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Virologie. Volume 8, Number 3, 225-34, mai-juin 2004, Revue

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Author(s) : A. Beby‐Defaux, G. Agius

Summary : HTLV1 is the etiologic agent for adult T‐cell leukemia and a neurodegenerative disorder. The viral genome contains a pX region encoding regulatory proteins from 4 open reading frames (ORF). Whereas Tax (ORF IV) and Rex (ORF III) have been extensively studied, much less is known about pX ORF I and II‐encoded proteins p12 I and p13 II\\p30 II, respectively. However, increasing evidence supports the importance of these ORFs in the replication and pathogenesis of HTLV1. pX ORF I is critical for establishment of persistent infection in vivo and for infection in quiescent primary lymphocytes in vitro. p12 I induces activation of NFAT mediated transcription and increases interleukin‐2 production in a calcium‐pathway dependent manner. pX ORF II is required for maintenance of high viral loads in vivo. p13 II alters mitochondrial morphology and disrupts the mitochondrial inner membrane potential whereas p30 II is a negative regulator of viral expression. This review details the functional properties of these proteins.

Keywords : HTLV1, pX region, p12 I, p13 II, p30 II, T‐cell activation, mitochondria, transcriptional regulation, signalling pathways