by Professor Vincent Racaniello:
No matter what antiviral drugs are used, resistant viral variants inevitably emerge.
For XMRV the process may be less problematic than for HIV-1.
Compared with HIV-1, isolates of XMRV isolates have limited sequence diversity. The genomes of all the XMRV isolates obtained to date differ from each other at 27 out of 8,100 nucleotides.
If this lack of diversity is a consequence of limited replication in the host, then the emergence of drug resistant variants could be significantly lower than HIV-1.
A combination of two drugs might therefore be effective in treating XMRV infection.
The authors note that after several months of propagating XMRV in the presence of raltegravir, drug resistant viruses have not emerged. But a human is very different from a dish of cultured cells.
Whether or not combinations of these drugs can be used to treat XMRV infection awaits the results of additional epidemiological studies, as well as clinical trials to determine efficacy. As the authors conclude:
If XMRV proves to be a causal factor in prostate cancer or CFS, these discoveries may allow for rational design of clinical trials. Read more>>