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Increase of Tospoviral Diversity in Brazil with the Identification of Two New Tospovirus Species, One from Chrysanthemum and One from Zucchini

First, fourth, and sixth authors: EMBRAPA Hortaliças, Cx. Postal 0218, 70359-970, Brasília, DF, Brazil; second and third authors: Departamento Biologia Celular, Universidade de Brasília, 70919-970, Brasília, DF, Brazil; and fifth author: Department of Virology, Agricultural University, 6709PD, Wageningen, the Netherlands

During a survey conducted in several different regions of Brazil, two unique tospoviruses were isolated and characterized, one from chrysanthemum and the other from zucchini. The chrysanthemum virus displayed a broad host range, whereas the virus from zucchini was restricted mainly to the family Cucurbitaceae. Double-antibody sandwich-enzyme-linked immunosorbent assay and western immunoblot analyses demonstrated that both viruses were serologically distinct from all reported tospovirus species including the recently proposed peanut yellow spot virus and iris yellow spot virus (IYSV) species. The nucleotide sequences of the nucleocapsid (N) genes of both viruses contain 780 nucleotides encoding for deduced proteins of 260 amino acids. The N proteins of these two viruses displayed amino acid sequence similarities with the previously described tospovirus species ranging from 20 to 75%, but they were more closely related to each other (80%). Based on the biological and molecular features, these viruses are proposed as two new tospovirus species, designated chrysanthemum stem necrosis virus (CSNV) and zucchini lethal chlorosis virus (ZLCV). With the identification of CSNV and ZLCV, in addition to tomato spotted wilt virus, groundnut ring spot virus, tomato chlorotic spot virus, and IYSV, Brazil harbors the broadest spectrum of tospovirus species reported.

Additional keywords: Bunyaviridae, multiple sequence alignments, phylogeny tree, tospovirus epidemiology.