Current Topics in Microbiology and Immunology Ergebnisse der Mikrobiologie und Immunitatsforschung Edited by WArber, Geneve . WBraun, New Brunswick· F. Cramer, Giittingen . R.Haas, Freiburg WHenle, Philadelphia . P. H. Hofschneider, Munchen . N. K. ferne, Frankfurt W. Kikuth, Dusseldorf· P. Koldovsky, Prague· H. Koprowski, Philadelphia· O. Maaloe, Berkelry . R. Rott, Giefen . H.-G. Schweiger, Wilhelmshaven . M. Sela, Rehovoth L. Syrucek, Prague . P. K. Vogt, Denver . E. Wecker, Wurzburg Volume 42 Springer-Verlag New York Inc. 1968 Insect Viruses Edited fD; Karl Maramorosch With 34 Figures Springer-Verlag New York Inc. 1968 Karl Maramorosch, Ph. D., Boyce Thompson Institute tor Plant Research, 1086 North Broadway, Yonkers, N. Y. 10701jUSA lSBN-13: 978-3-642-46117-0 e-lSBN-13: 978-3-642-46115-6 DOl: 10.1007/978-3-642-46115-6 AIl rights reserved. No part of this book may be translated or reproduced in any form without written permission from Springer Verlag. ©by Springer-Verlag Berlin· Heidelberg ·1968. Library of Congress Catalog Card Number 15-12910. Softcover reprint of the hardcover 1st edition I!)1iS The use of general descriptive names, trade names, trade marks, etc. in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. Title No. 4690. Introduction This volume contains seven chapters, based on papers presented at a Symposium on Insect Viruses, held in conjunction with the 67th Annual Meeting of the American Society for Microbiology in New York, N. Y., on 30 April-4 May, 1967. The Symposium was organized to bring together outstanding workers interested in various areas of insect virology, and allow an opportunity for a discussion of problems, approaches, and methods that would lead to further progress in basic and applied research. One of the princi pal reasons for holding the Symposium at this time was the feeling that the divergent areas of research, up to now studied separately by entomologists, medical and public health workers, geneticists, and plant pathologists, would be brought together, crossing the artificial borders and finding new, exciting and inspiring vistas. Insect viruses provide a rare opportunity to get acquainted with the work and methods of investigators in such related and yet distant fields. Following the symposium, a decision was made to publish the papers in a single volume, extending the contents to provide a complete and scholarly review of each subject. Since viruses affecting insects have received little attention until recent years, it was felt that a fully documented presentation of diverse areas of insect virology merited publication. The invited authors, all recognized authorities in their respective fields, prepared their contri butions in such a way that each is a concise unit. Typical viruses that attack and kill insects are discussed in two chapters. The first is by GORDON R. STAIRS ("Inclusion-type Viruses"), and the second by C. VAGO ("Non-inclusion Viruses"). Arthropod-borne animal viruses that infect both vertebrates and blood-sucking arthropods constitute, by far, the largest group of known verte brate viruses, with over 200 different species described by 1967. This chapter ("Arboviruses") has been prepared by Roy W. CHAMBERLAIN. The unique congenital carbon dioxide sensitivity of fruit flies, caused by a virus now known to be very similar to that causing vesicular stomatitis, but until recently studied almost exclusively as a genetic trait, has been covered by ROBERT L. SEECOF ("Sigma Virus of Drosophila"). The group of plant pathogenic viruses that infect plants, as well as insects, sometimes causing fatal insect diseases, has been reviewed by KARL MARAMOROSCH ("Plant Pathogenic Viruses in Insects"), who acted as the convener of the 1967 Sym posium and editor of this volume. An account of the increasingly popular techniques and achievements in insect tissue culture has been given by J. L. VAUGHN ("Insect Viruses in VI Introduction Tissue Culture"). "Viruses-Living Insecticides" is the title of the last chapter, written by C. M. IGNOFFO. The subject of insect viruses is of considerable scientific interest and im portance, and one that appeals to an audience recruited from students of ento mology, human and veterinary medicine, virology, genetics, biochemistry, zoology, plant pathology, microbiology, and other branches of biology. Those who attended the Symposium and participated in the formal and informal discussions realized how the details or aspects of a particular group of insect viruses may have a bearing on other groups. It is hoped that the publication of the revised and enlarged papers will add to the success attained by the New York City Symposium, by reaching a much wider audience of biologists and public health officials. The Editor would like to pay special tribute to Dr. WERNER HENLE, who not only helped in the organization of the Symposium and arrangements with the publisher, but also showed remarkable skill and persuasiveness in obtaining the manuscripts. The Editor also wishes to thank the American Society for Microbiology for help in sponsoring the Symposium, and all of the contributors for their excellent contributions. January 16, 1968 Yonkers, New York KARL MARAMOROSCH Boyce Thompson Institute for Plant Research Table of Contents Inclusion-Type Insect Viruses. By GORDON R. STAIRS. With 6 Figures 1 Non-Inclusion Virus Diseases of Invertebrates. By C. VAGO . . . .. 24 Arboviruses, the Arthropod-Borne Animal Viruses. By Roy W. CHAM- BERLAIN ... 38 The Sigma Virus Infection of Drosophila Melanogaster. By ROBERT SEECOF. With 2 Figures . . . . . . . . . . . . . . . . . 59 Plant Pathogenic Viruses in Insects. By KARL MARAMOROSCH. With 6 Figures . . . . . . . . . . . . . . . . . . . . . . . . . . 94 A Review of the Use of Insect Tissue Culture for the Study of Insect-Asso ciated Viruses. By JAMES L. VAUGHN . . . . . . . . . . . . . . 108 Viruses-Living Insecticides. By CARLO M. IGNOFFO. With 20 Figures 129 Subject Index. . . . . . . . . . . . . . . . . . . . . . . . . . 168 Inclusion-Type Insect Viruses G. R. STAIRS * With 6 Figures Introduction The best known insect viruses cause the formation of inclusions in the cells they infect. They were first observed in the mid-nineteenth century and since then have received considerable attention from entomologists and microbio logists. In recent years, several authors have reviewed studies on this group of viruses (BERGOLD, 1958; AIZAWA, 1963; SMITH, 1963; HUGER, 1963) and the present review will be concerned more specifically with structure and chemistry, the infection process, quantitative virus-host relationships and the natural occurrence of viruses in their host populations. The nuclear-polyhedroses of Lepidoptera and Hymenoptera (SAWFLIES), the cytoplasmic polyhedroses of Lepidoptera and the granuloses of Lepidoptera are discussed in detail. Structure and Chemistry Three major types of insect viruses cause the formation of inclusion bodies. These bodies are proteins and are not themselves infectious but infectious virions are usually occluded within them. One type of virus causes the formation of numerous many-sided (polyhedral) inclusions in the nuclei of infected cells. These inclusions are crystalline, very refractive, and are easily seen in tissue smears of squashed preparations examined under the light microscope. They are usually 0.5 fL to 15 fL in diameter. A characteristic name has been applied to this type and they have become known as nuclear-polyhedrosis viruses. Another type causes the formation of very numerous, minute granules in the nuclei of infected cells. These inclusions are also crystalline protein but much smaller than polyhedra and not so easily seen under the light microscope. They range in size from 0.2 fL to 0.5 fL and appear as small granules, hence, the name granulosis viruses has been applied to them. Both of these types are characteriz ed by the formation of rod-shaped virions that contain DNA nucleoprotein sur rounded by two membranes (Figs. 1, 2, and 3). The third inclusion-type virus appears to be quite different from these. Inclusion bodies are formed only in the cytoplasm of susceptible cells and the virions are spherical or subspherical * Department of Zoology and Entomology. The Ohio State University, Columbus, Ohio 1 C. T. in Microbiology, Vol. 42 2 G. R. STAIRS: Fig. 1. A section through a polyhedron of the nuclear-polyhedrosis virus of the greater wax moth, Galleria mellonella (L.), showing (A) a cross-section of a bundle of virions and the associated membranes. 180,000 X. Electron micrograph by W. B. PARRISH Fig. 2. Similar to Fig. 1 but showing longitudinal sections through virion bundles. 150,000 X. Electron micrograph by W. B. PARRISH containing RNA nucleoprotein and no membrane structures. The inclusions, in which many virions are usually occluded, are crystals of protein with numerous flat sides. These inclusions are also called polyhedra and the viruses are known as cytoplasmic-polyhedrosis viruses (Fig. 4). The inclusion bodies of all types appear to be of similar fine-structure and chemistry. In thin sections observed under the electron microscope the protein Inclusion-Type Insect Viruses Fig. 3. A section of a cell of the codling moth, Carpocapsa pommonella (L.) infected with a granulosis virus showing individual virions in each granule. 100,000 x. Electron micrograph by W. B. PARRISH subunits are arranged in very regular patterns (BERGOLD, 1963). Although the granulosis virus granules are not as large, their fine-structure is very similar to that of the polyhedra. The mechanisms of formation and crystallization of these proteins are not known but the sequence of events in relation to the de velopment of the virions has been investigated. Apparently, the formation of mature virions and crystallization of the protein occur simultaneously in ad jacent parts of the cell (BIRD, 1964, 1966). An inclusion body continues to grow and occlude virions until it reaches a size of 0.5 !1. to 15 !1.. Each inclusion body or polyhedron may contain many virions. On the other hand, a single inclusion is formed around each virion in the granulosis-type viruses. There is some controversy concerning the control of inclusion-body for mation within infected cells and recent evidence suggests the virion controls events leading to the formation of specific inclusions (STAIRS, 1964). In the 1 * 4 G. R. STAIRS: Fig. 4. A section through a polyhedron of cytoplasmic-polyhedrosis virus of the salt marsh caterpillar, Estigmene acrea (D.) showing the virions (A.) 50,000 x. Electron micrograph by W. B. PARRISH granulosis viruses, many virions develop in a single cell-nucleus and the size and shape of each inclusion body may vary considerably. In some instances, the formation of large cuboidal inclusions and the more regular, small inclusions occur in the same cell (Fig. 3). A suspension of large cuboidal inclusions fed to susceptible larvae causes the development of cuboidal-type inclusions only. This strain was passaged through five host generations without reversion to the normal type. There was considerable variation in size but the shape was always cuboidal (Fig. 5). These cuboidal variants are also found in the granulosis virus es of Choristoneura jumijerana (CLEMENS), Carpocapsa pomonella (L.), and Argy rotaenia velutinana (WLKR.) and further investigation may show that they occur commonly in many species of the families Tortricidae and Olethreutidae. The first chemical studies of nuclear-polyhedra were made at the beginning of this century when it was observed that they dissolved in weak alkali solutions