Nature 254, 328 - 329 (27 March 1975); doi:10.1038/254328a0

Enzyme synergistic for insect viruses

YOSHINORI TANADA^* & SABURO HARA^†

^*Division of Entomology and Parasitology, University of California, Berkeley, California 94720
^†Department of Chemistry, Osaka University College of Science, Toyonaka, 560, Japan

A GRANULOSIS virus (GV) and a nuclear-polyhedrosis virus (NPV) of the armyworm, Pseudaletia unipuncta, form a synergistic association in which the infection of the NPV is enhanced¹. The synergistic factor responsible for the enhancement (56-fold) occurs in the protein of the inclusion body (capsule) that surrounds the particle of GV^2,3. This factor is present in detectable quantities in one strain of GV (Hawaiian) but not in another (Oregonian)^4,5. It has been purified by Sephadex gel filtration and seems to be a simple or conjugated protein³. We now report that the synergistic factor has properties of an enzyme and can enhance not only the NPV and GV of the armyworm but also other insect viruses. Earlier studies^1,2 had shown that the synergistic factor was heat labile. It became inactive when heated at 85 °C for 10 min (ref. 1). The viral activity, on the other hand, was destroyed at 75 °C for 10 min.

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