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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Imported Fire Ant and Household Insects Research » Research » Publications at this Location » Publication #236081
Title: Isolation and characterization of Solenopsis invicta virus 3, a new positive-strand RNA virus infecting the red imported fire ant, Solenopsis invicta

Author
item Valles, Steven
item HASHIMOTO, YOSHIFUMI - BOYCE THOMPSON INST.

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2009
Publication Date: 4/28/2009
Citation: Valles, S.M., Hashimoto, Y. 2009. Isolation and characterization of Solenopsis invicta virus 3, a new positive-strand RNA virus infecting the red imported fire ant, Solenopsis invicta. Virology. 388:354-361.

Interpretive Summary: The red imported fire ant was introduced into the United States in the 1930s and currently infests about 300 million acres. It causes economic losses that exceed 6 billion dollars annually in the United States and poses a threat to human health. USDA-ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology (Gainesville, FL) have discovered a new RNA virus in the fire ant (representing only the third virus infecting the fire ant). The new virus, named Solenopsis invicta 3 (or SINV-3), is associated with fire ant colony mortality and may find utility as a biological control agent (or microbial insecticide) for fire ants.

Technical Abstract: We report the discovery of a new virus from the red imported fire ant, Solenopsis invicta. Solenopsis invicta virus 3 (SINV-3) represents the third virus identified from this ant species using the metagenomics approach. The single (positive)-strand RNA, monopartite, bicistronic genome of SINV-3 was sequenced in entirety (Accession number FJ528584), comprised of 10,386 nucleotides and polyadenylated at the 3' terminus. This genome size was confirmed by Northern analysis. The genome revealed 2 large open reading frames (ORFs) in the sense orientation with an untranslated region (UTR) at each end and between the two ORFs. The 5' proximal ORF (ORF 1) encoded a predicted protein of 299,095 Da (2,580 amino acids). The 3' proximal ORF (ORF 2) encoded a predicted protein of 73,186 Da (651 amino acids). RNA-dependent RNA polymerase (RdRp), helicase and protease domains were recognized in ORF 1. SDS-PAGE separation of purified SINV-3 particles yielded 2 bands (ostensibly capsid proteins) with a combined molecular mass of 77,250 Da which was similar to the mass predicted by ORF 2 (73,186 Da). Phylogenetic analysis of the conserved amino acid sequences containing domains I to VIII of the RdRp from dicistroviruses, iflaviruses, plant small RNA viruses, picornaviruses, and 4 unassigned positive-strand RNA viruses revealed a trichotomous phenogram with SINV-3 and Kelp fly virus comprising a unique cluster. Electron microscopic examination of negatively stained samples of SINV-3 revealed isometric particles with apparent projections and a diameter of 27.3 ±1.3 nm. SINV-3 was successfully transmitted to uninfected workers by feeding. The minus (replicative) strand of SINV-3 was detected in worker ants indicating replication of the virus. The possibility of using SINV-3 as a microbial control agent for fire ants is discussed.