A silencing suppressor protein (NSs) of a tospovirus enhances baculovirus replication in permissive and semipermissive insect cell lines.
The nonstructural protein (NSs) of the Tomato spotted wilt virus (TSWV) has been identified as an RNAi suppressor in plant cells. A recombinant Autographa californica multiple nucleopolyhedrovirus (AcMNPV) designated vAcNSs, containing the NSs gene under the control of the viral polyhedrin (polh) gene promoter, was constructed and the effects of NSs in permissive, semipermissive and nonpermissive insect cells to vAcNSs infection were evaluated. vAcNSs produced more budded virus when compared to wild type in semipermissive cells. Co-infection of vAcNSs with wild type baculoviruses clearly enhanced polyhedra production in all host cells. Confocal microscopy analysis showed that NSs accumulated in abundance in the cytoplasm of permissive and semipermissive cells. In contrast, high amounts of NSs were detected in the nuclei of nonpermissive cells. Co-infection of vAcNSs with a recombinant AcMNPV containing the enhanced green fluorescent protein (egfp) gene, significantly increased EGFP expression in semipermissive cells and in Anticarsia gemmatalis-hemocytes. Absence of small RNA molecules of egfp transcripts in this cell line and in a permissive cell line indicates the suppression of gene silencing activity. On the other hand, vAcNSs was not able to suppress RNAi in a nonpermissive cell line. Our data showed that NSs protein of TSWV facilitates baculovirus replication in different lepidopteran cell lines, and these results indicate that NSs could play a similar role during TSWV-infection in its thrips vector.
Departamento de Biologia Celular, Universidade de Brasília, 70910-900 Brasília, Distrito Federal, Brazil.
Virgínia Carla
VC
Oliveira
Lorrainy
L
Bartasson
Maria Elita Batista
ME
de Castro
José Raimundo
JR
Corrêa
Bergmann Morais
BM
Ribeiro
Renato Oliveira
RO
Resende
D000818:Animals; D016367:Baculoviridae / Q000235:genetics / Q000254:growth & development*; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D003593:Cytoplasm / Q000737:chemistry; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007915:Lepidoptera; D011995:Recombination, Genetic; D013194:Staining and Labeling / Q000379:methods; D017865:Tospovirus / Q000472:pathogenicity*; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D037521:Virulence Factors / Q000378:metabolism*
D017361:Viral Nonstructural Proteins; D037521:Virulence Factors; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins