Characterization of Leanyer virus: resemblance to Bunyavirus.

The properties of Leanyer virus, isolated in Northern Australia in 1974, were compared with those of Bunyamwera virus. Leanyer virus replicated in BHK-21 and Vero cells. In sucrose gradients it had a density of 1.17 g/cm3 and sedimented with the same s value as Bunyamwera virus. The diameter of negatively stained virions was approximately 110 nm. Three species of RNA sedimenting at 30S (L), 26S (M) and 14S (S) and four virion proteins (L, G1, G2, N) were detected in preparations of purified virions. The results were consistent with the classification of Leanyer virus as a member of the family Bunyaviridae, possibly within the Bunyavirus genus.

Establishment and partial characterisation of a human fibrosarcoma cell line MR-83.

We describe a mycoplasma-free human fibrosarcoma cell line, MR-83, which grows readily in liquid culture and as clones in semi-solid agar with a plating efficiency of about 0.5%. It has a stable karyotype consisting of a modal number of 49-51 chromosomes, with two translocations and a deletion. The cell line shows resistance to adriamycin in semi-solid agar assay, and responds to Epidermal Growth Factor (EGF) by increased DNA synthesis, as measured by thymidine uptake.

Inactivation and clearance of viruses during the manufacture of high purity factor IX.

Haemophilia is a bleeding disorder characterised by a deficiency in Factor IX. Replacement therapy in the form of a Factor IX concentrate is a widely accepted practice. In this paper we describe a double virus inactivated chromatographic process for producing a high purity Factor IX product, MonoFIX((R))-VF. The process involves separation of the prothrombin complex by cryoprecipitation, fraction I precipitation and DEAE-cellulose adsorption, further ion-exchange chromatography of crude Factor IX, followed by solvent/detergent treatment. Heparin affinity chromatography is then used to further purify Factor IX. Final nanofiltration is sequential through 35 nm then 15 nm membrane filters. The principal virus inactivation/removal steps are solvent/detergent treatment and nanofiltration and the partitioning of relevant and model viruses provides further reduction in virus load through the production process.Solvent/detergent treatment was shown to achieve log reduction factors of 4.5 for HIV-1, 5.1 for Sindbis virus, 6.1 for vesicular stomatitis virus (VSV), 5.1 for bovine viral diarrhoea virus (BVDV) and 5.3 for pseudorabies virus (PRV). BVDV is a model for hepatitis C virus (HCV), and pseudorabies virus (PRV), like hepatitis B virus (HBV) is an enveloped DNA virus. Using scaled down models of the production process, we have also demonstrated the neutralization/partitioning of at least 6 logs of hepatitis A virus (HAV) during cryoprecipitation, Fraction I precipitation, and the DEAE adsorption and elution step, and a further 1.6 log reduction in HAV load as a result of heparin affinity chromatography. The log reduction factors for HAV as a result of the second ion-exchange chromatography step and as a result of enhanced neutralisation associated with solvent/detergent treatment were not significant. Nanofiltration was shown to contribute a further log reduction factor of 6.7 for HAV and 5.8 for BVDV indicating that log reduction factors of this order would be obtained with other viruses of a similar or larger size, such as HIV, HBV and HCV.Overall, these studies indicate that MonoFIX-VF is a product with an extremely high level of viral safety.