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Purification is an important step in the production of viral vaccines that strongly affects product recovery and subsequent immune responses. The present study was carried out with the aim of improving the purification of infectious bursal disease virus (IBDV) by the tangential flow filtration (TFF) method. Then, the effect of the purified virus on the induction of immune responses against IBDV in specific pathogen free (SPF) chickens was investigated. The IBD07IR strain was propagated in embryonated SPF eggs. The virus was purified using a 100 kDa cassette. The quality of the recovered viruses was evaluated by titration. A total number of 60 SPF chickens were randomly divided into three groups (n = 20) and received the concentrated viral antigen, commercial live IBDV vaccine and phosphate-buffered saline at the age of 3 weeks by eye drop method. The bursa of Fabricius was examined histopathologically for possible changes. Sera were collected at 1-week intervals from day 0 until the end of 6 weeks after vaccination. The IBDV-specific antibody levels, induction of cell-mediated immunity and mRNA expression levels of cytokines were evaluated. The results showed that despite a relative raise in virus titer from 7.66 to 8.17 embryo infectious dose (EID)50 mL-1 following purification, both the purified IBDV and commercial vaccine are able to induce strong immune responses against the virus. Within a context of egg-based IBDV vaccine production, a single-step TFF can be applied for the relatively purification. This platform requires a further study in the selection of multiple membranes to optimize the operating conditions and final product. [ABSTRACT FROM AUTHOR]

The effectiveness of inactivated H9N2 influenza vaccines is doubtful due to changes in antigenic regions of the virus hemagglutinin (HA) protein. One strategy for the development of the efficacious vaccine is the use of nanoparticles that display more immunogenic regions of the influenza virus. In this study, chitosan (CS)-based nanoparticles were developed as a delivery system for intranasal immunization using recombinant H9N2 virus HA1 and nucleoprotein (NP), for the induction of humoral and cellular responses. CS-HA1 and CS-NP nanoparticles were prepared by the ionic gelation method and characterized for their physicochemical properties and shape. The immunogenicity and the protective efficacy were evaluated by measuring antibody titers, T cell proliferation response, CD4+/CD8+ ratio, and quantitative real-time RT-PCR following intranasal administration of the prepared nanoparticles alone or in combination in chickens compared to an inactivated H9N2 vaccine. The average size, surface charge, and spherical structure of the synthesized nanoparticles showed high quality. Serologic analysis revealed that the immunization of inactivated vaccine groups resulted in strong influenza antibodies, which were significantly (p < 0.05) higher compared to the other groups. The vaccinated chickens with CS-HA1+CS-NP developed higher specific anti-influenza antibodies than in those vaccinated with each of rHA1 and rNP. Administration of a combination of the protein-based nanoparticles has stimulated the activation of both CD4+ and CD8+T cells and induced a significantly higher T cell proliferation. The viral shedding was significantly lower in CS-HA1+CS-NP and inactivated vaccine groups compared with other challenged groups. The data demonstrate the potential of CS-HA1+CS-NP nanoparticles for eliciting specific influenza antibodies and conferring protection in chickens. [ABSTRACT FROM AUTHOR]

Utilizing subunit vaccines is one of the strategies to address influenza infection. Recent innovations have focused on high doses of vaccine antigens and immune enhancers or adjuvant to induce more robust and long-lasting immune responses. Here, an effect of the B cell-activating factor receptor (BAFF-R) to increase the magnitude and durability of immune responses of the recombinant HA1 (rHA1) protein against the H1N1 influenza virus was studied. The HA1 protein and the effector domain of BAFF-R were expressed in the pET-28a (+) vector. Eight-week-old BALB/c mice were equally grouped into five groups (n=20). The 15 and 25 μg/μL of rHA1 were mixed with 2 μg/μL of rBAFF-R and injected three times for vaccinated groups. Three control groups were received normal saline and two concentrations of rHA1. The ability of rBAFF-R in eliciting HA-specific antibody response and stimulating T lymphocyte proliferation to induce the cell-mediated immunity was assayed. Induction of protection was evaluated following the challenge with PR8 strain. Analysis of immune responses showed that the co-administration of rBAFF-R with rHA1 boosted HI responses to the antigen in mice, whilst it was not able to promote the T cell proliferation responses against influenza. Compared to rHA1alone, the rBAFF-R/rHA1 generated efficient protection for the animals. There were no significant differences in eliciting the immune responses in mice immunized with the lower dose of rHA1 than that with the higher dose. The data indicate the rBAFF-R can enhance the primary and memory immune responses to protect against influenza infection. [ABSTRACT FROM AUTHOR]

Introduction: The virulent Newcastle disease virus (NDV) strains cause an economically important infectious disease in poultry. The common vaccination program with genotype II NDV strains is routinely practiced to provide a better protection level against Newcastle disease (ND). Nevertheless, the emergence of new antigenic and genetic variants within the circulating NDVs raises the importance of improved control strategies. The genotype VII NDV is associated with many of the most recent outbreaks of the disease worldwide. Methods: We evaluated the impacts of genetic divergence between the genotypes II and VII on the immunity against NDV to choose a suitable vaccine virus candidate by focusing on the F and HN proteins. Comparative bioinformatics analyses based on B- and T-cell epitopes binding affinity, protein secondary structure and physicochemical properties predictions were applied for genotypes II and VII. Results: Although the results showed more differences in HN protein than F protein, there was no major difference between the predicted antigenicity values, epitope regions, affinity binding to MHC-I and MHC-II, secondary structures, surface accessibility, and stability of these immunogens between genotypes II and VII. Conclusion: The results suggest that genotype II-based live vaccines can induce immune responses against NDV; however, an inactivated vaccine formulated by genotype VII should be considered in combination with the traditional live vaccine to provide better protection in controlling programs against ND. [ABSTRACT FROM AUTHOR]

Infectious laryngotracheitis (ILT) is a poultry respiratory disease associated with considerable mortality in chicken and decreasing egg production. Vaccination along with biosecurity measures are considered as the main strategy for ILT control. This study was aimed to evaluate the potency of an inactive ILT vaccine candidate derived from a local ILTV isolate. The isolated virus was characterized and treated with various chemicals and their concentrations. The virus infectivity was entirely abolished by treatment of 3 mM binary ethylene imine following 16 h incubation. The immune response of inactivated ILTV suspension with adjuvans was evaluated in both SPF chickens (experiment-I) and Hyline pullets (experiment-II). Efficacy of the inactivated and live ILT vaccines combination was compared. The results of experiment-I showed that the inactivated antigen induced specific antibody titers against ILTV. In experiment-II, despite the increase in serum antibody level administration of the inactivated antigen alone did not offer sufficient protection. The full protection was found in chickens that received the combination regimen. We conclude that simultaneous administration of the inactivated and live ILT vaccines was efficient for induction of immunity against ILTV. [ABSTRACT FROM AUTHOR]

Despite the robust induction of humoral immune responses, a limitation of many adjuvants is their weak stimulation of cellular immunity. The development of synthetic gene-encoding adjuvants for simultaneous induction of both humoral and cell-mediated immune responses is under study. In this study, we examined the impact of toll/interleukin-1 receptor (TIR) domain of toll-like receptor 7 (TLR7) as molecular adjuvants on potency of inactivated infectious bursal disease (IBD) vaccines. A total of 60 specific pathogen-free week-old chicks were randomized grouped to receive either TIR-TLR7-adjuvanted IBD-inactivated vaccine or inactivated IBD antigen along with an unvaccinated control. Serum antibody titers were measured to estimate the humoral immunity, as well as lymphocyte proliferation activity for cellular immune responses. The protection was estimated after challenge with a very virulent IBD virus (IBDV) strain at 4 weeks postvaccination. The results indicated that one dose of IBD/TIR-TLR7 vaccine induced specific antibody responses, whereas a lower response after administration of inactivated IBD antigen was observed. The stimulation of splenocytes results indicated that the TIR-TLR7 adjuvanted IBD vaccine is capable of modulating cell-mediated immune response in treated chickens. A full protection against IBDV infection was achieved by injection of one dose IBD/TIR-TLR7 vaccine in the challenge trial. This study demonstrated that codelivery of TIR-TLR7 with inactivated IBD antigen resulted in simultaneous enhancing immune responses against IBD. [ABSTRACT FROM AUTHOR]

Immunization with DNA vaccines as a novel alternative to conventional vaccination strategy requires adjuvant for improving vaccine efficacy. The conserved immunogenic HA2 subunit, which harbors neutralizing epitopes is a promising vaccine candidate against influenza viruses. In this study, for the first time we explore the idea of using host interferon inducible Mx protein to increase the immunogenicity of HA2 H9N2 influenza DNA vaccine. The potency and safety of the Mx adjuvanted-HA2 vaccine was evaluated in BALB/c mice by different prime-boost strategies. To assess the effect of the vaccination on the virus clearance rate, mice were challenged with homologous influenza virus. Administration of the adjuvanted vaccine and boosting with the same regimen could effectively enhance both humoral and cellular immune responses in treated mice. These data demonstrated that Mx as host defense peptide can be potentiated for improving influenza vaccine efficacy. [ABSTRACT FROM AUTHOR]

Purpose: The direct transmission of avian influenza viruses to human and increasing drug resisted strains posing new threats for public health. Therefore, development of efficient vaccines is needed to generate protective and persistent immunity to the viruses. Methods: Three motifs of Mx protein sequence in human, mouse and poultry located in interferon induced (GTP ase) domain were candidate as biologic adjuvant for enhancing the immune responses against influenza virus. Chimera proteins composed with the conserved HA2 subunit of influenza virus and the Mx motifs named HA2/Mx were modeled and evaluated by in silico analysis includes bioinformatics algorithms in order to explore biological characteristics of these peptides. Results: Amongst the predicted models, HA2/Mx1 peptide showed the better results following protein structures prediction, antigenic epitopes determination and model quality evaluation. Comparative homology modeling was performed with Swiss Model and the model was validated using ProSA. Epitope predictions revealed the construct could induce both B and T cell epitopes that expect a high immune response. Conclusion: Taken together, these data indicate that the HA2/Mx1 chimera peptide can be potentiated for developing an adjuvant-fused influenza vaccine capable of stimulating effective immune response. [ABSTRACT FROM AUTHOR]