A greater prevalence of X4 viruses in HIV type 1 intravenous drug users reflects a 'CD4+ effect'.

摘要

Editor: Classification of HIV-1 isolates as X4 or R5 viruses based on their differential use of CCR5 and CXCR4 chemokine receptors has replaced the previous distinction of isolates into syncytium- (SI) and non-syncytium-inducing (NSI), and the SI/X4 and NSI/R5 denominations are currently used interchangeably. Coreceptor tropism (CTR) plays a crucial role in AIDS progression; in fact, the R5/X4 shift is associated with a more rapid decrease of CD4 cells, and X4 viruses tend to emerge late in the course of HTV infection. Since the activity of CCR5 antagonists is limited to patients in whom R5 viruses can be detected, determination of CCR5 usage of HIV-1 is a prerequisite for prescribing the current CCR5 antagonist maraviroc. Consequently, there is a renewed interest in these viral characteristics, and studies assessing viral tropism in different populations are required to identify the most suitable candidates for use of maraviroc.