Respiratory Syncytial Virus Subunit Vaccine Research Articles

A foldon-free prefusion F trimer vaccine for respiratory syncytial virus to reduce off-target immune responses

Respiratory syncytial virus (RSV) is a major cause of severe respiratory disease in infants and older people. Current RSV subunit vaccines are based on a fusion protein that is stabilized in the prefusion conformation and linked to a heterologous foldon trimerization domain to obtain a prefusion F (preF) trimer. Here we show that current RSV vaccines induce undesirable anti-foldon antibodies in non-human primates, mice and humans. To overcome this, we designed a foldon-free RSV preF trimer by elucidating the structural basis of trimerization-induced preF destabilization through molecular dynamics simulations and by introducing amino acid substitutions that negate hotspots of charge repulsion. The highly stable prefusion conformation was validated using antigenic and cryo-electron microscopy analysis. The preF is immunogenic and protective in naive mouse models and boosts neutralizing antibody titres in RSV-pre-exposed mice and non-human primates, while achieving similar titres to approved RSV vaccines in mice. This stable preF design is a promising option as a foldon-independent candidate for a next-generation RSV vaccine immunogen.

Efficacy, Safety, and Immunogenicity of Subunit Respiratory Syncytial Virus Vaccines: Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Respiratory syncytial virus (RSV) is garnering increasing attention, with a growing number of subunit RSV vaccines under active clinical investigation. However, comprehensive evidence is limited. We conducted a comprehensive search across PubMed, Embase, the Cochrane Library, Web of Science, and ClinicalTrials.gov from database inception to 12 January 2024, focusing on published randomized controlled trials (RCTs). A total of 17 studies were included, encompassing assessments of efficacy (5 studies), safety (17 studies), and immunogenicity (12 studies) of RSV subunit vaccines. The pooled risk ratio (RR) for RSV-associated acute respiratory infection (RSV-ARI) with subunit vaccines was 0.31 (95% CI: 0.23-0.43), for RSV-associated lower respiratory tract infection (RSV-LRTI), it was 0.32 (95% CI: 0.22-0.44), and for severe RSV-LRTI (RSV-SLRTI), it was 0.13 (95% CI: 0.06-0.29). There was no significant difference in serious adverse events (SAEs) between the vaccine and placebo groups, with a pooled RR of 1.05 (95% CI: 0.98-1.14). The pooled standardized mean difference (SMD) for the geometric mean titer (GMT) of neutralizing antibodies was 2.89 (95% CI: 2.43-3.35). Subunit RSV vaccines exhibit strong efficacy, favorable safety profiles, and robust immunogenicity. Future research should focus on the cost-effectiveness of various vaccines to enhance regional and national immunization strategies.

Construction and immunological evaluation of hepatitis B virus core virus-like particles containing multiple antigenic peptides of respiratory syncytial virus

Respiratory syncytial virus (RSV) infection causes severe disease in the lower respiratory tract of infants and young children. Currently, no licensed vaccine is available. In this study, we generated the chimeric virus-like particles (tHBc/FE1E2, tHBc/FE1E2/M282-90 and tHBc/FE1E2/M282-90/tG VLPs) containing multiple antigenic peptides of RSV proteins based on a truncated hepatitis B virus core carrier (tHBc). We investigated the immune protection against RSV infection induced by these VLPs in a mouse model. Immunization with the VLPs elicited RSV-specific IgG and neutralizing antibody production and conferred protection against RSV infection in vivo. Compared with UV-RSV or tHBc/FE1E2/M282-90/tG VLPs, the tHBc/FE1E2 and tHBc/FE1E2/M282-90 VLPs induced significantly decreased Th2 cytokines (IL-4, IL-5) and increased Th1 cytokines (IFN-γ, TNF-α, IL-2) as well as increased IgG2a/IgG1 ratios. tHBc/FE1E2 and tHBc/FE1E2/M282-90 VLPs also elicited an increased regulatory T (Treg) cell frequency and IL-10 secretion in the lungs of vaccinated mice, thereby relieving pulmonary pathology upon subsequent RSV infection. Our results demonstrate that the VLPs containing antigenic peptides of F protein combined with a CTL epitope of M2 may represent a promising RSV subunit vaccine candidate.

Development of a High Yielding Bioprocess for a Pre-fusion RSV Subunit Vaccine

Respiratory syncytial virus (RSV) is a highly contagious virus causing severe infection in infants and the elderly. Various approaches are being used to develop an effective RSV vaccine. The RSV fusion (F) subunit, particularly the cleaved trimeric pre-fusion F, is one of the most promising vaccine candidates under development. The pre-fusion conformation elicits the majority of neutralizing antibodies during natural infection. However, this pre-fusion conformation is metastable and prone to conversion to a post-fusion conformation, thus hindering the potential of this construct as a vaccine antigen. The Vaccine Research Center (VRC) at the National Institutes of Health (NIH) designed a structurally stabilized pre-fusion F glycoprotein, DS-Cav1, that showed high immunogenicity and induced a neutralizing response in animal studies. To advance this candidate to clinical manufacturing, a production process that maintained product quality (i.e. a cleaved trimer with pre-fusion conformation) and delivered high protein expression levels was required. This report describes the development of the vaccine candidate including vector design and cell culture process development to meet these challenges. Co-transfection of individual plasmids to express DS-Cav1 and furin (for DS-Cav1 cleavage and activation) demonstrated a superior protein product expression and pre-fusion conformation compared to co-expression with a double gene vector. A top clone was selected based on these measurements. Protein expression levels were further increased by seeding density optimization and a biphasic hypothermia temperature downshift. The combined efforts led to a high-yield fed-batch production of approximately 1,500 mg/L (or up to 15,000 doses per liter) at harvest. The process was scaled up and demonstrated to be reproducible at 50 L-scale for toxicity and Phase I clinical trial use. Preliminary phase I data indicate the pre-fusion antigen has a promising efficacy (Crank et al., 2019).

Biology of Infection and Disease Pathogenesis to Guide RSV Vaccine Development

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract disease in young children and a substantial contributor to respiratory tract disease throughout life and as such a high priority for vaccine development. However, after nearly 60 years of research no vaccine is yet available. The challenges to developing an RSV vaccine include the young age, 2-4 months of age, for the peak of disease, the enhanced RSV disease associated with the first RSV vaccine, formalin-inactivated RSV with an alum adjuvant (FI-RSV), and difficulty achieving protection as illustrated by repeat infections with disease that occur throughout life. Understanding the biology of infection and disease pathogenesis has and will continue to guide vaccine development. In this paper, we review the roles that RSV proteins play in the biology of infection and disease pathogenesis and the corresponding contribution to live attenuated and subunit RSV vaccines. Each of RSV's 11 proteins are in the design of one or more vaccines. The G protein's contribution to disease pathogenesis through altering host immune responses as well as its role in the biology of infection suggest it can make a unique contribution to an RSV vaccine, both live attenuated and subunit vaccines. One of G's potential unique contributions to a vaccine is the potential for anti-G immunity to have an anti-inflammatory effect independent of virus replication. Though an anti-viral effect is essential to an effective RSV vaccine, it is important to remember that the goal of a vaccine is to prevent disease. Thus, other effects of the infection, such as G's alteration of the host immune response may provide opportunities to induce responses that block this effect and improve an RSV vaccine. Keeping in mind the goal of a vaccine is to prevent disease and not virus replication may help identify new strategies for other vaccine challenges, such as improving influenza vaccines and developing HIV vaccines.

Chimeric virus-like particles containing a conserved region of the G protein in combination with a single peptide of the M2 protein confer protection against respiratory syncytial virus infection

To investigate the feasibility and efficacy of a virus-like particle (VLP) vaccine composed of the conserved antigenic epitopes of respiratory syncytial virus (RSV), the chimeric RSV VLPs HBcΔ-tG and HBcΔ-tG/M282-90 were generated based on the truncated hepatitis B virus core protein (HBcΔ). HBcΔ-tG consisted of HBcΔ, the conserved region (aa 144–204) of the RSV G protein. HBcΔ-tG was combined with a single peptide (aa 82–90) of the M2 protein to generate HBcΔ-tG/M282-90. Immunization of mice with the HBcΔ-tG or HBcΔ-tG/M282-90 VLPs elicited RSV-specific IgG and neutralizing antibody production and conferred protection against RSV infection. Compared with HBcΔ-tG, HBcΔ-tG/M282-90 induced decreased Th2 cytokine production (IL-4 and IL-5), increased Th1 cytokine response (IFN-γ, TNF-α, and IL-2), and increased ratios of IgG2a/IgG1 antibodies, thereby relieving pulmonary pathology upon subsequent RSV infection. Our results demonstrated that chimeric HBcΔ-tG/M282-90 VLPs represented an effective RSV subunit vaccine candidate.

The preventive effect of vaccine prophylaxis on severe respiratory syncytial virus infection: A meta-analysis.

Respiratory syncytial virus (RSV) is the key underlying cause of acute lower respiratory tract infection in infants; however, no licensed vaccine against RSV infection is currently available. This study was undertaken to assess the preventive effect of vaccine on RSV infection. In this metaanalysis, 1,792 published randomized clinical trials of RSV vaccines from Jan 1973 to Sep 2015 were examined. Among thirteen studies that met the inclusion criteria, eleven studies estimated the impact of RSV vaccines and four studies estimated the effect of adjuvants. The odds ratios (ORs) were 0.31 (95% CI, 0.15-0.67) and 0.62 (95% CI, 0.29-1.34), respectively. We found that RSV subunit vaccines can significantly reduce the incidence of RSV infection and that whether vaccination with adjuvant therapy was an effective strategy still remained to be studied. This analysis of the preventive effect of vaccines on RSV infection has direct applications for the prevention of RSV infections.

Induction of mucosal immunity and protection by intranasal immunization with a respiratory syncytial virus subunit vaccine formulation

The majority of infections, including those caused by respiratory syncytial virus (RSV), occur at mucosal surfaces. As no RSV vaccine is available our goal is to produce an effective subunit vaccine with an adjuvant suitable for mucosal delivery and cross-presentation. A truncated secreted version of the RSV fusion (ΔF) protein formulated with polyI : C, an innate defence regulator peptide and polyphosphazene, induced local and systemic immunity, including affinity maturation of RSV F-specific IgG, IgA and virus-neutralizing antibodies, and F-specific CD8(+) T-cells in the lung, when delivered intranasally. Furthermore, this ΔF protein formulation promoted the production of CD8(+) central memory T-cells in the mediastinal lymph nodes and provided protection from RSV challenge. Formulation of ΔF protein with this adjuvant combination enhanced uptake by lung dendritic cells and trafficking to the draining lymph nodes. The ΔF protein formulation was confirmed to be highly efficacious and safe in cotton rats.

Respiratory syncytial virus subunit vaccine based on a recombinant fusion protein expressed transiently in mammalian cells

Although respiratory syncytial virus (RSV) causes severe lower respiratory tract infection in infants and adults at risk, no RSV vaccine is currently available. In this report, efforts toward the generation of an RSV subunit vaccine using recombinant RSV fusion protein (rRSV-F) are described. The recombinant protein was produced by transient gene expression (TGE) in suspension-adapted human embryonic kidney cells (HEK-293E) in 4 L orbitally shaken bioreactors. It was then purified and formulated in immunostimulating reconstituted influenza virosomes (IRIVs). The candidate vaccine induced anti-RSV-F neutralizing antibodies in mice, and challenge studies in cotton rats are ongoing. If successful in preclinical and clinical trials, this will be the first recombinant subunit vaccine produced by large-scale TGE in mammalian cells.

Protective effect of a RSV subunit vaccine candidate G1F/M2 was enhanced by a HSP70-Like protein in mice

Respiratory syncytial virus (RSV) is a major respiratory pathogen in newborns. Neonate vaccine should induce strong protective immunity. We have engineered a subunit vaccine candidate G1F/M2. A major problem in developing subunit vaccines is their limited immunogenicity. Aluminium adjuvants with a long history of use with routine childhood vaccines have some limitations, especially inability to elicit CTL response. There is a need for alternative adjuvants. Heat shock proteins (HSPs) are characterized as potent immunoadjuvants. In this study, HSP70-like protein 1 (HSP70L1) gene was cloned. The recombinant protein HSP70L1 was expressed in E. coli, purified and renaturated. We evaluated the potential of HSP70L1 used as the adjuvant of G1F/M2. G1F/M2 was chemically cross-linked with HSP70L1 (HSP-G1F/M2). HSP70L1 enhanced significantly the immunogenicity and protective effect of G1F/M2. HSP-G1F/M2 induced significant higher levels of antibodies, neutralizing antibodies and CTL activity than unadjuvanted G1F/M2. The antibody titers induced by HSP-G1F/M2 were similar to that by G1F/M2+Alum. RSV-specific CTL activity induced by HSP-G1F/M2 was stronger than that by G1F/M2+Alum. Interestingly, the protective effect of HSP-G1F/M2 against RSV was significantly stronger than that of G1F/M2+Alum. The results suggest that HSP70L1 is a potent adjuvant of G1F/M2.

GENETIC CHARACTERIZATION OF THE F PROTEIN OF RESPIRATORY SYNCYTIAL VIRUS STRAINS ISOLATED IN THE BEIJING, CHINA, AREA

INTRODUCTION: Respiratory syncytial virus (RSV) is the most common viral pathogen for lower respiratory tract infection among young children. However, pathogenic mechanisms and molecular characteristics of RSV are still not completely understood, so the development of an effective vaccine has been hindered. F protein has been shown to be a potential RSV subunit vaccine candidate, so the study on genetic characteristics of F protein may be important for further investigation. OBJECTIVE: Our goal was to determine the genetic characteristics of the F protein. METHODS: Seventy-six strains of human RSV were isolated from 2001 to 2004 in Beijing, China, of which 6 representative strains were chosen. RESULTS: Among the 6 Beijing isolates, 4 belonged to subgroup A. The F gene of the isolates shared 97.0% to 97.4% nucleotide sequence identity and 92.1% to 93.0% amino acid sequence identity. They were highly homologous with GenBank Nos. AY198175, AY198176, and AY198177 (China Hebei). The other 2 isolates belonged to subgroup B, and 97.3% and 98.2% sequence identity was seen at nucleotide and amino acid levels, respectively. The nucleotide sequences of subgroup B showed the highest identities with GenBank Nos. NC001781 and AF013254. Phylogenetic analysis of nucleotide sequences revealed that those 4 within group A were monophyletic and closely related to each other, but those 2 within group B were distributed in 2 distinct clusters. AA200-225 and AA259-278 on the F gene are conservative between subgroups A and B. CONCLUSIONS: Subgroup A and B strains cocirculated, which indicates that there were different transmission chains in Beijing from 2001 to 2004. AA200-225 and AA259-278 are potential segments to develop an effective vaccine in Beijing or even in China.

Long-lasting balanced immunity and protective efficacy against respiratory syncytial virus in mice induced by a recombinant protein G1F/M2

Respiratory syncytial virus (RSV) is the primary cause of serious lower respiratory tract illness in young children. We have engineered a recombinant candidate vaccine G1F/M2, consisting of a cytotoxic T lymphocyte (CTL) epitope of RSV-M2 protein and a domain of RSV-G protein. In this study, the long-term immunogenicity and protective effect were evaluated. In G1F/M2-immunized mice, special antibodies lasted for more than 19 weeks, and the IgG1/IgG2a ratio remained a balanced level till the end of the study, suggesting mixed Th1/Th2 type of responses. Concomitantly, G1F/M2 elicited long-lived RSV-specific CTL activity that was detectable at 12 weeks after the final immunization. Stronger CTL responses were induced with immunization once more at 13 weeks after the last immunization in G1F/M2-primed mice than those in F/M2-primed mice. These results suggest that G1F/M2-induced long-lasting balanced humoral and cellular immunity responses, and immunological memory in mice. Furthermore, following RSV challenge, long-term protective efficacy was observed. RSV replication in lungs of G1F/M2-primed mice elicited also mixed Th1/Th2 responses, a property that is considered advantageous for the safety of an RSV vaccine. Therefore, G1F/M2 is a promising RSV subunit vaccine.

Intranasal proteosome-based respiratory syncytial virus (RSV) vaccines protect BALB/c mice against challenge without eosinophilia or enhanced pathology

A safe and effective vaccine against respiratory syncytial virus (RSV) is still unavailable. Proteosome-based adjuvants are derived from the outer membrane proteins (OMP) of Neisseria species and are potent inducers of both mucosal and systemic immunity in humans and animals. Candidate RSV subunit vaccines comprising enriched RSV proteins (eRSV) formulated with proteosomes alone or with LPS (Protollin) were produced. Administered intranasally in BALB/c mice, both vaccines elicited long-lasting systemic and mucosal RSV-specific antibodies and fully protected against challenge. In vitro restimulation of lymphocytes from the Protollin-eRSV immunized mice with F (MHC-I) and G (MHC-II) peptides elicited F peptide-specific CD8(+) T cells and supernatant IFNgamma, TNFalpha, IL-2 and IL-10 while the formalin-inactivated RSV (FI-RSV) vaccine elicited predominantly IL-5. Pulmonary eosinophilia did not develop following immunization with either proteosome-based vaccine following challenge compared to mice immunized with FI-RSV. Proteosome-based eRSV vaccines can therefore protect against RSV challenge in mice without increasing the risk of pulmonary immunopathologic responses.

Induction of balanced immunity in BALB/c mice by vaccination with a recombinant fusion protein containing a respiratory syncytial virus G protein fragment and a CTL epitope

Respiratory syncytial virus (RSV), an important pathogen of the lower respiratory tract, is responsible for severe illness both in new born and young children and in elderly people. However, development of a RSV vaccine has been hampered by the outcome of the infant trials in the 1960s with a formalin-inactivated RSV (FI-RSV) preparation. Previous studies in mice indicated that G protein immunization resulted in antibody and Th2-type response and failed to induce MHC I-restricted CD8 + T-cell response. Vaccines designed to induce CD8 + T-cell along with antibody response might be ideal. In the present report, a fusion protein G1F/M2 containing a RSV-G protein fragment (G: 125–225 amino acid) and a CD8 + T-cell epitope from RSV-M2 protein was investigated. G1F/M2 was cloned, expressed in E. coli, purified and renaturated. In BALB/c mice, G1F/M2 induced not only humoral immunity but also cellular immunity. In addition, interestedly, G1F/M2 elicited balanced IgG1/IgG2a response. These results suggest that the fusion protein G1F/M2 is potential as a RSV subunit vaccine.

The future of respiratory syncytial virus vaccine development.

Respiratory syncytial virus (RSV) is the leading cause of viral lower respiratory tract illness in infants and children and is an important cause of lower respiratory tract illness in other populations. Despite decades of research there are currently no licensed vaccines for prevention of RSV disease. A review of the obstacles to RSV vaccine development; current live, attenuated and subunit RSV vaccines in clinical development; and the potential for developing additional vaccine candidates based on recombinant technology. A number of biologically derived live attenuated RSV vaccines were evaluated in Phase I clinical trials in adults and children, and one vaccine (cpts 248/404) was evaluated in infants as young as 1 month of age. These vaccines displayed a spectrum of attenuation, with cpts 248/955 being the least attenuated and cpts 248/404 being the most attenuated candidate vaccine. None of these was sufficiently attenuated for young infants. The ability to generate recombinant RSV vaccines has led to the development of large numbers of candidate vaccines containing combinations of known attenuating point mutations and deletions of nonessential genes. Clinical evaluation of many of these candidates is in progress. Three types of RSV subunit vaccines have recently been evaluated in clinical trials: purified F glycoprotein vaccines (PFP-1, PFP-2 and PFP-3), BBG2Na and copurified F, G and M proteins. Additional studies of the F/G/M protein vaccine are being conducted. During the past 10 years, considerable progress has been made in RSV vaccine development. It is likely that different RSV vaccines will be needed for the various populations at risk.

Enhanced pulmonary immunopathology following neonatal priming with formalin-inactivated respiratory syncytial virus but not with the BBG2NA vaccine candidate

Prevention of respiratory syncytial virus (RSV) disease will implicate neonatal priming. However, neonatal antigen exposure frequently results into Th2-like responses, some of which are critical for formalin-inactivated RSV (FI-RSV)-associated lung immunopathology. Neonatal immunization of mice may thus represent a more stringent model of RSV-enhanced pathology than adults. Indeed, after RSV challenge, lung cell infiltration, lymphocyte activation, and eosinophilia were higher following neonatal compared with adult FI-RSV priming of BALB/c mice. Unexpectedly, similar findings were obtained with Al(OH) 3-adsorbed live RSV. In contrast, neonatal priming with BBG2Na, a recombinant RSV subunit vaccine candidate, formulated in either Al(OH) 3 or TiterMax ® (a Th1-driving adjuvant) resulted in predominant Th2- or Th1-like responses, respectively, but never elicited lung immunopathology post-challenge. Importantly, our data emphasize that the induction of Th2-like responses by RSV subunit vaccines do not necessarily imply lung immunopathology.

Differential histopathology and chemokine gene expression in lung tissues following respiratory syncytial virus (RSV) challenge of formalin-inactivated RSV- or BBG2Na-immunized mice.

A BALB/c mouse model of enhanced pulmonary pathology following vaccination with formalin-inactivated alum-adsorbed respiratory syncytial virus (FI-RSV) and live RSV challenge was used to determine the type and kinetics of histopathologic lesions induced and chemokine gene expression profiles in lung tissues. These data were compared and contrasted with data generated following primary and/or secondary RSV infection or RSV challenge following vaccination with a promising subunit vaccine, BBG2Na. Severe peribronchiolitis and perivascularitis coupled with alveolitis and interstitial inflammation were the hallmarks of lesions in the lungs of FI-RSV-primed mice, with peak histopathology evident on days 5 and 9. In contrast, primary RSV infection resulted in no discernible lesions, while challenge of RSV-primed mice resulted in rare but mild peribronchiolitis and perivascularitis, with no evidence of alveolitis or interstitial inflammation. Importantly, mice vaccinated with a broad dose range (20 to 0.02 microg) of a clinical formulation of BBG2Na in aluminium phosphate demonstrated histopathology similar to that observed in secondary RSV infection. At the molecular level, FI-RSV priming was characterized by a rapid and strong up-regulation of eotaxin and monocyte chemotactic protein 3 (MCP-3) relative gene expression (potent lymphocyte and eosinophil chemoattractants) that was sustained through late time points, early but intermittent up-regulation of GRO/melanoma growth stimulatory activity gene and inducible protein 10 gene expression, while macrophage inflammatory protein 2 (MIP-2) and especially MCP-1 were up-regulated only at late time points. By comparison, primary RSV infection or BBG2Na priming resulted in considerably lower eotaxin and MCP-3 gene expression increases postchallenge, while expression of lymphocyte or monocyte chemoattractant chemokine genes (MIP-1beta, MCP-1, and MIP-2) were of higher magnitude and kinetics at early, but not late, time points. Our combined histopathologic and chemokine gene expression data provide a basis for differentiating between aberrant FI-RSV-induced immune responses and normal responses associated with RSV infection in the mouse model. Consequently, our data suggest that BBG2Na may constitute a safe RSV subunit vaccine for use in seronegative infants.

Respiratory syncytial virus vaccine: a systematic overview with emphasis on respiratory syncytial virus subunit vaccines

Objective: To explore whether RSV vaccines are efficacious in preventing respiratory syncytial virus (RSV) lower respiratory infection (LRI). Methods: Randomized clinical trials were sought through Medline using the following search terms: ‘RSV’ or ‘RSV infection’ and ‘viral vaccine’. Randomized controlled trials in adults or children that provided data on clinical outcomes (RSV LRIs, all LRI, all RSV infections) were included. Control groups could receive placebo or another vaccine. Qualitative assessment and summary data were obtained independently by three authors and summarized on a pre-printed form. Where disagreements occurred, the studies were reviewed by all investigators. These disagreements were mainly clerical, such as misinterpretations of the table or text or transcription errors. Consensus was obtained for all studies. Summary statistics consists of relative risk (RR) and number needed to vaccinate to prevent the above outcomes. Results: Because of the outcomes examined, only studies of a purified F protein subunit (PFP) vaccine were included in the meta-analysis. These clinical trials were phase I studies to determine vaccine safety rather than efficacy. Efficacy of PFP-1 or PFP-2 vaccine were analyzed together. A statistically significant RR in overall number of RSV infections was observed RR 0.55 (95%CI, 0.35, 0.88), but the test of heterogeneity was significant raising doubts about the validity of this conclusion. The effect of vaccination on RSV LRI did not reach statistical significance. Conclusions: RSV subunit vaccines were found to reduce the overall incidence of all RSV infections. However, RSV subunit vaccines must be tested in large field trials because of concerns about the appropriateness of pooling, the risk of publication bias and the fact that the clinically important outcome of RSV LRI was not reduced.

BBG2Na an RSV subunit vaccine candidate intramuscularly injected to human confers protection against viral challenge after nasal immunization in mice

Respiratory syncytial virus (RSV) is a major respiratory pathogen responsible for severe pulmonary disease. We have developed a parenterally administered vaccine, BBG2Na, which is currently in a phase III clinical trial. BBG2Na comprises residues 130–230 of RSV-A G protein (G2Na) fused to the BB carrier protein. In this study, we show that BBG2Na can be delivered by the nasal route and generates both mucosal and systemic antibody responses when co-administered with cholera toxin B or a newly described delivery system, zwittergent 3–14. We found that nasal BBG2Na administration protects against RSV challenge and does not induce lung immunopathology upon subsequent RSV challenge.

Residual DNA Quantification in Clinical Batches of BBG2Na, a Recombinant Subunit Vaccine Against Human Respiratory Syncytial Virus

BBG2Na, a well-defined recombinant protein produced in Escherichia coli, is a promising human respiratory syncytial virus subunit vaccine candidate. This study describes the quantification of residual DNA in large scale batches used in phase I to III clinical trials. Two different analytical methods were developed and applied on five different final bulks of Drug Substance and their associated in process control samples, namely a chemiluminescent hybridisation assay and the total DNA Threshold™ System assay. These two complementary methods demonstrated the clearance of residual DNA during the downstream purification process. The amount of residual DNA found in the final bulks was below 20pg of DNA per 300μg BBG2Na, the highest tested clinical dose of antigen. This is very low level of residual DNA for a recombinant subunit vaccine produced in a bacteria and contribute to make for BBG2Na a well-characterised biopharmaceutical. This study also provides data concerning the validation of the hybridisation dot blot assay and the total DNA Threshold™assay.