Chimeric influenza viruses incorporating epitopes of outer membrane protein F as a vaccine against pulmonary infection with Pseudomonas aeruginosa.

Abstract

Peptide 10 (NATAEGRAINRRVE, residues 305-318 of mature protein F) is one of two linear B-cell epitopes within outer membrane protein F of Pseudomonas aeruginosa both of which have been shown to elicit whole cell-reactive antibodies and to afford protection in animal models against P. aeruginosa infection. Influenza A virus was chosen as a vector to present this epitope in a human-compatible vaccine. Various lengths of the peptide 10 epitope ranging from a 5-mer (GRAIN), 7-mer (AINRRVE), 8-mer (TAEGRAIN), 9-mer (GRAINRRVE), 11-mer (AEGRAINRRVE) to a 12-mer (TAEGRAINRRVE) were attempted to be presented into the antigenic B-site of the hemagglutinin (HA) of live recombinant influenza virus. Using PCR, DNA sequences encoding these various peptide 10 lengths were inserted into the HA gene of influenza A/WSN/33 virus. By using a reverse-genetics transfection system, RNA transcribed in vitro from these chimeric HA genes was reassorted into infectious virus. To date chimeric viruses have been rescued and purified containing the peptide 10 5-mer, 7-mer, 8-mer, and 11-mer. RT-PCR and sequencing have confirmed the presence of P. aeruginosa sequences in the HA RNA segment of each chimeric virus. Each of the four chimeric viruses produced to date was used to immunize mice to determine the ability of each chimeric virus to elicit antibodies reactive with whole cells of P. aeruginosa. The immunization protocol consisted of a series of three intranasal inoculations, followed by two intramuscular injections of the chimeric virus. The chimeric virus incorporating the 11-mer elicited IgG antibodies that reacted with various immunotype strains of P. aeruginosa in a whole cell ELISA at titers of 80 to 2,560, whereas the chimeric virus incorporating the 8-mer elicited whole cell-reactive IgG antibodies at titers of 320 to 2,560. These data suggest that these two chimeric viruses may have vaccine efficacy against P. aeruginosa infection. These studies may result in the development of a chimeric influenza virus-protein F vaccine which would prove to be suitable for use in children with cystic fibrosis for the prevention of pulmonary colonization of these children with P. aeruginosa.