Outer capsid protein heterogeneity of rice dwarf phytoreovirus

Abstract

The 46K outer capsid protein encoded by RNA segment $8 and the 42K polypeptide, previously thought to be the segment S9-encoded structural protein, were isolated from a rice dwarf phytoreovirus purified preparation, and then analysed by peptide mapping and electroblot-ELISA. Staphylococcus aureus V8 protease peptide mapping patterns of the 42K and 46K proteins were similar. Two monoclonal antibodies (MAbs), obtained after immunization with virus particles dissociated by 0.1% SDS, were each specific for both the 42K and 46K proteins. Furthermore, the MAbs bound common peptide fragments which were generated by digestion of the 42K and 46K proteins with V8 protease or proteinase K. These results strongly suggest that the 42K protein is not a gene product of $9 but a product overlapping with the 46K outer capsid protein. Whether the two proteins are functionally distinct remains to be determined.Rice dwarf phytoreovirus (RDV) (Boccardo & Milne, 1984) is considered to contain a genome composed of t2 segmented dsRNAs and seven structural proteins. The genomic RNAs are termed S1 to Sl2 in increasing order of mobility in a polyacrylamide gel. It was reported by Nakata et al. (1978) that the seven constituent proteins were encoded by S1, $2, $3, $5, $7, $8 and $9 based both on their potential coding capacities as monocistronic mRNAs and on the sizes of the polypeptides detected in the virus particles.

In vitro translation of rice dwarf phytoreovirus genome segments S4 to S10

“…However, we showed previously that the 39 k protein was not the S9-coded product but a product overlapping with the 43 k, S8-coded, outer capsid protein [18]. The present study revealed that $9 encodes a protein with an apparent Mr of 49 k, larger than that of P8.…”

“…Treatment with such organic solvents is considered to result in loss of the amorphous outer protein layer but not loss of the outer capsids [1,14]. The conclusion reached from the present and previous studies [18] is, therefore, that RDV P9 is not an outer capsid protein but a nonstructural protein. In addition to P9 stated above, P4, P6, and P10 are considered to be nonstructural proteins.…”

“…The data summarized in Table i should provide a basis for a Data are from [9,[17][18][19][20][21][22] and this study for RDV and from [11] for WTV b Calculated from the nucleotide sequence c Calculated from SDS-PAGE data detection and purification of the viral proteins, which are essential for investigation of their functions.…”

Close similarity between genome structures of rice black-streaked dwarf and maize rough dwarf viruses

“…They have been classified into three different groups, Phytoreovirus, Fijivirus and the rice ragged stunt virus (RRSV) group (possible genus), based on particle morphology, number of dsRNA genome segments and vector species (Boccardo & Milne, 1984;Francki et al, 1985). Recent genomic analyses of wound tumour virus (WTV) genome segments 4 to 12 (Asamizu et al, 1985;Anzola et al, 1987Anzola et al, , 1989aXu et al, 1989;Dall et al, 1989), rice dwarf virus (RDV) genome segments 3 to 11 (Uyeda et al, 1987a(Uyeda et al, , 1989(Uyeda et al, , 1990aOmura et al, 1988Omura et al, , 1989Yamada et al, 1990;Suzuki et al, 1990a, b;Suzuki & Sugawara, 1991) and rice gall dwarf virus genome segments 8 to 10 (Koganezawa et al, 1990;Noda et al, 1991) revealed molecular relationships between the viruses within the genus Phytoreovirus. These three viruses were found to share a conserved terminal oligonucleotide sequence (Asamizu et al, 1985;Kudo et al, 1991).…”

Molecular analysis of rice ragged stunt oryzavirus segment 9 and sequence conservation among isolates from Thailand and India

“…reoviruses: wound tumor virus (WTV) genome segments 4 to 12 [23], rice dwarf virus (RDV) genome segments 1 to 12 [28][29][30][31][32]35], rice gall dwarf virus (RGDV) genome segments 8 to 10 [14,22], maize rough dwarf virus (MRDV) genome segment 6 [18], and rice black-streaked dwarf virus (RBSDV) genome segments 7, 8 and 10 [1,33]. To date the only nucleotide sequence information about RRSV is confined to the 5' and 3' termini (5' G A U A A A ---and ---G U G C 3') which was obtained by direct R N A sequencing [39].…”