- CHICAGO (Reuters Health)
- An international research team has identified very rare and previously
unseen HIV variations in 17 Rwandan HIV patients who have lived for more
than 12 years with the infection.
- The variations could weaken the virus or may have been
evolved by the virus to adapt to a strong immune system response, but more
research is needed to answer this question, Dr. Francois Roman of CRP-Sante
in Luxembourg told Reuters Health. He presented his findings here Sunday
at the Interscience Conference on Antimicrobial Agents and Chemotherapy.
- Roman and his colleagues sequenced a specific part of
the envelope enclosing the human immunodeficiency virus known as the V3
loop. The envelope, he noted, is the first part of the virus to interact
with a cell, and the V3 loop--which has tremendous genetic variability--helps
determine which cells the virus will infect. The V3 loop also helps neutralize
the immune response to HIV.
- The 17 patients had all lived for more than 12 years
with the virus, and had ``very good immune parameters,'' Roman said. Their
clinical stage of HIV infection was relatively low, and all had CD4 T cell
counts higher than 500, which shows their immune systems were still functioning
- The genetic sequence of the patients' V3 loops was compared
with the Los Alamos HIV database, which contains more than 500 HIV gene
sequences. Roman and colleagues found that the Rwandan patients had V3-loop
variants that were either not present at all in the Los Alamos database
or were seen in less than 0.5% of strains in the database.
- One of the very rare variants was seen in three of the
Rwandan patients and another in two of the patients. Two of the patients
shared one of the previously unseen variants.
- Roman said that while it is not yet clear what role the
V3-loop variants play in HIV infection, he and his colleagues hypothesize
that they may somehow weaken the virus. He also noted that the patients
may have had a very strong immune response to infection, which could force
the virus to evolve in a certain way.
- Roman said he and his colleagues have checked the V3-loop
proteins of another group of Rwandan HIV patients who were not long-term
survivors, and found they did not have the variants.
- The next step, Roman said, will be to look for these
V3 variants in groups of HIV patients from a different geographical area,
and to test the ability of HIV with these particular mutations to infect
cells in the laboratory.