Comparative assessment of β-propiolactone, binary ethyleneimine and formaldehyde in inactivating Foot and Mouth Disease virus serotype O

Inactivation of foot-and-mouth disease virus (FMDV) with Formalin (FA) and binary ethyleneimine (BEI) is a slow process and takes long time.The purpose of this study was to evaluate β-Propiolactone (BPL), an alkylating agent that is frequently used in vaccine development and production, as a candidate for the inactivation of FMDV serotype O. Virus was grown on confluent monolayer of BHK-21 cell line.Harvesting was performed between 18 and 20 hours after infection, when CPE was between 90 and 95%.The virus was subjected to inactivation with formalin (0.02%), BEI (2mM, 2.5mM, 3mM) and BPL (0.1%, 0.2 and 0.4%) at 4°C and 37°C.Samples (05 mL/each) were collected after 0, 2, 4, 8, 16, and 24 hours post treatment.The biological titer (TCID50/ml) of each inactivated sample was measured.An innocuity test was used to further confirm the inactivation.RT-PCR was used to detect viral genome damage by amplification of VP1 gene.Data were analyzed by one-way analysis of variance and pair wise comparison was made by post hoc Tukey's HSD test.Linear regression was used in Microsoft Excel Version 2010.The virus titers after 0.02% formalin treatment were 7.172±0.298and 4.584±1.362at 4°C and 37°C respectively.The virus titers were 6.036±0.513,5.622±0.298,and 5.150±0.449with 2mM, 2.5mM, 3mM BEI at 4°C and 1.646±1.0210,1.050±0.644,0.492±0.492at 37°C respectively.Inactivation with 0.1%, 0.2% and 0.4% BPL at 4°C resulted in virus titers of 2.386±1.1104,1.4400±0.9445and 0.6960±0.6960respectively.Rapid inactivation of virus with all three BPL concentrations at 37°C gave mean titer of 0.00±0.00.There was a significant difference (P<0.05)among all treatment groups with highest inactivation rates recorded for BPL.