Roseate spoonbill

A poem

Selection and characterisation of two attenuated vaccine lines of Eimeria tenella in Australia

Objective To attenuate two strains of Eimeria tenella by selecting for precocious development and evaluate the strains in characterisation trials and by field evaluation, to choose one precocious line for incorporation into an Australian live coccidiosis vaccine for poultry. Design Two strains from non-commercial flocks were passaged through chickens while selecting for precocious development. Each strain was characterised for drug sensitivity, pathogenicity, protection against homologous and heterologous challenge, and oocyst output in replicated experiments in which the experimental unit was a cage of three birds. Oocyst output and/or body weight gain data collected over a 10 to 12 day period following final inoculation were measured. Feed conversion ratios were also calculated where possible. Results Fifteen passages resulted in prepatent periods reduced by 24 h for the Redlands strain (from 144 h to 120 h)and 23 h for the Darryl strain (from 139 h to 116 h). Characterisation trials demonstrated that each precocious line was significantly less pathogenic than its parent strain and each effectively induced immunity that protected chickens against challenge with both the parent strain and other virulent field strains. Both lines had oocyst outputs that, although significantly reduced relative to the parent strains, remained sufficiently high for commercial vaccine production, and both showed susceptibility to coccidiostats. Conclusion Two attenuated lines have been produced that exhibit the appropriate characteristics for use in an Australian live coccidiosis vaccine.

The vaccination-challenge trial: the gold standard test to evaluate the protective efficacy of infectious coryza vaccines

Infectious coryza is an upper respiratory tract disease of chickens with the major impact occurring in multi-age flocks. We investigated the relationship between the level of antibodies, as detected by a haemagglutination-inhibition (HI) assay, in infectious coryza-vaccinated chickens and the protection against challenge in those chickens. In one experiment, chickens given a single dose of either of two infectious coryza vaccines lacked a detectable HI response to vaccination but showed significant levels of protection 11 weeks after vaccination. In contrast, in chickens given two doses of an infectious coryza vaccine and challenged 3 weeks after the second vaccine dose, there was a strong serological response with 36/40 birds having a HI titre of 1/20 or greater. In this trial there was an apparent relationship between titre and subsequent protection, with none of the 32 chickens with a titre of 1/40 or 1/80 showing any clinical signs and only one of the same group yielding the challenge organism on culture. In contrast, three of the four vaccinated chickens with a HI titre less than 1/5 developed the typical clinical signs of coryza and yielded the challenge organism on culture. Overall, our results suggest that HI titres cannot be regarded as a definitive predictor of vaccine efficacy. We suggest that the vaccination-challenge trial is the gold standard for the evaluation of the immune response to infectious coryza vaccines.

Development and validation of an ELISA for detecting antibodies to Eimeria tenella in chickens

The aim of this study was to develop and validate an ELISA for detecting chicken antibodies to Eimeria tenella. An initial comparison of merozoite and sporozoite antigen preparations revealed few differences in their ability to monitor the onset, kinetics and magnitude of the antibody response suggesting that both antigens would be equally useful for development of an ELISA. Furthermore the cross-reactivity of these antigens with sera from birds infected with chicken Eimeria species was similar. The merozoite antigen was selected for further evaluation because it was easier to prepare. Discrimination between sera from birds experimentally infected with E. tenella and birds maintained in an Eimeria-free isolation facility was excellent. In sera collected from free-range layers and commercial broilers there also appeared to be clear discrimination between infected and uninfected birds. The ELISA should prove useful for monitoring infectivity in vaccination programmes in layer and breeder flocks and for assessing the effectiveness of biosecurity measures in broiler flocks.

Antibody response against endogenous stages of an attenuated strain of Eimeria tenella

The application of attenuated vaccines for the prevention of chicken coccidiosis has increased exponentially in recent years. In Eimeria infections, protective immunity is thought to rely on a strong cell mediated response with antibodies supposedly playing a minor role. However, under certain conditions antibodies seem to be significant in protection. Furthermore, antibodies could be useful for monitoring natural exposure of flocks to Eimeria spp. and for monitoring the infectivity of live vaccines. Our objective was to investigate the chicken antibody response to the different parasite lifecycle stages following infection with an attenuated strain of Eimeria tenella. Western blotting analysis of parasite antigens prepared from the lining of caeca infected with the attenuated strain of E. tenella revealed two dominant antigens of 32 and 34 kDa, apparently associated with trophozoites and merozoites that were present at high concentrations between 84 and 132 h post-infection. When cryosections of caeca infected with E. tenella were probed with IgY purified from immune birds the most intense reaction was observed with the asexual stages. Western blotting analysis of proteins of purified sporozoites and third generation merozoites and absorption of stage-specific antibodies from sera suggested that a large proportion of antigens is shared by the two stages. The time-courses of the antibody response to sporozoite and merozoite antigens were similar but varied depending on the inoculation regime and the degree of oocyst recirculation.

Rapid and sensitive detection of Avibacterium paragallinarum in the presence of other bacteria using a 5' Taq nuclease assay: A new tool for diagnosing infectious coryza

A 5' Taq nuclease assay specific for Avibacterium paragallinarum was designed and optimized for use in diagnosing infectious coryza. The region chosen for assay design was one of known specificity for Av. paragallinarum. The assay detected Av. paragallinarum reference strains representing the three Page and the eight Kume serovars, and field isolates from diverse geographical locations. No cross-reactions were observed with other Avibacterium species, with other bacteria taxonomically related to Av. paragallinarum nor with bacteria and viruses likely to be present in swabs collected from suspected infectious coryza cases. The detection limit for the assay was 6 to 60 colony-forming units per reaction. Twenty-two out of 53 swabs collected from sick birds reacted in the 5' Taq nuclease assay, whereas Av. paragallinarum was not isolated from any of the swabs. All of the 22 swabs yielded other bacteria in culture. The presence of Av. paragallinarum in the swabs was also demonstrated by sequencing, thereby confirming the ability of the assay to detect Av. paragallinarum in the presence of other bacteria. The ability to quantify bacterial load in the swabs using the 5' Taq nuclease assay was demonstrated.

Semantic Fluency in Mild and Moderate Alzheimer's Disease

Alzheimer's disease (AD) is characterized by an impairment of the semantic memory responsible for processing meaning-related knowledge. This study was aimed at examining how Finnish-speaking healthy elderly subjects (n = 30) and mildly (n=20) and moderately (n = 20) demented AD patients utilize semantic knowledge to performa semantic fluency task, a method of studying semantic memory. In this task subjects are typically given 60 seconds to generate words belonging to the semantic category of animals. Successful task performance requires fast retrieval of subcategory exemplars in clusters (e.g., farm animals: 'cow', 'horse', 'sheep') and switching between subcategories (e.g., pets, water animals, birds, rodents). In this study, thescope of the task was extended to cover various noun and verb categories. The results indicated that, compared with normal controls, both mildly and moderately demented AD patients showed reduced word production, limited clustering and switching, narrowed semantic space, and an increase in errors, particularly perseverations. However, the size of the clusters, the proportion of clustered words, and the frequency and prototypicality of words remained relatively similar across the subject groups. Although the moderately demented patients showed a poor eroverall performance than the mildly demented patients in the individual categories, the error analysis appeared unaffected by the severity of AD. The results indicate a semantically rather coherent performance but less specific, effective, and flexible functioning of the semantic memory in mild and moderate AD patients. The findings are discussed in relation to recent theories of word production and semantic representation. Keywords: semantic fluency, clustering, switching, semantic category, nouns, verbs, Alzheimer's disease

Evaluation of the most effective measures of infectivity of a precocious line of Eimeria acervulina in poultry

Coccidiosis is an economically important parasitic disease of chickens that, in Australia, is caused by seven species of the genus Eimeria.1 The disease has traditionally been controlled by prophylactic drugs, but vaccination with attenuated lines of the parasites2–4 is rapidly gaining acceptance world wide. Live Eimeria vaccines are produced in batches which are not frozen and have a limited shelf life. The per cent infectivity of vaccine seed stocks and the vaccines produced from them must therefore be accurately monitored using standardised dose dependant assays to ensure that shelf life, quality control and vaccine release specifications are met. Infectivity for the chicken host cannot readily be determined by microscopic observation of oocysts or sporocyst hatching.5 Dose dependent parameters such as body weight gain, feed conversion ratio, visual lesion scores, mortality, oocysts production, clinical symptoms and microscopic lesion counts could be used as measures of infectivity.6–11 These parameters show significant dose dependant effects with field strains, but lines of vaccine parasites that have been selected for precocious development with associated reduced virulence and reproductive capability may not have the same effect.3,4 The aim of this trial was to determine which parameters provide the most effective measures of infective dose in birds inoculated with a precocious vaccine strain.

Quantifying Transmission of Campylobacter jejuni in Commercial Broiler Flocks

Since meat from poultry colonized with Campylobacter spp. is a major cause of bacterial gastroenteritis, human exposure should be reduced by, among other things, prevention of colonization of broiler flocks. To obtain more insight into possible sources of introduction of Campylobacter into broiler flocks, it is essential to estimate the moment that the first bird in a flock is colonized. If the rate of transmission within a flock were known, such an estimate could be determined from the change in the prevalence of colonized birds in a flock over time. The aim of this study was to determine the rate of transmission of Campylobacter using field data gathered for 5 years for Australian broiler flocks. We used unique sampling data for 42 Campylobacter jejuni-colonized flocks and estimated the transmission rate, which is defined as the number of secondary infections caused by one colonized bird per day. The estimate was 2.37 +/- 0.295 infections per infectious bird per day, which implies that in our study population colonized flocks consisting of 20,000 broilers would have an increase in within-flock prevalence to 95% within 4.4 to 7.2 days after colonization of the first broiler. Using Bayesian analysis, the moment of colonization of the first bird in a flock was estimated to be from 21 days of age onward in all flocks in the study. This study provides an important quantitative estimate of the rate of transmission of Campylobacter in broiler flocks, which could be helpful in future studies on the epidemiology of Campylobacter in the field.

Reflections on the Research Students' 2015 Art Exhibition and Operetta/morality play "The Trial of Homo Economicus: The dollar hunting animal"

The paper outlines the process of organising research student participants and creating a public musical performance at QUT. The theme of the Operetta/Morality play is the clash between economic values of humans necessitating growth and the basic needs of the other life on planet earth. The one act play is set in a court room presided over by a judge who adjudicates the court proceedings.Homo economicus is in the dock and victims(various animals and birds) raise their grievances.

Foods of pigeons and doves in fragmented landscapes of subtropical eastern Australia

We report dietary items of pigeons and doves from northern New South Wales and southern Queensland, obtained from opportunistic sampling of the gut contents of dead birds and observing foraging birds. Most records were from fragmented rainforest habitats, which now support abundant invasive fleshy-fruited plants. The fruits and seeds of invasive plants, particularly Camphor Laurel Cinnamomum camphora, formed the dominant food of several of the species sampled, although in some cases these birds appear to destroy most of the ingested seeds in the gizzard, thereby not contributing to weed dispersal. We also describe the first records of White-headed Pigeons Columba leucomela eating flowers and Brown Cuckoo-Doves Macropygia amboinensis eating flower buds. Camphor Laurel, via flowers, green and ripe fruits, and seeds, provided food for White-headed Pigeons in the Goolmangar district of New South Wales throughout the entire year. Seventy percent of the plant species whose fruits and seeds were recovered from the gut had not previously been recorded as food items for those bird species, illustrating how little is known about the diets of pigeons and doves in fragmented Australian landscapes.

Dispersal and establishment of bird-dispersed weed and native species in early successional subtropical habitats

Eve White, Anna Barnes and Gabrielle Vivian-Smith recently published their paper 'Dispersal and establishment of bird-dispersed weed and native species in early successional subtropical habitats' in Proceedings of the 16th Australian Weeds Conference. Eve also presented this paper at the conference. They investigated patterns of dispersal and establishment of bird-dispersed weeds and native species in early successional habitats in northern New South Wales. Patterns varied among growth forms, between native species and weeds, and among vegetation types. Their results indicated that the number of seeds dropped by birds is not necessarily a good predictor of recruitment and that post-dispersal factors, such as microsite characteristics, may be more important influences on seedling recruitment. This knowledge will assist with designing management strategies for bird-dispersed weeds in natural areas.

Growth of koster’s curse (Clidemia hirta) from seedlings to reproductive maturity and following mechanical damage

Koster´s curse is a highly invasive, perennial shrub with potential to become a major weed in many parts of Queensland and elsewhere in Australia. Presently, there is one infestation discovered in Australia and the species is a Class 1 weed. It grows to 5 m and can produce over 500 berries annually which are dispersed by birds and water. This study quantified growth and the effects of damage on survival and time to reproduction under both field and shade house conditions in the Wet Tropics of north Queensland. Plants recovered to their original size and were capable of setting seed in as few as 86 days and 194 days after being cut back to 10 cm and 0 cm respectively.