Effect of butylated hydroxyl toluene on the immune response of Rift Valley fever vaccine in a murine model.

The present study was planned to examine the effect of butylated hydroxy toluene (BHT) on the immune response of Rift Valley fever vaccine (RVFV) in Swiss mice. Animals were divided into four equal groups. The first group was kept as negative control. The 2nd group was orally administrated with the acceptable daily intake (ADI) of BHT 0.3 mg/kg b.wt. daily for 21 days and the 3rd group were vaccinated only by inactivated RVFV at a dose of 0.2 ml I/P two times. The 4th group was orally administrated BHT as in the 2nd group and vaccinated by inactivated RVFV as in the 4th group. Blood samples were collected from all groups two weeks from booster vaccination. The cellular immunity was determined by leucocytic indices and the neutrophil-lymphocyte ratio (NLR) whereas, humoral immunity was evaluated with IgG antibodies titer using enzyme-linked immune-sorbent assay (ELISA) test, serum neutralization test (SNT) and challenge test. BHT induced leucopenia, neutrophilia and marked lymphocytopenia in both non-vaccinated and vaccinated mice. Moreover, BHT significantly decreased the efficiency of vaccination by inducing 70% cytopathic effect (CPE) in the infected cell cultures and increasing the ED50 value of RVFV vaccine. The present study indicates that BHT possesses a potential for decreasing both cellular and humoral mediated mechanisms.