Determining the size of non-A, non-B hepatitis virus by filtration.

The approximate size of the H strain of non-A, non-B (NANB) hepatitis virus was determined by filtration through polycarbonate membranes. The accuracy and reproducibility of such filtrations were monitored by filtering selected reference viruses. These studies indicate that strain H, representative of the principal blood-borne NANB hepatitis virus, is 30-60 nm in diameter. It is therefore highly unlikely that NANB hepatitis virus is a retrovirus, as has been suggested.