Rice stripe virus(RSV) is the type member of the genus Tenuivirus.RSV is known to have four segmented,single-stranded RNA molecules and causes rice stripe disease in the rice fields of China,Japan,and Korea.Based on the complete genomic sequences of the determined 6 RSV isolates(from Yunnan,Jiangsu,Zhejiang,and Liaoning Provinces,China) and 27 other RSV isolates(from Yunnan,Jiangsu,Anhui,Henan,and Shandong Provinces of China,also Japan and Korea) downloaded from GenBank,we provided a genotyping profile of RSV field isolates and described the population structure of RSV.All RSV isolates,except isolate CX,could be divided into two subtypes,one including 6 isolates from Yunnan Province,and the other including 26 isolates from different parts of China,Japan,and Korea,which were referred to as subtype II and subtype I,respectively.The amino acid distances between subtypes range from 0.053 to 0.085.RSV isolates in Yunnan Province were genetically differentiated from other parts of China,Japan,and Korea and showed infrequent gene flow.The RSV populations collected from other parts of China,Japan,and Korea were only composed of subtype I and showed very low genetic diversity.We speculated that isolate CX may be the result of recombination of isolates from two subtypes.Two potential recombination events were detected in RNA4 of isolate CX.
Aphid-borne Zucchini yellow mosaic virus(ZYMV) is one of the most economically important viruses of cucurbitaceous plants.To survey and control this virus,it is necessary to develop an efficient detection technique.Using purified ZYMV virion and the conventional hybridoma technology,three hybridoma cell lines(16A11,5A7 and 3B8) secreting monoclonal antibodies(MAbs) against ZYMV Zhejiang isolate were obtained.The working titers of the ascitic fluids secreted by the three hybridoma cell lines were up to 10^(-7) by indirect enzyme-linked immunosorbent assay(ELISA).All MAbs were isotyped as lgG1,kappa light chain.Western blot analysis indicated that the MAb 3B8 could specifically react with the coat protein of ZYMV while MAbs 5A7 and 16A11 reacted strongly with a protein of approximately 51 kDa from the ZYMV-infected leaf tissues.According to this molecular weight,we consider this reactive protein is likely to be the HC-Pro protein.Using these three MAbs,we have now developed five detection assays,i.e.,antigen-coated-plate ELISA(ACP-ELISA),dot-ELISA,tissue blot-ELISA,double-antibody sandwich ELISA(DAS-ELISA),and immunocapture-RT-PCR(IC-RT-PCR),for the sensitive,specific,and easy detection of ZYMV.The sensitivity test revealed that ZYMV could be readily detected respectively by ACP-ELISA,dot-ELISA,DAS-ELISA and IC-RT-PCR in 1:163840,1:2560,1:327680 and 1:1 310720(w/v,g mL^(-1)) diluted crude extracts from the ZYMV-infected plants.We demonstrated in this study that the dot-ELISA could also be used to detect ZYMV in individual viruliferous aphids.A total of 275 cucurbitaceous plant samples collected from the Zhejiang,Jiangsu,Shandong and Hainan provinces,China,were screened forthe presence of ZYMV with the described assays.Our results showed that 163 of the 275 samples(59%) were infected with ZYMV.This finding indicates that ZYMV is now widely present in cucurbitaceous crops in China.RT-PCR followed by DNA sequencing and sequence analyses confirmed the accuracy of the five assays.We consider that these detection assays
Maize chlorotic mottle virus (MCMV) infects maize plants and causes significant losses in corn production worldwide. In this study, purified MCMV particles were used as the immunogen to produce monoclonal antibodies (MAbs) and polyclonal antibodies (PAbs). Four murine MAbs (4B8, 8C11, 6F4, and 9G1) against MCMV were obtained through the hybridoma technology. The triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA), dot-immunobinding assay (DIBA), and immunocapture reverse transcription-polymerase chain reaction (IC-RT-PCR) using the MAb 4B8 were then developed for sensitive, specific, and rapid detection of MCMV in fields. MCMV could be detected in infected leaf crude extracts at dilutions of 1:327 680, 1:64000, and 1:3276800 (w/v, g/ml) by TAS-ELISA, DIBA, and IC-RT-PCR, respectively. One hundred and sixty-one maize field samples showing virus-like symptoms and sixty-nine symptomless maize field samples from ten different provinces of China were collected and screened for the presence of MCMV using the established serological methods. A phylogenetic tree was constructed based on the full length CP genes and Chinese MCMV isolates formed one branch with Thailand isolates. The detection results demonstrated that MCMV is one of most prevalent viruses infecting maize in the Yunnan and Sichuan provinces of China.
