Abstract: A complex of polyriboinosinic-polyribocytidylic acid (poly I:C) with poly-L-lysine hydrobromide ([lysine.HBr].sub.n) having a defined molecular weight is prepared which is about 5-15 times as resistant to hydrolysis by pancreatic ribonuclease as the parent poly I:C. A pharmaceutical solution, containing a relatively high concentration of the complex, prepared as described, induces significant antiviral levels of serum interferon in monkeys under conditions in which poly I:C itself induces little or no interferon. An important feature of this invention is that the product is a soluble material requiring no special solubilizing agent, thereby facilitating the preparation of solutions having the desired concentration. The product will hereinafter be designated as poly I:C/poly-L-lysine.

Abstract: The invention provides an improved process for the growth of lymphoblastoid cells in a medium supplemented with human albumin. The invention further provides for the production of interferon by viral infection of these lymphoblastoid cells in a medium also supplemented with human albumin. This invention eliminates the necessity for adding animal proteins.

Abstract: Polynucleotides which are multistranded are active as inducers of interferon production in living animal cells. They may be:A. Synthetically complexed polymers of two homopolynucleotides.B. A nucleic acid released by phenol from a ribonucleic acid complex elaborated by the growth of Penicillium funiculosum.C. A ribonucleic acid from reovirus type 3 virions.D. Replicative forms of nucleic acids.

Abstract: Hepatitis B antigen useful as vaccine is prepared from clarified plasma of hepatitis B donors by treating with pepsin at a pH wherein pepsin is enzymatically active, treating with urea, and optionally treating with formaldehyde.