Phylogenetic analysis of acute hepatitis C virus genotype 4 infections among human immunodeficiency virus-positive men who have sex with men in Germany

Background An ongoing HCV epidemic currently affects a growing proportion of HIV-positive men who have sex with men (MSM) in Europe. Recently in the North-Rhine region of Germany, we have observed an increase in acute HCV infections of genotype 4 (HCV-4). Aims To characterize the current spread of HCV-4 among German MSM using a molecular epidemiological approach. Methods Patient characteristics and sera were collected for HIV-positive MSM diagnosed with acute HCV-4 infections in the North-Rhine region (n=14), Hamburg (n=14), Frankfurt (n=4) and Berlin (n=4). Part of the HCV NS5B region (436 bp) was amplified, sequenced and compared with HCV-4 sequences from HIV-positive Dutch, English and French MSM (n=50) as well as unrelated HCV risk groups (n=61). Results NS5B sequences were obtained from 35/36 (97%) of German cases, all of which were HCV subtype 4d (HCV-4d). The phylogenetic analysis of HCV sequences revealed two MSM-specific HCV-4d clusters of 71 and 12 sequences. All except one of the German MSM belonged to a large MSM-specific HCV cluster containing MSM from all four different European countries. None of the HCV-4 strains circulating among injecting drug users or in HCV-4 endemic areas were part of the MSM-specific clusters. Conclusions HCV rapidly spreads among European HIV-positive MSM through a joint international transmission network, separate from that of injecting drug users. In order to contain this epidemic, non-parenteral routes of transmission, such as unsafe sex, must be taken into consideration and prevention measures should be refocused accordingly.