The data were analyzed using the GraphPad Prism 4 ver. 4.03 software (GraphPad Software, La Jolla, CA). Data are presented as mean ± SD. Difference between CCR5−/− mice and CCR5+/+ mice were compared using t test. A value of p<0.05 was considered to be statistically significant. Survival data were presented by Kaplan-Meier survival estimates and compared and calculated by Log-rank (Mantel-Cox) Test in GraphPad Prism.