Effect of some compounds on propagation of Rift Valley Fever virus on tissue culture

Abstract EN

The effect of four salts (CaCl2 ; CaHPO4 ; MSG and DEA-dextran) was investigated in the nutrient media overlaying Rift Valley Fever (RVFV) infected Vero cell monolayer in an attempt to maximize the virus titre of the obtained infected fluids.

Prior safety testing of these salts carried out on Swiss albino mice.

Toxicity test on vero cells revealed absolute safety with MSG.

The least toxic salts were DEA-dextran and CaCl2.

CaHPO4 showing moderate toxicity.

MSG enhanced the detection of CPE of RVFV in vero cells.

Maximum TCID50 titres were obtained with CaCl2 (8.2 – 8.5 log10).

While the lowest titer was detected with MSG (7.5 – 7.8 log10).

Maximum mice lethal infective dose (MLID50) titres were found with DEA-dextran (7.8 – 8.0 log10).

The lowest value was found with MSG (6.0 log10).

The use of either CaCl2 or CaHPO4 improved the thermotolerance of the virus stored at 4ºC (7 log10 TCID50 titres after 48 hours exposure).

At 37ºC, CaCl2 was the best to be used (3.5 log10 TCID50, 48 hours exposure).

Cryostability potentiality at (-20ºC) was best with both CaCl2 and DEA-dextran showing virus titers of (6.8 log10 TCID50 after 6 months exposure) and at -70ºC, the use of CaCl2 proved to potentiate cryostability with a titer of (8.0 log10 TCID50 after 6 months exposure).

The obtained results would be of value in RVFV-vaccine production.