Ive samples were collected in 13 prefectures of Hubei province of China. Transmission risk factors for the infection with GBV-C were deduced from the viral prevalence in the HIV risk groups. Heterosexual promiscuity (59.6 ) was the main risk factors in our patients, while the remaining patients had a history of blood transfusion (17.5 ), male homosexual promiscuity (15.8 ) or injection drug abuse (5.3 ). Only one out of 57 patients was the vertical transmission of HIV from infected mother to infant. All samples were tested for the presence of GBV-C RNA using primers from the 59-UTR. Fifty seven cases of active GBV-C infections were identified, resulting in a prevalence of 36.5 GBV-C among the HIV-1 infected subjects in Hubei province. Among those tested as positive for GBV-C RNA, only patient QC_5 was detected anti-E2 antibody positive, others were anti-E2 antibody negative. Of the total 57 dual-infected patients, 36 
(63.2 ) were males and 21(36.8 ) females, 38 (66.7 ) patients were on Highly Active Anti-Retroviral Therapy (HAART), and the others were untreated. To determine how the pairwise differences among the sequences within each patient were distributed, we performed the mismatch distribution analysis. With the KS 176 site exception of two patients (JZ_26 and QC_5), the observed mismatch histograms for the remaining eight patients were unimodal and the hypothesis of GBV-C viral population expansion within each host Anlotinib price couldn’t be rejected (p.0.05). While the mismatch histogram in patient JZ_26 declined from a peak of zero difference, the distribution in QC_5 was ragged (Fig. 3C). The L-shape curve in JZ_26 (Fig. 3B) indicated the viral population has recovered from a bottleneck effect followed by sudden population expansion (p.0.05). The ragged distribution of QC_5 suggested that either the viral population within QC_5 was relatively stable or indicated the presence of an admixture of multiple viral populations. To determine how the viral population within each host changed over time, we reconstructed the Bayesian skyline plot (BSP) for each patient (Fig. 4). With the exception of QC_5, the BSP for each patient has revealed three phase growth patterns: a constant population followed by the sudden population expansion and stabilized thereafter. However, the timing of each phase in respective patients seemed to be different (Fig. 4A). Based on the estimation of TMRCAs, viral population in QC_5 was estimated to have diverged approximately during the year 1996 (95 HPD: 1990?001) and relatively was the oldest (Table 3). Unlike other viral populations, viral population in QC_5 was shown to be relatively stable followed by a steady increase (Fig. 4B). GBV-C sequences from patients XA_M_20, QC_M_05, and JZ_M_26 appeared to form a monophyletic group with strong bootstrap support (Fig. 2), thus allowed us to employ the Bayesian coalescent approach to estimate the time of divergence among the viral lineages in these three patients. GBV-C viral strains in patients XA_M_20 and JZ_M_26 shared a common ancestor and estimated to have diverged approximately during the year 1915 (95 HPD: 1889?939). The two male patients XA_M_20 and JZ_M_26 infected with HIV through heterosexual and homosexual route respectively, the CD4 cell counts were 203 and 237 cells/ mL respectively, and the HIV loads of them were under detection baseline. The TMRCA for all the three viral lineages was estimated as the year 1885 (95 HPD: 1851?912) (Fig. 5). The dN/dS for each viral popula.Ive samples were collected in 13 prefectures of Hubei province of China. Transmission risk factors for the infection with GBV-C were deduced from the viral prevalence in the HIV risk groups. Heterosexual promiscuity (59.6 ) was the main risk factors in our patients, while the remaining patients had a history of blood transfusion (17.5 ), male homosexual promiscuity (15.8 ) or injection drug abuse (5.3 ). Only one out of 57 patients was the vertical transmission of HIV from infected mother to infant. All samples were tested for the presence of GBV-C RNA using primers from the 59-UTR. Fifty seven cases of active GBV-C infections were identified, resulting in a prevalence of 36.5 GBV-C among the HIV-1 infected subjects in Hubei province. Among those tested as positive for GBV-C RNA, only patient QC_5 was 
detected anti-E2 antibody positive, others were anti-E2 antibody negative. Of the total 57 dual-infected patients, 36 (63.2 ) were males and 21(36.8 ) females, 38 (66.7 ) patients were on Highly Active Anti-Retroviral Therapy (HAART), and the others were untreated. To determine how the pairwise differences among the sequences within each patient were distributed, we performed the mismatch distribution analysis. With the exception of two patients (JZ_26 and QC_5), the observed mismatch histograms for the remaining eight patients were unimodal and the hypothesis of GBV-C viral population expansion within each host couldn’t be rejected (p.0.05). While the mismatch histogram in patient JZ_26 declined from a peak of zero difference, the distribution in QC_5 was ragged (Fig. 3C). The L-shape curve in JZ_26 (Fig. 3B) indicated the viral population has recovered from a bottleneck effect followed by sudden population expansion (p.0.05). The ragged distribution of QC_5 suggested that either the viral population within QC_5 was relatively stable or indicated the presence of an admixture of multiple viral populations. To determine how the viral population within each host changed over time, we reconstructed the Bayesian skyline plot (BSP) for each patient (Fig. 4). With the exception of QC_5, the BSP for each patient has revealed three phase growth patterns: a constant population followed by the sudden population expansion and stabilized thereafter. However, the timing of each phase in respective patients seemed to be different (Fig. 4A). Based on the estimation of TMRCAs, viral population in QC_5 was estimated to have diverged approximately during the year 1996 (95 HPD: 1990?001) and relatively was the oldest (Table 3). Unlike other viral populations, viral population in QC_5 was shown to be relatively stable followed by a steady increase (Fig. 4B). GBV-C sequences from patients XA_M_20, QC_M_05, and JZ_M_26 appeared to form a monophyletic group with strong bootstrap support (Fig. 2), thus allowed us to employ the Bayesian coalescent approach to estimate the time of divergence among the viral lineages in these three patients. GBV-C viral strains in patients XA_M_20 and JZ_M_26 shared a common ancestor and estimated to have diverged approximately during the year 1915 (95 HPD: 1889?939). The two male patients XA_M_20 and JZ_M_26 infected with HIV through heterosexual and homosexual route respectively, the CD4 cell counts were 203 and 237 cells/ mL respectively, and the HIV loads of them were under detection baseline. The TMRCA for all the three viral lineages was estimated as the year 1885 (95 HPD: 1851?912) (Fig. 5). The dN/dS for each viral popula.