Enterovirus 71
infection causes significant morbidity and mortality in children, yet there is no effective treatment. In this study, a
protein-bound pigment,
allophycocyanin purified from blue-green algae is first reported to exhibit anti-enterovirus 71 activity.
Allophycocyanin neutralized the enterovirus 71-induced cytopathic effect in both human
rhabdomyosarcoma cells and African green monkey kidney cells. The 50% inhibitory concentration of
allophycocyanin for neutralizing the enterovirus 71-induced cytopathic effect was approximately 0.045 +/- 0.012 microM in green monkey kidney cells. The cytotoxic concentrations of
allophycocyanin for
rhabdomyosarcoma cells and African green monkey kidney cells were 1.653 +/- 0.003 microM and 1.521 +/- 0.012 microM, respectively. A plaque reduction assay showed that the concentrations of
allophycocyanin for reducing plaque formation by 50% were approximately 0.056 +/- 0.007 microM and 0.101 +/- 0.032 microM, when
allophycocyanin were added at the state of viral adsorption and post-adsorption, respectively.
Antiviral activity was more efficient in cultures treated with
allophycocyanin before
viral infection compared with that in the cultures treated after
infection.
Allophycocyanin was also able to delay
viral RNA synthesis in the infected cells and to abate the apoptotic process in enterovirus 71-infected
rhabdomyosarcoma cells with evidence of characteristic DNA fragmentation, decreasing membrane damage and declining cell sub-G1 phase. It is concluded that
allophycocyanin possesses
antiviral activity and has a potential for development as an anti-enterovirus 71 agent.