Aerosol immunization with NYVAC and MVA vectored vaccines is safe, simple, and immunogenic

Abstract

Each year, approximately five million people die worldwide from putatively vaccine-preventable mucosally transmitted diseases. With respect to mass vaccination campaigns, one strategy to cope with this formidable challenge is aerosol vaccine delivery, which offers potential safety, logistical, and cost-saving advantages over traditional vaccination routes. Additionally, aerosol vaccination may elicit pivotal mucosal immune responses that could contain or eliminate mucosally transmitted pathogens in a preventative or therapeutic vaccine context. In this current preclinical non-human primate investigation, we demonstrate the feasibility of aerosol vaccination with the recombinant poxvirus-based vaccine vectors NYVAC and MVA. Real-time in vivo scintigraphy experiments with radiolabeled, aerosol-administered NYVAC-C (Clade C, HIV-1 vaccine) and MVA-HPV vaccines revealed consistent mucosal delivery to the respiratory tract. Furthermore, aerosol delivery of the vaccines was safe, inducing no vaccine-associated pathology, in particular in the brain and lungs, and was immunogenic. Administration of a DNA-C/NYVAC-C prime/boost regime resulted in both systemic and anal-genital HIV-specific immune responses that were still detectable 5 months after immunization. Thus, aerosol vaccination with NYVAC and MVA vectored vaccines constitutes a tool for large-scale vaccine efforts against mucosally transmitted pathogens.

Fig. 1.

Monitoring aerosol NYVAC-C and MVA-HPV deposition by in vivo real-time scintigraphy. (A) Upper respiratory tract vaccine deposition. The asterisk denotes the muzzle of the animal, and the arrowhead represents vaccine accumulation in the pharynx. (B) Pulmonary vaccine deposition. (C–E) Quantification of vaccine deposition upon aerosol immunization. NYVAC-C, open bars; MVA-HPV, filled bars. Aerosol delivery is expressed as percentage of the total virus inoculum.

Fig. 2.

Histological analysis of various organs after aerosol NYVAC-C and MVA-HPV delivery. (A) Brain. (B) Sinus. (C) Trachea. (D and E) Lung. (F) Normal lung tissue. Samples illustrated in A–D were from NYVAC-C-administered animals. Similar findings were seen in MVA-HPV-administered animals. The level of magnification is provided in the lower left-hand corner of each image. The treatment type is given in the lower right-hand corner. Images are representative of the entire organ.

Fig. 3.

Humoral immune responses induced by aerosol vaccination. (A) Systemic anti-gp120 IgG response. (B) Systemic anti-NYVAC IgG response. (C) Vaginal anti-NYVAC IgA response. Vaccination times are indicated by “D” and “N” for the DNA-C and NYVAC-C vaccines, respectively. Closed bars and open bars represent aerosol and i.m.-immunized animals, respectively.

Fig. 4.

Cellular immune responses induced by aerosol vaccination. Shown are induced HIV-specific IFNg (Left), IL-2 (Center), and IL-4 (Right) systemic cellular immune responses in the two vaccinated cohorts as measured by EILISPOT analysis. The average mean response is illustrated by a gray bar. The responses are the sums of eight HIV peptide pools.

Fig. 5.

Broad-breadth cellular immune responses induced by aerosol vaccination. (A) Percentage of aerosol responders to individual peptide pools. (B) Percentage of i.m. responders to individual peptide pools. Week-8, -24, and -48 responses are shown as white, gray, and black bars, respectively. G, Gag; P, Pol; E, Env; N, Nef.