Potato mop-top virus (PMTV

No abstract

The leaves of Luvunga sarmentosa yielded two new apotirucallane triterpenoids, 3-epi-skimmiarepin A (1) and 21,23-epoxy-7alpha,21-dihydroxyapotirucalla-14,24-dien-3-one (2), and a new tirucallane triterpene, 3-epi-flindissol (3). Because of a hemiacetal functionality at C-21, all compounds occurred as mixtures of 21-epimers. 3-epi-Skimmiarepin A (1) and 3-epi-flindissol (3) were oxidized to the corresponding gamma-lactones. The structures have been elucidated on the basis of mass and NMR spectroscopic methods.

Mouse hybridoma cells, secreting monoclonal antibodies (MCA) against tomato spotted wilt virus, were produced and screened for virus specificity by an indirect triple antibody ELISA, using a rabbit polyclonal antiserum for antigen trapping. A Bulgarian virus isolate from tobacco was used for immunisation of mice and rabbits. One fusion eventually led to 10 stable hybridoma cell lines, all of which produced antibodies of IgG-type though of different subgroups. Since none of the MCAs reacted with TSWV structural proteins after electrophoresis and transfer to nitrocellulose, other methods were chosen to examine their protein specificity. Purified viral cores and detergent-solubilised envelope proteins were used as antigens for ELISA, or, alternatively, glycosylated viral envelope proteins were trapped onto microtitre plates coated with lectins in order to detect MCAs specific for them. Both methods, independently, led to the identification of two MCAs that were specific for envelope proteins of TSWV. Only these two antibodies reacted with intact TSWV particles when examined by immunogold labelling in the electron microscope. The reaction of all MCAs with 11 different TSWV isolates eventually led to the selection of one core-and one envelope-specific antibody for routine use. Core-specific MCAs revealed serological differences between isolates belonging to the common serotype ( = lettuce serotype), but did not react with the serotype TSWV-I. When comparing different ELISA procedures, broadest reactivity and highest sensitivity with different isolates were obtained in an indirect test procedure, using goat anti-mouse antibody conjugates.

No abstract

No abstract

Libraries of cloned cDNA were prepared from complete genomic RNA and isolated S RNA of the Bulgarian L3 isolate of tomato spotted wilt virus (TSWV-L3). Northern blotting of TSWV genomic RNA detected clones specific for the L, M and S RNAs in the library from complete RNA. S RNA-specific clones selected from both libraries covered approximately 2-8 kb (about 95 %) of the S RNA. Sequencing of these clones showed TSWV-L3 S RNA to be ambisense. It contains two open reading frames (ORFs); one of 1401 nucleotides located on the viral RNA encodes an Mr 52400 (52K) protein, and the other of 774 nucleotides on the complementary strand encodes an Mr 28 900 (29K) protein. Expression of the 29K ORF in bacteria and immunological analysis of the fusion protein synthesized confirmed that the 29K protein is the N protein of TSWV-L3. Comparison with the published sequence for the S RNA of a Brazilian TSWV isolate, CNPH1, revealed almost complete identity in the amino acid sequences for the 29K protein, but several clustered amino acid exchanges in the putative 52K protein. In addition, the separating non-translated intergenic region of the S RNA of the Bulgarian isolate is 81 nucleotides longer than that of CNPH1.

No abstract