Evaluation of Measles Vaccine Virus as a Vector to Deliver Respiratory Syncytial Virus Fusion Protein or Epstein-Barr Virus Glycoprotein gp350

Mok, Hoyin; Cheng, Xing; Xu, Qi; Zengel, James R; Parhy, Bandita; Zhao, Jackie; Wang, C. Kathy; Jin, Hong

Cotton rats had previously been demonstrated to be semipermissive to measles virus infection [40] and are the best available small animal model for MV infection. In addition, cotton rats are susceptible to RSV infection and have been used in the evaluation of RSV vaccines [41, 42] and anti-RSV antibody investigated for prophylactic application [43] . The ability of rEZ vectored vaccines to induce humoral responses to measles virus and RSV F or EBV gp350 protein were assessed in cotton rats. Cotton rats were immunized Fig. (2) . Growth kinetics of measles vectors encoding soluble RSV F or soluble EBV gp350 was similar to that of recombinant measles constructs. Vero cells were infected at MOI of 0.01 with measles vectors. Cells were incubated at 35 o C for 7 days. Cells and supernatant were sampled daily for virus titers using standard plaque assay. * denotes statistically significant difference in titer of sF3 versus sF1, rEZ and EZ using the Kruskal-Wallis test. Fig. (3) . RSV F-specific and EBV gp350-specific splenocytes were induced in the spleens of cotton rats immunized i.m. with measles vectors. Cotton rats were vaccinated on days 0 and 28 with measles vectors. Splenocytes were harvested 7 days after the second measles vectors vaccination. A total of 3 x 10 5 cells were stimulated with either RSV F protein (A and C) or EBV gp350 protein (B and D) in vitro for 20 h, and the numbers of IFN-spot-forming cells (A and B) and IL-4 spot-forming cells (C and D) were quantified by an ELISPOT assay. Spots were counted with an automated counting device and are expressed as numbers of spots per 10 6 cells. Groups are compared using Mann-Whitney rank sum test. Each symbol represents an individual animal. Table 1) . The control animals vaccinated with UVinactivated sF3 or RSV A2 virus did not have detectable MV Ab titer (data not shown).