Fourteen strains of cucumber mosaic virus (CMV) from Australia have been characterized by their host range and symptomatology. They were classified as subgroup I or II strains by a dot‐blot molecular hybridization assay between their total viral RNAs and selected cDNAs. The strains FNY and LNy, both from the USA, were used as the subgroup I‐ and subgroup II‐type strains, respectively. A range of serological tests was used to compare these isolates. Gel immunodiffusion tests, with standard antigens homologous to the antisera prepared against glutaraldehyde‐fixed virus of 11 strains, showed that they could be divided into three serogroups on the basis of spur formation in heterologous reactions. Two of the serogroups included either subgroup I or subgroup II isolates, whereas the third serogroup consisted of only one strain (YWA) which was homologous to all the strains tested. Use of heterologous standard antigens in this test failed to show further subgrouping of the antigens. Double‐antibody sandwich (DAS) ELISA using polyclonal antibodies to distinct virus strains also placed the 14 strains in the same three serogroups. When eight different monoclonal antibodies (MAbs) were used in indirect ELISA, one of them distinguished subgroup‐I strains and another distinguished subgroup‐II strains; the YWA strain fell into subgroup II. Other MAbs showed narrower or broader specificity. Thus both molecular hybridization with total RNA and specific MAbs may be useful for separating isolates of CMV into subgroups I and II. Spur formation using heterologous standard antigens to the antisera, as well as being more difficult to interpret, was not a reliable criterion for classification.

When sap of asymptomatic or mealybug wilt-affected pineapple plants of the Smooth Cayenne group was negatively stained and examined in an electron microscope, clostero-like virus particles were occasionally seen. However, numerous clostero-like virus particles and occasionally some bacilliform particles were seen in partially purified preparations from both asymptomatic and wilted pineapple leaves. An antiserum, made by injecting partially purified preparations of clostero-like particles into a rabbit, trapped and decorated the clostero-like particles. Using this antiserum, the clostero-like particles (c. 1700 -1900x12 nm) were found in almost all plants tested of Smooth Cayenne selections C10, C13, C30 and F-180, the hybrid cv. 53-116 and a selection of the rough leaf Queen group. The particles were more readily trapped from extracts of roots of hybrid cv. 53-116 and Smooth Cayenne selection C10 than from leaves, crowns and fruits. They were not detected in seedlings of a cross between a Queen selection and the Smooth Cayenne selection C10. The clostero-like particles are similar to those reported to occur in pineapple plants in Hawaii and South Africa. This is the first report of their occurrence in Australia. Trapping and decoration tests of particles in pineapples in quarantine from Brazil, France, Malaysia and Taiwan indicated that a similar clostero-like virus occurs in all these countries. The bacilliform particles measured about 133x33 nm. They were trapped and decorated by the Queensland pineapple virus antiserum and also by an antiserum to sugarcane bacilliform badnavirus. They were detected occasionally in various smooth leaf and rough leaf pineapples in north and south Queensland and northern New South Wales. However, in one commercial planting of Smooth Cayenne selection C10 in south Queensland, bacilliform particles were trapped from 29/47 plants. This is the first report of a small bacilliform virus, probably belonging to the badnavirus group, occurring in pineapple plants. The relationship of the clostero-like and bacilliform viruses to yield loss and mealybug wilt in pineapples is unknown.

A previously undescribed sub-group 2 rhabdovirus was isolated in Queensland from Datura stramonium with symptoms of vein yellowing, leaf distortion and reduced leaf size. Particles accumulated in the perinuclear space of infected cells of D. stramonium and measured 77 x 166 nm in preparations from sap. The virus was named datura yellow vein virus (DYVV) and was graft-transmitted to several hosts in the Solanaceae including Lycopersicon esculentum, Nicotiana tabacum and Solanum melongena, but not to Capsicum annuum or Solanum tuberosum. DYVV was not transmitted by mechanical inoculation and no insect vector was found. Purified particles of DYVV contained four structural proteins with molecular weights of about 78, 47, 41 and 36 kd. The 78 kd protein bound the lectin concanavalin A, thus identifying it as the viral glycoprotein. DYVV was serologically distinct from 1 1 other rhabdoviruses belonging to both subgroups, including potato chlorotic stunt, potato yellow dwarf (2 isolates) and tomato vein yellowing viruses. The glycoprotein only of DYVV cross-reacted with a polyclonal antiserum to sonchus yellow net virus.

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