Institut für Viruskrankheiten der Pflanzen, Biologische Bundesanstalt für Land- und Forstwirtschaft, 3300 Braunschweig, Germany
Geographical Distribution etc
Association with Vectors
Relations with Cells and Tissues
Relationships within the Taxon
Notes on Tentative Members
Affinities with Other Groups
Thermal inactivation point 55-70°C, longevity in sap a few days, dilution end-point usually 10-3-10-4, occasionally up to 10-6. Most carlaviruses have restricted host ranges, but the different viruses occur in a wide range of monocotyledonous and dicotyledonous hosts. Infections in natural hosts are often latent, but sometimes mosaic symptoms are produced. Carlaviruses are transmitted mechanically and usually in the non-persistent manner by aphids. Some are seed-transmitted. Virus particles occur in the cytoplasm singly or more often in large aggregates which are sometimes banded. The carlavirus group has recently been reviewed by Wetter & Milne (1981).
Table 1. Definitive and possible members of the carlavirus groupa
|Reported particle length (nm)|
|Alfalfa latent (ALV; 211); possibly a strain of PSV (Hampton, 1981)||630-651|
|Cactus 2 (CaV2; Brandes & Wetter, 1963/64)||c. 650|
|Carnation latent (CLV; 61)||650|
|Chrysanthemum B (CVB; 110)||685|
|Elderberry carlavirus (ECV; van Lent, Wit & Dijkstra, 1980)||678|
|Helenium S (HelVS; Kuschki et al., 1978)||640|
|Hop latent (HopLV; Probasco & Skotland, 1978)||610|
|Hop mosaic (HopMV; 241)||650|
|Lilac mottle (LcMV; Waterworth, 1972)||575-610|
|Lily symptomless (LiSV; 96)||640|
|Lonicera latent (LonLV; van der Meer, Maat & Vink, 1980) (=honeysuckle latent? Brunt, Phillips & Thomas, 1980)||656|
|Mulberry latent (MuLV; Tsuchizaki, 1976)||c. 700|
|Muskmelon vein necrosis (MmVNV; Freitag & Milne, 1970)||674|
|Narcissus latent (NaLV; 170; Brunt, 1977)||650|
|Nerine latent (NeLV; Maat et al., 1978) (= hippeastrum latent?)||664|
|Passiflora latent (PasLV; Brandes & Wetter, 1963/64)||650|
|Pea streak (PSV; 112)||620-630|
|Pepino latent (PepLV; Thomas, Mohamed & Fry, 1980)||660-680|
|Poplar mosaic (PopMV; 75)||675|
|Potato M (PVM; 87)||650|
|Potato S (PVS; 60)||650|
|Red clover vein mosaic (RCVMV; 22)||645|
|Shallot latent (ShLV; 250)||651|
|B.||Possible or poorly characterized members|
|Artichoke latent (ArLV; Majorana & Rana, 1970)||673|
|Caper vein banding (CapVBV; Majorana, 1970)||678|
|Cassia mild mosaic (CasMMV; Lin et al., 1979)||640|
|Chicory blotch (ChiBV; Brcák & Cech, 1962)||657|
|Cole latent (CoLV; Kitajima, Camargo & Costa, 1970)||650|
|Cowpea mild mottle (CpMMV; 140)b||650|
|Cynodon mosaic (CynMV; Bhargava, Joshi & Rishi, 1971)||509-632|
|Daphne S (DaVS; Milne & Forster, 1976)||716|
|Dulcamara carlavirus A (DuCVA; Lesemann, Weidemann & Bartels, 1971)||663|
|Dulcamara carlavirus B (DuCVB; Lesemann et al., 1971)||676|
|Eggplant mild mottle (EMMV; Khalil, Nelson & Wheeler, 1978)||677-693|
|Fuchsia latent (FuLV; Johns, Stace-Smith & Kadota, 1980)||650|
|Garlic mosaic (GaMV; Cadilhac et al., 1976)||610-640|
|Gentiana carlavirus (GeCV; D.-E. Lesemann & R. Koenig, unpubl. data)||c. 650|
|Groundnut crinkle (GrCV; Dubern & Dollet, l981)b||650|
|Gynura latent (GyLV; Gumpf, Osman & Weathers, 1977) (= strain of CVB?)||680|
|Helleborus carlavirus (HeCV; Koenig & Lesemann, 1978)||665|
|Kalanchoe carlavirus (KaCV; Koenig & Lesemann, 1978; Hearon, 1981)||600-650|
|Nasturtium mosaic (NasMV; da Graça & Martin, 1977)||650-710|
|Plantain 8 (PlV8; Hammond, 1980)|
|Voandzeia mosaic (VoMV; Monsarrat, Fauquet & Thouvenel, 1981)b||612|
|White bryony mosaic (WBMV; Tomlinson & Walker, 1972)||650|
a Acronym and Description number or other reference given in parentheses.
b According to A. A. Brunt (pers. comm.) the white-fly transmitted CpMMV and the serologically related VoMV and GrCV possibly form a separate virus group or a subgroup of the carlavirus group. The reported serological relationship between CpMMV and CLV has not been confirmed. Recently, however, GrCV has been reported to be serologically closely related to CLV, PasLV and PVS (Dubern & Dollet, 1981).
Cytoplasmic inclusions containing large masses of endoplasmic reticulum interspersed with ribosomes and often unaggregated virus particles are found with several carlaviruses (reviewed by Edwardson & Christie, 1978; see also Kuschki et al., 1978). Cytoplasmic crystalline inclusions consisting of protein and RNA and containing densely aggregated spherical granules are typical of infections with many RCVMV strains (Rubio-Huertos & Bos, 1973).
The u.v. absorbance spectra of carlaviruses are typical of nucleoproteins, with maxima at 258 to 260 nm, minima at 243 to 248 nm and Amax/Amin ratios of 1.1 to 1.2. The A260/A280 ratios of 1.1 to 1.3 indicate a nucleic acid content of 5-7%. The absorption coefficient A260(0.1%; 1 cm) which has been calculated for only a few carlaviruses, ranges from 2.1 to 2.8. Particles sediment at 147 to 176 S, and have a buoyant density in CsCl of 1.31 to 1.33 g/cm³.
Carlaviruses have a single coat protein (M. Wt 3.1-3.4 x 104). Increasing amounts of lower M. Wt material may be found in stored virus preparations or in fresh ones in which the virus was exposed to prolonged contact with crude plant sap during the purification procedure. The protein subunits form a primary helix with a pitch of 3.3-3.45 nm. The reported number of subunits per turn of the helix is 10 for RCMV and 12 for CLV (Varma et al., 1968). A particle weight of c. 50-60 x 106, estimated from data for nucleic acid and protein contents and M. Wt, indicates that each particle contains c. 1600 to 1800 protein subunits. A slightly higher estimate of c. 1700 to 2500 is obtained from data for modal length, basic pitch of the helix and number of subunits per turn of the helix.
Serological relationships in the carlavirus group. Numbers refer to the references listed below. Blank squares indicate that no results of serological tests have been published. Red numbers (on pink background) indicate that serological tests gave positive results at least with some antisera. Grey numbers (on pale blue background) indicate that tests gave negative results. Further tests with different antisera may nevertheless give positive results as was found with other distantly related viruses.
REFERENCES: (1) Brunt, 1977; (2) Brandes & Wetter, 1963/64; (3) Varma et al., 1970; (4) Hakkaart et al., 1962; (5) van Lent et al., 1980; (6) Kuschki et al., 1978; (7) Adams & Barbara, 1980; (8) Brunt et al., 1980; (9) van der Meer et al., 1980; (10) Waterworth, 1972; (11) Desc. 96; (12) Tsuchizaki, 1976; (13) Maat et al., 1978; (14) Thomas et al., 1980; (15) Berg, 1964; (16) Probasco & Skotland, 1978; (17) Bos et al., 1978; (18) Bos et al., 1972; (19) Freitag & Milne, 1970; (20) R. Koenig, unpublished data.