| Tomato mosaic virus (ToMV) is one important member of the genus Tobamovirus. It has very closely serological relationship with Tobacco mosaic virus (TMV), and it is relatively difficult to distinguish ToMV and TMV using polyclonal antibodies. Four monoclonal antibodies (MAbs) against ToMV had been produced with hybridroma technology after immunizing with purified ToMV, two MAbs could specifically react with ToMV, while another two MAbs could detect both ToMV and TMV. The titers of ascitic fluids of the four MAbs determined by ELISA ranged from 1:32000 to 1:1024000. Western blot analysis showed two MAbs could react specifically with the 17.6 kDa coat protein (CP) of ToMV, while the other two MAbs could not and were supposed to recognize the conformational determinants of ToMV CP. The triple antibody sandwich-ELISA (TAS-ELISA) was established for detecting and TMV and ToMV, with the sensitivity of over 1:2000 dilution for infected plant saps. TAS-ELISA with field samples collected from tobacco, tomato and pepper in Zhejiang and Yunnan provinces showed that these crops were mainly infected by TMV.ToMV and TMV are the closely related viruses, but they induce obviously different sizes of necrotic lesions in tobacco plants containing the N gene. In order to find the determinant for the size difference of necrotic lesions, symptoms produced by TMV, ToMV and a chimeric virus (T/OMP), in which the TMV movement protein (MP) gene was replaced by the ToMV MP gene, the results showed T/OMP caused necrotic lesions that were similar in size to those of ToMV in tobacco plants containing the N gene. Accumulation of the coat protein and MP of the three viruses in planta was compared, and all the three viruses accumulated with similar levels in testing period. Northern blot analysis showed that the replication level of TMV and T/OMP in protoplast also had no difference. Comparison of the activities of defense-related enzymes (PAL, POD and PPO) induced by the three viruses also showed that the variability of enzyme activity induced by T/OMP was similar to that induced by TMV, but different from that induced by ToMV. The results indicate that the size difference of necrotic lesions induced by TMV and ToMV in tobacco plants containing the N gene is resulted from functionaldifference of their MP genes.Cucumber mosaic virus (CMV) is one of the most economically important viruses occurring throughout the world. Numerous CMV isolates or strains had been characterized. According to biological, serological and nucleic acid properties, CMV isolates could be divided into two main subgroups. The BAL B/C mice were immunized with purified virions of CMV-RB (subgroup I isolate) and CMV-Z (subgroup II isolate), respectively, 9 cell lines stably secreting MAbs were obtained after fusion, screening and cloning. The titers of ascitic fluids of the nine MAbs determined by indirect ELISA ranged from 1:32000 to 1:512000. The specificity of MAbs was detected by TAS-ELISA, it was indicated that 6 MAbs were specific for CMV subgroup I or II isolates, while 2 MAbs could detect both subgroup I and II isolates, and 1 MAbs could only react with purified CMV-Z but not with infected plant saps.TAS-ELISA based on MAbs against CMV was established for differentiation of subgroups for CMV isolates. As compared with indirect ELISA, both TAS-ELISA and indirect ELISA could detect subgroup I isolates successfully, but for subgroup II isolates, TAS-ELISA was more sensitive than indirect ELISA. 197 fields samples collected from different regions were tested by TAS-ELISA, and CMV could be detected from 130 samples, among which 121 samples were subgroup I isolates (93.1 %) and 9 samples were subgroup II isolates (6.9%). Immuno-capture reverse transcript PCR (IC-RT-PCR) was also developed for differentiation of subgroups for CMV isolates, and the positive samples in TAS-ELISA were used for detecting viruses with IC-RT-PCR. The subgroup I samples could only be amplified with subgroup I specific primers with a specific band of about 500 bp, whereas the subgr...
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