应用免疫电镜技术快速检测菜豆黄花叶病毒、马铃薯M病毒和燕麦花叶病毒

应用免疫吸附电流技术(ISEM)可有效地检测腐汁液中的菜豆黄花叶病毒(BYMV)、马铃薯M病毒(PVM)和燕麦花叶病毒(OMV)。BYMV,PVM和OMV三种抗血清的适宜工作浓度和对铜网的适宜包被时间均为1000倍和1小时,对同源病毒的适宜捕获时间分别为4℃下2、2和8小时。PVM和OMV的病汁液检测灵敏度均为稀释4000倍,而BYMV病汁液稀释16000倍时还能检测到少量病毒料子。ISEM捕获法和修饰法的结果表明,这三种病毒之间无血清学交叉反应。     

Characterization of cymbidium mosaic virus coat protein gene and its expression in transgenic tobacco plants

Cymbidium mosaic virus (CyMV) is the most prevalent virus infecting orchids. Here, we report the isolation of partial cDNA clones encoding the genomic RNA of CyMV. Like most of the polyadenylated monopartite positive-strand RNA viruses, the open reading frame (ORF) coding for the viral coat protein (CP) is located at the 3 end. The ORF predicts a polypeptide chain of 220 amino acids with a molecular weight of 23 600. Sequence comparison of this ORF to the CP sequences of potato virus X(PVX) and white clover mosaic virus (WCIMV) revealed a strong amino acid homology in the mid-portion of the CP, but the overall homology was low. The CyMV CP gene was placed downstream of a cauliflower mosaic virus 35S promoter and the chimaeric gene was transferred into Nicotiana benthamiana. Transgenic plants expressing the CyMV CP were protected against CyMV infection.     

Rubus host range of rubus yellow net virus and its involvement with other aphid-borne latent viruses in inducing raspberry veinbanding mosaic disease

After graft inoculation with rubus yellow net virus (RYNV), 12 of 34 Rubus species and cultivars developed noticeable symptoms. R. macraei developed the most conspicuous symptoms and is recommended as an improved indicator plant. In attempts to determine the cause of raspberry veinbanding mosaic, a disease in which RYNV is involved, several European and North American red raspberry cvs were graft-inoculated with RYNV and three other aphid-borne viruses, black raspberry necrosis (BRNV), raspberry leaf mottle (RLMV) and raspberry leaf spot, singly and in all combinations. In periods of up to 4 yr, classical veinbanding mosaic symptoms developed in sensitive cvs only when they contained both RYNV and RLMV. These symptoms were intensified in plants co-infected with additional viruses. Veinbanding mosaic disease did not develop in any of 11 cvs infected with RYNV + BRNV, the combination of viruses previously assumed to be responsible for this disease in Britain and North America.     

Distinction of strains of bean common mosaic virus and blackeye cowpea mosaic virus using antibodies to N- and C- or N-terminal peptide domains of coat proteins

Earlier attempts to discriminate serologically strains NL1, NL3 and NY15 of bean common mosaic virus (BCMV) and strain W of blackeye cowpea mosaic virus (B1CMV) had been unsuccessful. Antibodies directed towards N- and C-, or N-terminal peptide regions of the coat proteins of the above strains enabled the distinction between B1CMV-W, BCMV-NY15 and BCMV-NL3 in electroblot immunoassay and in ELISA. The distinction was better with antibodies directed towards N-termini than with those to N- and C-termini. Strain NL1 of BCMV cross-reacted with both B1CMV-W and BCMV-NY15, but not with BCMV-NL3. Taxonomic implications of these findings are discussed.     

Schistosoma mansoni: mice infected with different worm strains.

Infections with five geographical strains and substrains of Schistosoma mansoni were compared in mice. Two substrains (Lc-1 and Lt-1) were derived from the parent (L-1) St. Lucian strain on the basis of differing infectivity for various snail strains. The Puerto Rican strains (PR-1 and PR-2) were obtained with an interval of 25 years. Consistent differences among the lines were found in egg distribution and numbers of eggs in tissues and feces. One Puerto Rican strain (PR-2) and one St. Lucian substrain (Lc-1) had longer prepatent periods than the other strains. Mice infected with the PR-1 strain consistently had the highest egg accumulation in the tissues per worm pair. Relatively few eggs were passed in the feces of the Lt-1 strain. By Week 9 of infection, eggs were noted in the spleens of mice carrying each of the strains and substrains.     

Methylation of TMV RNA

Several plant and animal viral RNAs contain a tRNA like structure at their 3′ ends. In this communication we show that tobacco mosaic virus (TMV) RNA is an acceptable substrate for a specific tRNA methyltransferase. Using a crude preparation of $\text{E. coli}$ ribothymidine (rT) forming uracil methylase and (methyl ³H) S-adenosyl-L-methionine (SAM) as a methyl donor, 0.7 moles of methyl group is incorporated per mole of TMV RNA in 10 hours at 30°C. Upon T₂ RNAse digestion of the labeled RNA, all of the radioactivity was found to be in TMP. T₁ RNAse digestion of ³H methylated TMV RNA showed that all of the label was located in a tetranucleotide which co-migrated with authentic TpψpCpGp, an oligonucleotide characteristically found in normal cellular tRNA.The use of this specific methyl transferase reaction may provide a simple assay for the detection of tRNA like structures in large RNAs.