five animals each: naïve or preinfested Indian or European cattle. CHT was induced by intradermal inoculation of 0.1 ml of ULE cattle tick B. microplus (50 μg protein) in the calf ear. Ear thickness was measured using calipers before and 10 min, 1, 2, 6, 18, 24, 48, 72, 96, and 144 h postinoculation (PI). Preinfested European calves showed only an immediate type reaction with maximum response (75% increase in ear thickness) at 10 min PI. On the other hand, preinfested Indian calves presented an immediate response with maximum reaction (70% increase in ear thickness) between 10 min and one hour PI, and a delayed type reaction at 72 h PI (60% increase in ear thickness). These results point out the crucial role of the cellular immune response of cattle in the expression of resistance to cattle tick B. microplus. Skin test might be useful in the ranking of cattle according to the susceptibility/resistance to ticks.

Susceptibility of tangerines to citrus variegated chlorosis

Citrus variegated chlorosis (CVC), a citrus disease first discovered in Brazil in 1987, is caused by the bacterium Xylella fastidiosa and transmitted by sharpshooters and budwood. Since the disease affects almost all sweet orange cultivars, it has become one of the most serious problems for Brazilian citriculture. To evaluate their resistance to CVC disease, fifteen tangerines or mandarins (C. reticulata Blanco) and their hybrids were grafted on Rangpur lime (C. limonia Osb.) and inoculated with CVC-contaminated Pera sweet orange (C. sinensis (L.) Osb.) by twig grafting in a greenhouse. Tangerines and their hybrids Wilking, Fortune, Sunki, Ellendale, Orlando tangelo, Nunes clementine, Nova, Sun Shu Sha Kat, Suenkat, and Batangas showed CVC leaf symptoms and gave positive results on enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) (with specific primers for X. fastidiosa), indicating that they are susceptible to CVC. Although X. fastidiosa bacteria were detected by ELISA and PCR in inoculated plants of tangerines Cravo and Oneco, no CVC leaf symptoms were observed on these two cultivars, suggesting that they are tolerant to the disease. CVC leaf symptoms were not observed and X. fastidiosa was not detected in tangerine Dancy and mandarins Okitsu satsuma and Ponkan after inoculation, showing that they are resistant to the disease.

Detection of infectious bronchitis virus in experimentally infected chickens by an antigen-competitive ELISA

An antigen-competitive enzyme-linked immunosorbent assay (Ag-C-ELISA) was developed for the detection of infectious bronchitis virus (IBV) antigens, M41 strain, in tissues from experimentally infected chickens, or in allantoic fluid harvested from inoculated embryonated eggs. The detection limit of IBV in the Ag-C-ELISA was 104.1 median embryo infective doses (EID50)/well. Tracheal and lung samples from chickens vaccinated with 102.5 EID50 of live attenuated infectious bronchitis (H120) vaccine were negative in the direct detection Ag-C-ELISA. The results indicate that the Ag-C-ELISA has the potential to detect IBV, either directly in tissue samples or when combined with the passage of material in embryonated eggs, thereby constituting an alternative method for the diagnosis of IBV.

Activity of benomyl for control of postbloom fruit drop of citrus caused by Colletotrichum acutatum

Postbloom fruit drop (PFD) of citrus caused by Colletotrichum acutatum produces orange-brown lesions on petals and induces the abscission of young fruitlets and the retention of the calyces. Despite the fact that C. acutatum is not highly sensitive to benomyl in culture, this fungicide provides good control of the disease under field conditions. This study was undertaken to determine the effect of benomyl on various stages of disease development to understand the basis for its effectiveness in the field. We found that benomyl at 1.0 μg/ml reduced colony area of C. acutatum by about 75% and completely inhibited growth of C. gloeosporioides. Benomyl did not prevent conidial germination even at 100 μg/ml, but reduced germ tube elongation at 10 and 100 μg/ml. When benomyl was applied to flower clusters on screen-house-grown plants before inoculation, disease severity was greatly reduced. Applications at 24 and 48 h, but not at 72 h, after inoculation reduced PFD severity. Application of benomyl to symptomatic petals not bearing conidia did not prevent or reduce production of inoculum. Application to petals bearing conidia reduced viability of these fungal propagules by only about 50%. The viability of appressoria on mature leaves was not affected by benomyl application. Even when appressoria on mature leaves were stimulated to germinate by treatment with flower extracts, subsequent application of benomyl did not reduce propagule numbers below original levels. Benomyl appears to act by preventing infection and early development of the fungus in petals. However, once symptoms have developed, this fungicide has only minimal effects on further disease development and spread.

Efeito do bálsamo de copaíba (Copaitéra reticulata ducke) sobre a Germinação de esporos de Fusarium

The germinative capacity of spores of Fusarium was studied in the presence of copahiba balsam (5 to 100%). The culture was carried out in Erlenmeyer flasks with 50ml of ICI medium and 1 ml of the pre-inoculated fungus. In some specific cases, 1 ml of copahiba balsam was added to the medium. The development of spores was significantly reduced in the presence of copahiba balsam. Sensibility to copahiba balsam varied with the different strains of Fusarium.

Viability of Streptococcus mutans on transparent and opaque toothbrushes.

PURPOSE: The objective of this study was to evaluate the viability of the microorganism Streptococcus mutans on toothbrushes made of opaque and transparent materials. METHODS: Twenty-eight toothbrushes (14 opaque and 14 transparent) were inoculated in tubes with brain heart infusion (BHI) broth of a standard strain of S. mutans and incubated in candle jars at 37 degrees C for 24 hours. Both the opaque and transparent toothbrushes were removed at T = 0 h (control); T = 0.5 h; T = 1 h; T = 2 h; T = 4 h; T = 8 h; and T = 24 h. Individual toothbrushes were subjected to agitation in a saline solution and samples of the solution were diluted and inoculated in Bacitracin Sucrose Agar--SB-20. RESULTS: After half an hour (T2) there was a significant decrease in the number of microorganisms on the transparent and opaque toothbrushes, respectively 6.0 x 10(5) and 9.4 x 10(5), when compared to the control. After the T3 = 1 hour, T4 = 2 hours, T5 = 4 h, the number of microorganisms decreased from 4.1 x 10(5); 2.1 x 10(5); 1.4 x 10(5); and 9.2 x 10(5); 5.7 x 10(5); 1.2 x 10(5) to zero (0.0) in T6 = 8 h, respectively on the transparent and opaque toothbrushes. The reduction in viable microorganisms was more obvious with the transparent toothbrushes, although the number of viable microorganisms was not significantly different for the two types of toothbrushes at the end of the experiment, T5 = 1.4 x 10(5) (transparent) and T5 = 1.2 x 10(5) (opaque). CONCLUSIONS: With both opaque and transparent toothbrushes, the number of microorganisms decreased with time. A reduction in the number of microorganisms on the transparent toothbrushes was observed following inoculation and incubation. This suggests the transparent toothbrushes inhibit the viability of the S. mutans.

Avaliação clínica e hematológica em bezerros Nelore infectados experimentalmente com isolados de Babesia bigemina das regiões Sudeste, Nordeste e Norte do Brasil

A comparative study was made regarding the clinical and hematological alterations caused by isolates of Babesia bigemina from southeastern, northeastern and northern Brazil in experimentally infected Nelore calves. Eighteen calves between 7 and 9 months of age, without antibodies against Babesia sp and raised free from ticks, were used. Three animals were previously inoculated with 2.0×109 parasitic erythrocytes (PE) for each stabilate. The other 15 calves were subdivided into three groups, with five animals each, that were subinoculated with 1.0×1010 PE of the respective isolates. The clinical and hematological alterations were evaluated by the determination of parasitaemia, haemogram, plasmatic fibrinogen, reticulocyte count, descriptive analysis of the bone marrow and erythrocytic osmotic fragility, for 30 days, totalizing seven moments of observation. The follow-up of the immunological response by the indirect fluorescent antibody test was carried out daily until the 10th day after inoculation (DAI) and after that, on the 15th, 20th, 25th and 30th DAI. A mild clinical manifestation of the disease was observed. The laboratory findings revealed low levels of parasitaemia; decrease of the erythrogram values; absence of reticulocytes, initial decrease in the total count of leukocytes, neutrophils and lymphocytes with a posterior elevation of the number of these cells; hypercellularity of the erythrocytic series and decrease of the myeloid: erythroid relation which was more accentuated between the 8th and 12th DAI, and an increase of the erythrocytic osmotic fragility in the groups inoculated with the Southeast and Northeast isolates. None of the three isolates of B. bigemina gave rise to the clinical characteristic form of the disease, although they induced an humoral immune response.

Comparative experimental infection of Lacazia loboi in BALB/c and B10.A mice

Both hind foot pads of BALB/c and B10.A mice strains, were inoculated with a fungal suspension of Lacazia loboi obtained from a Jorge Lobo's disease patient. The suspension had 9 × 105 cells/ml and its viability index was 45%. The animals were sacrificed at different time periods varying from 24 h to 18 months after inoculation. The BALB/c mice developed an extensive granulomatous infiltrate, similar to the disease in humans, that progressively evolved. The number of fungal elements also increased as the disease progressed, and after the seventh month of inoculation, macroscopic changes of the foot pads were evident. Although the B10.A mice developed an exuberant granulomatous infiltrate, macroscopic changes were not detected. The number of fungal cells in the infected tissues increased in number, but they were lower then the numbers found in the BALB/c strain. The viability indexes were also lower for the B10.A strain. Considering the histopathological findings, the presence of macroscopic changes and the great amount of fungal cells in the infected tissues, the authors concluded that the BALB/c mice strain was more susceptible to L. loboi infection than the B10.A strain.

Effectiveness of Microwave Sterilization on Three Hard Chairside Reline Resins

Purpose: The aim of this study was to evaluate the effectiveness of microwave irradiation sterilization on hard chairside reline resins. Materials and Methods: Specimens of three reline resins (Kooliner, Tokuso Rebase, and Ufi Gel Hard) were fabricated and subjected to ethylene oxide sterilization. The specimens were then individually inoculated (107 cfu/mL) with Tryptic Soy Broth media containing one of the tested microorganisms (C albicans, S aureus, B subtilis, and P aeruginosa). After 48 hours at 37°C, the samples were vortexed for 1 minute and allowed to stand for 9 minutes, followed by a short vortex to resuspend any organisms present. After inoculation, 40 specimens of each material were immersed in 200 mL of water and subjected to microwave irradiation at 650 W for 6 minutes. Forty non-irradiated specimens were used as positive controls. Replicate specimens (25 μL) of suspension were plated at dilutions of 10-3 to 10-6 on plates of selective media appropriate for each organism. All plates were incubated at 37°C for 48 hours. After incubation, colonies were counted, and the data were statistically analyzed by the Kruskal-Wallis test. Twelve specimens of each material were prepared for SEM. Results: All immersed specimens showed consistent sterilization of all the individual organisms after microwave irradiation. SEM examination indicated an alteration in cell morphology after microwave irradiation. Conclusion: Microwave sterilization for 6 minutes at 650 W proved to be effective for the sterilization of hard chairside reline resins.

Papel das proteínas Yops de Yersinia pseudotuberculosis na ativação dos linfócitos B

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mango cultivars behavior in relation to fusarium subglutinans

The mango malformation, caused by the fungus Fusarium subglutinans Wollenweb & Reinking, is probably one of the diseases that causes more damages in the mangoes production in Brazil and other producing countries. This fungus was isolated of a Tommy Atkins plant with advanced symptoms of malformation, purified and prepared to be inoculated in 15 cultivars of national and imported mangoes. Initially, 10 cultivars had been inoculated in July/2000: Bourbon IAC - 100, Coração de Boi, Keitt, Parvin, Primor de Amoreira, Sensation, Smith, Surpresa, Tommy Atkins and Van Dyke. Another group was inoculated in December/2000, on the cultivars: Adams, Bhadauran, Palmer, Princesa and Zill, and with others cultivars Primor de Amoreira, Sensation and Tommy Atkins, that were inoculated in the first time, with the purpose to compare the two times of inoculation. Throughout the evaluated data at the two times of inoculation, after 11 months of evaluation, were maden the analysis of the variance in function of the involved sources of variation and the test of Duncan to compare the averages of inoculated cultivars. With the results obtained, the cultivars Bhadauran, Palmer, Parvin, Sensation, Van Dyke and Zill presents less percentage of plants with malformation symptoms or less progression of symptoms in relation to the others inoculated cultivars, under protected environmental conditions, where the assays were carried out.

Amblyomma cajennense ticks induce immediate hypersensitivity in horses and donkeys

Since host immune reaction to ticks interferes with tick-borne pathogen transmission, it is important to recognize naturally occurring tick-host immune relationships to better understand the epidemiology of such infectious diseases. Amblyomma cajennense is an important tick-borne disease vector in the Neotropical region and horses maintain it in domestic environments. In the present work intradermal testing of A. cajennense tick exposed horses and donkeys using crude tick antigens was used to evaluate the type of hypersensitivity induced by infestations. Animals sensitized by A. cajennense infestation displayed an immediate hypersensitivity reaction at the antigen inoculation site. Foals sensitized with experimental infestations and field sensitized horses presented the most intense reactions (40% of ear thickness increase). Field sensitized donkeys presented less intense reaction reaching no more than 22% of mean thickness increase. Control horses (non-sensitized) had the least intense reaction, with a peak of no more 12% of increase. The presence of a prominent immediate hypersensitivity in equids sensitized experimentally or by field infestations indicates that A. cajennense ticks induce in this host an immune response that is associated with IgE production and which is known to be inappropriate against intracellular pathogens. Differences observed between horses and donkeys are discussed.

Avaliação da formação do biofilme de Candida albicans sobre superfície de titânio revestida com hidroxiapatita por meio de microscopia eletrônica de varredura

In this study Candida albicans biofilm formation on the surface of commercially pure titanium (cp-Ti) coated with hydroxyapatite was observed by means of scanning electron microscope. The biofilm was formed after 45 days of incubation of the samples in liquid culture medium inoculated with fungus cells in a tube of polystyrene with screw cap and sterilized. After the biofilm removal with 10% EDTA solution was observed pitting on the surface of cp-Ti coated.

Experimental candidosis and recovery of Candida albicans from the oral cavity of ovariectomized rats

The aim of this study was to analyze the development of candidosis and the recovery of C. albicans from the oral cavity of ovariectomized and sham-ovariectomized rats. One hundred aiid twenty-four rats originally negative for Candida spp. in the oral cavity were divided into two groups: ovariectomized and sham-ovariectomized. Fifty-eight ovariectomized and the same quantity of sham-ovariectomized rats were inoculated with C. albicans for the study of candidosis development and recovery of yeast. Four animals from each group were not inoculated with yeast suspension and were submitted to tongue dorsum morphologic analysis by optical and scanning electron microscopy. The development of candidosis in the tongue dorsum was observed by optical and scanning electron microscopy in the periods of 6 hr, 24 hr, 7 days and 15 days after the last inoculation. Recovery of C. albicans was performed by oral samples plating on Sabouraud agar after 1,2, 5 and 7 days and progressively at each 15-day interval until negative cultures for yeasts were obtained. The results were analyzed by Mann-Whitney and Student's t tests. The tongue dorsum of sham-ovariectomized and ovariectomized rats, not infected by Candida, presented normal aspect. Among the infected rats, the ovariectomized group showed less occurrence of candidosis lesions and lower recovery of C. albicans from the oral cavity in relation to the sham-ovariectomized group. It could be concluded that candidosis was less frequent from the oral cavities of ovariectomized rats in relation to sham-ovariectomized.