Echinhibin-1 - an inhibitor of Sendai virus isolated from the venom of the snake Echis coloratus

Gadi Borkow, Michael Ovadia

Research output: Contribution to journalArticlepeer-review

Abstract

The snake venom of Echis coloratus was found to abolish the hemagglutinating activity, hemolytic activity and in vivo infectivity of Sendai virus. The active factor (Echinhibin-1) was purified by gel filtration on Sephadex G-50, followed by chromatography on DEAE-Sepharose and CM-Sepharose. Echinhibin-1 is a protease with a molecular weight of about 25 kDa, an isoelectric point of 7 and is stained by PAS, indicating that it is a glycoprotein. It showed a strong azocollase activity that was stable up to 68°C and at pH values of 4.5-10.5. Ten μg/ml were sufficient to abolish the hemolytic effect of the virus on human erythocytes when inculbation was at 37°C for 2 h, while 20 μg/ml abolished the hemagglutinating activity. Addition of Echinhibin-1 after the adsorption of Sendai virions onto washed erythrocytes at 4 °C did not inhibit the subsequently hemolytic activity at 37 °C, indicating that Echinhibin-1 interferes with virus adsorption to the cells. Of various protease inhibitors, only Na2 EDTA and o-phenanthroline inhibited the antiviral activity of the purified factor, indicating that it is a metalloproteinase. In vivo, mice inoculated intranasally with the virus pretreated with Echinhibin-1 developed well and gained weight, whereas untreated virus-infected mice lost weight and died within 1 week. Intravenous administrations of the purified factor up to 80 μg/mouse produced no signs of toxicity and subcutaneous injections caused no hemorrhagic activity, while the whole venom is very hemorrhagic with an LD50 of 250 μg/kg for mice.

Original languageEnglish
Pages (from-to)161-176
Number of pages16
JournalAntiviral Research
Volume23
Issue number2
DOIs
StatePublished - Feb 1994

Keywords

  • Antiviral protease
  • Echinhibin-1
  • Sendai virus
  • Snake venom

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