Unidentified virus-like particles are detected in plasmas with elevated ALT levels: are they significant of etiological agent(s) of non-B, non-C hepatitis?

• Published in: Medical molecular morphology 2007-03, Vol.40 (1), p.23-28
• Main Authors: Kaito, Masahiko, Tanaka, Hideaki, Horiike, Shinichiro, Fujita, Naoki, Iwasa, Motoh, Kobayashi, Yoshinao, Gabazza, Esteban Cesar, Adachi, Yukihiko, Konishi, Masayoshi, Watanabe, Shozo
• Format: Article
• Language: English
• Subjects: Alanine Transaminase - blood; Biomedical research; Blood Donors; Blood tests; GB virus; GB virus C - genetics; GB virus C - isolation & purification; GB virus C - ultrastructure; Genomics; Hepatitis; Hepatitis B virus; Hepatitis C virus; Hepatitis G virus; Hepatitis, Viral, Human - blood; Hepatitis, Viral, Human - virology; Humans; Microscopy, Electron, Transmission; Molecular biology; Original Paper; Plasma; Viruses
• ISSN: 1860-1480; 1860-1499
• DOI: 10.1007/s00795-006-0342-7

GB virus C (GBV-C) and hepatitis G virus (HGV) have been proposed as new viruses etiologically implicated in non-B, non-C hepatitis, but the morphology of these particular virus particles is still unknown, and most cases of non-A to E hepatitis do not relate to their infections. We tried to visualize virus-like particles (VLPs) in plasma samples from hepatitis B surface antigen- and antibody to hepatitis C virus (HCV)-negative blood donors with elevated alanine aminotransferase (ALT), and examined the association of the virus-like particles and the genomes of parenterally transmissible GBV-C/HGV. Twenty-three plasma samples, 13 with elevated ALT levels and 10 with normal ALT values, from blood donors without infections of hepatitis B virus (HBV) and HCV, were subjected to a 20%-60% sucrose density gradient centrifugation, and virus-like particles were observed by electron microscopy. GBV-C/HGV RNAs in the plasmas were tested. Virus-like particles were found in the fractions with densities of 1.15-1.16 g/ml from 12 of 13 (92.3%) plasmas with elevated ALT levels and 1 of 10 (10%) normal controls. The ultrastructural morphology of visualized VLPs was pleomorphic in size and appearance; the majority of the VLPs were 50- to 80-nm spherical particles with a 35- to 45-nm inner core and 9- to 12-nm-long surface spike-like projections. Rodlike VLPs 50-70 nm in diameter with a length of 110-160 nm were also observed in the same samples. The incidence of detection of the circulating VLPs was significantly (P < 0.001) related to elevated ALT levels, but GBV-C/HGV RNAs were detected in none of the plasmas containing the virus-like particles. Spherical VLPs are detected in HBV- and HCV-negative plasmas significantly correlated with the elevation of ALT, suggesting that they are implicated in non-B, non-C hepatitis.