Experience with production of interferon and Japanese encephalitis vaccine in continuous cell lines.

Two continuous cell lines, lymphoblastoid cell (Namalwa) and BHK-21, were studied for production of interferon and Japanese Encephalitis vaccine. Lymphoblastoid cells (Namalwa) were induced with 100 HAU/ml of Sendai virus while the cell density was 10(7) cells/ml. A titre of Ig 4.0-5.01 U/ml interferon was obtained at 16-18 hours after induction. A semi-continuous production technique was established in a fermentor. Thirty days of cell cultivation and induction was carried out continuously with a regular production of interferon. The crude lymphoblastoid interferon was purified with precipitation with trichloro-acetic acid, buffer solution treatment and blue-sepharose chromatography. The specific activity reached 10(6)-10(7) I.U/mg. No residual DNA was detected in the purified interferon. Four malignant tumour patients were treated with lymphoblastoid interferon. The preliminary result of the clinical trial was encouraging. BHK-21 C13 cell was tested for the karyological characteristics and its sensitivity to Japanese Encephalitis (JE) virus. No karyological change was observed after 52 passages. After infection of the monolayer cell culture with JE virus, a typical cytopathic effect (CPE) was observed. The virus titre in the maintenance medium rose gradually while the CPE developed and more than log TCID50 7.0/0.1 ml could be obtained. After inactivation with 1:2000 formalin, a vaccine of high potency was successfully produced. It is expected that a suspension culture technique using a fermentor will give a higher titre of virus. A large scale production of inactivated vaccine will be succeeded when the characterization of BHK-21 C13 cell line and purification procedure are standardized.