MNI群ウイルスの同時増殖に関する研究 (第II報):HVJ (Z) ウイルスとインフルエンザ (A) PR8ウイルスの発育鶏卵漿尿腔内同時増殖実験

As previously reported, the HVJ virus and the influenza (A) PR8 virus were made to multiply simultaneously in the CAC of a developing embryonated egg, and upon examination of the multiplied strains by the CCA test utilizing the heat fragility of the Z virus and by the inhibition test with the aid of antiserum, the heat fragility of the CCA activity and the antigenicity of the strains were detected to undergo some change. This is phenotypic mixing, but as most of the clones showing such phenotypic mixing were found to revert to the pure Z virus or PR8 virus in its original form in the course of serial passages, it was impossible to preserve their characters generation after generation by means of limiting dilution passage. This might be considered to be probably due to a very slight affinity existing between the Z virus and the PR8 virus. Instead of the PR8 virus, therefore, the NWS virus regarded to be weaker in its resistance to various sorts of experimental processes and to have characters highly similar to those of the Z virus was taken up, and by mixed inoculation of these two strains so as to make them multiply simultaneously, isolation of viruses in a recombinant form was attempted.The result proved the same then as when the PR8 virus was employed. Clones clearly showing the phenotypic mixing of the NWS virus and the Z virus could be produced, but as these clones of this type were found to revert to the pure Z virus or NWS virus by means of limiting dilution passages, it was impossible to preserve their characters generation after generation. The author is uncertain as to whether such viruses showing phenotypic mixing carry abortive infection or have a strong inclination to revert to the pure, original form, and it is hardly possible to say definitely that this phenomenon of phenotypic mixing was caused by some recombinant form of virus clearly attributable to the gene of these strains.