FIG. 8.

Model of mature virion core morphology. (A) In wild-type virions, the vRNP complex begins as an elongated, uncondensed structure, similar in appearance to influenza virus RNPs (38). The vRNA dimer and NC undergo a conformational change during maturation, and the core condenses into a sphere. (B) With alteration of the p10 domain, maturation of the vRNA and the Gag protein are incomplete. Condensation of the RNP complex is impaired, and viral cores adopt a variety of different appearances, depending on the angle from which they are viewed. This illustration suggests a possible mechanism for how multiple cores, elongated cores, and fragmented or horseshoe-shaped cores might be formed in p10 mutant virus particles.