Hop mosaic virus
D. J. Barbara
East Malling Research Station, Maidstone, Kent, England
A. N. Adams
East Malling Research Station, Maidstone, Kent, England
- Disease first described by Salmon (1923). Virus first described by Bock
(1967) and Adams & Barbara (1980).
- A virus with filamentous RNA-containing particles c. 14 x 650 nm
frequently occurring in hop (Humulus lupulus) in Europe, Tasmania and
North America. Transmitted in the non-persistent manner by aphids and by
mechanical inoculation of sap.
Lethal to Golding-type hop cultivars (e.g. Bramling. Eastwell Golding,
Wye Mathon), which are no longer widely grown, but does not cause symptoms
in tolerant cultivars. Severe disease problems have occurred in sensitive
cultivars grown close to virus-infected tolerant ones (Keyworth, 1943
). Cultivars of the Golding type show chlorotic vein-banding, recurving of
the leaf margins and stunting, the plant tending to fall away from its support
); affected plants yield poorly and usually die prematurely. Mild
strains of the virus (Fig.2
) (Legg, 1959
) may be common and are probably the
cause of several diseases described by Blattný & Osvald (1949)
of chlorotic mosaic disease in France (Cairaschi, 1953
Common in Europe (Keyworth, 1947
; Schmidt & Klinkowski, 1965
Tasmania (Cartledge, 1956
), and North America (Skotland, 1960
Host Range and Symptomatology
Experimentally the virus infected 11 out of 44 species in 5 out of 14
families but symptoms have been seen only in sensitive cultivars of hop. The
virus has been detected in wild plants of Urtica urens
in England (Adams
& Barbara, 1980
) and in Stellaria media, Chenopodium album, Plantago major
and Polygonum aviculare
in West Germany (Eppler, 1980
- Diagnostic species
- Humulus lupulus (hop) cultivars of the sensitive Golding type react in
the same way as field-infected plants when graft inoculated (see Main diseases).
- Propagation species
- Nicotiana clevelandii is suitable for maintaining cultures and as a
source of virus for purification.
- Assay species
- No local lesion host is known. The virus may be assayed by determining the
proportion of Nicotiana clevelandii plants that become infected.
Most studies have been with virulent isolates. However, isolates causing
mild symptoms in hop were reported by Legg (1959)
and may be common.
Transmission by Vectors
Transmitted in the non-persistent manner by the aphids Myzus persicae,
and Phorodon humuli
(Adams & Barbara,
). Experimental transmission between hop plants by P. humuli
inefficient; Paine & Legg (1953)
obtained transmission only by spring
alatae of this aphid but transmission is also possible by glasshouse-reared
alienicolae (A. N. Adams, unpublished data).
Transmission through Seed
None found in hop, Nicotiana clevelandii
or Urtica urens.
Antisera with homologous titres of up to 1/3200 in tube precipitin tests
were readily obtained by injecting rabbits intramuscularly with preparations
of intact virus particles. Virus degraded by pyrrolidine was poorly immunogenic
(Adams & Barbara, 1980
). Extracts from infected Nicotiana
and hop plants react at dilutions in excess of 10-4
in ELISA, which has been used extensively for the detection of the virus in
tolerant cultivars (Thresh et al., 1977
A mild strain reported by Legg (1959)
protected hop plants against infection
with severe isolates; it is not known whether mild and virulent isolates differ
serologically. The properties of the virus suggest that it is a member of the
: it is serologically distantly related to carnation latent
, cowpea mild mottle
and hop latent
viruses (Adams & Barbara, 1980
Stability in Sap
The following procedure yields up to 40 mg virus/kg inoculated Nicotiana
leaves (Adams & Barbara, 1980
); 0.05 M borate buffer (pH 8)
is used throughout. One month after inoculation, extract leaves at 4°C in
buffer (5 ml/g leaf) containing 10 g/l sodium sulphite and centrifuge at 18,000
for 20 min. To the supernatant fluid add polyethylene glycol
(M. Wt 6000) and sodium chloride to 50 and 6 g/l respectively. Keep the mixture
at 4°C for 1 h and centrifuge at 18,000 g
for 40 min.
Resuspend the pellets in 1/15th original volume of extract and subject to one
cycle of differential centrifugation. Resuspend pellets overnight, clarify by
low speed centrifugation and further purify by sucrose gradient centrifugation.
Properties of Particles
Purified preparations show one component in sucrose density gradient
A260/A280: 1.22 (corrected for light-scattering.)
Straight or slightly flexuous filamentous particles c.
14 x 650 nm
Particle CompositionNucleic acid:
RNA, single-stranded, c.
5-7% of the particle weight
(estimated from the A260
ratio), M. Wt c.
(estimated by polyacrylamide gel electrophoresis; Adams &
Protein: c. 93-95% of the particle weight (estimated from the
A260/A280 ratio). M. Wt of the single protein species
c. 34,000 (estimated by polyacrylamide gel electrophoresis; Adams &
Relations with Cells and Tissues
At least two other viruses with similar filamentous particles occur in hop.
Hop latent virus
, a carlavirus
which induces local lesions in Chenopodium
but does not infect N. clevelandii,
occurs in Europe (Schmidt,
Schmidt & Eisbein, 1966
; Thresh & Ormerod, 1969
) and the USA (Probasco
& Skotland, 1976a
). An unnamed virus which has a wider host range
than hop mosaic virus, and infects Chenopodium quinoa
common in hop in the USA where it was first isolated by Probasco & Skotland
. It has been detected in Europe in introductions from the USA
(A. N. Adams, unpublished results). All three viruses can occur together in hop
plants that are apparently symptomless but the viruses are distinct both
serologically and in host range.
- Adams & Barbara, Ann. appl. Biol. 96: 201, 1980.
- Bock, Rep. E. Malling Res. Stn for 1966: 163, 1967.
- Blattný & Osvald, Ochr. Rost. 22: 5, 1949.
- Cairaschi, Revue Path. vég. Ent. agric. Fr. 32: 175, 1953.
- Cartledge, Tasm. J. Agric. 27: 210, 1956.
- Eppler, Dissertation zum Doktor der Naturwissenschaften der Fakultät für Biologie der Eberhard Karls-Universität Tübingen, 1980.
- Keyworth, J. Inst. Brew. 49: 128, 1943.
- Keyworth, Rep. E. Malling Res. Stn for 1946: 142, 1947.
- Legg, Rep. E. Malling Res. Stn for 1958: 116, 1959.
- Paine & Legg, Nature, Lond. 171: 263, 1953.
- Probasco & Skotland, Can. J. Microbiol. 22: 1160, 1976a.
- Probasco & Skotland, Proc. Am. Phytopath. Soc. 3: 319, 1976b.
- Salmon, J. Minist. Agric. Fish. 29: 927, 1923.
- Schmidt & Klinkowski, Phytopath. Z. 54: 122, 1965.
- Schmidt, Schmidt & Eisbein, Zentbl. Bakt. ParasitKde Abt. II 120: 461, 1966.
- Skotland, Phytopathology 50: 655, 1960.
- Thresh, Adams, Barbara & Clark, Ann. appl. Biol. 87: 57, 1977.
- Thresh & Ormerod, Rep. E. Malling Res. Stn for 1968: 41, 1969.
Sensitive Golding hop cultivar infected with a severe strain of
mosaic showing shortened internodes, failure of the bine to twine, vein-banding
and recurved leaves.
Mature leaf of a sensitive Golding hop cultivar showing chlorotic mosaic.
Healthy hop plant.
Hop mosaic virus particles negatively stained with 2% sodium
phosphotungstate, pH 6.5. Scale bar represents 200 nm.