Protein composition of tomato spotted wilt virus

201

The complete sequence of the tomato spotted wilt virus (TSWV) M RNA segment has been determined. The RNA is 4821 nucleotides long and has an ambisense coding strategy similar to that of the S RNA segment. The M RNA segment contains two open reading frames (ORFs), one in the viral sense which encodes a protein with a predicted size of 33-6K, and one in the viral complementary sense which encodes the precursor to the G 1 and G2 glycoproteins, with a predicted size of 127.4K. Both ORFs are expressed via the synthesis of subgenomic mRNAs that possibly terminate at a stable hairpin structure, located in the intergenic region. The precursor for the glycoproteins contains a sequence motif (RGD) which is characteristic of cellular attachment domains. Significant sequence homology was found between the G1 glycoproteins of members of the genus Bunyavirus and a corresponding region in the glycoprotein precursor of TSWV, indicating a close evolutionary relationship between these viruses. With the elucidation of the M RNA sequence, the complete nucleotide sequence of TSWV has been determined. TSWV represents the first member of the Bunyaviridae shown to contain two ambisense RNA segments.

Section: Introductionmentioning

confidence: 99%

The nucleotide sequence of the M RNA segment of tomato spotted wilt virus, a bunyavirus with two ambisense RNA segments

Kormelink¹,

Haan²,

Meurs³

et al. 1992

201

“…200K), putatively the viral transcriptase. Two membrane glycoproteins of 78K (G 1) and 58K (G2) form the spikes on the viral envelope (Mohamed et al, 1973;Tas et al, 1977;de Haan et al, 1989a).…”

Section: Introductionmentioning

confidence: 99%

Viral RNA synthesis in tomato spotted wilt virus-infected Nicotiana rustica plants

Kormelink¹,

Haan²,

Peters³

et al. 1992

The synthesis of viral RNA species in tomato spotted wilt virus-infected Nicotiana rustica plants was followed in terms of time and relative abundance. Systemic symptoms were visible after 4 days postinoculation (p.i.), but viral (v) and viral-complementary (vc) strands of all three genomic RNA segments [large (L) RNA, medium (M) RNA and small (S) RNA] were detected from 2 days p.i. In addition, two subgenomic mRNAs, derived from S RNA, were detected. For the L RNA segment no subgenomic mRNAs were detected, suggesting that this segment is expressed via the synthesis of a genome-sized vc mRNA. A possible M-specific subgenomic mRNA was detected, showing a similar time course of appearance as the subgenomic mRNAs derived from the S RNA segment. Analysis of cytoplasmic RNA fractions revealed that both v and vc strands of all three genomic segments associate with the nucleocapsid protein into nucleocapsid structures, the vcRNA species being present in lower amounts. Intact, enveloped virus particles contained only the v strand of the L RNA segment and, surprisingly, both v and vc strands of the M and S RNA segment, though in different ratios.

“…TSWV virions are spherical enveloped particles, about 80 to 110 nm in diameter, that contain four different proteins: an internal nucleocapsid protein (N) of Mr 27000 (27K), two membrane glycoproteins (G1 and G2) of 78K and 58K respectively, and a large protein (L) of approximately 120K (Mohamed et al, 1973;Tas et al, 1977). The genome consists of three linear ssRNA molecules approximately 3100 (S RNA), 5400 (M RNA) and 8200 (L RNA) nucleotides long, each complexed with N proteins to form circular nucleocapsids (van den Hurk et al, 1977;Mohamed, 1981;de Haan et al, 1989a).…”

Section: Introductionmentioning

confidence: 99%

The S RNA Segment of Tomato Spotted Wilt Virus has an Ambisense Character

Haan

Wagemakers

Peters

et al. 1990

277

130

The complete nucleotide sequence of the S RNA of tomato spotted wilt virus (TSWV) was determined. The RNA is 2916 nucleotides long and has an ambisense coding strategy. The sequence contains two open reading frames (ORFs), one in the viral sense which encodes a protein with a predicted Mr of 52"4K and one in the viral complementary sense which encodes the viral nucleocapsid protein of Mr 28"8K. Both proteins are expressed by translation of two subgenomic RNA species that possibly terminate at a long stable hairpin structure, located at the intergenic region. The structure of this RNA segment resembles that of the arthropod-borne phleboviruses (family Bunyaviridae). The absence of significant sequence homology between TSWV and bunyaviruses infecting animals suggests that TSWV should be considered as a representative of a new genus within the Bunyaviridae.