Effect of R77Q, R77A and R80A changes in Vpr on HIV-1 replication and CD4 T cell depletion in human lymphoid tissue ex vivo.
BACKGROUND
It has been suggested that mutations of R77A and R80A in the HIV-1 viral protein R (Vpr) impair its proapoptotic activity and that a naturally occurring R77Q variation is associated with non-progressive HIV-1 infection.


BACKGROUND
To assess the effect of Vpr R77Q, R77A and R80A mutations on the efficiency of CCR5(R5)- and CXCR4(X4)-tropic HIV-1 replication and cytopathicity in human lymphoid tissue (HLT).


METHODS
Vpr mutants of the X4-tropic HIV-1 NL4-3 clone and an R5-tropic derivative were generated by PCR mutagenesis. Virus stocks established by transfection of 293T cells were used to infect macrophages and ex vivo HLT. HIV-1 replication was assessed by measuring p24 core antigen in the culture supernatants and CD4 T-cell depletion and apoptosis were measured by flow cytometric analysis.


RESULTS
The R5-tropic HIV-1 Vpr mutants replicated with slightly (R77A, R77Q) to moderately (R80A) reduced efficiency in ex vivo-infected HLT and macrophages. In comparison, the changes in Vpr had negligible effects on replication of the X4-tropic forms in lymphatic tissues. Mutation of R77Q and R80A reduced apoptosis of HIV-1-infected cells in ex vivo-infected HLT independently of the viral coreceptor tropism. However, only the R5-tropic HIV-1 Vpr mutants caused markedly less CD4 T-cell depletion than wild-type HIV-1 at the end of ex vivo HLT culture.


CONCLUSIONS
The observation that Vpr R77Q reduces the cytopathicity of R5-tropic HIV-1 in lymphoid tissues supports a role in non-progressive HIV-1 infection but the attenuating effects might be dependent on the viral subtype and coreceptor tropism.
Department of Virology, University of Ulm, Germany.
Devi
D
Rajan
Steffen
S
Wildum
Elke
E
Rücker
Michael
M
Schindler
Frank
F
Kirchhoff
D017209:Apoptosis; D015153:Blotting, Western; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016334:Genes, vpr / Q000235:genetics*; D015658:HIV Infections / Q000276:immunology / Q000473:pathology / Q000821:virology*; D015497:HIV-1 / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology; D006801:Humans; D008221:Lymphoid Tissue / Q000276:immunology / Q000473:pathology / Q000821:virology*; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D046509:Tissue Culture Techniques; D014779:Virus Replication