SUMMARY: The amount, type and properties of nucleic acid have been estimated in the two end fractions, Ryan supernatant (Ryan Sup.) and Ryan final filaments (Ryan F.F.) of a purification procedure applied to allantoic fluid preparations of filamentary Ryan virus. Ryan Sup. consists of 80% spherical particles and 20% short filaments (length:diameter < 6). Analysis indicates an average nucleic acid content of 0.75% (PR 8 = 0.91%). The value of the ratio, adenine + uracil: guanine + cytosine for the nucleic acid of A strains of influenza virus varies between 1.22 and 1.28. The value for Ryan Sup. is 1.20; for a mutant strain of Ryan virus which exists almost exclusively as spheres, the value is also 1.20.

The ratio of filaments to spherical particles in Ryan F.F. is about 50:50. On a dry-weight basis, Ryan F.F. contains about 0.25% RNA. There may be small amounts of DNA present. On a particle basis, the residual filamentary structures contain about eight times as much RNA as do PR 8 spheres. The value of the above ratio of bases however is about 0.9. Treatments of filaments with diethyl ether releases a soluble complement-fixing antigen (CFA) which on purification is found to have the same nucleic acid content per unit of CF activity as does soluble CFA isolated from either PR 8 or Ryan Sup. viruses. In each case the value of the above ratio of bases is about 1.25. On a particle basis filaments in Ryan F.F. contain 3 to 4 times as much soluble CFA as does PR 8 virus so that the residual RNA in Ryan F.F. must closely correspond in properties to RNA from the potential host cell which has a value for the above ratio of about 0.6. Exposure of Ryan F.F. to ribonuclease or to a procedure which degrades the filamentary form to smaller spherical units does not affect the amount or properties of the associated RNA.

A tentative scheme is proposed for the formation of virus particles of Ryan F. preparations. It is postulated that most of the spheres present in such preparations arise by fragmentation of the tip of forming filaments where there is a relative concentration of viral type RNA. The filaments which are found in the allantoic fluid thus represent only part of the original filamentary structures. This concept implies that filaments break more readily at those places where there is an enrichment of viral type nucleic acid.


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