Submitted to: Virus Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/11/2008
Publication Date: 9/1/2008
Publication URL: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T32-4SN8TY6-3&_user=2139813&_coverDate=09%2F30%2F2008&_rdoc=25&_fmt=high&_orig=browse&_srch=doc-info(%23toc%234934%232008%23998639998%23693558%23FLA%23display%23Volume)&_cdi=4934&_sort=d&_docanchor=&_ct=29&_version=1&_urlVersion=0&_userid=2139813&md5=8ad6208febaae78fab5238ced4cbac65
Citation: Valles, S.M., Hashimoto, Y. 2008. Characterization of structural proteins of Solenopsis invicta virus 1. Virus Research. 136(1):189-191. 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 significant economic losses in livestock and agricultural production and poses a serious threat to human health. Biocontrol is widely considered the most sustainable method of controlling the fire ant over its entire range. USDA-ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology (CMAVE, Gainesville, FL) have discovered the first virus (SINV-1) known to infect the fire ant. Further characterization of this virus is crucial to its development as a microbial insecticide. CMAVE scientists have characterized the proteins that comprise the viral coat of SINV-1. This information will advance our understanding of this and related viruses, and provide information necessary to its development as a microbial insecticide.
Technical Abstract: Purification of SINV-1 from its host, Solenopsis invicta, and subsequent examination by electron microscopy revealed a homogeneous fraction of spherical particles with a diameter of 30-35 nm. Quantitative PCR with SINV-1-specific oligonucleotide primers verified that this fraction contained high copy numbers of the SINV-1 genome. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the SINV-1 purified fraction revealed 3 major and 1 minor protein bands. The protein bands were labeled VP1 (40.8 ±1.4 kDa), VP2 (35.7 ±2.8 kDa), VP3 (25.2 ±1.8 kDa), and VP4 (22.2 ±2.5 kDa) based on mass. N-terminal sequence was acquired successfully for VP1, VP2, and VP3, but not VP4, and delineated each capsid protein within the 3'-proximal open reading frame. Positional organization of the viral proteins within the SINV-1 structural polyprotein were consistent with other dicistroviruses (when based on homology). Blastp analysis of SINV-1 VP1, VP2, and VP3 revealed significant homology with corresponding structural capsid proteins of positive-strand RNA viruses. The most significant homologues with the highest identities to the SINV-1 VPs included Acute bee paralysis virus (ABPV), Kashmir bee virus (KBV) and Israeli acute paralysis virus (IAPV). Phylogenetic analyses of the viral proteins confirmed the close relationship between SINV-1, ABPV, IAPV, and KBV in that these viruses formed a distinct clade among insect-infecting dicistroviruses. Amino acid residues about the scissile bonds for VP1 and VP3 were consistent with other dicistroviruses and insect-infecting picorna-like viruses.