PARTIAL CLONING OF THE GENOME OF INFECTIOUS HYPODERMAL AND HEMATOPOIETIC NECROSIS VIRUS, AN UNUSUAL PARVOVIRUS PATHOGENIC FOR PENAEID SHRIMPS - DIAGNOSIS OF THE DISEASE USING A SPECIFIC PROBE

The infectious hypodermal and haematopoietic necrosis virus (IHHNV), p athogenic for penaeid shrimp, is an icosahedral unenveloped particle, 22 nm in diameter, with an ssDNA linear genome, and proposed to be a m ember of the Parvoviridae. A large majority of minus-strand DNA is inc orporated into the capsids compared to the plus-strand. A small amount of reannealed plus- and minus-strands (dsDNA) obtained after nucleic acid extraction was blunt-ended and cloned into the system pUC18/Esche richia coli strain DH5alpha. Selected clones were studied and characte rized using restriction enzymes. One of them, BQ31, was used to constr uct different sized probes labelled with digoxigenin-11-dUTP. These pr obes failed to hybridize with DNA of some insect parvoviruses and with DNA of a parvo-like virus of shrimp. They reacted strongly with dilut ions of homogenized IHHNV-infected shrimp tissues and, conversely, did not react with uninfected shrimp tissues. They hybridized in situ, in sections of infected animals, labelling strongly the target cells and particularly the nuclear Cowdry type A inclusion body, which is the m ost diagnostic characteristic of this disease.