sopB of Salmonella enterica serovar Typhimurium is a potential DNA vaccine candidate in conjugation with live attenuated bacteria

The immune response against Salmonella is multi-faceted involving both the innate and the adaptive immune system. The characterization of specific Salmonella antigens inducing immune response could critically contribute to the development of epitope based vaccines for Salmonella. We have tried to identify a protective T cell epitope(s) of Salmonella, as cell mediated immunity conferred by CD8+ T cells is the most crucial subset conferring protective immunity against Salmonella. It being a proven fact that secreted proteins are better in inducing cell mediated immunity than cell surface and cytosolic antigens, we have analyzed all the genbank annotated Salmonella pathogenicity island 1 and 2 secreted proteins of Salmonella enterica serovar Typhimurium (S. typhimurium) and S. enterica serovar Typhi (S. typhi). They were subjected to BIMAS and SYFPEITHI analysis to map MHC-I and MHC-II binding epitopes. The huge profile of possible T cell epitopes obtained from the two classes of secreted proteins were tabulated and using a scoring system that considers the binding affinity and promiscuity of binding to more than one allele, SopB and SifB were chosen for experimental confirmation in murine immunization model. The entire SopB and SifB genes were cloned into DNA vaccine vectors and were administered along with live attenuated Salmonella and it was found that SopB vaccination reduced the bacterial burden of organs by about 5-fold on day 4 and day 8 after challenge with virulent Salmonella and proved to be a more efficient vaccination strategy than live attenuated bacteria alone.

Vaccination with an Insulin-like Growth Factor Binding Protein-1 (IGFBP-1)-bBased Vaccine Improves Growth in Feed-Restricted Brahman Steers

Dry-season weight loss in grazing cattle in northern Australia has been attenuated using a number of strategies (Hunter and Vercoe, 1987, Sillence et al. 1993, Gazzola and Hunter, 1999). Furthermore, the potential to improve efficiency of feed utilisation (and thus, dry-season performance) in ruminants through conventional modulation of the insulin-like growth factor (IGF) axis (Oddy and Owens, 1997, Hill et al., 1999) and through immunomodulation of the IGF axis (Hill et al., 1998a,b) has been demonstrated. The present study investigated the use of a vaccine directed against IGFBP-1 in Brahman steers which underwent a period of nutritional restriction followed by a return to wet-season grazing.

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.

Evaluation of the immunogenicity of the P97R1 adhesin of Mycoplasma hyopneumoniae as a mucosal vaccine in mice.

The immunogenicity of P97 adhesin repeat region R1 (P97R1) of Mycoplasma hyopneumoniae, an important pathogenesis-associated region of P97, was evaluated in mice as a mucosal vaccine. Mice were immunized orally with attenuated Salmonella typhimurium aroA strain CS332 harbouring a eukaryotic or prokaryotic expression vector encoding IP97R1. Local and systemic immune responses were analysed by ELISA on mouse sera, lung washes and splenocyte supernatants following splenocyte stimulation with specific antigens in vitro. Although no P97R1-specific antibody responses were detected in serum and lung washes, significant gamma interferon was produced by P97R1-stimulated splenocytes from mice immunized orally with S. typhimurium aroA harbouring either expression system, indicating induction of a cell-mediated immune response. These results suggested that live bacterial vectors carrying DNA vaccines or expressing heterologous antigens preferentially induce a Th1 response. Surprisingly, however, mice immunized with the vaccine carrier S. typhimurium aroA CS332 induced serum IgG, but not mucosal IgA, against P97R1 or S. typhimurium aroA CS332 whole-cell lysate, emphasizing the importance of assessing the suitability of attenuated S. typhimurium antigen-carrier delivery vectors in the mouse model prior to their evaluation as potential vaccines in the target species, which in this instance was pigs.

A blowfly strike vaccine requires an understanding of host-pathogen interactions

The phase-out of Mulesing by 2010 means the Australian wool industry requires immediate and viable alternatives for the control and prevention of blowfly strike, an economically important parasitic disease of sheep. In this review we have analysed previous research aimed toward the development of a vaccine against blowfly strike and the reasons why the approaches taken were unsuccessful at the time. Close scrutiny has provided new insight into this host-parasite interaction and identified new opportunities for the development of a vaccine. Here we propose that addressing immunosuppression together with the induction of cellular immunity is likely to result in an anti-blowfly strike vaccine, as opposed to the use of "standard" approaches aimed at inducing humoral immunity.

Development of a vaccine for Chlamydia trachomatis: Challenges and current progress

Chlamydia trachomatis remains an enigmatic bacterial pathogen with no vaccine yet available to treat human ocular and genital tract infections caused by tissue-tropic serovars of the organism. Globally, it is the leading cause of preventable blindness as well as the leading cause of bacterial sexually transmitted infections. The pathogen has a range of virulence factors that enable it to successfully evade both the innate and adaptive immune system of the host. The host immune system, although protective, paradoxically is also associated closely with the pathologies of trachoma and pelvic inflammatory disease – disease sequelae of some chlamydial infections and reinfections in some genetically susceptible hosts. In this review, we focus on what is known currently about the pathogenesis of ocular and genital infections caused by this mucosal pathogen. We also discuss novel insights into the pathogenesis of infections caused by the genital and ocular serovars of C. trachomatis, including a discussion of both pathogen and host factors, such as the human microbiota at these mucosal sites as well as the current immunological challenges facing vaccine development. Finally, we discuss the current progress toward development of a vaccine against C. trachomatis. A wide range of recombinant protein antigens are being identified and, hence, are available for vaccine trials. A plasmid-free live strain has recently been produced and evaluated in the mouse (Chlamydia muridarum) and monkey (C. trachomatis) models. The data for ocular infections in the monkey model was particularly encouraging, although the path to regulatory approval of a live vaccine is still uncertain. While still a major challenge, vaccines for ocular and genital C. trachomatis infections are looking more promising.

CFD Analysis of conjugate natural convection in a vertical annulus

Conjugate natural convection in a vertical annulus with a centrally located vertical heat generating rod is studied numerically. The governing equations are discretized on a staggered mesh and are solved using a pressure-correction algorithm. A parametric study is performed by varying the Grashof number, aspect ratio, and the solid-to-fluid thermal conductivity ratio over wide ranges with the Prandtl number fixed at 0.7. Results are presented for the variation of several quantities of interest such as the local Nusselt numbers on the inner and outer boundaries, the axial variation of the centerline and interface temperatures, maximum solid, average solid and average interface temperature variations with Grashof number, and the average Nusselt number variation for the inner and outer boundaries with Grashof number. The average Nusselt number from the conjugate analysis is found to be between the Nusselt numbers of the isothermal and the isoflux cases. The average Nusselt numbers on the inner and outer boundaries show an increasing trend with the Grashof number. Correlations are presented for the Nusselt number and the dimensionless temperatures of interest in terms of the parameters of the problem.

Positive results in a real-time PCR for type A influenza associated with the use of an inactivated vaccine.

A real-time reverse transcription polymerase chain reaction (qRT-PCR) test for the matrix gene of type A influenza viruses was used during the 2007 Australian equine influenza (EI) outbreak in order to confirm diagnosis and, later, eradication of the virus. During the EI outbreak, horses being exported required vaccination and individual proof of freedom from EI. At the end of the outbreak, positive results were obtained from four horses destined for export, because of contamination of the samples with the vaccine. This report highlights the need for EI testing and vaccination to occur on separate days and with the collection of swabs for testing to precede vaccination.

Human papillomavirus infection and vaccination: Awareness and knowledge of HPV and acceptability of HPV vaccine among mothers of teenage daughters in Weihai, Shandong, China

In preparation for the introduction of human papillomavirus (HPV) vaccine, we investigated awareness and knowledge of HPV/HPV vaccine and potential acceptability to HPV vaccine among mothers with a teenage daughter in Weihai, Shandong, China. A cross-sectional survey was conducted in 2013 with a sample of 1850 mothers who had a daughter (aged 9–17 years) attending primary, junior and senior high schools. In the final sample (N = 1578, response rate 85.30%), awareness of HPV was reported by 305 (19.32%) mothers. Awareness varied significantly by daughter’s age (P<0.01), mother’s education level (P<0.01), mother’s occupation (P<0.01), household income (P<0.01) and residence type (P<0.01). Knowledge about HPV/HPV vaccine was poor with a mean total score of 3.56 (SD = 2.40) out of a possible score of 13. Mothers with a higher education level reported higher levels of knowledge (P = 0.02). Slightly more than one-fourth (26.49%) of mothers expressed their potential acceptability of HPV vaccine for their daughters. Acceptability increased along with increased daughters’ age (P<0.01), household income (P<0.01) and knowledge level (P<0.01). House wives and unemployed mothers had the highest acceptability (P<0.01). The most common reasons for not accepting HPV vaccination were “My daughter is too young to have risk of cervical cancer (30.95%)”, “The vaccine has not been widely used, and the decision will be made after it is widely used (24.91%)”, “Worry about the safety of the vaccine (22.85%)”. Awareness and knowledge of HPV/HPV vaccines are poor and HPV vaccine acceptability is low among these Chinese mothers. These results may help inform appropriate health education programs in this population.

Rhipicephalus (Boophilus) microplus tick in vitro feeding methods for functional (dsRNA) and vaccine candidate (antibody) screening

Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) ticks cause economic losses for cattle industries throughout tropical and subtropical regions of the world estimated at $US2.5 billion annually. Lack of access to efficacious long-lasting vaccination regimes and increases in tick acaricide resistance have led to the investigation of targets for the development of novel tick vaccines and treatments. In vitro tick feeding has been used for many tick species to study the effect of new acaricides on the transmission of tick-borne pathogens. Few studies have reported the use of in vitro feeding for functional genomic studies using RNA interference and/or the effect of specific anti-tick antibodies. In particular, in vitro feeding reports for the cattle tick are limited due to its relatively short hypostome. Previously published methods were further modified to broaden optimal tick sizes/weights, feeding sources including bovine and ovine serum, optimisation of commercially available blood anti-coagulant tubes, and IgG concentrations for effective antibody delivery. Ticks are fed overnight and monitored for ∼5–6 weeks to determine egg output and success of larval emergence using a humidified incubator. Lithium-heparin blood tubes provided the most reliable anti-coagulant for bovine blood feeding compared with commercial citrated (CPDA) and EDTA tubes. Although >30 mg semi-engorged ticks fed more reliably, ticks as small as 15 mg also fed to repletion to lay viable eggs. Ticks which gained less than ∼10 mg during in vitro feeding typically did not lay eggs. One mg/ml IgG from Bm86-vaccinated cattle produced a potent anti-tick effect in vitro (83% efficacy) similar to that observed in vivo. Alternatively, feeding of dsRNA targeting Bm86 did not demonstrate anti-tick effects (11% efficacy) compared with the potent effects of ubiquitin dsRNA. This study optimises R. microplus tick in vitro feeding methods which support the development of cattle tick vaccines and treatments.

Freeze-drying of ovalbumin loaded mesoporous silica nanoparticle vaccine formulation increases antigen stability under ambient conditions

Amino functionalised mesoporous silica nanoparticles (AM-41) have been identified as a promising vaccine delivery material. The capacity of AM-41 to stabilise vaccine components at ambient temperature (23–27 °C) was determined by adsorbing the model antigen ovalbumin (OVA) to AM-41 particles (OVA-41). The OVA-41 was successfully freeze-dried using the excipients 5% trehalose and 1% PEG8000. Both the immunological activity of OVA and the nanoparticle structure were maintained following two months storage at ambient temperature. The results of immunisation studies in mice with reconstituted OVA-41 demonstrated the induction of humoral and cell-meditated immune responses. The capacity of AM-41 particles to facilitate ambient storage of vaccine components without loss of immunological potency will underpin the further development of this promising vaccine delivery platform.

Novel vaccine acceptance in emerging infectious diseases: a case study of Hendra virus vaccine uptake in Australia

Background: The development of a horse vaccine against Hendra virus has been hailed as a good example of a One Health approach to the control of human disease. Although there is little doubt that this is true, it is clear from the underwhelming uptake of the vaccine by horse owners to date (approximately 10%) that realisation of a One Health approach requires more than just a scientific solution. As emerging infectious diseases may often be linked to the development and implementation of novel vaccines this presentation will discuss factors influencing their uptake; using Hendra virus in Australia as a case study. Methods: This presentation will draw on data collected from the Horse owners and Hendra virus: A Longitudinal cohort study To Evaluate Risk (HHALTER) study. The HHALTER study is a mixed methods research study comprising a two-year survey-based longitudinal cohort study and qualitative interview study with horse owners in Australia. The HHALTER study has investigated and tracked changes in a broad range of issues around early uptake of vaccination, horse owner uptake of other recommended disease risk mitigation strategies, and attitudes to government policy and disease response. Interviews provide further insights into attitudes towards risk and decision-making in relation to vaccine uptake. A combination of quantitative and qualitative data analysis will be reported. Results: Data collected from more than 1100 horse owners shortly after vaccine introduction indicated that vaccine uptake and intention to vaccinate was associated with a number of risk perception factors and financial cost factors. In addition, concerns about side effects and veterinarians refusing to treat unvaccinated horses were linked to uptake. Across the study period vaccine uptake in the study cohort increased to more than 50%, however, concerns around side effects, equine performance and breeding impacts, delays to full vaccine approvals, and attempts to mandate vaccination by horse associations and event organisers have all impacted acceptance. Conclusion: Despite being provided with a safe and effective vaccine for Hendra virus that can protect horses and break the transmission cycle of the virus to humans, Australian horse owners have been reluctant to commit to it. General issues pertinent to novel vaccines, combined with challenges in the implementation of the vaccine have led to issues of mistrust and misconception with some horse owners. Moreover, factors such as cost, booster dose schedules, complexities around perceived risk, and ulterior motives attributed to veterinarians have only served to polarise attitudes to vaccine acceptance.

Application of the Conjugate Gradient Method to a Problem on Minimum Time Orbit Transfer

This correspondence considers the problem of optimally controlling the thrust steering angle of an ion-propelled spaceship so as to effect a minimum time coplanar orbit transfer from the mean orbital distance of Earth to mean Martian and Venusian orbital distances. This problem has been modelled as a free terminal time-optimal control problem with unbounded control variable and with state variable equality constraints at the final time. The problem has been solved by the penalty function approach, using the conjugate gradient algorithm. In general, the optimal solution shows a significant departure from earlier work. In particular, the optimal control in the case of Earth-Mars orbit transfer, during the initial phase of the spaceship's flight, is found to be negative, resulting in the motion of the spaceship within the Earth's orbit for a significant fraction of the total optimized orbit transfer time. Such a feature exhibited by the optimal solution has not been reported at all by earlier investigators of this problem.