Blood 110:3472C3479 [PubMed] [Google Scholar] 18

Blood 110:3472C3479 [PubMed] [Google Scholar] 18. not in the marrows of RSV-immunized mice. Adoptive transfer of enriched splenic B cells from VLP-immunized mice into immunodeficient for seven consecutive days every other week (39). All protocols requiring open cages were accomplished in biosafety cabinets. BALB/c mice were immunized by intramuscular (i.m.) inoculation of 10 to 30 g of total VLP protein in 0.05 ml of phosphate-buffered saline (PBS) containing 10% sucrose. For contamination of wild-type BALB/c or test) of the data were accomplished using GraphPad Prism 5 software. RESULTS Long-term antibody responses to VLP-H/G+F/F and RSV. To assess the ability of VLPs made up of both the RSV F protein and G protein ectodomains to induce persistent levels of serum antibodies to the RSV proteins, the anti-F and anti-G protein antibody titers Rabbit Polyclonal to LMO3 were measured, by ELISA, periodically over 430 days after a single immunization and compared to mice infected intranasally (i.n.) with a single dose of RSV. Imexon VLPs made up of the RSV F and G Imexon protein ectodomains (VLP-H/G+F/F) were purified and characterized as previously explained (23). Groups of five mice were injected, intramuscularly (i.m.) to mimic vaccination, with either 10 or 30 g of total VLP/mouse, whereas another group of mice was infected i.n. with RSV to mimic natural infection. Unfavorable control groups received bufferC10% sucrose i.m. Sera were collected from these animals from 30 to 430 days, and the total anti-F and anti-G protein IgG antibody titers with time are shown in Fig. 1A and ?andB,B, respectively. VLP immunization resulted in strong anti-F and anti-G protein IgG antibody titers that remained relatively constant for 430 days. Similarly, serum anti-F and anti-G protein anti-IgG antibody titers after i.n. contamination with RSV remained relatively constant over the course of the experiment, even though titers were lower than those observed with VLP immunization. These results are consistent with the VLP activation of long-lived antibody responses in the absence of adjuvants at both Imexon doses of VLP tested. Open in a separate windows Fig 1 Titers of serum anti-F and anti-G protein antibodies with time after immunization or contamination. Groups of five BALB/c mice were immunized i.m. with VLP-H/G+F/F. One group received 10 g of total VLP/mouse (0.7 g of F protein and 0.8 g of G protein) or 30 g of total VLP protein/mouse (2.1 g of F protein and 2.4 g of G protein). Antibody titers in sera, with time after immunization, were measured as explained in Materials and Methods. Another group of five mice was infected with RSV i.n. (2.25 106 PFU/mouse). Mice immunized i.m. with PBS (50 l) served as negative controls. (A) Anti-F protein Imexon antibody titers; (B) anti-G protein antibody titers. Long-term neutralizing antibody responses to VLP-H/F+F/F and infectious RSV. In humans, whereas RSV contamination may result in detectable antibody responses that persist for some time, protective responses diminish rapidly, resulting in susceptibility to subsequent infection in many individuals (examined in recommendations 8 and 35). To assess the longevity of neutralizing antibody responses in the murine system, the neutralization titers of sera obtained over time after VLP immunization or RSV contamination were decided. Figure 2 shows that the neutralizing antibody titers after VLP immunization were maximal by 60 to 100 days and, while decreasing slightly between 125 and 430 days, remained high for 14 months. However, after RSV i.n. contamination, serum neutralizing antibodies levels failed to reach those seen with VLP immunization and declined markedly by 100 days, despite the fact that total anti-F and G protein IgG antibody titers Imexon were relatively stable after RSV contamination. These results suggest that VLP immunization produced an antibody response that is different in character than that induced by RSV.