The occurrence of sporadic cases of non-ABCDE hepatitis gave reason to suspect the existence of another hepatotropic virus to of investigators in England, Northern Italy, France, United States and India. The infection was not only sporadic but also enterically transmitted. The first report came from India in 1983 (Khuroo et al., Am. J. Epidemiol.118:360-4, 1983).Reports followed from England (Achenon et al. Lancet i:798-991987), France (Pillot et al. Ann Inst. Pasteur/Viro.138:145-158, 1987) and Italy (Caredda et al. Lancet i:58,1988) 4-5 years later. In 1987 the disease was transmitted to cynomolgus macaques and tamarins and 27-34 nm viral-like particles were recovered. (Bradley et al., Proc. Nat. Acad. Sci.USA 84:6277-81,1987). This agent was probably the virus "F".In 1994,7 years later, Uchida and associates thought that the infective agent in these cases is a mutant of HBV, a "silent" mutant of HBV. However, in December 1994 a group from New Delhi reported that the viral particles represented a"novel agent" that they called HFV. (Deka et al.J. of Virology, 68(12):7810-15,1994). Stool extracts from 5 French sporadic icteric cases were inoculated into rhesus monkeys. Viral particles were recovered from stools.

The Virus
Round 27-37 nm Virus-Like Particles (VLP) were seen. They contain a double stranded DNA with 20 bk. Similar agent was also detected from stools of human patients. The virus was seen in the cytoplasm of hepatocytes only in one experimental monkey. Sequencing of the entire viral genome has not been accomplished to this date. (Deka et al. J. Of Virology, 68(12):7810-15,1994)

The disease
In infected animals viral antigens and elevation of transaminases appear in an average of 20 days. The liver morphology shows the picture of an acute hepatitis. The disease in humans may assume a fatality course in around 20% of the cases. HFV antigen Has been detected by ELISA in 66% of coded specimen.(Deka et al. J. Of Virology, 68 (12): 7810-15 1994).

Note: These findings reported by this team have not yet been confirmed by other investigators.