Construction and immunogenicity of recombinant adenovirus expressing the major outer membrane protein (MOMP) of Chlamydophila psittaci in chicks

Cellular Basis for the Enhanced Efficacy of the Fms-Like Tyrosine Kinase 3 Ligand (FL) Adjuvanted VCG-Based Chlamydia abortus Vaccine

Efficacious vaccines are needed to control genital chlamydial diseases in humans and the veterinary industry. We previously reported a C. abortus (Cab) vaccine comprising recombinant Vibrio cholerae ghosts (rVCG) expressing the conserved and immunogenic N-terminal region of the Cab polymorphic membrane protein D (rVCG-Pmp18.1) protein that protected mice against intravaginal challenge. In this study, we investigated the immunomodulatory effect of the hematopoietic progenitor activator cytokine, Fms-like tyrosine kinase 3-ligand (FL) when co-administered with the rVCG-Pmp18.1 vaccine as a strategy to enhance the protective efficacy and the potential mechanism of immunomodulation. Groups of female C57BL/6J mice were immunized and boosted twice intranasally (IN) with rVCG-PmpD18.1 with and without FL or purified rPmp18.1 or rVCG-gD2 (antigen control) or PBS (medium) per mouse. The results revealed that co-administration of the vaccine with FL enhanced antigen-specific cellular and humoral immune responses and protected against live Cab genital infection. Comparative analysis of immune cell phenotypes infiltrating mucosal and systemic immune inductive tissue sites following immunization revealed that co-administration of rVCG-Pmp18.1 with FL significantly enhanced the number of macrophages, dendritic and NK cells, γδ and NK T cells in the spleen (systemic) and iliac lymph nodes (ILN) draining the genital tract (mucosal) tissues compared to rVCG-Pmp18.1 alone. Furthermore, FL enhanced monocyte infiltration in the ILN, while CD19+ B cells and CD4+ T cells were enhanced in the spleen. These results indicate that the immunomodulatory effect of FL is associated with its ability to mobilize innate immune cells and subsequent activation of robust antigen-specific immune effectors in mucosal and systemic lymphoid tissues.

Intranasal immunization with inactivated chlamydial elementary bodies formulated in VCG-chitosan nanoparticles induces robust immunity against intranasal Chlamydia psittaci challenge

Vaccines based on live attenuated Chlamydia elementary bodies (EBs) can cause disease in vaccinated animals and the comparably safer inactivated whole EBs are only marginally protective. Recent studies show that a vaccine formulation comprising UV-inactivated EBs (EB) and appropriate mucosal delivery systems and/or adjuvants induced significant protective immunity. We tested the hypothesis that intranasal delivery of UV-inactivated C. psittaci EB formulated in Vibrio cholerae ghosts (VCG)-chitosan nanoparticles will induce protective immunity against intranasal challenge in SPF chickens. We first compared the impact of VCG and CpG adjuvants on protective immunity following IN mucosal and IM systemic delivery of EB formulated in chitosan hydrogel/microspheres. Immunologic analysis revealed that IN immunization in the presence of VCG induced higher levels of IFN-γ response than IM delivery or the CpG adjuvanted groups. Also, vaccine efficacy evaluation showed enhanced pharyngeal bacterial clearance and protection against lung lesions with the VCG adjuvanted vaccine formulation, thereby establishing the superior adjuvanticity of VCG over CpG. We next evaluated the impact of different concentrations of VCG on protective immunity following IN mucosal immunization. Interestingly, the adjuvanticity of VCG was concentration-dependent, since protective immunity induced following IN mucosal immunization showed dose-dependent immune responses and protection. These studies reveal that formulation of inactivated chlamydial antigens with adjuvants, such as VCG and chitosan increases their ability to induce protective immune responses against challenge.

Common bacterial, viral, and parasitic diseases in pigeons (Columba livia): A review of diagnostic and treatment strategies

Pigeons (Columba livia) have been associated with humans for a long time now. They are raised for sport (pigeon race), exhibition (display of fancy breeds), food, and research. Most of the pigeons kept are Racing Homers, trained to compete in the pigeon race. Other breeds, such as Rollers, Nose Divers, Doneks are bred for their aerial abilities. Incorporation of a good preventive medicine program is one of the most critical factors in averting infectious diseases in pigeon flocks. This review summarizes the common bacterial, viral, and parasitic infections in pigeons. The different clinical signs, symptoms, diagnostic strategies, prevention, and treatments were described in this review. Current researches, molecular diagnostic assays, and treatment strategies such as vaccines and drug candidates were included. The information found in this review can provide insights for veterinarians and researchers studying pigeons to develop effective and efficient immunoprophylactic and diagnostic tools for pigeon diagnosis and therapeutics.

Simultaneous Intramuscular And Intranasal Administration Of Chitosan Nanoparticles-Adjuvanted Chlamydia Vaccine Elicits Elevated Protective Responses In The Lung

Background

Chlamydia psittaci is a zoonotic bacteria closely associated with psittacosis/ornithosis. Vaccination has been recognized as the best way to inhibit the spread of C. psittaci due to the majority ignored of infections. The optimal Chlamydia vaccine was obstructed by the defect of single immunization route and the lack of availability of nontoxic and valid adjuvants.

Methods

In this study, we developed a novel immunization strategy, simultaneous (SIM) intramuscular (IM) and intranasal (IN) administration of a C. psittaci antigens (Ags) adjuvanted with chitosan nanoparticles (CNPs). And SIM-CNPs-Ags were used to determine the different types of immune response and the protective role in vivo.

Results

CNPs-Ags with zeta-potential values of 13.12 mV and of 276.1 nm showed excellent stability and optimal size for crossing the mucosal barrier with high 71.7% encapsulation efficiency. SIM-CPN-Ags mediated stronger humoral and mucosal responses by producing meaningfully high levels of IgG and secretory IgA (sIgA) antibodies. The SIM route also led to Ags-specific T-cell responses and increased IFN-γ, IL-2, TNF-α and IL-17A in the splenocyte supernatants. Following respiratory infection with C. psittaci, we found that SIM immunization remarkably reduced bacterial load and the degree of inflammation in the infected lungs and made for a lower level of IFN-γ, TNF-α and IL-6. Furthermore, SIM vaccination with CNPs-Ags had obviously inhibited C. psittaci disseminating to various organs in vivo.

Conclusion

SIM immunization with CNPs-adjuvanted C. psittaci Ags may present a novel strategy for the development of a vaccine against the C. psittaci infection.

Prevalence, Diagnosis, and Vaccination Situation of Animal Chlamydiosis in China

Since the first case of Chlamydia infection in duck had been reported in 1956 and the first case from domestic animal had been reported in 1979 in China, the chlamydia prevalence in China was heavily according to the published data. The Chlamydia in avian prevalence has been reported at least 11 provinces, Chlamydia in sheep and goats at least 11 provinces, in swine at least 15 provinces, in cows at least 13 provinces and in yaks at least 5 provinces with result of IHA detection. Different diagnostic method such as CFT, ELISA and ABC-ELISA (avidin-biotin-complex ELISA) had been established besides IHA. The inactivated vaccines have been developed with isolated strains from sheep, goats, swine and cows. These inactivated vaccines have been used since 1980s and Chlamydia prevalence in China has been successfully controlled in domestic animal. However, the inactivated vaccines of Chlamydia isolated from avian species have not been successful, although a series of experimental vaccine have been done. Due to the unsustainable eradication plan of Chlamydia in China, sporadic outbreak in animal would happen if the vaccinations were suspended and economy lose in some farmers. Although Chlamydia prevalence in China has a long history, however, almost all published studies are in Chinese, which, in some degree, blocked scientists in other countries to understand the prevalence situation and control measures of Chlamydia in China.

A Promising Recombinant Herpesvirus of Turkeys Vaccine Expressing PmpD-N of Chlamydia psittaci Based on Elongation Factor-1 Alpha Promoter

The obligate intracellular Gram-negative bacterium Chlamydia psittaci often causes avian chlamydiosis and influenza-like symptoms in humans. However, the commercial subunit C. psittaci vaccine could only provide a partial protection against avian chlamydiosis due to poor cellular immune response. In our previous study, a recombinant herpesvirus of turkeys (HVT)-delivered vaccine against C. psittaci and Marek’s disease based on human cytomegalovirus (CMV) promoter (rHVT-CMV-pmpD) was developed and provided an effective protection against C. psittaci disease with less lesions and reduced chlamydial loads. In this study, we developed another recombinant HVT vaccine expressing the N-terminal fragment of PmpD (PmpD-N) based on human elongation factor-1 alpha (EF-1α) promoter (rHVT-EF-pmpD) by modifying the HVT genome within a bacterial artificial chromosome. The related characterization of rHVT-EF-pmpD was evaluated in vitro in comparison with that of rHVT-CMV-pmpD. The expression of PmpD-N was determined by western blot. Under immunofluorescence microscopy, PmpD-N protein of both two recombinant viruses was located in the cytoplasm and on the cell surface. Growth kinetics of rHVT-EF-pmpD was comparable to that of rHVT-CMV-pmpD, and the growth rate of rHVT-EF-pmpD was apparently higher than that of rHVT-CMV-pmpD on 48, 72, and 120 h postinfection. Macrophages activated by rHVT-EF-pmpD could produce more nitric oxide and IL-6 than that activated by rHVT-CMV-pmpD. In this study, a recombinant HVT vaccine expressing PmpD-N based on EF-1α promoter was constructed successfully, and a further research in vivo was needed to analyze the vaccine efficacy.

Chlamydial polymorphic membrane proteins: regulation, function and potential vaccine candidates

Pmps (Polymorphic Membrane Proteins) are a group of membrane bound surface exposed chlamydial proteins that have been characterized as autotransporter adhesins and are important in the initial phase of chlamydial infection. These proteins all contain conserved GGA (I, L, V) and FxxN tetrapeptide motifs in the N-terminal portion of each protein. All chlamydial species express Pmps. Even in the chlamydia-related bacteria Waddlia chondrophila, a Pmp-like adhesin has been identified, demonstrating the importance of Pmps in Chlamydiales biology. Chlamydial species vary in the number of pmp genes and their differentially regulated expression during the infectious cycle or in response to stress. Studies have also demonstrated that Pmps are able to induce innate immune functional responses in infected cells, including production of IL-8, IL-6 and MCP-1, by activating the transcription factor NF-κB. Human serum studies have indicated that although anti-Pmp specific antibodies are produced in response to a chlamydial infection, the response is variable depending on the Pmp protein. In C. trachomatis, PmpB, PmpC, PmpD and PmpI were the proteins eliciting the strongest immune response among adolescents with and without pelvic inflammatory disease (PID). In contrast, PmpA and PmpE elicited the weakest antibody response. Interestingly, there seems to be a gender bias for Pmp recognition with a stronger anti-Pmp reactivity in male patients. Furthermore, anti-PmpA antibodies might contribute to adverse pregnancy outcomes, at least among women with PID. In vitro studies indicated that dendritic cells infected with C. muridarum were able to present PmpG and PmpF on their MHC class II receptors and T cells were able to recognize the MHC class-II bound peptides. In addition, vaccination with PmpEFGH and Major Outer Membrane Protein (MOMP) significantly protected mice against a genital tract C. muridarum infection, suggesting that Pmps may be an important component of a multi-subunit chlamydial vaccine. Thus, Pmps might be important not only for the pathogenesis of chlamydial infection, but also as potential candidate vaccine proteins.

Potential Impact of Food Safety Vaccines on Health Care Costs

Foodborne pathogens continue to cause several outbreaks every year in many parts of the world. Among the bacterial pathogens involved, Shiga toxin-producing Escherichia coli, Campylobacter jejuni, and nontyphoidal Salmonella species cause a significant number of human infections worldwide, resulting in a huge annual economic burden that amounts to millions of dollars in health care costs. Human infections are primarily caused by the consumption of contaminated food. Vaccination of food-producing animals is an attractive, cost-effective strategy to lower the levels of these pathogens that will ultimately result in a safer food supply and fewer human infections. However, producers are often reluctant to routinely vaccinate animals against these pathogens since they do not cause any detectable clinical symptoms. This review highlights recent approaches used to develop effective food safety vaccines and the potential impact these vaccines might have on health care costs.

Construction of Recombinant HVT Expressing PmpD, and Immunological Evaluation against Chlamydia psittaci and Marek's Disease Virus

Chlamydia psittaci (C. psittaci) is an obligate intracellular zoonotic pathogen that can be transmitted to humans from birds. No efficacious commercial vaccine is available for clearing chlamydial infection due to lack of potential vaccine candidates and effective delivery vehicles. Herpesvirus of turkeys (HVT) is an efficacious commercially available vaccine against Marek’s Disease virus (MDV). In this study, a recombinant HVT-delivered vaccine against C. psittaci and Marek’s disease was developed and examined. The 5'-terminus of pmpD gene (pmpD-N) encoding the N-terminal fragment of polymorphic membrane protein D of C. psittaci was inserted into a nonessential region of HVT genome using reverse genetics based on an infectious bacterial artificial chromosome (BAC) clone of HVT. The recombinant virus (rHVT-pmpD-N) was recovered from primary chicken embryo fibroblast (CEF) cells by transfection of modified HVT BAC DNA containing the pmpD-N gene. The rHVT-pmpD-N construct was confirmed to express PmpD-N by immunoblot and immunofluorescence. The rHVT-pmpD-N was stable during 20 passages in vitro. The growth kinetics of rHVT-pmpD-N was comparable to that of parental HVT in vitro and in vivo. One-day-old SPF chickens inoculated subcutaneously with rHVT-pmpD-N displayed increased PmpD-specific antibody levels and a vigorous PmpD-specific lymphocyte proliferation response using HVT vector or CEF cells as control. Furthermore, the percentage of CD4+ cells was significantly elevated in rHVT-pmpD-N-immunized birds as compared to the parental HVT. All chickens vaccinated with rHVT-pmpD-N or parental HVT were protected completely against challenge with a very virulent strain of Marek’s Disease virus (MDV) RB-1B. Post challenge with C. psittaci CB7 strain, a significant decrease in respiratory distress, lesions and Chlamydia load was found in the rHVT-pmpD-N-vaccinated group compared to the parental HVT. In conclusion, our study suggests that the rHVT-pmpD-N live vaccine may be viable as a candidate dual vaccine that provides protection against both very virulent MDV and C. psittaci.

Salmonella vaccines in poultry: past, present and future

Salmonella species are important zoonotic pathogens that cause gastrointestinal disease in humans and animals. Poultry products contaminated with these pathogens are one of the major sources of human Salmonella infections. Vaccination of chickens, along with other intervention measures, is an important strategy that is currently being used to reduce the levels of Salmonella in poultry flocks, which will ultimately lead to lower rates of human Salmonella infections. However, despite numerous studies that have been performed, there is still a need for safer, well-defined Salmonella vaccines. This review examines the different classes of Salmonella vaccines that have been tested, highlighting the merits and problems of each, and provides an insight into the future of Salmonella vaccines and the platforms that can be used for delivery.

Protective efficacy against Chlamydophila psittaci by oral immunization based on transgenic rice expressing MOMP in mice

Avian chlamydiosis is caused by Chlamydophila psittaci (Cp. psittaci) and major outer membrane protein (MOMP) of Cp. psittaci is an excellent vaccine candidate. In this study, the MOMP gene was expressed in rice callus by the Agrobacterium tumefaciens vector. The production of protein in transgenic rice seeds was confirmed and quantified by Western-blot and ELISA, the results demonstrating that the antigen was expressed stably. The transgenic rice seeds expressing the MOMP protein were administered by the oral route to BALB/c mice, which developed MOMP-specific serum IgG and fecal IgA antibodies and a splenocyte MOMP-specific proliferative response and significant levels of IFN-γ, IL-2, IL-4, IL-5 and TGF-β production. Immunization with MOMP transgenic seeds induced partial protection (50%) against a lethal challenge with the highly virulent Cp. psittaci 6BC strain. Lung function after challenge was less affected compared non-MOMP immunized animals. The results demonstrate the feasibility of using transgenic rice seeds as an oral vaccine to generate protective immunity and reduce the lung lesions in mice against virulent Cp. psittaci 6BC strain. This finding has implications for further development of an oral vaccine against avian chlamydiosis.

Advances in avian immunology--prospects for disease control: a review

In order to develop novel solutions to avian disease problems, including novel vaccines and/or vaccine adjuvants, and the identification of disease resistance genes which can feed into conventional breeding programmes, it is necessary to gain a more thorough understanding of the avian immune response and how pathogens can subvert that response. Birds occupy the same habitats as mammals, have similar ranges of longevity and body mass, and face similar pathogen challenges, yet birds have a different repertoire of organs, cells, molecules and genes of the immune system compared to mammals. This review summarises the current state of knowledge of the chicken's immune response, highlighting differences in the bird compared to mammals, and discusses how the availability of the chicken genome sequence and the associated postgenomics technologies are contributing to theses studies and also to the development of novel intervention strategies againts avian and zoonotic disease.

Immunization trials with an avian chlamydial MOMP gene recombinant adenovirus

Chicks were inoculated with a live vector vaccine of avian chlamydial MOMP gene recombinant adenovirus to evaluate efficacy, safety and viability of the vaccine. Five batches of the recombinant adenovirus vaccines, which were prepared using the 22nd generation avian chlamydial MOMP gene recombinant adenovirus cultured in HEK293 cells, were used to vaccinate 7 days-old chicks negative for chlamydial antibody. The recombinant adenovirus vaccine was shown to be both safe and effective in inducing specific immunity in vaccinated chicks.

Protection of budgerigars (Melopsittacus undulatus) against Chlamydophila psittaci challenge by DNA vaccination

Plasmid DNA (pcDNA1::MOMP A) expressing the major outer membrane protein (MOMP) of Chlamydophila psittaci genotype A strain 89/1051 has been tested for its ability to induce protective immunity against Cp. psittaci challenge in budgerigars. Eight pairs of male and female budgerigars were housed in eight separate bird cages placed in two negative pressure isolators, four cages per group. All budgerigars were immunised twice intramuscularly with 100 microasmid DNA. Both groups received a primary DNA inoculation at day 0 followed by a booster inoculation 3 weeks later. Group 1 received pcDNA1::MOMP A, while group 2 received the placebo vaccine pcDNA1. Budgerigars were challenged by aerosol 2 weeks following the booster vaccination. The challenge consisted of 10(8) TCID(50) of the homologous Cp. psittaci genotype A strain. Cloacal and pharyngeal swabs of all budgerigars, taken prior to the experimental infection were negative in both PCR and culture. However, all budgerigars showed low pre-existing serum antibody titres. This indicates that animals were previously infected. Nevertheless, DNA immunisation could significantly reduce clinical signs, macroscopic lesions, pharyngeal and cloacal excretion as well as chlamydial replication, even in the presence of pre-existing serum antibodies, as compared to the placebo-vaccinated controls.