Abstract:

Meliacine, a peptide associated with antiviral activity isolated from the high plant Melia azedarach L (MA) inhibits the replication of different strains of foot and mouth disease virus (FMDV) and poliovirus in BHK-21 or Vero cells, respectively, infected at a multiplicity of infection (m.o.i.) of 1. A leaf extract of MA, containing meliacine was added to the culture medium after virus adsorption and maintained up to virus harvest (18 hs). FMDV O1 Campos and O69 strains showed 60% and 52% inhibition, respectively. A24 and A87 strains proved to be inhibited more than 90%, and the C3 Resende and O1 Case-ros strains were not sensitive to the extract. Regarding the three types of poliovirus, the most susceptible one was type 1 (84%). Types 2 and 3 were inhibited only 69% and 32%, respectively. Treatment of the cells with the antiviral for 24 hours before infection (pretreatment), was not effective for the two above mentioned viruses. Since the extract of MA is very active against other RNA viruses (i.e. vesicular stomatitis virus), the susceptibility of FMDV strain O1 Campos and poliovirus type 3 was tested using lower m.o.i. The results showed that MA produced an inhibition of viral replication of 99% at a m.o.i. of 0.001 in both cases. These results suggest that picornaviruses are also susceptible to MA. However, to demonstrate its antiviral effect it is necessary to slow down the rate of virus-cell killing by reducing the m.o.i.