Reproducibility of a virus-neutralization test for infectious laryngotracheitis virus

A virus-neutralization test for infectious laryngotracheitis virus was performed in microtiter plates using standard techniques. To assess the reproducibility of the test, 11 sera were each titrated repeatedly once a week for 8 weeks, and the results were compared to a standard. The standard used for reproducibility was that the 95% logarithmic confidence intervals of the mean calculated from three titrations of the same serum had to be smaller than the logarithmic distance "within" two microtiter plate wells. For the virus neutralization test to give reproducible results, such confidence intervals had to fall "within" two wells at least 75% of the time. Over the 8 weeks, percent reproducibility varied from 43.5% to 81.5%. The infectious laryngotracheitis virus-neutralization test did not meet our defined standard of reproducibility with positive antisera. Results with negative control sera were reproducible, however. Percent reproducibility varied from 31.8% to 93.8% for different sera tested, but it was not related to the titer of the sera.     

Leaf-trait responses to irrigation of the endemic fog-oasis tree Myrcianthes ferreyrae: can a fog specialist benefit from regular watering?

Myrcianthes ferreyrae is an endemic, endangered species, with a small number of individuals located only in hyperarid, fog-oases known as lomas along the Peruvian desert in southern Peru, where fog is the main source of water. Following centuries of severe deforestation, reforestation with this native species was conducted in the Atiquipa lomas, Arequipa-Perú. On five slopes, five 2-year-old seedlings were irrigated monthly with water trapped by raschel-mesh fog collectors, supplementing natural rainfall with 0, 20, 40, 60 and 80 mm month(-1) from February to August 2008. We measured plant growth, increment in basal diameter, height and five leaf traits: leaf mass area (LMA), leaf carbon isotope composition (δ(13)C), nitrogen per leaf area, total leaf carbon and stomatal density; which are indicative of the physiological changes resulting from increased water supply. Plant growth rates, estimated from the variation of either shoot basal diameter or maximum height, were highly correlated with total biomass. Only LMA and δ(13)C were higher in irrigated than in control plants, but we found no further differences among irrigation treatments. This threshold response suggests an on-off strategy fitted to exploit pulses of fog water, which are always limited in magnitude in comparison with natural rain. The absence of a differential response to increased water supply is in agreement with the low phenotypic plasticity expected in plants from very stressful environments. Our results have practical implications for reforestation projects, since irrigating with 20 mm per month is sufficient to achieve the full growth capacity of this species.     

Quantitative analysis of the resorption and osteoconduction of a macroporous calcium phosphate bone cement for the repair of a critical size defect in the femoral condyle

Clinical orthopaedic use of calcium phosphate cement has been limited due to its slow resorption rate, but a new macroporous alpha-tricalcium phosphate (alpha-TCP) bone cement has been designed to accelerate resorption and to increase bone ingrowth. To assess its clinical potential, the in vivo behaviour of alpha-TCP was evaluated in a critical-size defect drilled in the femoral condyles of 36 adult female New Zealand rabbits. Macroporous or standard cement was injected immediately after preparation of the defect. The foaming agent was albumen, which gave up to 75% porosity. The rabbits were divided into three groups and the lesions examined histopathologically at 1, 4 and 12 weeks. No inflammatory reaction was detected at any time period following implantation with either macroporous or standard cement. At 12 weeks, the area of the implanted macroporous cement was approximately 35% of the initial lesion size. Bone growth and revascularisation was observed inside the central pores of the macroporous cement, not only at the margins, as was found with standard calcium phosphate cement. The results indicated that both cements were osteoconductive, biocompatible and biodegradable but their different physicochemical and biological properties had a marked influence on their post-implant behaviour.     

Azinphos-methyl and carbaryl resistance in adults of the codling moth (Cydia pomonella (L.), Lepidoptera: Tortricidae) from Northeastern Spain

The resistance of Cydia pomonella (L.) to organophosphates is widespread throughout the pome fruit growing areas. The lethal effects of two insecticides inhibitors of the acetylcholine esterase, azinphos-methyl and carbaryl, were evaluated in adults of five and four field populations of the codling moth, respectively. The lethal concentrations (LC₅₀ and LC₉₀) of these insecticides were determined in a susceptible strain from Spain (S_Spain). Topical bioassays using the approximate LC₉₀ values (3000 mg (a.i.)/L of carbaryl and 2000 mg (a.i.)/L of azinphos-methyl) that were obtained in S_Spain were tested as diagnostic concentrations. The enzymatic activities of mixed-function oxidases (MFO), glutathione S-transferases (GST) and esterases (EST) were measured to investigate their potential role in the detoxification of these insecticides.Carbaryl and azinphos-methyl caused ?53% and ?39% corrected mortality, respectively, in field populations, although the diagnostic concentrations applied were twofold and fourfold higher than the maximum concentration registered in Spain, respectively. The activities of MFO and GST were 7.3- to 16.1-fold higher and 2.5- to 3.7-fold higher in all the field populations compared to those in S_Spain, respectively.     

Papular dermatitis due to Leishmania spp. infection in dogs with parasite-specific cellular immune responses

Papular dermatitis due to Leishmania spp. infection was diagnosed in three boxers and two Rottweilers with Leishmania-specific cellular immunity. Diagnosis was based on histological and immunohistochemical examination of papules in four dogs and on cytological examination in one dog. Serum protein electrophoresis was within reference ranges and low antibody levels to Leishmania infantum were detected. Delayed-type hypersensitivity (DTH) reaction to leishmanin was evaluated before treatment in three dogs with positive results. After meglumine antimoniate therapy for 3 to 4 weeks and allopurinol treatment for 6 to 10 months, all dogs were clinically normal, had positive DTH reactions to leishmanin and reduced antibody titres. In conclusion, we suggest that this previously unreported cutaneous presentation of canine leishmaniosis appears to be associated with specific immunocompetence and, consequently, with a favourable prognosis.     

Dynamics of Mycoplasma hyopneumoniae infection in 12 farms with different production systems

This study had 2 objectives: 1) to determine the involvement of Mycoplasma hyopneumoniae in respiratory outbreaks in herds of pigs, with the use of a nested polymerase chain reaction (nPCR) and an enzyme-linked immunosorbent assay (ELISA); and 2) to determine if the dynamics of M. hyopneumoniae infection differ between 3-site versus 1- or 2-site production systems (in which at least farrowing/gestation and nursery pigs are on the same site). Animals of different ages from 12 Spanish farms with respiratory problems were randomly sampled. Blood samples and nasal swabs were collected in a single farm visit, and ELISA and nPCR tests, respectively, were performed. All the farms demonstrated M. hyopneumoniae. According to the proportions of infected animals and the appearance of clinical signs in the different age groups, the farms were divided into 2 groups: farms in which M. hyopneumoniae probably played an important role in the observed respiratory outbreak and farms in which M. hyopneumoniae was not the main agent involved in the outbreak. Although seroconversion occurred in most herds in the finishing units, the number of seropositive pigs in the first group of farms was greater than the number in the second group. Statistically significant differences (P < 0.0001) between farms with a 1- or 2-site production system versus those with a 3-site production system were detected in nPCR results but not in rates of seroconversion. The farm effect also had a great influence on both controlled parameters: the pathogen’s DNA and antibody detection. Thus, although M. hyopneumoniae was present in all the studied farms, there were significant differences in the infection dynamics and clinical implications according to the type of production system, and M. hyopneumoniae colonization and seroconversion were greatly influenced by the effect of the individual farm.     

Biological and phylogenetic characterization of virulent Newcastle disease virus circulating in Mexico

In 2002-2003, velogenic Newcastle Disease Virus outbreaks, closely related to the Mexican isolates, were confirmed in the United States (U.S.) in southern California, Arizona, Nevada, and Texas. In this report, virulent NDVs isolated in Mexico between 1998 and 2006 were subjected to biologic characterization, using standard pathogenicity tests, and to phylogenetic analysis. Chicken embryo mean death time (MDT) test results ranged from 39.7 to 61.5 hours, and intracerebral pathogenicity index (ICPI) values were between 1.59 and 1.94, compared to a possible maximum value of 2.0. These isolates showed a dibasic amino acid motif at the fusion protein cleavage site sequence required for host systemic replication. Phylogenetic analysis indicated that the Mexican virulent NDVs belong to the class II, genotype V viruses and can be clearly divided in two groups as follows: isolates from 1998 to 2001 with close epidemiologic relationship with the latest U.S. NDV outbreaks, and phylogenetically distinct viruses, isolated from 2004 to 2006, which showed higher virulence. The assessment of the evolution of viruses from Mexico and other neighboring countries will aid in the U.S surveillance efforts for early detection of highly virulent NDV.