AEGiS-15IAC: New insights in retroviral pathogenicity: The Raf-binding domain of Nef is involved in acute lethal enteropathy.

15th International AIDS Conference

Bangkok, Thailand - July 11-16, 2004

New insights in retroviral pathogenicity: The Raf-binding domain of Nef is involved in acute lethal enteropathy.

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. ThOrA1442)

Flory E, Sanzenbacher R, Tschulena U, Plesker R, Coulibaly C, Raupp S, Wenig R, Cichutek K
Paul-Ehrlich-Institut, 63225 Langen, Germany

BACKGROUND: In this study, we analyzed the physiological role of a so far functionally not characterized domain within the viral accessory protein Nef. Interestingly, this conserved domain is also defective in many strains of HIV long-term survivors. On the molecular level, it has been shown for HIV-1 Nef that this domain interacts with the Raf-1 kinase, a cellular molecule involved in the regulation of mitogenic signals. As a model system we used the simian immunodeficiency virus strain SIV[SM]PBj, as it shows the unique features to replicate in and to induce proliferation of unstimulated peripheral blood mononuclear cells (PBMCs)in vitro. Moreover, infection of pig-tailed macaques leads to an acute lethal enteropathy within 14 days. Surviving animals develop an AIDS-like disease.

METHODS: For analysis, we constructed a virus mutated in two adjacent amino acids in the respective "Raf-binding domain" (RBD) and compared the biological properties of mutant and wildtype virus in vitro and in vivo.

RESULTS: Despite similar replication kinetics and Nef expression of wildtype and mutant virus, the mutant lost the ability to induce cellular proliferation and IL-2 synthesis. This was accompanied by a reduced capability of the mutant virus to induce activation of the mitogenic signaling cascade and NFkappaB in vitro. Most important, inoculation of pig-tailed macaques with mutant virus did not result in acute enteropathic pathogenicity as was observed upon inoculation with wildtype-virus. Histopathological analysis revealed that animals inoculated with wildtype virus showed characteristic blunting and fusion of intestinal villi, whereas animals inoculated with mutant virus showed no pathological changes. Conclusion Our results indicate that acute enteropathic pathogenesis of retrovirus infection can be linked on the molecular level to the capability of the viral Nef protein to interact with distinct cellular MAPK signaling pathways.

Keywords: AEGIS, SIV, Cell Proliferation, Simian Acquired Immunodeficiency Syndrome, Virulence, Virus Replication, HIV-1, Acquired Immunodeficiency Syndrome, Macaca, Intestinal Diseases, Animal, In Vitro, pathogenicity, metabolism, pharmacokinetics, virology

040711
ThOrA1442