1170 



MANUAL OF DETERMINATIVE BACTEEIOLOGY 



Induced disease : In tomato, some 

 primary lesions necrotic, ring-like or 

 spot-like, others masked, or disclosed 

 only by chlorophyll retention in yellowing 

 leaves. In young plants, systemic ne- 

 crotic lesions may cause death ; in older 

 plants, growth ceases, young leaves be- 

 come pale j'ellow ; growing points may die, 

 inducing growth of axillary buds to 

 produce a bushy top ; older leaves become 

 yellowed and show some purple colora- 

 tion. In White Burley tobacco, local 

 necrosis only, lesions small, red at first, 

 then white. In cowpea, reddish necrotic 

 primary lesions only. 



Transmission: By inoculation of e.\- 

 pressed juice. Through dodder, Cuscvta 

 campestris Yuncker {COA'VOLVULA- 

 CEAE). Not through seeds of diseased 

 plants. No insect vector is known. 



Serological relationships : A specific 

 antiserum, prepared by a single intra- 

 venous injection of rabbits with 2 mg of 

 purified virus, gives granular, compact 

 precipitates, serving for quantitative es- 

 timation of this virus, antiserum being 

 used at dilutions of 1 :200 or 1 :800, virus 

 at dilutions to 10"". 



Immunological relationships: Will in- 

 fect plants previously invaded by tobac- 

 co-mosaic virus, tomato spotted-wilt 

 virus, tobacco-ringspot virus, and Ber- 

 gerac-ringspot virus. 



Filterability : Passes membranes down 

 to 40 millimicrons average pore diameter. 



Other properties: Virus crystallizes 

 from solutions of ammonium sulfate as 

 isotropic, rhombic dodecahedra, which 

 shrink and swell reversiblj' on drying and 



rewetling; shrinkage reduces size to 80 

 per cent of the wet dimensions. In the 

 presence of heparin, non-birefringent 

 prisms, rather than dodecahedra, appear. 

 820° = 132 X 10-13 cm. sec.-i dyne"!. 

 Particle approximately spherical, 27.4 

 millimicrons in diameter by X-ray meas- 

 urements (average diameter by filtration 

 data, 14 to 20 millimicrons). Solutions 

 do not show anisotropy of flow. Inac- 

 tivated by drying. Molecular weight 

 8,800,000. Density 1.353. Molecular 

 weight may be as high as 24,000,000 in 

 solution, but the density is then lower, 

 1 .286. Analysis : carbon 47 to 50 per cent , 

 nitrogen 15.8 to 16.4 per cent, phosphorus 

 1.3 to 1.5 per cent, ash 1.7 to 5 per cent, 

 hj^drogen 7.2 to 8.2 per cent, sulfur 0.4 

 to 0.8 per cent, carbohydrate 5 to 6 per 

 cent. 



Literature: Ainsworth, Jour. Ministry 

 Agr., 43, 1936, 266-269 ; Bawden and Pirie, 

 Nature, HI, 1938, 513; Brit. Jour. Exp. 

 Path., 19, 1938, 251-263; Bernal and 

 Fankuchen, Jour. Gen. Physiol., 25, 1941, 

 111-165; Bernal et al., Nature, lJt2, 1938, 

 1075; Cohen, Jour. Biol. Chem. lU, 1942, 

 .353-362; Proc. Soc. Exp. Biol, and Med., 

 51, 1942, 104-105; Lauffer, Jour. Phys. 

 Chem., U, 1940, 1137-1146; LaufTer and 

 Stanley, Jour. Biol. Chem., 135, 1940, 

 463-472; Neurath and Cooper, Jour. Biol. 

 Chem., 1S5, 1940, 455-462; Smith, Nature, 

 135, 1935, 908; Ann. Appl. Biol., 22, 1935, 

 731-741 ; Jour. Roy. Hort. Soc, 60, 1935, 

 448-451; Smith and MacClement, Para- 

 sitol., 33, 1941, 320-330; Stanley, Jour. 

 Biol. Chem., 135, 1940, 437-454. 



Key to the species of the Tobacco-Etch Virus Group. 

 Viruses relatively susceptible to heat inactivation (inactivated at 52 to 58° C in 10 

 minutes). A small, closely allied group, tending to replace or to be replaced by each 

 other, if present in mixture in tobacco. 



I. Not replaced, if in mixture, by other viruses of this group ; dominant member 

 of the group in tobacco. 



6. M armor erodens. 



II. Replaced by No. 6, not by No. 8, if in mixture with it in tobacco. 



7. Marmor hyoscyami. 

 III. Replaced by No. 6 or 7 if in mixture with either in tobacco. 



8. Marmor upsilon. 



