Phenotype variation in human immunodeficiency virus type 1 transmission and disease progression

Mariangela Cavarelli, Gabriella Scarlatti

Research output: Contribution to journalArticlepeer-review


Human immunodeficiency virus type I (HIV-1) infects target cells through interaction with the CD4 molecule and chemokine receptors, mainly CCR5 and CXCR4. Viral isolates can be phenotypically classified based on the co-receptor they utilize to infect target cells. Thus, R5 and X4 virus use respectively CCR5 and CXCR4, whereas R5X4 virus can use either CCR5 or CXCR4. This review describes the central role played by co-receptor expression and usage for HIV-1 cell tropism, transmission and pathogenesis. We discuss various hypotheses proposed to explain the preferential transmission of R5 viruses and the mechanisms driving the change of HIV-1 co-receptor usage in the course of infection. Recent insights in the intrinsic variability of R5 viruses and their role in influencing disease progression in both adults and children are also discussed.

Original languageEnglish
Pages (from-to)121-136
Number of pages16
JournalDisease Markers
Issue number3-4
Publication statusPublished - 2009


  • Co-receptor usage
  • Disease progression
  • HIV-1
  • Transmission
  • Tropism

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Genetics
  • Molecular Biology
  • Biochemistry, medical


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