IMMUNOFLUORESCENT LOCALIZATION OF TOBACCO RINGSPOT NEPOVIRUS IN THE VECTOR NEMATODE XIPHINEMA-AMERICANUM

An indirect immunofluorescent technique was developed to localize toba cco ringspot nepovirus (TRSV) in the vector nematode Xiphinema america num sensu stricto. A population of this nematode that efficiently tran smitted TRSV was given an acquisition access period of 10 days on TRSV -infected cucumber. Treatment of fragments of viruliferous nematodes w ith a polyclonal antiserum against TRSV followed by fluorescein isothi ocyanate-conjugated goat anti-rabbit immunoglobulin G resulted in viru s-specific bright fluorescence only in the lumen of the styler extensi on and esophagus. Virus-specific fluorescent signals were observed in the virus-retention region of 44% of the nematode fragments examined. The percentage of nematodes labeled with virus-specific fluorescence i ncreased as the acquisition access period increased from 0 to 22 days; the increase paralleled the increase in the transmission efficiency o f the nematode population. Visualization of the entire virus-retention region of individual nematodes within a population of vector or nonve ctor nematodes provides a rapid and simple means of monitoring specifi c attachment of plant viruses.