Multiplex detection of Solenopsis invicta viruses -1, -2, and -3.

Multiplex reverse transcription and polymerase chain reaction (PCR) methods were developed to detect Solenopsis invicta viruses -1, -2, and -3 simultaneously in their host, the red imported fire ant, S. invicta. cDNA synthesis was conducted in a single reaction containing an oligonucleotide primer specific for each virus. Multiplex PCR was subsequently conducted with oligonucleotide primer pairs specific for each virus. The method was specific and sensitive, capable of detecting as few as 500 copies of the viral genomes consistently. Specificity was verified by PCR and amplicon sequencing. The method was evaluated against field-collected samples of ant workers from colonies in Argentina (n=135 ant colonies) and the United States (n=172 ant colonies). The prevalence of each virus in fire ant colonies varied considerably from site to site. A number of colonies exhibited multiple virus infections. However, the multiple SINV infection rate was lower than for single infections. Comparison of viral infection prevalence between S. invicta colonies in Argentina and the U.S. showed no statistical differences, regardless of infection category. This method is anticipated to facilitate epidemiological and related studies concerning the S. invicta viruses in fire ants.