Virus-like Particles in Penicillin producing Strains of Penicillium chrysogenum

Abstract

UNTIL quite recently the edible mushroom viruses¹ were the only viruses known to infect fungi. During the past 2 yr, however, virus-like particles with interferon stimulating properties have been described in strains of Penicillium stoloniferum^2–5 and Penicillium funiculosum⁴. We have screened various fungi for possible viral content as part of our research programme relating to fungal viruses and interferon stimulation. Following reports of anti-viral and interferon stimulating agents isolated from Penicillium chrysogenum (ref. 6 and personal communication from P. Van Dijck, E. De Clercq, C. Cocito and P. De Somer), we have examined various strains of this fungus for virus content. Virus-like particles have been found in seven penicillin producing strains of P. chrysogenum: NRRL 1951, NRRL 1951 B.25, X.1612, Q.176, Wis. 48–701, Wis. 51–20 C and BRL 700. (With the exception of strain BRL 700, these strains are all available from the American Type Culture Collection; results using strain BRL 700, a high yielding industrial strain, were obtained through collaboration with Beecham Research Laboratories, Brockham Park, Betchworth, Surrey, who also supplied this strain.) These penicillin producing strains are interrelated and are all derived from strain NRRL 1951 by mutation and strain selection procedures. The relationships between the various strains are illustrated diagrammatically in Fig. 1.