VSV-G pseudotyping rescues HIV-1 CA mutations that impair core assembly or stability

Sonia Brun¹^,2^,3 , Maxime Solignat¹^,2^,3 , Bernard Gay¹^,2^,3 , Eric Bernard¹^,2^,3 , Laurent Chaloin¹^,2^,3 , David Fenard¹^,2^,3^,4 , Christian Devaux¹^,2^,3 , Nathalie Chazal¹^,2^,3 and Laurence Briant¹^,2^,3

¹Université Montpellier 1, Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé (CPBS), France

²CNRS, UMR 5236, CPBS, F-34965, Montpellier, France

³Université Montpellier 2, CPBS, F-34095, Montpellier, France

⁴GENETHON, 1bis rue de l'Internationale – BP60, 91002 EVRY cedex, France

author email corresponding author email

Retrovirology 2008, 5:57doi:10.1186/1742-4690-5-57


Published:	7 July 2008

Abstract

Background

The machinery of early HIV-1 replication still remains to be elucidated. Recently the viral core was reported to persist in the infected cell cytoplasm as an assembled particle, giving rise to the reverse transcription complex responsible for the synthesis of proviral DNA and its transport to the nucleus. Numerous studies have demonstrated that reverse transcription of the HIV-1 genome into proviral DNA is tightly dependent upon proper assembly of the capsid (CA) protein into mature cores that display appropriate stability. The functional impact of structural properties of the core in early replicative steps has yet to be determined.

Results

Here, we show that infectivity of HIV-1 mutants bearing S₁₄₉A and S₁₇₈A mutations in CA can be efficiently restored when pseudotyped with vesicular stomatitis virus envelope glycoprotein, that addresses the mutant cores through the endocytic pathway rather than by fusion at the plasma membrane. The mechanisms by which these mutations disrupt virus infectivity were investigated. S₁₄₉A and S₁₇₈A mutants were unable to complete reverse transcription and/or produce 2-LTR DNA. Morphological analysis of viral particles and in vitro uncoating assays of isolated cores demonstrated that infectivity defects resulted from disruption of the viral core assembly and stability for S₁₄₉A and S₁₇₈A mutants, respectively. Consistent with these results, both mutants failed to saturate TRIM-antiviral restriction activity.

Conclusion

Defects generated at the level of core assembly and stability by S₁₄₉A and S₁₇₈A mutations are sensitive to the way of delivery of viral nucleoprotein complexes into the target cell. Addressing CA mutants through the endocytic pathway may compensate for defects generated at the reverse transcription/nuclear import level subsequent to impairment of core assembly or stability.