MOLECULAR CHARACTERIZATION OF ALFALFA CRYPTIC VIRUS-1

Alfalfa cryptic virus 1 (ACV1) was purified from alfalfa plant clone (Medicago sativa) and characterized. The genome of ACV 1 consists of two dsRNAs, one with an estimated Mr of 1?27 × 106 (RNA 1) and the other of Mr 1?17 × 106 (RNA 2); the virus capsid is built from one polypeptide of estimated Mr 54000. An RNA-dependent RNA polymerase able to replicate the genomic RNAs in vitro is associated with purified virus particles. In vitro translation showed that each of the genomic RNAs encodes a polypeptide and that encoded by RNA 2 is the capsid protein. These polypeptides account for about 95% and 83% of the coding capacity of RNA 1 and RNA 2, respectively. In Western and Northern blot experiments close affinity was found between ACV 1 and hop trefoil cryptic virus 1, a cryptovirus found in Medicago lupulina. No affinity was detected with any other cryptovirus tested.