Method for the detection of viruses

A method for the quantitative detection of viruses comprising the steps of:

• (a) contacting a virus infected cell culture with a polypeptide having the following formula:
• ##SPC4##
• wherein the symbols "Ala", "Arg", "Asn", "Cys", "Gln", "Gly", "Leu", "Lys", "Phe", "Pro", "Ser", "Thr", "Tyr" and "Val" indicate, respectively, the residues of the levo rotatory forms of alanine, arginine, asparagine, 1/2 cystine, glutamine, glycine, leucine, lysine, phenylalanine, proline, serine, threonine, tyrosine and valine, and wherein R.sub.1 -R.sub.5 indicate (1) the residues of the L-amino acids lysine, asparagine, leucine, threonine and aspartic acid, respectively, or (2) wherein R.sub.1 is arginine, R.sub.2 and R.sub.5 are glycine, R.sub.3 is isoleucine and R.sub.4 is serine, respectively, the symbols " " represent --S--S-- bonds and the arabic numerals included in the structural formula near certain amino acid residues constitute the sequence number of said amino acids in turn from the N-terminal and physiologically acceptable salts thereof, said polypeptide and salts thereof being present in an amount sufficient to selectively kill virus infected cells;
• (b) incubating said virus infected cell culture for a period for time sufficient to selectively kill cells infected with said virus;
• and
• (c) measuring the number of cells in said cell culture which are killed by said virus.