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Facteurs de non‐pathogénicité de l‘infection à SIVagm chez le singe vert d‘Afrique Volume 7, issue 4, Juillet 2003

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Authors
Unité de biologie des rétrovirus, Institut Pasteur, 28, rue du Docteur Roux, 75724 Paris Cedex 15. Institut Pasteur de Dakar, 36, avenue Pasteur, BP220, Dakar, Sénégal. Centre international de recherches médicales, Franceville, Gabon

African primates are natural carriers of simian immunodeficiency virus (SIV). Among them, African green monkeys (AGM) exhibit high SIV seroprevalence rates and are considered as the main reservoir for SIV in natura. In contrast to pathogenic HIV1 and SIVmac infections in humans and macaques, respectively, the most striking feature of SIVagm infection is the lack of AIDS‐like disease despite long‐term infection and continuous viral replication. Indeed levels of viremia can reach those reported in pathogenic infections. In contrast, the viral burden in lymph nodes (LN) of long‐term SIVagm‐infected AGM is lower than that of HIV1 and SIVmac infections. This low LN viral burden is associated with signs of a lower T cell activation state as indicated by the absence of an abnormal rate of peripheral T CD4 + lymphocytes undergoing apoptosis, the absence of LNs‘ follicular hyperplasia and the lack of CD8 + cell infiltrations into LNs‘ germinal centers. Altogether, this indicates that SIVagm, despite high viremia levels, does not induce chronic abnormal activation of T lymphocytes in AGMs. Further studies in AGMs might yield clues about the specific virus‐host interactions inducing host responses that are essentially protective and not harmful to the host.