Virus-like particles and GB agent hepatitis

ALTHOUGH the MS-1 1 and CR326 2 strains of human hepatitis A virus have been well characterised morphologically and shown to be indistinguishable, controversy has plagued characterisation of the GB agent of hepatitis 3 . Presumably derived from a surgeon with acute hepatitis, the GB agent has been transmitted serially in marmoset monkeys 3 but has been shown to be unrelated serologically to any known human hepatitis virus 4 . Recently, Almeida et al. 5 reported the detection after prolonged search of 20–22-nm particles aggregated by endogenous antibody in a pool of marmoset sera (pool H205, GB pass 11) known to contain the GB agent. These antibody-coated particles resembled parvoviruses morphologically, appeared in “empty”, “full”, and fragmented crescent-shaped forms, and were undetectable in normal marmoset serum. On the basis of previous filtration data from Deinhardt et al. 6 which suggest that the GB agent is approximately 20 nm in diameter and the previous finding by others that anti-complementary activity—thought to represent the presence of circulating antigen–antibody complexes—occurs during acute viral hepatitis, Almeida et al. suggested that the virus-like particle they have detected is the GB agent 5 .