The citrus ringspot isolate CtRSV-4 was purified, and the dsRNA associated with the bottom component in a sucrose gradient was reverse transcribed and cloned. One of the clones (224m) was partially sequenced and, from this sequence, a set of primers encompassing a 218 bp fragment was designed. These primers were used for reverse transcription and amplification by the polymerase chain reaction (RT-PCR) of crude extracts from healthy or infected citrus tissue. A 218 bp DNA segment was obtained

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... m plants infected with ringspot CtRSV-4 or with psorosis CPsAV-90-1-1 but not from healthy plants, indicating that both viruses were specifically detected in infected citrus.