Enhanced Disease and Pulmonary Eosinophilia Associated with Formalin-Inactivated Respiratory Syncytial Virus Vaccination Are Linked to G Glycoprotein CX3C-CX3CR1 Interaction and Expression of Substance P

Abstract

Vaccination with formalin-inactivated respiratory syncytial virus (FI-RSV) vaccine or RSV G glycoprotein results in enhanced pulmonary disease after live RSV infection. Enhanced pulmonary disease is characterized by pulmonary eosinophilia and is associated with a substantial inflammatory response. We show that the absence of the G glycoprotein or G glycoprotein CX3C motif during FI-RSV vaccination or RSV challenge of FI-RSV-vaccinated mice, or treatment with anti-substance P or anti-CX3CR1 antibodies, reduces or eliminates enhanced pulmonary disease, modifies T-cell receptor V␤ usage, and alters CC and CXC chemokine expression. These data suggest that the G glycoprotein, and in particular the G glycoprotein CX3C motif, is key in the enhanced inflammatory response to FI-RSV vaccination, possibly through the induction of substance P.Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections in infants and young children (1,50,54,59). RSV can also cause serious lower respiratory tract disease in patients of any age with compromised immune, respiratory, or cardiac systems (7,13,14,20,26,60,62). Despite the importance of RSV as a respiratory pathogen, there is presently no safe and effective RSV vaccine available. The first RSV vaccine trial with a formalin-inactivated RSV (FI-RSV) vaccine yielded disastrous results in young vaccinees who were subsequently naturally infected with RSV, as many developed enhanced pulmonary disease leading to hospitalization, and even to death in a few vaccine recipients (5,17,73). This outcome prompted investigators to search for viral and/or host factors that may contribute to enhanced disease in the effort to ensure that RSV vaccines would be safe.Studies with BALB/c mice have provided some indication of the mechanisms that may have contributed to FI-RSV-enhanced pulmonary disease. BALB/c mice vaccinated with vectors expressing G glycoprotein, purified G glycoprotein, or FI-RSV develop extensive enhanced pulmonary disease characterized by pulmonary eosinophilia, weight loss, exaggerated Th2-type cytokine responses, selective priming of V␤14 ϩ CD4ϩ T cells, and augmented substance P (SP) expression when challenged with RSV (23,27,51,68,70,71). Interestingly, the soluble form of the G glycoprotein has been shown to be most effective at sensitizing for enhanced disease (34, 35). Studies from our laboratory comparing the immune responses to infection with wild-type RSV or an RSV mutant lacking the G and SH genes have shown that RSV G and/or SH glycoprotein expression alters pulmonary trafficking of innate immune cells (CD11b ϩ cells, polymorphonuclear cells [PMN], and NK cells), Th1-and Th2-type cytokine patterns, and CC and CXC chemokine mRNA expression by bronchoalveolar lavage (BAL) cells and is associated with increased pulmonary SP expression (64,67,68). In addition, recent studies from our laboratory have shown that the G glycoprotein contains a CX3C chemokine motif that interacts with the CX3C chemokine receptor CX3CR1, induces leukocyte chemo...

Formulation with CpG Oligodeoxynucleotides Prevents Induction of Pulmonary Immunopathology following Priming with Formalin-Inactivated or Commercial Killed Bovine Respiratory Syncytial Virus Vaccine

“…Enhanced disease and pulmonary eosinophilia associated with FI-HRSV were reported in the 1960s, when a disease-exacerbating FI vaccine was administered to infants and children in the United States (9,17,35,61), and were also demonstrated in mice (12,20,25,28,44). In the present study, the percentage of eosinophils was 34% in the lungs of mice vaccinated with FI-BRSV, while this was reduced to 1% when CpG ODN was added.…”

Antibody-dependent enhancement and vaccine development

“…A similar enhancement is also seen when mice are sensitized with the RSV-G glycoprotein [16] or vaccinia virus expressing the secreted form of the RSV G glycoprotein [17]. The severe disease that followed challenge with RSV was associated with elevated levels of IL-4, -5, -13 and eotaxin [18].…”

“…Early trials with formalin-inactivated respiratory syncytial virus (FI-RSV) found that the vaccines not only did not protect children against RSV but also appeared to increase the attack rate and clinical severity of later natural infection with RSV [13][14][15], possibly contributing to some deaths [16]. It has been suggested that exacerbation of disease after RSV vaccination and, possibly also in the presence of maternal antibodies, was also due to ADE mechanisms during later natural infections with RSV [13].…”

Treatment with respiratory syncytial virus G glycoprotein monoclonal antibody or F(ab′)2 components mediates reduced pulmonary inflammation in mice

“…Through this motif, the RSV G protein binds to the fractalkine receptor, CX3CR1, and this interaction facilitates virus infection and modulates leukocyte chemotaxis (Tripp et al, 2001), including adversely affecting CX3CR1 + T cell responses (Harcourt et al, 2006). Studies have shown that antibodies that block G protein CX3C-CX3CR1 interaction protect against some of the G protein-associated enhanced inflammation observed after RSV infection (Haynes et al, 2003). In addition, anti-RSV G protein antibody responses after natural infection or vaccination with live-attenuated RSV vaccine in young children are associated with the inhibition of G protein-mediated human leukocyte migration and G protein CX3C-CX3CR1 interaction (Harcourt et al, 2004).…”