Novel bivalent vectored vaccine for control of myxomatosis and rabbit haemorrhagic disease

A novel, recombinant myxoma virus-rabbit haemorrhagic disease virus (RHDV) vaccine has been developed for the prevention of myxomatosis and rabbit haemorrhagic disease (RHD). A number of laboratory studies are described illustrating the safety and efficacy of the vaccine following subcutaneous administration in laboratory rabbits from four weeks of age onwards. In these studies, both vaccinated and unvaccinated control rabbits were challenged using pathogenic strains of RHD and myxoma viruses, and 100 per cent of the vaccinated rabbits were protected against both myxomatosis and RHD.     

Hf-W Isotopic Evidence for Rapid Accretion and Differentiation in the Early Solar System

The time scales over which inner solar system objects accreted and differentiated are unclear because the isotopic systems of many meteorites are disturbed. 182Hf decays to 182W with a half-life of 9 million years and is a particularly useful chronometer because both elements are highly refractory and immobile. Tungsten isotopic data for IIA, IIIA, IVA, and anomalous iron meteorites and H, L, and LL chondrites indicate that their parent bodies accreted rapidly and segregated metal within just a few million years.     

The colonization of host-root and soil by rhizobia—II. strain differences in the species Rhizobium trifolii

The ability of four strains of Rhizobium trifolii to colonize host-root and soil was compared at 5-day intervals up to 70 days from sowing into a field soil. Strain differences in colonizing ability were demonstrated, with one strain (TA1) consistently inferior to the other three which comprised another introduced strain (UNZ29) and two locally isolated strains.     

Epidemiology and conservation implications of Trichomonas gallinae infection in the endangered Mauritian pink pigeon

Despite increasing recognition of the role of exotic pathogens in species decline, comprehensive studies of wildlife disease epidemiology in threatened species are rare. We investigated the epidemiology of the protozoan parasite Trichomonas gallinae, which causes the avian disease trichomonosis, in the five wild subpopulations of the endangered pink pigeon Columba mayeri in Mauritius. An average of 89% of the entire population was screened for T. gallinae infection every 2 months between September 2002 and April 2004. A total of 426 individual pink pigeons (all >3 months of age) was screened, and 359 (84.3%) of these tested positive for T. gallinae at least once. Average prevalence of T. gallinae infection across all subpopulations and sampling periods was 50.3% but ranged from 19.6% to 82.4%. Trichomonas gallinae infection was significantly different among subpopulations and prevalence gradually decreased over the entire screening period. Infection prevalence also increased with host age. Observed pathogenicity of T. gallinae was low; active trichomonosis signs were recorded in ca. 1.9% of birds which tested positive. However, birds which persistently tested positive for T. gallinae (33.5% of birds screened) were at least 10% less likely to survive 2 yrs post-screening than birds which tested negative at least once in three consecutive periods; a finding which should be considered by wildlife disease investigators if no pathogenic effects are apparent from the results of studies based on a single screening episode. We conclude that T. gallinae is an additional population limiting factor for pink pigeons and our study highlights the importance of screening other endangered columbids for this pathogen.     

Evidence of sedimentation inequality along riparian areas colonised by Impatiens glandulifera (Himalayan balsam)

Soil loss from riparian areas supporting the annual invasive weed, Impatiens glandulifera (Himalayan balsam), was measured and compared with equivalent values recorded at nearby, topographically similar areas supporting perennial vegetation over a cumulative seven-year period, along sections of two separate river systems; one in Switzerland, and one in the UK. Soil loss from colonised locations was significantly greater than from reference locations in four of the seven measurement periods. Despite contrasting results, standard deviations, based on soil losses and gains, were predominantly higher for colonised areas at both rivers over most monitoring periods. These findings indicated that areas colonised by Himalayan balsam experience higher sediment flux in comparison with areas free of invasion. Here, we test those original interpretations by reinterrogating the datasets using a more robust analysis of inequality. Nine datasets were tested, five of which (i.e. 56%) showed that sediment flux was significantly greater at Himalayan balsam-invaded areas than at reference areas. Three datasets showed no difference in sediment flux between invaded and reference areas (33%), and one (11%) showed higher sediment flux at reference areas. Most results uphold our original interpretations and support our hypothesis that hydrochory probably dictates where colonisation initially occurs, by depositing Himalayan balsam seeds in slack or depressional areas along river margins. Once Himalayan balsam becomes established and sufficient perennial vegetation is displaced, seasonal die-off and depleted vegetation cover may increase the risk that some areas will experience significantly higher sediment flux.     

Efficacy of feline panleucopenia vaccine to prevent infection with an isolate of CPV2b obtained from a cat.

Cats vaccinated against FPLV were protected against infection with a feline isolate of CPV2b. Nonvaccinated cats developed a lymphopenia and excreted virus which infected susceptible in-contact cats.     

The kinetics of insecticide action. Part IV: the in-vivo distribution of pyrethroid insecticides during insect poisoning

The distribution of pyrethroids in insects has been studied using a combination of mathematical modelling and experimental observation. This approach has resulted in the formulation of a physiological model of the pharmaco-kinetics of cypermethrin applied topically to larvae of Spodoptera littoralis. Development of this model from simpler two- and three-compartment models is described. Simple models, whilst capable of complex behaviour, consider only the average rates and magnitudes of pharmaco-kinetic processes over whole animals, and cannot account for differences in concentration of insecticide between individual tissues. This can be achieved by using physiological models, but these require more experimental information for their validation. Moreover, unless simplifying assumptions are made, analytical solutions are not feasible for the large number of equations necessary to define such models. The modelling studies prompted an investigation of (1) in-vivo binding of insecticide to insect tissues, (2) the sizes of body compartments, and (3) the factors which affect the distribution of toxicant between these compartments. Binding has a marked effect on pharmacokinetic profiles and may result in oscillatory behaviour. During poisoning, the total bound cypermethrin increases proportionally to the cube root of the elapsed time. This results in a rapid rate of increase over early elapsed times (< 3h) which slows to approach a more linear form thereafter. Average sizes for the body compartments of larvae of Spodoptera littoralis Boisd, and the steady-state distribution of cypermethrin in these compartments are described. Although the haemolymph, which acts as the main distributive phase during poisoning, forms the largest compartment by volume, it has a low affinity for cypermethrin and distribution reaches steady state within 5 min after topical application. The nerve cord (the target tissue), which is the smallest compartment, has the highest steady-state concentration of cypermethrin. The distribution of cypermethrin in larval tissues is related to the ratios of tissue dry matter to water content.     

Aerococcus viridans expression of Cpn60 is associated with virulence during infection of the American lobster, Homarus americanus Milne Edwards

The Gram-positive bacterium Aerococcus viridans var. homari is a well-documented causative agent of the lethal systemic disease gaffkemia in both the American lobster, Homarus americanus, and the European lobster, Homarus gammarus. Previous phenotypic characterization has been unsuccessful at differentiating avirulent from virulent strains without performing lethal animal infection trials. Recent genetic characterization of A. viridans strains through 16S rRNA sequencing and random amplification of polymorphic DNA fingerprinting has revealed the presence of two subtypes. However, subtype 1 contains both virulent and avirulent strains which are genetically identical. The purpose of this study was to determine the proteomic mediators of virulence in A. viridans. Quantitative proteomic mapping of these two strains has revealed 29 differentially expressed protein spots, seven of which are only expressed in the virulent strain and could act as virulence factors. One protein, chaperonin 60 (Cpn60), is uniquely expressed in the virulent strain and has been shown to act as a virulence factor in many other bacteria. The proteomic mapping strategy employed in this study is the first to show phenotypic differences between virulent and avirulent strains. Cpn60 expression represents a potentially useful tool for identifying the virulent strains of A. viridans in epidemiological studies.