Tropism Testing Facts Challenges Vision Arevir Meeting May 2011 - - PowerPoint PPT Presentation

Tropism Testing – Facts Challenges Vision

Arevir Meeting May 2011

Therapy examples

• situation I:

– Therapy: Kaletra/AZT/3TC virus: wt – after 1 year: PR: L63P RT: 41L, 215Y, 184V

• what to change?
• Who is out!

Therapy examples

• situation II:

– Therapy: AZT/3TC/MVC; virus: wt, R5- tropic – after 1 year: RT: 41L, 215Y, X4-tropic

• who is out and why ??

Stability of Tropism under ART

Resistance vs. Tropism shift

• HIV exposure to drug selects for resistance

= virus becomes non-responsive

• After resistance selection: the affected drug is lost!
• CCR5 antagonists select resistances within R5‐tropic viruses!
• Tropism shift under MVC therapy is NOT a “resistance”!

= a selection mechanism for existing X4‐tropic virus or for new virus evolution

• X4 viruses emerge under insufficient backbone pressure!
• Disappears when MVC is removed!(?)

Challenges of R-Testing remain…

(will we ever need it?)