PARTIAL CLONING OF THE GENOME OF AN UNUSUAL SHRIMP PARVOVIRUS (HPV) - USE OF GENE PROBES IN DISEASE DIAGNOSIS

The DNA genome of the hepatopancreatic parvovirus (HPV) of penaeid shrimp was partially cloned. The largest insert obtained, from the clone OF44, was 2.3 kbp in size and characterized by mapping with restriction enzymes. It was used to construct 2 different DIG-11 dUTP labelled probes, which appeared specific to the virus, without any cross-reactivity with uninfected tissues or with a second shrimp parvovirus, infectious hypodermal and haematopoietic necrosis virus (IHHNV). In situ hybridization on paraffin sections of the hepatopancreas of infected and uninfected shrimp showed the probes react with infected tissue and not with uninfected tissue. In positive hepatopancreas, the probes produced a strong labelling of infected nuclei, especially of the nucleolus and the karyoplasm peripheric to the intranuclear inclusion body. Intranuclear inclusion bodies, which are the principal diagnostic feature of HPV infections by histology, also reacted with the probes, but less intensely. In heavily infected hepatopancreas, cell debris reacted strongly with the probes, as did the microvilli on the surface of epithelial cells.