Researchers report rapid re-infection of HCV via sexual transmission at HCV2012 Conference
by Rebecca Grey 14th November 2012
Cautious optimism was the general tone of the recent HCV 2012 meeting, where some recent set-backs for new direct-acting anti-retroviral (DAA) drugs in Phase III trials were discussed along side of promising results for other options. However even as we inch closer to a pharmaceutical cure for all genotypes, epidemiological realities still present significant barriers to the goal of eradication.
Even after a successful clearance of the virus following treatment, re-infection with a new virus is a major concern for high-risk individuals. At the meeting, Janke Schinkel’s group from the Academic Medical Center in Amsterdam reported that among MSM co-infected with HIV, re-infection rates following successful eradication of the virus was >30% over 5 years. Re-infection with a different genotype (typically genotype 4) occurred much more frequently than re-infection with the same genotype (typically genotype 1a, the most common in Amsterdam), suggesting that a partial immunity to re-infection may only be protective against the original genotype.
These data are worrying for a number of reasons, says Schinkel. Treatment with DAA’s is now beginning in this cohort, and individuals for whom the treatment was not successful may contribute to some of the re-infections. This means that potentially drug-resistant variants could be transmitted, a huge cause for concern for future treatment options. Although drug-resistant variants appear to have a lower fitness and are ‘outcompeted’ by the non-resistant variant in the absence of therapy, previous studies have found that drug-resistant variants may persist for months after treatment and their ability to initiate a new infection is unknown. Second, new genotypes are now entering the Amsterdam area, which may provide a new opportunity for additional re-infection events for which there is little cross-immunity. Finally the fact that these infections are in MSM with little to no reported IDU behaviour suggests that this might be a population for whom closer monitoring is warranted.
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