Brazilian avian metapneumovirus subtypes A and B: experimental infection of broilers and evaluation of vaccine efficacy

Santos M.B., Martini M.C., Ferreira H.L., Silva L.H.A., Fellipe P.A., Spilki F.R. & Arns C.W. 2012. Brazilian avian metapneumovirus subtypes A and B: experimental infection of broilers and evaluation of vaccine efficacy. Pesquisa Veterinaria Brasileira 32(12):1257-1262. Laboratorio de Virologia, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato s/n, Cx. Postal 6109, Campinas, SP 13083-970, Brazil. E-mail: arns@unicamp.br Avian metapneumovirus (aMPV) is a respiratory pathogen associated with the swollen head syndrome (SHS) in chickens. In Brazil, live aMPV vaccines are currently used, but subtypes A and, mainly subtype B (aMPV/A and aMPV/B) are still circulating. This study was conducted to characterize two Brazilian aMPV isolates (A and B subtypes) of chicken origin. A challenge trial to explore the replication ability of the Brazilian subtypes A and B in chickens was performed. Subsequently, virological protection provided from an aMPV/B vaccine against the same isolates was analyzed. Upon challenge experiment, it was shown by virus isolation and real time PCR that aMPV/B could be detected longer and in higher amounts than aMPV/A. For the protection study, 18 one-day-old chicks were vaccinated and challenged at 21 days of age. Using virus isolation and real time PCR, no aMPV/A was detected in the vaccinated chickens, whereas one vaccinated chicken challenged with the aMPV/B isolate was positive. The results showed that aMPV/B vaccine provided a complete heterologous virological protection, although homologous protection was not complete in one chicken. Although only one aMPV/B positive chicken was detected after homologous vaccination, replication in vaccinated animals might allow the emergence of escape mutants.

Lyotropic mixture made of potassium laurate/1-undecanol/K2SO4/water presenting high birefringences and large biaxial nematic phase domain: a laser conoscopy study

The lyotropic liquid crystalline quaternary mixture made of potassium laurate (KL), potassium sulphate, 1-undecanol and water was investigated by experimental optical methods (optical microscopy and laser conoscopy). In a particular temperature and relative concentrations range, the three nematic phases (two uniaxial and one biaxial) were identified. The biaxial domain in the temperature/KL concentration surface is larger when compared to other lyotropic mixtures. Moreover, this new mixture gives nematic phases with higher birefringence than similar systems. The behavior of the symmetric tensor order parameter invariants sigma(3) and sigma(2) calculated from the measured optical birefringences supports that the uniaxial-to-biaxial transitions are of second order, described by a mean-field theory.

Occurrence and sorption of fluoroquinolones in poultry litters and soils from sao Paulo State, Brazil

Animal production is one of the most expressive sectors of Brazilian agro-economy. Although antibiotics are routinely used in this activity, their occurrence, fate, and potential impacts to the local environment are largely unknown. This research evaluated sorption-desorption and occurrence of four commonly used fluoroquinolones (norfloxacin, ciprofloxacin, danofloxacin, and enrofloxacin) in poultry litter and soil samples from Sao Paulo State, Brazil. The sorption-desorption studies involved batch equilibration technique and followed the OECD guideline for pesticides. All compounds were analyzed by HPLC, using fluorescence detector. Fluoroquinolones' sorption potential to the poultry litters (K-d <= 65 L kg(-1)) was lower than to the soil (K-d similar to 40,000 L kg(-1)), but was always high (>= 69% of applied amount) indicating a higher specificity of fluoroquinolones interaction with soils. The addition of poultry litter (5%) to the soil had not affected sorption or desorption of these compounds. Desorption was negligible in the soil (<= 0.5% of sorbed amount), but not in the poultry litters (up to 42% of sorbed amount). Fluoroquinolones' mean concentrations found in the poultry litters (1.37 to 6.68 mg kg(-1)) and soils (22.93 mu g kg(-1)) were compatible to those found elsewhere (Austria, China, and Turkey). Enrofloxacin was the most often detected compound (30% of poultry litters and 27% of soils) at the highest mean concentrations (6.68 mg kg(-1) for poultry litters and 22.93 mu g kg(-1) for soils). These results show that antibiotics are routinely used in poultry production and might represent one potential source of pollution to the environment that has been largely ignored and should be further investigated in Brazil. (C) 2012 Elsevier B.V. All rights reserved.

Urediospores of rust fungi are ice nucleation active at > -10°C and harbor ice nucleation active bacteria

Various features of the biology of the rust fungi and of the epidemiology of the plant diseases they cause illustrate the important role of rainfall in their life history. Based on this insight we have characterized the ice nucleation activity (INA) of the aerially disseminated spores (urediospores) of this group of fungi. Urediospores of this obligate plant parasite were collected from natural infections of 7 species of weeds in France, from coffee in Brazil and from field and greenhouse-grown wheat in France, the USA, Turkey and Syria. Immersion freezing was used to determine freezing onset temperatures and the abundance of ice nuclei in suspensions of washed spores. Microbiological analyses of spores from France, the USA and Brazil, and subsequent tests of the ice nucleation activity of the bacteria associated with spores were deployed to quantify the contribution of bacteria to the ice nucleation activity of the spores. All samples of spores were ice nucleation active, having freezing onset temperatures as high as −4 °C. Spores in most of the samples carried cells of ice nucleation-active strains of the bacterium Pseudomonas syringae (at rates of less than 1 bacterial cell per 100 urediospores), but bacterial INA accounted for only a small fraction of the INA observed in spore suspensions. Changes in the INA of spore suspensions after treatment with lysozyme suggest that the INA of urediospores involves a polysaccharide. Based on data from the literature, we have estimated the concentrations of urediospores in air at cloud height and in rainfall. These quantities are very similar to those reported for other biological ice nucleators in these same substrates. However, at cloud level convective activity leads to widely varying concentrations of particles of surface origin, so that mean concentrations can underestimate their possible effects on clouds. We propose that spatial and temporal concentrations of biological ice nucleators active at temperatures > −10 °C and the specific conditions under which they can influence cloud glaciation need to be further evaluated so as to understand how evolutionary processes could have positively selected for INA.