Climatic variation is an important driver of avian life history and population dynamics. Climate change models predict increased variability for many regions and to predict the effects on species, we need to examine how their life history characteristics influence their response to climate. I studied how environmental conditions influenced the ecology of white-tailed (Lagopus leucura) and rock ptarmigan (L. mutus) in tundra habitats of the southern Yukon Territory. Although sympatric in the study area, breeding territories were generally segregated, with white-tailed ptarmigan selecting steep, rocky slopes at higher elevations and rock ptarmigan preferring lower elevation sedge meadows. For both species, cold spring temperatures delayed the onset of breeding, resulting in smaller clutch sizes and fewer hatched young per female. However, delayed breeding led to a stronger reduction in these rates for rock ptarmigan, suggesting a lower resilience to extend reproductive effort in colder years. White-tailed ptarmigan were also more likely to re-nest following failure and had higher daily nest survival, both of which contributed to greater annual productivity compared to rock ptarmigan. Annual adult survival showed the opposite pattern to productivity as rock ptarmigan survival was 24 percent higher than white-tailed ptarmigan. This finding suggested a reproduction-survival trade-off exists for the two species, which may be driven by differing susceptibility to environmental factors in the region. Life history theory predicts that if the likelihood of future breeding opportunities is low, individuals should increase current reproductive effort, which may explain why white-tailed ptarmigan have longer breeding seasons and higher reproductive effort under unfavourable climatic conditions. Population models showed that growth rates (λ)were approximately stable for rock ptarmigan (λ=1.01), but declining for white-tailed ptarmigan (λ=0.96). Simulations showed that warmer spring temperatures over the next few decades would elevate λ by ~0.05 for both species, but the extent of increase in λ may be reduced with more variable spring conditions. Population growth will also depend on how changing winter conditions influence survival for each species. Model simulations suggest that if juvenile and adult survival are positively correlated, rock ptarmigan would be more resilient to severe years that simultaneously depress reproduction and survival.

Genetic immunization, also known as DNA or polynucleotide immunisation, is well documented to induce broad-based immunity in various animal models of infectious and non-infectious diseases. However, the low potency of DNA vaccines has to date precluded the development of commercial vaccines. The aim of this study was to systematically investigate a number of parameters to improve the potency of DNA vaccines for use in chickens, using a low pathogenic avian influenza (LPAI) virus as a proof-of-concept for their ability to produce a humoral immune response. The index virus used in the study was avian influenza virus A/coot/WA/2727/79 (H6N2), isolated from an apparently healthy Eurasian coot in 1979. Prior to any DNA experiments the virus was rigorously characterized. The virus strain was shown to be an H6 subtype by haemaglutination inhibition (HI) testing and as an N2 subtype by gene sequence analysis. The isolate was shown to be able to grow on MDCK cells in the absence of exogenous trypsin. It was further biologically characterized as LPAI with an intravenous pathogenicity index (IVPI) of 0.15 and a motif of 321PQAETRG328 at the cleavage site of the haemagglutinin (HA) protein. It was capable of infecting domestic chickens under experimental conditions with a low level of virus excretion via the cloaca and oropharynx following intravenous or oral and oculonasal inoculation. The full-length HA and nucleoprotein (NP) genes of this H6N2 virus were subsequently cloned into the eukaryotic expression vector VR1012 to generate VR-HA and VR-NP constructs. Six-week-old Hy-Line chickens were intramuscularly injected with either the VR-HA or VR-NP vaccine at different dose rates, with or without lipofectin as adjuvant. Minimal or no detectable antibody was produced, as measured by HI, ELISA and Western blotting-based assay, but high titres of H6-specific HI antibodies appeared 10 days after homologous virus challenge. In contrast to the empty vector controls, there was a significant difference in HI antibody titre between pre- and post-challenge in vaccinated birds, indicating some evidence for the priming effect of the DNA vaccines. Using the frequency of virus shedding as an indicator of protection, lower doses (50 or 100 ¦Ìg per chicken) of either adjuvanted VR-HA or VR-NP vaccine significantly reduced virus shedding in oropharyngeal and cloacal swabs compared to higher doses (300 or 500 ¦Ìg per chicken ) or empty vector control chickens. Although two vaccinations with naked VR-HA alone were not sufficient to induce an effective immune response against a homologous virus challenge, further repeat vaccinations and incorporation of adjuvant did lead to the generation of low to moderate HI antibody titres in some chickens and resulted in no or reduced virus shedding after challenge. Next, to examine the effect of expression vector, three different DNA vectors, pCI, pCI-neo and pVAX1 were used to clone the same HA gene and generate three DNA vaccine constructs. Once again, direct intramuscular injection of the three DNA constructs did not elicit measurable H6-specific HA antibody response in Hy-Line chickens but the 100 µg pCI-HA lipofectin adjuvanted vaccine group showed a significant increase in post-challenge HI titres from the naive control group, indicating that an anamnestic antibody response had been induced by the pCI-HA DNA vaccination. Compared with the controls, the three DNA constructs showed significantly reduced virus shedding in cloacal swabs post virus challenge, suggesting that the three DNA vaccines induced some level of immune response in vaccinated chickens. As with the VR-HA construct, the lower dose groups for each vaccine (50 or 100 g) were more effective at reducing virus shedding from the cloaca than the higher dose group (300 g). To further investigate why the DNA vaccines did not elicit a measurable antibody response, the HA gene incorporating a Kozak enhancer sequence was cloned into an alternative expression vector, pCAGGS, to produce the pCAG-HAk construct. Three-week-old SPF chickens were immunized with this construct either by the intramuscular route (IM) or electroporation (EP). H6 HI antibodies were present in some chickens by 3 weeks after the first IM vaccination and 75% of the chickens vaccinated with 10, 100 or 300 µg pCAG-HAk were antibody positive by 2 weeks after the second IM vaccination. For EP immunization, 87.5% of vaccinated birds seroconverted after the first vaccination and 100% seroconverted after the second vaccination and the H6 HI antibody titres were significantly higher than for chickens vaccinated by IM inoculation. Another group was given a single dose IM vaccination with 100 µg of the pCAG-HAk construct and showed a maximum sero-conversion rate of 53.3% with a peak H6 HI titre of 27 at 5 weeks post-vaccination. This demonstrated that optimization of the expression vector and insertion of a Kozak sequence could synergistically enhance expression of the H6 HA gene and result in a measurable H6 antibody response in SPF chickens. EP was also compared with IM inoculation with the 100 g pCI-HA construct in SPF chickens, resulting in a 50% sero-conversion rate and mean HI titre of 21.3 at 2 weeks after the second vaccination by EP. By comparison, only 25% chickens had trace HI titres by IM inoculation. This indicated that EP was more efficient than IM delivery for both constructs. A codon-optimized complete HA gene from A/coot/WA/2727/79 (H6N2) was then chemically synthesized and cloned into a pCAGGS vector to generate the pCAG-optiHAk construct. SPF chickens immunized twice with either 10 µg or 100 µg of pCAG-optHA showed 37.5% and 87.5% sero-conversion rates respectively, with a mean H6 HI tire of 21.4 and 22.6 at 3 weeks after the second immunization, but the differences were not statistically significant. There were also no significant differences in either the sero-conversion rate or the H6 HI titre between the pCAG-HAk and pCAG-optiHAk groups, suggesting that a codon-optimized HA DNA vaccine did not achieve significantly better immunogenicity than the pCAG-HAk vaccine. In vitro expression of the developed DNA constructs in chicken-, hamster-, monkey- and human-origin cells, as measured by Western blotting and immunofluorescence testing (IFT), showed the strength of H6 HA expression in the following descending order - pCAG-optiHAk/pCAG-HAk, pCI-HAk, VR-HA, pCI-HA, pCIneo-HA and pVAX-HA. The in vivo chicken vaccinations also showed that the pCI-HA construct was more effective than the pCI-neo-HA, and that the pCAG-optiHA or pCAG-HAk constructs were better than pCI-HAk in term of reduction in virus shedding after H6N2 virus challenge. Thus, in vitro HA gene expression directly correlated with the generation of immune responses in vivo, indicating that in vitro studies can be used for pre-selection of expression plasmids prior to development of avian influenza DNA vaccines. Lipofectin as a chemical adjuvant was shown to enhance the DNA-induced immune response but is prohibitively expensive for routine use in poultry vaccines. Thus, an experimental adjuvant for poultry DNA vaccines (Essai) and a new nanoparticle (Phema) adjuvant used for the first time in poultry were compared with conventional aluminum salts (alum) adjuvant in the present study. No HI antibody was detected in any adjuvant-vaccinated Hy-Line chickens following two immunizations. However, in comparison with the naive control group, the alum- and Phema adjuvanted pCAG-HAk groups significantly reduced the frequency of virus shedding in oropharyngeal swabs, but Essai adjuvant was not effective in augmenting the pCAG-HAk vaccine efficacy. This pilot study also emphasised that the traditional aluminum hydroxide adjuvant, either DNA binding or non-binding, may be useful as an adjuvant for enhancing DNA-induced immune responses in chickens owing to its low price and safety record. Overall, DNA immunization with various HA-expressing constructs was shown to be variably effective in inducing immune responses in chickens. The efficacy of DNA vaccines could be synergistically improved by taking appropriate approaches. With continuing research DNA vaccines have the potential to become an important tool for disease prevention and control.

The poultry industry occupies an important sector in Thai agriculture. The "Bird Flu" or "Avian Influenza (AI)" crisis, which first commenced in Thailand in 2004, has caused many problems. It has devastated the Thai chicken industry, the worlds fourth largest, with exports worth $A1.93 billion annually and employing hundreds of thousands of people. The European Union, the number two buyer of Thai chicken, and Japan, Thailands biggest customer, has banned imports of Thai chicken. / Locally, the marketing of chicken meat has posed a major economic problem because of a substantial fall in consumption. Many Thais, who learned about bird flu from the newspapers, have avoided buying and eating poultry as a simple precaution. Other Thais, who have continued to buy and consume fresh chicken meat, are doing so with caution. / This study attempted to examine perception factors and risk reduction strategies influencing consumers decisions to buy fresh chicken meat during a food risk situation in Thailand. In addition, an evaluation is made as to whether there is a difference between consumers perceptions and their purchasing decisions under specified demographic factors. / The current study focused on two key variables; namely, consumer perception factors and risk reduction strategies and their influence on Thai consumers purchasing decisions for fresh chicken meat. The four perception factors were 1) price, 2) product quality, 3) place, and 4) risk, based on studies by Schiffman and Kanuk (1997); Glitsch (2000), and Yeung and Morris (2001a). The risk reduction strategies, employed in this study, taken from previous literature (Glitsch, 2000); and Yeung and Morris, 2001b), include:1) purchasing reputable brands, 2) government control or guarantee labels, 3) purchasing from reliable outlets, 4) traceability, 5) avoiding “cheap prices”, and 6) personal controls. There is a long tradition for using demographic variables to explain the observed differences in consumption and food intake surveys. In this study, the demographic variables examined were age, gender, marital status, education, occupation, family size, and income. / Because the recognition of situational effects is an important guide to understanding and predicting consumer behaviour, the current study evaluated purchasing decisions in three situations: 1) in the current situation, do Thai consumers buy fresh chicken meat for consumption? 2) during the first bird flu crisis when there was a lot of adverse press on the effects of bird flu, did Thai consumers buy chicken meat for consumption? 3) in the future, if there is another bird flu crisis of similar severity, will Thai consumers be likely to buy chicken meat for consumption? / The research design was descriptive with the survey method used to gather data from the target respondents. Data was collected in six of Bangkoks largest markets, each located in a district with a population of approximately one million people. A total of 70 questionnaires were distributed in each of the six markets and 400 valid questionnaires were used to analyse the data. / The results showed that all four of the consumer perception factors, namely: price, product quality, place of purchase, and risk perception, influence purchasing decisions in the three different situations, in different ways. From the four perception factors, product quality had the highest influence on consumers purchasing decision, followed by risk and price perception. Place of purchase did not really influence their purchasing decision in the current situation. / Thesis (DBA(DoctorateofBusinessAdministration))--University of South Australia, 2007.

No description available.

I investigated parasitic infection and immunocompetence in populations of introduced bird species in New Zealand (NZ) that had experienced a range of population bottlenecks (11-808 individuals), and compared these parameters to non-bottlenecked conspecifics in the United Kingdom (UK). My aims were two-fold; firstly to assess if population bottlenecks are linked to increased parasite loads and/or decreased immunocompetence, and secondly, to assess at what severity of bottleneck these effects become evident. I found that ectoparasite load (chewing lice, Order: Phthiraptera, Sub-Orders: Amblycera & Ischnocera) was significantly higher in the more severely bottlenecked species in NZ than in the UK, whilst this difference became non-significant at more moderate bottlenecks. The difference was mainly driven by the Sub-Order Amblycera. The prevalence of avian malaria (Plasmodium spp.) was significantly negatively correlated to bottleneck size within NZ, after controlling for body mass. Total leucocyte and differential lymphocyte counts were elevated in the less bottlenecked species that were infected with malaria, whilst the populations at the more severe end of the bottleneck spectrum did not exhibit such a response. Furthermore, heterophil/lymphocyte (HL) ratio (a parameter used as an indicator of environmental and/or immunological stress), was significantly raised in the more bottlenecked species when compared to their UK counterparts, and this difference was correlated with the size of the bottleneck. Immunocompetence was further assessed by the experimental challenge of six introduced birds species in NZ with the mitogen phytohaemagglutinin (PHA). Immune response to PHA was significantly correlated to bottleneck size, but in the opposite direction to that predicted; immune response was greater in the more bottlenecked species. However, this may be an indication of increased investment in immunity, due to increased parasite and pathogen pressure or differential investment in varying components of the immune system. Finally, the immune response to PHA was compared in nestlings of two species that had experienced very different bottlenecks (70 vs. 653). After controlling for ectoparasitic infestation, I found no difference between the two species; however, this finding may be confounded by interspecific competition. Overall, my findings suggest that more severe population bottlenecks may result in increased susceptibility to pathogens, and impact on the immune system. This has a number of implications for the development of conservation protocols, and future avenues of research are suggested.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 194-237) Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Missouri--Columbia, 1996. / "May 1996." Typescript. Vita. Includes bibliographical references (leaves 131-150). Also available on the Internet.

Title from title page of PDF (University of Missouri--St. Louis, viewed March 22, 2010). Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 194-237) Also available online.