Abstract
The HIV-1 Vpu is required for efficient virus particle release from the plasma membrane and intracellular CD4 degradation in infected cells. In the present study, we found that the loss of virus infectivity as a result of envelope (Env) incorporation defect caused by a Gag matrix (MA) mutation (L30E) was significantly alleviated by introducing a start codon mutation in vpu. Inactivation of Vpu partially restored the Env incorporation defect imposed by L30E substitution in MA. This effect was found to be comparable in cell types such as 293T, HeLa, NP2 and GHOST as well as in peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages (MDM). However, in HeLa cells BST-2 knockdown was found to further alleviate the effect of Vpu inactivation on infectivity of L30E mutant. Our data demonstrated that the impaired infectivity of virus particles due to Env incorporation defect caused by MA mutation was modulated by start codon mutation in Vpu.
Highlights
The Human immunodeficiency virus type 1(HIV-1) Vpu plays an important role in HIV-1 pathogenesis via its interaction with various cellular proteins and overcoming antagonism by a restriction factor, BST-2 [1]
Molecular constructs possessing Gag MA mutation L30E (Leucine replaced with Glutamic acid at 30th position) with and without Vpu start codon mutation were made to study the combined effect of both mutations on virus replication and infectivity. pNL-AD8 backbones lacking Env were constructed by replacing env start codon with a stop codon to study the consequences of Vpu and Gag mutations on primary envelopes derived from patients
We have investigated the consequences of Vpu start codon mutation on HIV-1 release and infectivity
Summary
The Human immunodeficiency virus type 1(HIV-1) Vpu plays an important role in HIV-1 pathogenesis via its interaction with various cellular proteins and overcoming antagonism by a restriction factor, BST-2 ( known as tetherin) [1]. Based on observations that proposed the role of Gag MA in Vpu-mediated particle release, we examined whether there is any alteration in Vpu mediated particle release and infectivity due to a specific point mutation in Gag MA (L30E) that was previously shown to severely diminish virus infectivity and Env incorporation [24,25,32] and whether it is dependent on celltype. To test this hypothesis, 293T, HeLa, NP2 and GHOST cells were transfected with pNL-AD8 (WT) plasmid and its mutant derivatives (DVpu, L30E and L30E-DVpu). Significant reduction in particle release of DVpu and double mutant (L30E-DVpu) was monitored from HeLa cells as compared to 293T, NP2 and GHOST cells
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