Which HIV-1 infection strains are being analyzed in the current research studies?

Researchers are currently analyzing specific HIV-1 strains to understand how the virus spreads, how it resists drugs, and how the immune system fights it. Studies focus on recombinant forms like CRF_35AD in Iran and CRF01_AE in Shanghai, as well as viral tropism types such as R5 and X4 that determine which cells the virus infects. Additionally, scientists are using HIV-2 as a slower-progressing model to compare against HIV-1.

What the research says

In Iran, analysis of sequences from 2006 to 2013 found that the recombinant strain CRF_35AD was the most common, making up 78% of all sequences studied ⁴. This strain was found in the majority of genetic regions tested, including the pol, env, and gag genes ⁴.

In Shanghai, a different strain called CRF01_AE was the predominant type, accounting for 42.9% of cases in that region ⁶. Other strains found there included subtype B and various recombinant forms like CRF07_BC and CRF08_BC ⁶.

Researchers also study viral tropism, which describes which cells the virus infects. Studies show that about 72% of patients treated with specific drugs had an R5 profile, meaning the virus uses the CCR5 receptor to enter cells ⁵. A smaller percentage had an X4 profile, which uses a different receptor ⁵.

Separate research uses HIV-2 infection as a resource for HIV-1 cure studies because it naturally shows lower viral loads and slower disease progression ¹. However, scientists note that the transcriptional activity of HIV-2 varies and is not always uniform across different patients or study groups ¹.

What to ask your doctor

• What specific HIV-1 strain or recombinant form (like CRF_35AD or CRF01_AE) is present in my case?
• Does my virus have an R5 or X4 tropism profile that affects my treatment options?
• Are there new drug regimens being tested for the specific strain I have?
• How does my specific strain compare to the HIV-2 model used in current cure research?