Viruslike particles in the salivary glands of apparently virus-free leafhoppers

DISCUSSION AND PRELIMINARY REPORTS

et al . (4)

recently reported that production of defective phages was induced by treatment of B . subtilis with ntitomycin C . An electron micrograph of such defective phages shows great similarity to our micrographs . Both contain not only phage particles, but also headless tails with normal or contracted sheaths . Seaman et al . (4) suggested that such particles may represent a transitional evolutionary form betweenn an episome and a phage . The chemical and genetic nature of the phage reported herein is under investigation . REFERENCES 1 . RYAN, F . J ., FRIED, P ., and MLKAI, F ., Ricchim . Biophys . Acta 18,131 (1955) . 2 . KAGEYAMA, M ., J . Biochem . 55, 49-53 (1964) . 3 . MENNIOMANN, H . D ., Riochen . Biophys . Res. Conmnun . 16, 373-378 (1964) . 4 . SEAMAN, E ., TARMY, E ., and MARMIJR, J ., Biochemistry 3, 607--613 (1964) . HIDEYA ENDO KINSI AYABE

Division of Chemistry Cancer Research Institute Faculty of Medicine, Kyushu Univems,:ty Fukuoka, Japan KAZLNOBO AMAKO KEN71 TAKEYA

Department of Bacteriology Faculty of Medicine, Kyushu University

Pukuoka, Japan Accepted November

23, 1964

Viruslike Particles in the Salivary Glands of Apparently Virus-Free Leafhoppers ) I have recently described inclusions composed of short rods (270 mµ X 65 mµ) in wheat leaves infected with wheat striate mosaic virus (WSMV) and suggested that these rods may be virus particles (1) . To determine whether similar inclusions were present in the. leafhopper vector (Fndria inimica Say), thin sections of various organs were examined in the electron microscope . Nonviruliferous insects were reared on I Contribution no, 414, Plant Research Institute, Ottawa .

471

healthy Ramsey wheat (Triticum durum Deaf .), and viruliferous insects were obtained by caging nonviruliferous leafhoppers on virus-infected wheat for 14-21 days . Pieces of the salivary glands, alimentary tract, Malphighian tubules, and fat body were fixed in Palade's fixative (2) and embedded in Epou (3) . Sections were cut on a Porter-Blum microtome with a diamond knife . Observations were made with a Siemens Elmiskop I electron microscope . No short rods similar to those observed in infected plants were seen in sections of salivary glands, gut, Malpighian tubules, or fat body . However, osmiophilic rods (300 mp X 30 mp) were seen in the salivary glands from both virulifcrous and nonviruliferous insects (Fig . 1) . Internal structure was not visible in these rods . These rods cannot be linked to wheat striate mosaic virus . since the nonvirtiliferous insects were propagated on healthy wheat plants and never had access to virus-infected plants . Contamination was ruled out when several inoculation tests with nonviruliferous insects proved negative . Sections of salivary lobes from at least 30 nonvirldiferous insects confirmed the presence of rods . Virus-like particles have been observed in another plant virus vector . Moericke (4) in studying thin sections of the salivary glands and other organs of the green peach aphid ('Vl yzus persicae Sulz .) reported viruslike bodies in aphids carrying potato lea£roll virus and in nonvirtiliferous aphids . . rods observed in IL, is possible that the the salivary glands of E . inimica represent a latent insect virus infection, but they also could be an unidentified normal component of the salivary glands . REFERENCES 1 . LEE, P . E ., Virology 23, 145-151 (1964) . 2 . PALADE, C . E ., .I . Ezptl . Med . 95, 285298 (1952) . 3 . LuFT, .1 . H ., J. Biophys . Biochem . Cytol . 9, 409-414 (1961) . 4 . MOERTeKM, V ., Z . Pflanzenkrankh . Pflanzenschutz 70, 464-470 (1963) . PEwrKn E . LEE Plant Research Institute Canada Department of Agriculture

Ottawa, Canada Accepted December

17, 1964

472

DISCUSSION AND PRELIMINARY REPORTS

FIG. 1 . Osmiophilic particles in the salivary gland in cross and longitudinal orientations .

Aphid Honeydew as Inoculum for the Injection of Pea Aphids with Pea-Enation Mosaic Virus'

Studies on the persistent aphid-borne viruses are limited by the lack of simple bioassays . Since most of these viruses arc not juice inoculable, vectors are required for the bioassay of various virus-containing extracts . Carter (3) demonstrated that the leafhopper Circulifer tenellus (Baker) transmitted curly top virus after feeding through a membrane into solutions containing virus . Storey (17) repeated this technique with maize streak virus and in addition showed that leafhoppers transmitted virus after being injected with infectious plant, extracts (16) . The needle injection technique has become rather commonly used for leafhopper-borne viruses . ' Supported in part by a grant from the United States Public Health Service, AT 03497 .

of

the leafhopper

Endria in ica

Say . Particles

These two bioassay techniques have been recently applied to the aphid-borne persistent viruses . Barley yellow dwarf virus has been transmitted by the English grain aphid, Macrosiphuin granarium (Kirby), and by the apple grain aphid Rhopalosiphum pacli (L .) after feeding on liquid extracts from diseased plants (12, 13) . Although this is the only published example of successful acquisition of a persistent aphid-borne virus by the artificial feeding technique, perhaps the recent successes of 2\-littler and Dadd (9) and of Auclair and Cartier (2) in the artificial rearing of aphids will encourage further trials . More success has been obtained with needle inoculation of aphids, since four viruses have been transmitted by this method . Transmission of potato leaf roll virus has been reported after injection of green peach aphids. Myzus persicae (Sulzer),