Alum Adjuvant Enhances Protection against Respiratory Syncytial Virus but Exacerbates Pulmonary Inflammation by Modulating Multiple Innate and Adaptive Immune Cells

Respiratory syncytial virus (RSV) is well-known for inducing vaccine-enhanced respiratory disease after vaccination of young children with formalin-inactivated RSV (FI-RSV) in alum formulation. Here, we investigated alum adjuvant effects on protection and disease after FIRSV immunization with or without alum in comparison with live RSV reinfections. Despite viral clearance, live RSV reinfections caused weight loss and substantial pulmonary inflammation probably due to high levels of RSV specific IFN-γ+IL4-, IFN-γ-TNF-α+, IFN-γ+ TNF-α- effector CD4 and CD8 T cells. Alum adjuvant significantly improved protection as evidenced by effective viral clearance compared to unadjuvanted FI-RSV. However, in contrast to unadjuvanted FI-RSV, alum-adjuvanted FI-RSV (FI-RSV-A) induced severe vaccine- enhanced RSV disease including weight loss, eosinophilia, and lung histopathology. Alum adjuvant in the FI-RSV-A was found to be mainly responsible for inducing high levels of RSV-specific IFN-γ-IL4+, IFN-γ-TNF-α+ CD4+ T cells, and proinflammatory cytokines IL-6 and IL-4 as well as B220+ plasmacytoid and CD4+ dendritic cells, and inhibiting the induction of IFN-γ+CD8 T cells. This study suggests that alum adjuvant in FI-RSV vaccines increases immunogenicity and viral clearance but also induces atypical T helper CD4+ T cells and multiple inflammatory dendritic cell subsets responsible for vaccine-enhanced severe RSV disease

Nucleoprotein Nanostructures Combined with Adjuvants Adapted to the Neonatal Immune Context: A Candidate Mucosal RSV Vaccine

BACKGROUND: The human respiratory syncytial virus (hRSV) is the leading cause of severe bronchiolitis in infants worldwide. The most severe RSV diseases occur between 2 and 6 months-of-age, so pediatric vaccination will have to be started within the first weeks after birth, when the immune system is prone to Th2 responses that may turn deleterious upon exposure to the virus. So far, the high risk to prime for immunopathological responses in infants has hampered the development of vaccine. In the present study we investigated the safety and efficacy of ring-nanostructures formed by the recombinant nucleoprotein N of hRSV (N(SRS)) as a mucosal vaccine candidate against RSV in BALB/c neonates, which are highly sensitive to immunopathological Th2 imprinting. METHODOLOGY AND PRINCIPAL FINDINGS: A single intranasal administration of N(SRS) with detoxified E. coli enterotoxin LT(R192G) to 5-7 day old neonates provided a significant reduction of the viral load after an RSV challenge at five weeks of age. However, neonatal vaccination also generated an enhanced lung infiltration by neutrophils and eosinophils following the RSV challenge. Analysis of antibody subclasses and cytokines produced after an RSV challenge or a boost administration of the vaccine suggested that neonatal vaccination induced a Th2 biased local immune memory. This Th2 bias and the eosinophilic reaction could be prevented by adding CpG to the vaccine formulation, which, however did not prevent pulmonary inflammation and neutrophil infiltration upon viral challenge. CONCLUSIONS/SIGNIFICANCE: In conclusion, protective vaccination against RSV can be achieved in neonates but requires an appropriate combination of adjuvants to prevent harmful Th2 imprinting

Sub-Nucleocapsid Nanoparticles: A Nasal Vaccine against Respiratory Syncytial Virus

Background: Bronchiolitis caused by the respiratory syncytial virus (RSV) in infants less than two years old is a growing public health concern worldwide, and there is currently no safe and effective vaccine. A major component of RSV nucleocapsid, the nucleoprotein (N), has been so far poorly explored as a potential vaccine antigen, even though it is a target of protective anti-viral T cell responses and is remarkably conserved between human RSV A and B serotypes. We recently reported a method to produce recombinant N assembling in homogenous rings composed of 10–11 N subunits enclosing a bacterial RNA. These nanoparticles were named sub-nucleocapsid ring structure (N SRS). Methodology and Principal Findings: The vaccine potential of N SRS was evaluated in a well-characterized and widely acknowledged mouse model of RSV infection. BALB/c adult mice were immunized intranasally with N SRS adjuvanted with the detoxified E. coli enterotoxin LT(R192G). Upon RSV challenge, vaccinated mice were largely protected against virus replication in the lungs, with a mild inflammatory lymphocytic and neutrophilic reaction in their airways. Mucosal immunization with N SRS elicited strong local and systemic immunity characterized by high titers of IgG1, IgG2a and IgA anti-N antibodies, antigen-specific CD8+ T cells and IFN-c-producing CD4+ T cells. Conclusions/Significance: This is the first report of using nanoparticles formed by the recombinant nucleocapsid protein as an efficient and safe intra-nasal vaccine against RSV

Induction of Long-Term Protective Immune Responses by Influenza H5N1 Virus-Like Particles

Recurrent outbreaks of highly pathogenic H5N1 avian influenza virus pose a threat of eventually causing a pandemic. Early vaccination of the population would be the single most effective measure for the control of an emerging influenza pandemic.Influenza virus-like particles (VLPs) produced in insect cell-culture substrates do not depend on the availability of fertile eggs for vaccine manufacturing. We produced VLPs containing influenza A/Viet Nam1203/04 (H5N1) hemagglutinin, neuraminidase, and matrix proteins, and investigated their preclinical immunogenicity and protective efficacy. Mice immunized intranasally with H5N1 VLPs developed high levels of H5N1 specific antibodies and were 100% protected against a high dose of homologous H5N1 virus infection at 30 weeks after immunization. Protection is likely to be correlated with humoral and cellular immunologic memory at systemic and mucosal sites as evidenced by rapid anamnestic responses to re-stimulation with viral antigen in vivo and in vitro.These results provide support for clinical evaluation of H5N1 VLP vaccination as a public health intervention to mitigate a possible pandemic of H5N1 influenza

Complement-dependent cytotoxic antibodies to human T lymphotropic virus type I (HTLV-I)-infected cells in the sera of HTLV-I-infected individuals

To investigate whether HTLV-I induces the development of complement-dependent cytotoxic antibodies in humans, sera of asymptomatic HTLV-I carriers and of patients suffering from tropical spastic paraparesis/HTLV-I-associated myelopathy (TSP/HAM) or adult T cell leukaemia (ATL) were used in a cytotoxicity assay against a panel of target cells. This panel included uninfected cell lines (CEM, Jurkat, Molt and H9), cell lines chronically infected with HTLV-I (MT2, MT4, C91PL and HUT102), as well as lines H36 (H9 infected with HTLV-I), H9-IIIB (H9 infected with HIVIIIB) and H9-MN (H9 infected with HIVMN). HTLV-I+ sera induced lysis of H36 and of lines expressing HTLV-I antigens in the presence of rabbit complement, but did not lyse cells in presence of human complement. The HTLV-I+ sera also failed to lyse the HTLV-I− lines and H9 cells, suggesting that lysis was specific for HTLV-I. H36 cell lysis was prevented by IgG depletion of the sera and by dialysis of rabbit complement against EGTA or EDTA. Rabbit complement-dependent cytotoxic antibodies were present in the sera of 14/14 HTLV-I-infected individuals; the highest titres were predominantly found in the sera of the TSP/HAM patients. Such antibodies were also detected in 5/5 individuals coinfected with HIV-1 and HTLV-I, although no cytotoxic antibody could be found against HIV-infected cells. Vice versa, sera of HIV-1-infected individuals did not exert a lytic effect in the presence of complement (of human or rabbit origin) against HIV-1- or HTLV-I-infected cells. Incubation of the sera of four HTLV-I-infected patients with HTLV-I env-specific synthetic peptides demonstrated that some of the complement-dependent cytotoxic antibodies recognized epitopes located on gp46 between amino acids 190 and 209. There is no correlation of rabbit complement-dependent cytotoxic HTLV-I antibodies with the development of disease

T lymphocytes from human chimeras do recognize antigen in the context of allogeneic determinants of the major histocompatibility complex

Human stem cells from the fetal liver can be transplanted to immunodeficient patients and reconstitute their immunity by giving rise to immunocompetent T lymphocytes of donor origin. Despite full HLA mismatch between donor and host, the helper T cells and the cytotoxic T cells which develop in these chimeric patients are totally functional. They recognize the antigenic peptides presented in the context of the foreign HLA molecules of the recipient, indicating that donor stem cells have been positively selected in the host environment, probably the thymic epithelial cells. By contrast, negative selection appears to be imposed upon T cells by donor hemopoietic cells, probably macrophages or dendritic cells, migrating from the transplant to the host thymus. Clonal deletion is then responsible for tolerance to donor HLA antigens, while clonal anergy explains tolerance to host HLA antigen