Nucleotide sequence comprising a 1759 bp genomic DNA sequence (I) of a porcine circovirus called MAP ("maladie de lamaigrissement du porcelet" piglet fatal wasting disease), is new. Also claimed are: (1) The nucleotide sequence of the porcine circovirus is: (a) a fragment of (I) (b) a nucleotide sequence homologous to the nucleotide sequence of (a) (c) a nucleotide sequence complementary to (I) or complementary to the nucleotide sequence of (a) or (b) (d) a nucleotide sequence capable of hybridizing under stringent conditions to the nucleotide sequence of (a), (b) or (c) (e) a nucleotide sequence comprising (I) or the nucleotide sequences of (a), (b), (c) or (d) (f) a modified nucleotide sequence comprising the nucleotide sequence of (a), (b), (c), (d) or (e). (2) polypeptide encoded by the nucleotide sequence of (1) (3) cloning and/or expression vectors containing the nucleotide sequences (4) viral or pseudoviral particles generated from the vectors (5) host cells transformed with the vectors or (pseudo)viral particles (6) animals containing the transformed cells (7) synthetic polypeptides obtained using the amino acid sequence of a polypeptide as in (1) (8) hybrid polypeptides comprising at least one sequence of a polypeptide as in (2) or (7) and a sequence of an immunogenic polypeptide (9) nucleotide sequences encoding the hybrid polypeptides (10) vectors containing a sequence as in (9) (11) a method for the detection of the porcine circovirus (12) mono- or polyclonal antibodies or their fragments or chimeric antibodies capable of specifically recognising a polypeptide as in (2) or (7) and (13) compounds that are capable of binding to a polypeptide or nucleotide sequence as above or of recognising an antibody as in (12) and/or of modulating, inducing or inhibiting the expression of genes and/or of modifying the cellular replication of MAP circovirus or of inducing or inhibiting pathologies associated with MAP circovirus infection in pigs and are capable of being
