OBJECTIVE: In order to investigate antibody responses by musosal DNA vaccines encoding the codon-optimized F protein of human respiratory syncytial virus (RSV) delivered with attenuated Salmonella typhimurium aroA strain SL7207 (SL7207) via intranasal or intragastric routes. METHODS: After the codon-optimized F gene was synthesized, we constructed eukaryotic expression plasmid pcDNA3.1/Fsyn and transformed it into SL7207 to get recombinant SL7207 of SL7207/pcDNA3.1/Fsyn. Then, SL7207/pcDNA3.1/Fsyn was exploited to evaluate its immunogenicity in BALB/c mice administered intranasally or intragastrically. The resultant serum and mucosal antibody responses were analyzed by indirect ELISA. RESULTS: Compared with intragastric immunization group, intranasal immunization group achieved higher level of RSV specific serum IgG and secretion IgA (SIgA) (P < 0.05). Moreover, F protein expressed by the codon-optimized F gene of Fsyn was of elevated immunogenicity, compared with wild type F (Fwt) (P < 0.05). CONCLUSION: Intranasal immunization and codon optimization approaches can improve antibody responses of RSV DNA vaccine delivered by attenuated Salmonella typhimurium aroA strain SL7207.
OBJECTIVE: In order to investigate antibody responses by musosal DNA vaccines encoding the codon-optimized F protein of human respiratory syncytial virus (RSV) delivered with attenuated Salmonella typhimurium aroA strain SL7207 (SL7207) via intranasal or intragastric routes. METHODS: After the codon-optimized F gene was synthesized, we constructed eukaryotic expression plasmid pcDNA3.1/Fsyn and transformed it into SL7207 to get recombinant SL7207 of SL7207/pcDNA3.1/Fsyn. Then, SL7207/pcDNA3.1/Fsyn was exploited to evaluate its immunogenicity in BALB/c mice administered intranasally or intragastrically. The resultant serum and mucosal antibody responses were analyzed by indirect ELISA. RESULTS: Compared with intragastric immunization group, intranasal immunization group achieved higher level of RSV specific serum IgG and secretion IgA (SIgA) (P < 0.05). Moreover, F protein expressed by the codon-optimized F gene of Fsyn was of elevated immunogenicity, compared with wild type F (Fwt) (P < 0.05). CONCLUSION: Intranasal immunization and codon optimization approaches can improve antibody responses of RSV DNA vaccine delivered by attenuated Salmonella typhimurium aroA strain SL7207.