High prevalence of GB virus C strains genetically related to strains with Asian origin in Nicaraguan hemophiliacs.

The presence of hepatitis GB virus C (GBV-C), also known as hepatitis G virus (HGV), and hepatitis C virus (HCV) were investigated in sera from 45 hemophiliacs from nine locations in Nicaragua using a nested polymerase chain reaction (PCR). Primers used to detect GBV-C and HCV derived from the helicase region and 5'UTR, respectively. Seventeen (38%) patients were positive for GBV-C RNA in serum by PCR. Twelve (27%) patients were positive for HCV RNA by PCR. Six (13%) of these were coinfected with GBV-C. Anti-HCV was detected in all the 12 HCV RNA positive hemophiliacs and in another 14 (31%) individuals, in whom GBV-C RNA was found in 2. Ten patients (22%) lacked markers for both GBV-C and HCV. The mean age of the patients positive for GBV-C but negative for HCV by PCR was significantly lower than for those negative for GBV-C but positive for HCV by PCR (P < 0.05; Student's t-test), indicating that the risk for this group of hemophiliacs to acquire GBV-C infection is higher as compared to the risk of acquiring HCV infection. Eleven GBV-C strains were sequenced in the 5'UTR. Sequence comparison to previously published GBV-C strains revealed that all 11 strains were more similar to Asian strains than to strains of European and African origin. Sequences in the NS5-B region were available for 8 HCV strains, all of which were found to belong to genotype 1a. The similarity of the Nicaraguan GBV-C strains to strains from Asia indicates that the GBV-C strains in the region presumably have an Amerindian origin. It is also considered that the HTLV II strains in the New World aboriginal populations are ancient and brought there by the ancestral Amerindian populations from Asia. Further, the genotype F of hepatitis B virus, known to represent the strains in populations with Amerindian background, predominates in Central American populations with Hispanic background. It remains to be clarified why Amerindian strains of GBV-C as well as of HBV predominate also in populations with mixed ethnic background in Central America.