Growth inhibition of Newcastle disease virus upon superinfection of poliovirus in the presence of guanidine.

When HeLa cells were simultaneously infected with a high multiplicity of poliovirus and a low multiplicity of Newcastle disease virus (NDV), a definite inhibition of NDV growth was observed, while the growth of poliovirus was unaffected. Moreover, under conditions where the multiplication of poliovirus was prevented by guanidine, which is known to inhibit the formation of the ribonucleic acid (RNA)-dependent RNA polym-