Combining DNA and protein vaccines for early life immunization against respiratory syncytial virus in mice

Abstract

Early life responses to respiratory syncytial virus (RSV)‐F DNA and RSV‐F protein immunization were studied in murine models of neonatal immunization. RSV‐F DNA induced similar antibody (Ab) responses, antigen‐specific IFN‐γ production and cytotoxic T lymphocyte (CTL) responses in 1‐week‐old and adult BALB / c mice. In contrast, RSV‐F protein induced much higher IL‐5 responses in early life. Both vaccines elicited Ab and CTL responses in spite of maternal Ab, but with distinctive kinetics. Sequential RSV‐F DNA priming / protein boosting primed 1‐week‐old mice for RSV‐F‐specific CTL responses, reduced IL‐5 production and enhanced Ab responses. In contrast, IL‐5 exceeded IFN‐γ responses when young mice were primed with protein and boosted with DNA. Last, when protein and DNA immunization were combined, a single vaccine dose induced early Ab responses, preferential IL‐5 responses but strong CTL responses. Sequential or combined DNA / protein immunization thus represent interesting strategies for early life immunization.

Fusion to C3d Enhances the Immunogenicity of the E2 Glycoprotein of Type 2 Bovine Viral Diarrhea Virus

“…End-point titers were calculated as the reciprocal of the last serum dilution that gave a value 2.1-fold higher than the preimmune serum. Antibody titers below the cutoff of the assay were assigned an arbitrary titer one-half the cutoff in order to allow calculation of the geometric mean of the titers (29).…”

Immunization with non-replicating E. coli minicells delivering both protein antigen and DNA protects mice from lethal challenge with lymphocytic choriomeningitis virus

“…There is mounting evidence to suggest that the administration of both DNA and the corresponding protein antigen vaccines, either sequentially or in combination, is more effective at generating robust immune responses [23][24][25]. Preliminary studies suggest that minicells codelivering a eukaryotic expression plasmid and the corresponding protein antigen could generate much higher antigen-specific serum IgG antibody responses when administered intramuscularly (i.m.)…”

In vitro expression of full-length and truncated bovine respiratory syncytial virus G proteins and their antibody responses in BALB/c mice

“…Similarly, others have demonstrated a detectable anti-HRSV G IgG response in BALB/c mice following plasmid DNA immunization [24][25][26][27]. The anti-BRSV G IgG titers (1:80) were similar among each of the three treatment groups (i.e.…”

“…Immunization of mice with plasmid DNA encoding the HRSV F protein induced virus-neutralizing antibodies, CTLs, high levels of interferon-γ (IFN-γ), and protection against infection following viral challenge [23,24]. Moreover, immunization of mice with plasmid DNA encoding full-length or secreted HRSV G resulted in a balanced Th1/Th2 response following virus challenge, similar to that observed during a natural infection [25,26].…”