查看文章

In contrast to activated CD4⁺ T cells, resting human CD4⁺ T cells circulating in blood are highly resistant to infection with human immunodeficiency virus (HIV)^,,,. Whether the inability of HIV to infect these resting CD4⁺ T cells is due to the lack of a key factor, or alternatively reflects the presence of an efficient mechanism for defence against HIV, is not clear. Here we show that the anti-retroviral deoxycytidine deaminase APOBEC3G strongly protects unstimulated peripheral blood CD4⁺ T cells against HIV-1 infection. In activated CD4⁺ T cells, cytoplasmic APOBEC3G resides in an enzymatically inactive, high-molecular-mass (HMM) ribonucleoprotein complex that converts to an enzymatically active low-molecular-mass (LMM) form after treatment with RNase. In contrast, LMM APOBEC3G predominates in unstimulated CD4⁺ T cells, where HIV-1 replication is blocked and reverse transcription is impaired^,,. Mitogen …