This work evaluated the effects of dietary supplementation of A-Live (phytogenic) either individually or in combination with Aquaform (potassium diformate, acidifier) on juvenile Nile tilapia ( Oreochromis niloticus ) growth performance, innate immune parameters, gut microbiome, and resistance against Francisella noatunensis subsp. orientalis challenge. Each experimental group contained 140 fishes (34.3 ± 0.33) in two 150L tanks. The experimental design consisted of five groups: a negative control; treated groups (G1, G2, G3) supplemented with different concentrations of A-Live and Aquaform in the feed; and a positive control (PC) for pathogen infection. Groups G1, G2, G3, and PC were challenged with Francisella spp. after 15 days. After infection, the mortality was significantly lower in groups G1, G2, and G3 (p < 0.01). Furthermore, these groups showed significant increase (p < 0.05) in daily weight gain, feed conversion rate, and specific growth rate. The PC group presented increase (p < 0.05) in the leukocytes and neutrophils number. Innate immunity parameters showed no difference between treatments after infection. Microbiome analysis revealed an increased number of bacteria belonging to the Vibrionaceae family after pathogen infection suggesting a secondary pathogen function of these bacteria. These results validate the beneficial effects of these products in tilapia farming.
ABSTRACT. Most epidemiologic studies on bovine leptospirosis are based on serological tests that use antibodies against several serotypes, including the serovar Hardjo, which is widespread and considered to be the most adapted to bovine hosts. However, using only serological studies is not sufficient to identify and distinguish species of leptospires. The aim of this study was report the first isolation in Brazil of two strains serovar Hardjo obtained in urine samples from naturally infected cows in a small Brazilian dairy herd and find the genetic species and consequently the type strain Therefore, more studies are needed including isolation and molecular characterization from regional strains to obtain a better knowledge about epidemiology of serovar Hardjo in bovine which may assist in future strategies of prevention and control of bovine leptospirosis.
The Leptospira serovar Hedjo belongs to the serogroup sejroe and this serovar is the most prevalent in bovine herds worldwide. The sejroe serogroup is the most frequently detected by serology in Brazilian cattle herds suggesting that it is due serovar Hardjo. In the molecular classification, this serovar has two genotypes: Hardjobovis and Hardjoprajitno. This serovar is as considered as fastidious pathogens, and their isolation is one of the bottlenecks in leptospirosis laboratories. In addition, its molecular characterization using genomic approaches is oftentimes not simple and time-consuming. This study describes a method for isolating the two genotypes of serovar Hardjo using culture medium formulations and suggests a get-at-able molecular characterization. Ten cows naturally infected which were seropositive were selected from small dairy farms, and their urine was collected for bacterial isolation. We evaluated three modifications of liquid Leptospira medium culture supplemented with sodium pyruvate, superoxide dismutase enzyme and fetal bovine serum, and the isolates were characterized by molecular techniques. After isolation and adaptation in standard culture medium, the strains were subcultured for 1 week in the three modified culture media for morphologic evaluation using electronic microscopy. Strains were molecularly identified by multilocus variable-number tandem-repeat analysis (MLVA), partial sequencing and phylogenic analyses of gene sec Y. Combining the liquid culture medium formulations allowed growth of the Leptospira serovar Hardjo in three tubes. Two isolates were identified as genotype Hardjobovis, and the other as genotype Hardjoprajitno. Morphologically, compared with control media, cells in the medium supplemented with the superoxide dismutase enzyme were more elongated and showed many cells in division. The cells in the medium supplemented with fetal bovine serum were fewer and lost their spirochete morphology. This indicated that the additional supplementation with fetal bovine serum assisted in the initial growth and maintenance of the viable leptospires and the superoxide dismutase enzyme allowed them to adapt to the medium. These culture strategies allowed for the isolation and convenient molecular characterization of two genotypes of serovar Hardjo, creating new insight into the seroepidemiology of leptospirosis and its specific genotypes. It also provides new information for the immunoprophylaxis of bovine leptospirosis.
Francisellosis is a disease responsible for severe economic losses in aquaculture. Currently, this disease is controlled via biosecurity measures and treatment of affected batches. In this study, tilapia juveniles were challenged with Francisella orientalis via immersion and fed with oxytetracycline‐medicated feed, at 100 mg kg fish−1 and 200 mg kg fish−1, under prophylactic and therapeutic strategies for 16 and 15 days respectively. All doses and treatment strategies reduced the fish mortality. The detection of the pathogen from the spleen was lower in the treated groups. Histopathology analysis showed that challenged fish that received the highest dosage presented fewer granuloma in their spleens and less inflammatory infiltrate in their livers than untreated fish. Fish that received the prophylactic treatment, regardless of the dose, presented fewer granuloma in their livers than untreated fish. Fish treated with 100 mg kg fish−1 had better scores for hepatocyte accumulations than fish treated with the higher dosage. Furthermore, 20% of the unchallenged fish that received the higher dosage presented mild inflammatory infiltrate in their livers. No differences were observed in the serum hepatocyte lesion enzyme quantifications. The results indicate that oxytetracycline‐medicated feed is safe, even at the higher dose, and effective at controlling francisellosis in tilapia.
The bacterial resistance for antibiotics is one of the most important problems in public health and only a small number of new products are in development. Antagonistic microorganisms from soil are a promising source of new candidate molecules. Products of secondary metabolism confer adaptive advantages for their producer, in the competition for nutrients in the microbial community. The biosynthesis process of compounds with antibiotic activity is the key to optimize their production and the transcriptomic study of microorganisms is of great benefit for the discovery of these metabolic pathways. Pseudomonas aeruginosa LV strain growing in the presence of copper chloride produces a bioactive organometallic compound, which has a potent antimicrobial activity against various microorganisms. The objective of this study was to verify overexpressed genes and evaluate their relation to the organometallic biosynthesis in this microorganism. P. aeruginosa LV strain was cultured in presence and absence of copper chloride. Two methods were used for transcriptomic analysis, genome reference-guided assembly and de novo assembly. The genome referenced analysis identified nine upregulated genes when bacteria were exposed to copper chloride, while the De Novo Assembly identified 12 upregulated genes. Nineteen genes can be related to an increased microbial metabolism for the extrusion process of exceeding intracellular copper. Two important genes are related to the biosynthesis of phenazine and tetrapyrroles compounds, which can be involved in the bioremediation of intracellular copper and we suggesting that may involve in the biosynthesis of the organometallic compound. Additional studies are being carried out to further prove the function of the described genes and relate them to the biosynthetic pathway of the organometallic compound.
Sheep breeding has been important in agribusiness, transforming the Brazilian productive scenario. However, it is still deficient due to the damages caused by infectious diseases. Leptospirosis is a severe disease with global distribution, caused by bacteria from the Leptospira genre affecting both humans and animals. The general infection is unapparent, or its clinical signs, when present, are similar to other infections. Brucellosis is an infectious disease caused by bacteria from the Brucella genre responsible for reproductive disorders in animals, especially ruminants. The purpose of this paper was to seroepidemiological study of Leptospira spp. and Brucella ovis in sheep and dogs from nonmechanized rural properties from the northwestern region in the state of Paraná, Brazil. In order to detect anti-Leptospira antibodies, microscopic agglutination (MAT) was performed. For anti-Brucella antibodies, the agar gel immunodiffusion assay (AGID) was performed. From the total 542 samples from sheep sera analyzed, 11.25% were considered reagent to Leptospira spp. and 18.26% to Brucella ovis. From the 36 dog samples, 25% were reagent to MAT and AGID. From the 32 properties analyzed, 75% were considered positive for leptospirosis and 56.25% for brucellosis. Antibodies against the most probable serovars were Hardjo (34.42%) and Butembo (44.44%) in sheep and dogs, respectively, and the variable exchange of animals among properties was associated to leptospiric infection (p=0.028) in sheep. Leptospirosis and brucellosis are present in the sheep herd and dogs in the rural properties studied, and such result is a warning of the zoonotic importance and the need to establish sanitary programs directed to these animal species. ResumoA ovinocultura tem se destacado no agronegócio, transformando o cenário produtivo do Brasil, porém ainda possui uma deficiência devido aos danos causados por doenças infecciosas. A leptospirose é uma doença grave de distribuição mundial causada por bactérias do gênero Leptospira que afeta o homem e os animais. A infecção geralmente é inapetente, ou os sinais clínicos, quando presentes, são similares aos de outras infecções. A brucelose é uma enfermidade infecciosa causada por bactérias do gênero Brucella responsáveis por desordens reprodutivas nos animais, especialmente nos ruminantes. O objetivo deste trabalho foi realizar um estudo soroepidemiológico de Leptospira spp. e Brucella ovis ovinos e cães de propriedades rurais não tecnificadas da região noroeste do estado do Paraná, Brasil. Para detecção de anticorpos anti-Leptospira foi realizada a soroaglutinação microscópica (SAM), e para anticorpos anti-Brucella, a prova de imunodifusão em gel de ágar (IDGA). Das 542 amostras de soro ovino analisadas, foram consideradas reagentes 11,25% para Leptospira spp. e 18,26% para Brucella ovis. Das 36 amostras de cães, 25% foram regentes a SAM e IDGA. Das 32 propriedades, 75% foram consideradas positivas para leptospirose e 56,25% para brucelose. Os anticorpos contra os sorovares mais prováveis for...
The objective of this study was to determine the prevalence of antibodies against Leptospira spp and their geographic distribution and to identify the risk factors associated with this disease in cattle herds with reproductive activity in the state of Paraná. A total of 14 163 females aged ≥24 months originating from 1 926 herds that were not vaccinated against Leptospira spp were evaluated. To detect the Leptospira spp antibodies, all serum samples were submitted for a microscopic serum-agglutination test (MAT). An epidemiological questionnaire was performed at each farm visited to characterize the management practices and study the risk factors associated with the presence or absence of Leptospira spp. To perform geoprocessing, the geographical coordinates of each farm were recorded with a Global Positioning System (GPS), which were then used to create a map. The apparent prevalence of bovine leptospirosis in the herds was the parameter used to generate the final risk map.
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