A tomato spotted wilt-like virus with a serologically distinct N protein

Abstract

A serologically distinct member of the tomato spotted wilt virus (TSWV) group was isolated from the hybrid flower crop New Guinea impatiens (Impatiens sp.) and termed TSWV-I. TSVW-I type isolates have frequently been detected in a wide variety of flower crops throughout the United States. TSWV-shares many characteristics with TSWV, such as symptomatology and possession of three ssRNA species (L, M and S of 8·3 kb, 5·2 kb and 3·4 kb, respectively) and three structural proteins (G1, G2 and N of 78K, 52K and 28K respectively). The TSWV-I G1 and G2 glycoproteins were serologically related to the respective proteins of TSWV, but the TSWV-I nucleocapsid or N protein was serologically unrelated to that of TSWV. Hybridization analysis under high stringency conditions revealed no hybridization between clones of TSWV-1 S and M and the S and M RNAs of TSWV, respectively and in addition, a TSWV S clone hybridized only with TSWV S RNA. The cytopathology of TSWV-1 also differed from that of TSWV. TSWV-1- infected tissue primarily contained filamentous structures arranged in paracrystalline arrays, which were also observed by immunosorbent electron microscopy of tissue extracts. The filamentous structures were only trapped by TSWV-1 antibodies. The conserved serological relatedness between TSWV types for G1 and G2, but not N, is consistent with serological analyses of the nairovirus and phlebovirus genera of the Bunyaviridae, the virus family that TSWV most closely resembles.