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Variation in coat protein genes among five geographically different isolates of rice tungro spherical virus

Zhang S, Lee G, Davies JW, Hull R

Arch Virol, 1997;142(9):1873-9.
PMID: 9672645

The variation in the sequence of the coat protein genes of four isolates of rice tungro spherical virus from different countries, Malaysia, Thailand, India and Bangladesh, was compared with an isolate from the Philippines. The evidence from RT-PCR, Southern blot hybridization and sequences of the coat protein genes indicated that the isolates appeared to fall into two groups. One comprised the Philippine and Malaysian isolates (about 95% sequence similarity) and the other the Bangladeshi and Indian isolates, the sequences of which differed by about 15% from that of the Philippine isolate. The Thai isolate seemed to be a mixture of these two subgroups.

Matched MeSH terms: Waikavirus/classification; Waikavirus/genetics*; Waikavirus/isolation & purification
Complete Genome Sequence of Rice Tungro Bacilliform Virus Infecting Asian Rice (Oryza sativa) in Malaysia

Kannan M, Saad MM, Talip N, Baharum SN, Bunawan H

Microbiol Resour Announc, 2019 May 16;8(20).
PMID: 31097500 DOI: 10.1128/MRA.00262-19

Rice tungro disease was discovered in Malaysia in the 1930s. The first and only genome of Rice tungro bacilliform virus (RTBV) isolated from rice in Malaysia was sequenced in 1999. After nearly two decades, here, we present the complete genome sequence of an RTBV isolate in rice from Seberang Perai, Malaysia.

Matched MeSH terms: Waikavirus
Fulltext Development of an Indirect ELISA and Dot-Blot Assay for Serological Detection of Rice Tungro Disease

Henry Sum MS, Yee SF, Eng L, Poili E, Lamdin J

Biomed Res Int, 2017;2017:3608042.
PMID: 29201901 DOI: 10.1155/2017/3608042

Rice tungro disease (RTD) is one of the most destructive diseases of rice in South and Southeast Asia. RTD is routinely detected based on visual observation of the plant. However, it is not always easy to identify the disease in the field as it is often confused with other diseases or physiological disorders. Here we report the development of two serological based assays for ease of detection of RTD. In this study we had developed and optimized an indirect ELISA and dot-blot assay for detection of RTD. The efficiency of both assays was evaluated by comparing the specificity and sensitivity of the assays to PCR assay using established primer sets. The indirect ELISA showed 97.5% and 96.6%, while the dot-blot assay showed 97.5% and 86.4% sensitivity and specificity, respectively, when compared to established PCR method. The high sensitivity and specificity of the two assays merit the use of both assays as alternative methods to diagnose RTD. Furthermore, the dot-blot assay is a simple, robust, and rapid diagnostic assay that is suitable for field test for it does not require any specialized equipment. This is a great advantage for diagnosing RTD in paddy fields, especially in the rural areas.

Matched MeSH terms: Waikavirus/genetics; Waikavirus/isolation & purification*; Waikavirus/pathogenicity
Expression and the antigenicity of recombinant coat proteins of tungro viruses expressed in Escherichia coli

Yee SF, Chu CH, Poili E, Sum MSH

J Virol Methods, 2017 02;240:69-72.
PMID: 27923590 DOI: 10.1016/j.jviromet.2016.12.001

Rice tungro disease (RTD) is a recurring disease affecting rice farming especially in the South and Southeast Asia. The disease is commonly diagnosed by visual observation of the symptoms on diseased plants in paddy fields and by polymerase chain reaction (PCR). However, visual observation is unreliable and PCR can be costly. High-throughput as well as relatively cheap detection methods are important for RTD management for screening large number of samples. Due to this, detection by serological assays such as immunoblotting assays and enzyme-linked immunosorbent assay are preferred. However, these serological assays are limited by lack of continuous supply of antibodies as reagents due to the difficulty in preparing sufficient purified virions as antigens. This study aimed to generate and evaluate the reactivity of the recombinant coat proteins of Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV) as alternative antigens to generate antibodies. The genes encoding the coat proteins of both viruses, RTBV (CP), and RTSV (CP1, CP2 and CP3) were cloned and expressed as recombinant fusion proteins in Escherichia coli. All of the recombinant fusion proteins, with the exception of the recombinant fusion protein of the CP2 of RTSV, were reactive against our in-house anti-tungro rabbit serum. In conclusion, our study showed the potential use of the recombinant fusion coat proteins of the tungro viruses as alternative antigens for production of antibodies for diagnostic purposes.

Matched MeSH terms: Waikavirus/genetics*; Waikavirus/immunology; Waikavirus/isolation & purification; Waikavirus/chemistry
Fulltext Sequence and Phylogenetic Analysis of the First Complete Genome of Ricetungro spherical virus in Malaysia

Kannan M, Mohamad Saad M, Zainal Z, Kassim H, Ismail I, Talip N, et al.

Iran J Biotechnol, 2020 Oct;18(4):e2566.
PMID: 34056024 DOI: 10.30498/IJB.2020.2566

Background: Rice tungro disease (RTD) is a viral disease mainly affecting rice in Asia. RTD caused by Rice tungro bacilliform virus and Rice tungro spherical virus. To date, there are only 5 RTSV isolates have been reported.
Objectives: In this study, we aimed to report the complete nucleotide sequence of Malaysian isolate of Rice tungro spherical virus Seberang Perai (RTSV-SP) for the first time. RTSV-SP was characterized and its evolutionary relationship with previously reported Indian and Philippines isolates were elucidated.
Materials and Methods: RTSV-SP isolate was isolated from a recent outbreak in a paddy field in Seberang Perai zone of Malaysia. Its complete genome was amplified by RT-PCR, cloned and sequenced.
Results: Sequence analysis indicated that the genome of RTSV-SP consisted of 12,173 nucleotides (nt). Comparative analysis of 6 complete genome sequences using Clustal Omega showed that Seberang Perai isolate shared the highest nucleotide identity (96.04%) with Philippine-A isolate, except that the sORF-2 of RTSV-SP is shorter than RTSV Philippine-A by 27 amino acid residues. RTSV-SP found to cluster in Southeast Asia (SEA) group based on the whole genome sequence phylogenetic analysis using MEGA X software.
Conclusions: Phylogenetic classification of RTSV isolates based on the complete nucleotide sequences showed more distinctive clustering pattern with the addition of RTSV-SP whole genome to the available isolates. Present study described the isolation and molecular characterization of RTSV-SP.

Matched MeSH terms: Waikavirus