The nucleotide sequence of RNA-1 of an isolate of the H serotype of Indian peanut clump virus (IPCV-H) was shown to comprise 5,841 nucleotides. The RNA contains three open reading frames (ORF) which are between nucleotides 133 and 3,522, nucleotides 3,526 and 5,103 (assuming expression by suppression of the ORF 1 termination codon) and nucleotides 5,168 and 5,539. The encoded polypeptides have M(r), of 129,687 (p130), 60,188 (p60) and 14,281 (p14). ORF 2 is thought to be expressed by suppression of the termination codon of ORF 1 to produce a M(r) 189,975 product (p190). p130 contains sequences characteristic of proteins with methyl transferase and NTP-binding properties and p190 contains these and sequences characteristic of RNA-dependent RNA polymerases. The nucleotide sequence of IPCV RNA-1 is similar to that of peanut clump virus (PCV) and corresponding encoded polypeptides are 88% (p130), 95% p60 and 75% (p14) identical. The sequences of the translation products are also similar to those of soil-borne wheat mosaic virus and barley stripe mosaic virus. Oligonucleotide primers, designed on the basis of the sequences of RNA-1 of IPCV and PCV, were effective in reverse transcription-PCR amplification of these RNAs and that of IPCV isolates of the serologically distinct L and T serotypes.