Indian cassava mosaic virus (Indian cassava mosaic).

Author(s):  
Olufemi J Alabi

Abstract Other than their countries of origin, India and Sri Lanka for ICMV and SLCMV, respectively, SLCMV has also been reported in India (Dutt et al., 2005; Jose et al., 2011) and Cambodia (Wang et al., 2016) while new strains of ICMV have been identified as causative agents of Jatropha curcas mosaic disease in Jatropha curcas from India (Snehi et al., 2012), Nigeria (Kashina et al., 2013) and Singapore (Wang et al., 2014). The primary means of spread of both viruses is via movement of infected cassava cuttings while secondary spread is facilitated by members of the Bemisia tabaci complex. Both ICMV and SLCMV are not on the IUCN or ISSG alert lis.

2021 ◽  
Author(s):  
Wanwisa Siriwan ◽  
Kingkan Saokham ◽  
Nuannapa Hemniam ◽  
Sukanya Roekwan ◽  
Sirikan Hunsawattanakul ◽  
...  

Cassava plantations in an area of 458 ha spanning five provinces along the Thailand–Cambodia border were surveyed from October 2018 to July 2019 to determine the prevalence of cassava mosaic disease (CMD) caused by Sri Lankan cassava mosaic virus (SLCMV) in the region. CMD prevalence was 40% in the whole area and 80% in Prachinburi, 43% in Sakaeo, 37% in Burium, 25% in Surin, and 19% in Sisaket provinces. Disease severity was generally scored as 2–3. The highest average disease severity was in Sakaeo province (3.7), followed by Buriram (3.6), Prachinburi (2.88), Surin (2.5), and Sisaket (2.4) provinces. Asymptomatic plants were identified in Surin (12%), Prachinburi (5%), Sakaeo (0.2%), and Buriram (0.1%) by PCR analysis. Interestingly, cassava cultivars CMR-89 and Rayong 11 were susceptible to CMD. In approximately 95% of cases, the infection was transmitted by whitefly ( Bemisia tabaci ), which had a high population density in Prachinburi but was sparse in Surin, with the largest populations observed in May and June. Nucleotide sequencing of the mitochondrial cytochrome oxidase 1 ( mtCO1 ) gene of whitefly ( Bemisia tabaci ) in Thailand revealed a similarity to the Asia II 1 whitefly gene. Furthermore, the AV1 gene—which encodes the capsid protein—showed 90% nucleotide identity with SLCMV. Phylogenetic analysis of completed nucleotide sequences of DNA-A and DNA-B components of the SLCMV genome determined by rolling circle amplification (RCA) indicated that they were similar to the nucleotide sequence of SLCMV isolates from Thailand, Vietnam, and Cambodia. These results provide important insights into the distribution, impact, and spread of CMD and SLCMV in Thailand.


2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Saengsoon Charoenvilaisiri ◽  
Channarong Seepiban ◽  
Mallika Kumpoosiri ◽  
Sombat Rukpratanporn ◽  
Nuchnard Warin ◽  
...  

Abstract Background Cassava mosaic disease (CMD) is one of the most devastating viral diseases for cassava production in Africa and Asia. Accurate yet affordable diagnostics are one of the fundamental tools supporting successful CMD management, especially in developing countries. This study aimed to develop an antibody-based immunoassay for the detection of Sri Lankan cassava mosaic virus (SLCMV), the only cassava mosaic begomovirus currently causing CMD outbreaks in Southeast Asia (SEA). Methods Monoclonal antibodies (MAbs) against the recombinant coat protein of SLCMV were generated using hybridoma technology. MAbs were characterized and used to develop a triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) for SLCMV detection in cassava leaves and stems. Assay specificity, sensitivity and efficiency for SLCMV detection was investigated and compared to those of a commercial ELISA test kit and PCR, the gold standard. Results A TAS-ELISA for SLCMV detection was successfully developed using the newly established MAb 29B3 and an in-house polyclonal antibody (PAb) against begomoviruses, PAb PK. The assay was able to detect SLCMV in leaves, green bark from cassava stem tips, and young leaf sprouts from stem cuttings of SLCMV-infected cassava plants without cross-reactivity to those derived from healthy cassava controls. Sensitivity comparison using serial dilutions of SLCMV-infected cassava sap extracts revealed that the assay was 256-fold more sensitive than a commercial TAS-ELISA kit and 64-fold less sensitive than PCR using previously published SLCMV-specific primers. In terms of DNA content, our assay demonstrated a limit of detection of 2.21 to 4.08 × 106 virus copies as determined by quantitative real-time PCR (qPCR). When applied to field samples (n = 490), the TAS-ELISA showed high accuracy (99.6%), specificity (100%), and sensitivity (98.2%) relative to the results obtained by the reference PCR. SLCMV infecting chaya (Cnidoscolus aconitifolius) and coral plant (Jatropha multifida) was also reported for the first time in SEA. Conclusions Our findings suggest that the TAS-ELISA for SLCMV detection developed in this study can serve as an attractive tool for efficient, inexpensive and high-throughput detection of SLCMV and can be applied to CMD screening of cassava stem cuttings, large-scale surveillance, and screening for resistance.


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