CD4 + T Cells Drive Lung Disease Enhancement Induced by Immunization with Suboptimal Doses of Respiratory Syncytial Virus Fusion Protein in the Mouse Model (original) (raw)
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Virology, 1999
The relative immunopathogenic potential of a recombinant fusion protein incorporating residues 130-230 of respiratory syncytial virus (RSV-A) G protein (BBG2Na), formalin-inactivated RSV-A (FI-RSV), and phosphate-buffered saline (PBS) was investigated in mice after immunization and RSV challenge. FI-RSV priming resulted in massive infiltration of B cells and activated CD4 ϩ and CD8 ϩ T lymphocytes in mediastinal lymph nodes (MLN) and lungs, where eosinophilia and elevated IFN-␥, IL-2, -4, -5, -10, and -13 mRNA transcripts were also detected. PBS-primed mice showed only elevated pulmonary IL-2 and IFN-␥ mRNAs, while an activated CD8 ϩ T cell peak was detected in MLN and lungs. Cell infiltration also occurred in MLN of BBG2Na-immunized mice. However, there was no evidence of T cell, B cell, or granulocyte infiltration or activation in lungs, while transient transcription of Th1-type cytokine genes was evident. The absence of pulmonary infiltration is unlikely due to insufficient viral antigen. Thus, this recombinant fusion RSV G fragment does not prime for adverse pulmonary immunopathologic responses.
Journal of Virology, 2004
Following respiratory syncytial virus (RSV) challenge, mice immunized with RSV G or with formalininactivated RSV (FI-RSV) exhibit severe disease associated with type 2 cytokine production and pulmonary eosinophilia. This has led to the proposal that the presence of RSV G is the factor in FI-RSV that induces disease-enhancing T-cell responses. Therefore, we evaluated the role of RSV G and its immunodominant region in the induction of aberrant immune responses during FI-RSV immunization. BALB/c mice were immunized with FI preparations of wild-type (wt) RSV or recombinant RSV (rRSV) containing deletions of (i) the entire G gene, (ii) the region of the G gene encoding amino acids 187 to 197 of the immunodominant region, or (iii) the entire SH gene. After challenge, illness, RSV titers, cytokine levels, and pulmonary eosinophilia were measured. Peak RSV titers postchallenge were significantly greater in mice immunized with FI preparations of the deletion viruses than in those immunized with FI-rRSV wt, suggesting that the absence of G or SH in FI-RSV reduced its protective efficacy. Deletion of G or its epitope did not reduce illness, cytokine production, or eosinophilia relative to that in mice immunized with FI-rRSV wt. While cytokine levels and eosinophilia were similar, illness was reduced in mice immunized with SH-deleted FI-RSV. These data suggest that G-specific immune responses may be important for vaccine-induced protection and are not solely the basis for FI-RSV vaccine-enhanced illness. These data suggest that the method of RSV antigen delivery, rather than the protein composition, influences the phenotype of the induced immune responses and that RSV G should not necessarily be excluded from potential vaccine strategies.
Virology, 1997
A subunit approach to the development of a respiratory syncytial virus (RSV) vaccine was investigated. It involved the production, in Escherichia coli, of an RSV (Long) G protein fragment (G2Na) as a C-terminal fusion partner to an albumin binding region (BB) of streptococcal protein G. G2Na incorporated amino acid residues 130 -230 and was specifically recognized by murine anti-RSV-A polyclonal serum. In mice, intraperitoneal immunization with BBG2Na induced high anti-RSV-A serum ELISA titers and low to moderate neutralization activity. The immune response induced by BBG2Na demonstrated a potent protective efficacy against upper and lower respiratory tract RSV-A infection. The immunogenicity and protective efficacy of BBG2Na was maintained for at least 47 and 48 weeks, respectively, and was as potent and durable as live RSV-A administered in a similar fashion. Intramuscular immunization of cotton rats with BBG2Na protected lungs from both homologous and heterologous virus challenge. In contrast to mice, however, cotton rat nasal tracts were not protected after BBG2Na immunization. Consistent with antibody-mediated protection, virus was cleared within 24 hr from the lungs of BBG2Na-immunized mice. The anti-RSV-A antibodies induced in mice were exclusively of the IgG1 isotype and were detected in the serum, lungs, and nasal tracts. Passive transfer of these antibodies prevented acute, and eliminated chronic, RSV-A lung infection in normal and immunodeficient mice, respectively, confirming that such antibodies are important and sufficient for BBG2Na-induced pulmonary protection. Our results clearly demonstrate that BBG2Na contains an important immunogenic domain of the RSV G protein. The prokaryotic origin of this protein indicates that glycosylation of the RSV G protein is not necessary for protective efficacy. Thus, BBG2Na has potential as an RSV subunit vaccine. ᭧ 1997 Academic Press et al., 1991); (5) residues 163-190 and 160-189 of sub-155
Journal of virology, 2017
Respiratory syncytial virus (RSV) infection of children previously immunized with a non-live, formalin-inactivated (FI)-RSV vaccine was associated with serious enhanced respiratory disease (ERD). Consequently, detailed studies of potential ERD are a critical step in the development of non-live RSV vaccines targeting RSV-naïve children and infants. The fusion glycoprotein (F) of RSV in either its post- or pre-fusion conformation is a target for neutralizing antibodies and therefore an attractive antigen candidate for a pediatric RSV subunit vaccine. Here we report the evaluation of RSV post-F and pre-F in combination with GLA-SE and Alum adjuvants in the cotton rat model. Immunization with optimal doses of RSV F antigens in the presence of GLA-SE induced high titers of virus neutralizing antibodies, and conferred complete lung protection from virus challenge, with no ERD signs in the form of alveolitis. To mimic a waning immune response, and to assess priming for ERD under suboptimal...
Pathogenesis of RSV lower respiratory tract infection: implications for vaccine development
Vaccine, 2001
Respiratory syncytial virus (RSV) infection is the most prevalent cause of severe respiratory disease in infants. It also causes considerable morbidity in older children and adults with underlying risk factors. RSV vaccine development has been complicated by the need to administer the vaccine at a very young age and by enhanced disease observed after vaccination with formalin inactivated RSV. For infants live attenuated vaccines, which may not be expected to predispose for vaccine induced enhanced pathology, hold the greatest promise. However, the balance between attenuation and immunogenicity appears to be delicate. For older risk groups, results with subunit vaccines are most promising.
Journal of Virology, 1987
Vaccinia virus (W) recombinants were constructed that contained full-length cDNA copies of the fusion (F) protein gene of human respiratory syncytial (RS) virus. The F protein gene was placed next to the strong early-late VV 7.5-kilodalton promoter and was located within the VV thymidine kinase (tk) gene. Full-length recombinant transcripts that initiated at both the tk and the 7.5-kilodalton promoters accumulated in cells early in infection, and one or more of these transcripts was translated to yield a glycoprotein which comigrated with F., the fusion protein precursor. This precursor was processed by proteolytic cleavage to produce the two disulfide-linked subunits F, and F2, which were both glycosylated and of the same electrophoretic mobility as authentic F, and F2. Immunofluorescence studies demonstrated that the mature F protein was transported to and expressed on the surface of recombinant W-infected cells. Inoculation of rabbits with a recombinant vector expressing F resulted in the production of antiserum specific for the RS virus F protein. This antiserum neutralized virus infectivity and was capable of preventing fusion in RS virus-infected cells. Mice were vaccinated with recombinants expressing the F protein. At 3 weeks postinoculation, these animals had serum antibody against RS virus F protein. At 5 days after intranasal challenge with RS virus, the lungs of the mice previously vaccinated with recombinants expressing F protein were free of detectable RS virus, whereas the lungs of unvaccinated mice contained 104.2 PFU of virus per g.
Respiratory syncytial virus (RSV) vaccines—Two steps back for one leap forward
Journal of Clinical Virology, 2008
Respiratory viruses are among the most important causes of morbidity and mortality worldwide. From a vaccine viewpoint, such viruses may be divided into two principle groups-those where infection results in long-term immunity and whose continued survival requires constant mutation, and those where infection induces incomplete immunity and repeated infections are common, even with little or no mutation. Influenza virus and respiratory syncytial virus (RSV) typify the former and latter groups, respectively. Importantly, successful vaccines have been developed against influenza virus. However, this is not the case for RSV, despite many decades of research and several vaccine approaches. Similar to natural infection, the principle limitation of candidate RSV vaccines in humans is limited immunogenicity, characterised in part by short-term RSV-specific adaptive immunity. The specific reasons why natural RSV infection is insufficiently immunogenic in humans are unknown but circumvention of innate and adaptive immune responses are likely causes. Fundamental questions concerning RSV/host interactions remain to be addressed at both the innate and adaptive immune levels in humans in order to elucidate mechanisms of immune response circumvention. Taking the necessary steps back to generate such knowledge will provide the means to leap forward in our quest for a successful RSV vaccine. Recent developments relating to some of these questions are discussed.
Virology, 1997
A subunit approach to the development of a respiratory syncytial virus (RSV) vaccine was investigated. It involved the production, in Escherichia coli, of an RSV (Long) G protein fragment (G2Na) as a C-terminal fusion partner to an albumin binding region (BB) of streptococcal protein G. G2Na incorporated amino acid residues 130 -230 and was specifically recognized by murine anti-RSV-A polyclonal serum. In mice, intraperitoneal immunization with BBG2Na induced high anti-RSV-A serum ELISA titers and low to moderate neutralization activity. The immune response induced by BBG2Na demonstrated a potent protective efficacy against upper and lower respiratory tract RSV-A infection. The immunogenicity and protective efficacy of BBG2Na was maintained for at least 47 and 48 weeks, respectively, and was as potent and durable as live RSV-A administered in a similar fashion. Intramuscular immunization of cotton rats with BBG2Na protected lungs from both homologous and heterologous virus challenge. In contrast to mice, however, cotton rat nasal tracts were not protected after BBG2Na immunization. Consistent with antibody-mediated protection, virus was cleared within 24 hr from the lungs of BBG2Na-immunized mice. The anti-RSV-A antibodies induced in mice were exclusively of the IgG1 isotype and were detected in the serum, lungs, and nasal tracts. Passive transfer of these antibodies prevented acute, and eliminated chronic, RSV-A lung infection in normal and immunodeficient mice, respectively, confirming that such antibodies are important and sufficient for BBG2Na-induced pulmonary protection. Our results clearly demonstrate that BBG2Na contains an important immunogenic domain of the RSV G protein. The prokaryotic origin of this protein indicates that glycosylation of the RSV G protein is not necessary for protective efficacy. Thus, BBG2Na has potential as an RSV subunit vaccine. ᭧ 1997 Academic Press et al., 1991); (5) residues 163-190 and 160-189 of sub-155