Mucosal delivery of a vectored RSV vaccine is safe and elicits protective immunity in rodents and nonhuman primates.
Bottom Line: Because RSV infection is restricted to the respiratory tract, we compared intranasal (IN) and intramuscular (M) administration for safety, immunogenicity, and efficacy in different species.In addition, animals primed in the nose developed mucosal IgA against the F protein.In conclusion, we have shown that our vectored RSV vaccine induces potent cellular and humoral responses in a primate model, providing strong support for clinical testing.
Affiliation: ReiThera Srl , Rome, Italy (former Okairos Srl).
Respiratory Syncytial Virus (RSV) is a leading cause of severe respiratory disease in infants and the elderly. No vaccine is presently available to address this major unmet medical need. We generated a new genetic vaccine based on chimpanzee Adenovirus (PanAd3-RSV) and Modified Vaccinia Ankara RSV (MVA-RSV) encoding the F, N, and M2-1 proteins of RSV, for the induction of neutralizing antibodies and broad cellular immunity. Because RSV infection is restricted to the respiratory tract, we compared intranasal (IN) and intramuscular (M) administration for safety, immunogenicity, and efficacy in different species. A single IN or IM vaccination completely protected BALB/c mice and cotton rats against RSV replication in the lungs. However, only IN administration could prevent infection in the upper respiratory tract. IM vaccination with MVA-RSV also protected cotton rats from lower respiratory tract infection in the absence of detectable neutralizing antibodies. Heterologous prime boost with PanAd3-RSV and MVA-RSV elicited high neutralizing antibody titers and broad T-cell responses in nonhuman primates. In addition, animals primed in the nose developed mucosal IgA against the F protein. In conclusion, we have shown that our vectored RSV vaccine induces potent cellular and humoral responses in a primate model, providing strong support for clinical testing.
No MeSH data available.
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Mentions: Because IN delivery can induce local immunity in the respiratory tract at the portal of virus entry,23 we compared T-cell and antibody responses in animals immunized by IM or IN delivery of 5 × 108 vp of PanAd3-RSV. IM immunization with PanAd3-RSV elicited stronger T-cell responses in the spleen compared with IN immunization (geometric mean = 3,224 versus 976 SFC/106 splenocytes), whereas comparable T-cell responses were observed in the lungs (8,300 versus 5,600 SFC/106) (Figure 2c). Low levels of serum antibodies to the F protein were induced 4 weeks after vaccination and unexpectedly, antibody titers were higher following IN vector delivery (Figure 2d). We next challenged BALB/c mice with HRSV, 4 weeks after IM or IN vaccination with 5 × 108 vp of PanAd3-RSV, to explore the effect of the strong Adeno-induced T-cell component in the absence of protective levels of neutralizing antibodies (Figure 3d). Following a high dose challenge with 4 × 106 plaque forming units (pfu) of HRSV, strain A2, vaccinated mice were fully protected against virus replication in the lung (Figure 3a). Importantly, none of the vaccinated animals showed eosinophils (Figure 3c) or increased number of leukocytes in bronchoalveolar lavages (BAL) compared with HRSV-infected, unvaccinated controls (Figure 3b). As expected, low levels of RSV-specific serum IgG were detected in both vaccinated groups at the day of the challenge, and levels of neutralizing antibodies were below the limit of detection in IM vaccinated mice and were log2 4 in IN vaccinated mice (Figure 3d). Following the high dose challenge, all mice lost weight following RSV infection; however, the onset of weight loss was more rapid in vaccinated mice than in controls and less pronounced in IN than in IM vaccinated mice (Figure 3e). IN delivery also showed a better efficacy profile also in terms of lung pathology relative to IM vaccinated mice. In fact, IM delivery induced higher scores of alveolitis (A) compared to either IN vaccinated mice or control animals (Figure 3f).
No MeSH data available.