Mode of inhibition of respiratory syncytial virus by a plant flavonoid, SP-303.
A natural-product polyphenolic polymer of molecular weight 2,100 daltons designated SP-303, was found to have antiviral activity against respiratory syncytial virus (RSV) in the 2-10 microM range in plaque reduction assays and cytopathic-effect-inhibition assays. The material was also virucidal. The 50% effective concentration (EC50) for virucidal activity was 28 microM. Experiments were done to determine the mode(s) of RSV inhibition by SP-303. Interferon was not induced. SP-303 did not inhibit attachment at antiviral concentrations. However, the EC50 for inhibition of virus penetration by SP-303 was 0.48 +/- 0.19 microM. These data suggest that abolition of RSV penetration into host cells is one mechanism whereby SP-303 inhibits RSV replication.
Institute for Antiviral Research, Utah State University, Logan.
D L
DL
Barnard
J H
JH
Huffman
L R
LR
Meyerson
R W
RW
Sidwell
D000998:Antiviral Agents / Q000494:pharmacology*; D001704:Biopolymers / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D012136:Respiratory Syncytial Viruses / Q000187:drug effects* / Q000254:growth & development; D010948:Viral Plaque Assay; D044945:Proanthocyanidins
D000998:Antiviral Agents; D001704:Biopolymers; D002392:Catechin; C546704:crofelemer; D044945:Proanthocyanidins