Intranasally administered protein coated chitosan nanoparticles encapsulating influenza H9N2 HA2 and M2e mRNA molecules elicit protective immunity against avian influenza viruses in chickens.

Chitosan nanoparticles (CNPs) represent an efficient vaccination tool to deliver immunogenic antigens to the antigen-presenting cells (APCs), which subsequently stimulate protective immune responses against infectious diseases. Herein, we prepared CNPs encapsulating mRNA molecules followed by surface coating with conserved H9N2 HA2 and M2e influenza proteins. We demonstrated that CNPs efficiently delivered mRNA molecules into APCs and had effectively penetrated the mucosal barrier to reach to the immune initiation sites. To investigate the potential of CNPs delivering influenza antigens to stimulate protective immunity, we intranasally vaccinated chickens with empty CNPs, CNPs delivering HA2 and M2e in both mRNA and protein formats (CNPs + RNA + Pr) or CNPs delivering antigens in protein format only (CNPs + Pr). Our results demonstrated that chickens vaccinated with CNPs + RNA + Pr elicited significantly (p < 0.05) higher systemic IgG, mucosal IgA antibody responses and cellular immune responses compared to the CNPs + Pr vaccinated group. Consequently, upon challenge with either H7N9 or H9N2 avian influenza viruses (AIVs), efficient protection, in the context of viral load and lung pathology, was observed in chickens vaccinated with CNPs + RNA + Pr than CNPs + Pr vaccinated group. In conclusion, we show that HA2 and M2e antigens elicited a broad spectrum of protection against AIVs and incorporation of mRNAs in vaccine formulation is an effective strategy to induce superior immune responses.

Salmonella Gallinarum delivering M2eCD40L in protein and DNA formats acts as a bivalent vaccine against fowl typhoid and H9N2 infection in chickens.

Fowl typhoid (FT), a septicemic disease caused by Salmonella Gallinarum (SG), and H9N2 influenza infection are two economically important diseases that affect poultry industry worldwide. Herein, we exploited a live attenuated SG mutant (JOL967) to deliver highly conserved extracellular domains of H9N2 M2 (M2e) to induce protective immunity against both H9N2 infection and FT. To increase the immunogenicity of M2e, we physically linked it with CD40L and cloned the fusion gene into either prokaryotic constitutive expression vector pJHL65 or mammalian expression vector pcDNA3.1+. Then pJHL65-M2eCD40L or pcDNA-M2eCD40L recombinant plasmid was electroporated into JOL967 strain and the resultant clones were designated as JOL2074 and JOL2076, respectively. We demonstrated that the chickens vaccinated once orally with a co-mix of JOL2074 and JOL2076 strains elicited significantly (p < 0.05) higher M2e-specific humoral and cell-mediated immunity compared to JOL2074 alone vaccinated group. However, SG-specific immune responses were comparable in both the vaccination groups. On challenge with the virulent H9N2 virus (105 TCID50) at 28th day post-vaccination, chickens that received a co-mix of JOL2074 plus JOL2076 strains exhibited significantly (p < 0.05) lower lung inflammation and viral load in both lungs and cloacal samples than JOL2074 alone vaccinated group. Against challenge with the lethal wild-type SG, both the vaccination groups exhibited only 12.5% mortality compared to 75% mortality observed in the control group. In conclusion, we show that SG delivering M2eCD40L can act as a bivalent vaccine against FT and H9N2 infection and further studies are warranted to develop this SG-M2eCD40L vaccine as a broadly protective vaccine against avian influenza virus subtypes.

Oral immunization with a novel attenuated Salmonella Gallinarum encoding infectious bronchitis virus spike protein induces protective immune responses against fowl typhoid and infectious bronchitis in chickens.

Fowl typhoid (FT), a septicemic disease caused by Salmonella Gallinarum (SG), and infectious bronchitis (IB) are two economically important avian diseases that affect poultry industry worldwide. Herein, we exploited a live attenuated SG mutant, JOL967, to deliver spike (S) protein 1 of IB virus (V) to elicit protective immunity against both FT and IB in chickens. The codon optimized S1 nucleotide sequence was cloned in-frame into a prokaryotic constitutive expression vector, pJHL65. Subsequently, empty pJHL65 or recombinant pJHL65-S1 plasmid was electroporated into JOL967 and the resultant clones were designated as JOL2068 and JOL2077, respectively. Our results demonstrated that the chickens vaccinated once orally with JOL2077 elicited significantly (p < 0.05) higher IBV-specific humoral and cell-mediated immunity compared to JOL2068 and PBS control groups. Consequently, on challenge with the virulent IBV strain at 28th day post-vaccination, JOL2077 vaccinated birds displayed significantly (p < 0.05) lower inflammatory lesions in virus-targeted tissues compared to control groups. Furthermore, 33.3% (2 of 6) of birds vaccinated with JOL2077 vaccine had shown virus recovery from tracheal tissues compared to 100% (6 of 6) recovery obtained in both the control groups. Against wild-type SG lethal challenge, both JOL2077 and JOL2068 vaccinated groups exhibited only 10% mortality compared to 80% mortality observed in PBS control group. In conclusion, we show that JOL2077 can induce efficient IBV- and carrier-specific protective immunity and can act as a bivalent vaccine against FT and IB. Further studies are warranted to investigate the potential of JOL2077 vaccine in broiler and young layer birds.

Potent O-antigen-deficient (rough) mutants of Salmonella Typhimurium secreting Lawsonia intracellularis antigens enhance immunogenicity and provide single-immunization protection against proliferative enteropathy and salmonellosis in a murine model.

The obligate intracellular pathogen Lawsonia intracellularis (LI), the etiological agent of proliferative enteropathy (PE), poses a substantial economic loss in the swine industry worldwide. In this study, we genetically engineered an O-antigen-deficient (rough) Salmonella strain secreting four selected immunogenic LI antigens, namely OptA, OptB, LfliC, and Lhly. The genes encoding these antigens were individually inserted in the expression vector plasmid pJHL65, and the resultant plasmids were transformed into the ∆asd ∆lon ∆cpxR ∆rfaL Salmonella Typhimurium (ST) strain JOL1800. The individual expression of the selected LI antigens in JOL1800 was validated by an immunoblotting assay. We observed significant (P < 0.05) induction of systemic IgG and mucosal IgA responses against each LI antigen or Salmonella outer membrane protein in mice immunized once orally with a mixture of four JOL1800-derived strains. Further, mRNA of IL-4 and IFN-γ were highly upregulated in splenic T cells re-stimulated in vitro with individual purified antigens. Subsequently, immunized mice showed significant protection against challenge with 106.9 TCID50 LI or 2 × 109 CFU of a virulent ST strain. At day 8 post-challenge, no mice in the immunized groups showed the presence of LI-specific genomic DNA (gDNA) in stool samples, while 50% of non-immunized mice were positive for LI-specific gDNA. Further, all the immunized mice survived the virulent ST challenge, compared to a 20% mortality rate observed in the control mice. Collectively, the constructed rough ST-based LI vaccine candidate efficiently elicited LI and ST-specific humoral and cell-mediated immunity and conferred proper dual protection against PE and salmonellosis.

Intranasally administered polyethylenimine adjuvanted influenza M2 ectodomain induces partial protection against H9N2 influenza A virus infection in chickens.

This study aimed to investigate whether intranasally coadministered four tandem copies of extracellular domains of M2 (M2e) and polyethyleneimine (PEI), a mucosal adjuvant, can protect chickens against H9N2 influenza A virus infection. Groups of chickens were intranasally vaccinated with M2e plus PEI adjuvant, M2e alone or PEI adjuvant, and antibody (serum IgG and mucosal IgA) and cellular (CD4+ T cells and IFN-γ levels) immune responses were measured post-vaccination. We demonstrated that the chickens vaccinated with M2e plus PEI adjuvant showed significantly (p < 0.05) higher M2e-specific systemic IgG and mucosal IgA responses compared to the chickens that received either M2e alone or PEI adjuvant. The IgA responses measured in lungs were almost comparable to that of the serum IgG levels. Upon restimulation of the vaccinated peripheral blood mononuclear cells (PBMCs) with M2e antigen, significantly (p < 0.05) higher IFN-γ levels were observed only in M2e plus PEI adjuvant vaccinated group. Lymphoproliferative and CD4+ T cell responses, as measured by MTT-based assay and flow cytometry, respectively, were also observed significantly (p < 0.05) higher in M2e plus PEI adjuvant vaccinated chickens. On challenge with the H9N2 virus (104TCID50) at 28th day post-vaccination, M2e plus PEI adjuvant vaccinated group exhibited lower lung inflammation and viral load compared to the chickens treated with either M2e alone or PEI adjuvant. In summary, we show that intranasally coadministered M2e and PEI adjuvant can elicit humoral and cell-mediated immune responses and can reduce viremia levels in chickens post H9N2 infection in chickens.

Human antigen presenting cells stimulated with Salmonella delivered influenza antigens induce cytokine production and proliferation of human CD4+ T cells in vitro.

This study aimed to investigate whether the human antigen presenting cells (APCs) can process and present Salmonella expressing H7N9 hemagglutinin (Sal-HA), neuraminidase (Sal-NA) or M2 ectodomain (Sal-M2e) to T cells and subsequently activate CD4+ T cell responses in vitro. In this study, APCs generated from human peripheral blood mononuclear cells (PBMCs) were first treated with mitomycin-C, followed by stimulation with Sal-HA, Sal-M2e, Sal-NA or Salmonella alone for 24 h. Subsequently, stimulated APCs were coincubated with untreated PBMCs (1:10) of the same individual for 24 or 72 h and then analysed for cytokine induction and T cell proliferations by qRT-PCR assay and flow cytometry, respectively. Our results demonstrated that APCs stimulated with Sal-HA, Sal-M2e or Sal-NA induced significantly (p < .05) higher CD3+CD4+ T cell proliferations compared to the APCs treated with Salmonella alone. Our data further revealved that APCs treated with Sal-HA induced significantly (p < .05) higher CD3+CD4+ T cell responses compared to the APCs treated with either Sal-M2e or Sal-NA, which both induced almost comparable levels. The T cell proliferation responses were further measured by lymphocyte proliferation assay and the results showed that Sal-HA and Sal-M2e stimulated APCs induced significantly (p < .05) higher proliferations in T cells compared to the APCs stimulated with either Sal-NA or Salmonella alone. With respect to cytokine inductions, APCs treated with either Sal-HA or Sal-M2e induced significantly (p < .05) higher mRNA transcription levels of proinflammatory (IL-1ß, IL-6, IL-12 and IL-23), Th1 (IFN-γ), Th17 (IL-17 and IL-21) and Th2 (IL-10 and TGF-ß) cytokines in T cells compared to Sal-NA or Salmonella alone treated APCs. In conclusion, we show that Salmonella system can efficiently deliver vaccine antigens to APCs and is, thus, capable to elicit heterologous antigen-specific adaptive immunity.

Clinical diagnosis of early dengue infection by novel one-step multiplex real-time RT-PCR targeting NS1 gene.

BACKGROUND: Dengue is a mosquito-borne disease that causes a public health problem in tropical and subtropical countries. Current immunological diagnostics based on IgM and/or nonstructural protein 1 (NS1) antigen are limited for acute dengue infection due to low sensitivity and accuracy. OBJECTIVES: This study aimed to develop a one-step multiplex real-time RT-PCR assay showing higher sensitivity and accuracy than previous approaches. STUDY DESIGN: Serotype-specific primers and probes were designed through the multiple alignment of NS1 gene. The linearity and limit of detection (LOD) of the assay were determined. The assay was clinically validated with an evaluation panel that was immunologically tested by WHO and Malaysian specimens. RESULTS: The LOD of the assay was 3.0 log10 RNA copies for DENV-1, 2.0 for DENV-3, and 1.0 for DENV-2 and DENV-4. The assay showed 95.2% sensitivity (20/21) in an evaluation panel, whereas NS1 antigen- and anti-dengue IgM-based immunological assays exhibited 0% and 23.8-47.6% sensitivities, respectively. The assay showed 100% sensitivity both in NS1 antigen- and anti-dengue IgM-positive Malaysian specimens (26/26). The assay provided the information of viral loads and serotype with discrimination of heterotypic mixed infection. CONCLUSIONS: The assay could be clinically applied to early dengue diagnosis, especially during the first 5 days of illness and approximately 14 days after infection showing an anti-dengue IgM-positive response.

Polymeric LabChip real-time PCR as a point-of-care-potential diagnostic tool for rapid detection of influenza A/H1N1 virus in human clinical specimens.

It is clinically important to be able to detect influenza A/H1N1 virus using a fast, portable, and accurate system that has high specificity and sensitivity. To achieve this goal, it is necessary to develop a highly specific primer set that recognizes only influenza A viral genes and a rapid real-time PCR system that can detect even a single copy of the viral gene. In this study, we developed and validated a novel fluidic chip-type real-time PCR (LabChip real-time PCR) system that is sensitive and specific for the detection of influenza A/H1N1, including the pandemic influenza strain A/H1N1 of 2009. This LabChip real-time PCR system has several remarkable features: (1) It allows rapid quantitative analysis, requiring only 15 min to perform 30 cycles of real-time PCR. (2) It is portable, with a weight of only 5.5 kg. (3) The reaction cost is low, since it uses disposable plastic chips. (4) Its high efficiency is equivalent to that of commercially available tube-type real-time PCR systems. The developed disposable LabChip is an economic, heat-transferable, light-transparent, and easy-to-fabricate polymeric chip compared to conventional silicon- or glass-based labchip. In addition, our LabChip has large surface-to-volume ratios in micro channels that are required for overcoming time consumed for temperature control during real-time PCR. The efficiency of the LabChip real-time PCR system was confirmed using novel primer sets specifically targeted to the hemagglutinin (HA) gene of influenza A/H1N1 and clinical specimens. Eighty-five human clinical swab samples were tested using the LabChip real-time PCR. The results demonstrated 100% sensitivity and specificity, showing 72 positive and 13 negative cases. These results were identical to those from a tube-type real-time PCR system. This indicates that the novel LabChip real-time PCR may be an ultra-fast, quantitative, point-of-care-potential diagnostic tool for influenza A/H1N1 with a high sensitivity and specificity.