Improved detection of citrus psorosis virus using polyclonal and monoclonal antibodies

Citrus psorosis is a serious and widespread disease associated with citrus psorosis virus (CPsV), a novel filamentous negative-stranded virus in the g enus Ophiovirus. Laborious and costly indexing on test plants has been the only routine diagnostic method available, but recently an antiserum usable in double antibody sandwich (DAS) ELISA has been prepared. Here, major impr ovements to the DAS-ELISA protocol, a new purification method, and producti on of two monoclonal antibodies (mabs) to CPsV, an IgG and an IgM are repor ted. A highly sensitive triple antibody sandwich (TAS) ELISA making use of the mabs is described. In glasshouse citrus the homologous virus was still detectable at a tissue dilution of 1/6250 in DAS and at 1/31250 in TAS-ELIS A. Both the DAS and IgG mab-TAS formats detected all CPsV isolates so far t ested (from Argentina, Italy, Lebanon, Spain and the USA). A few isolates w ere not detected by the IgM mab.