INFLUENZA-VIRUS HEMAGGLUTININ AND NEURAMINIDASE CYTOPLASMIC TAILS CONTROL PARTICLE-SHAPE

The cytoplasmic tails of the influenza virus glycoproteins hemagglutin in (HA) and neuraminidase (NA) are highly conserved in sequence for al l virus subtypes and it is believed that assembly of this enveloped vi rus depends on interactions of these domains with cytoplasmic viral co mponents. However, it is possible to rescue altered influenza viruses lacking either the HA or NA cytoplasmic tails, We have obtained an inf luenza virus that lacks both the cytoplasmic tail of HA and NA. Partic le production is reduced similar to 10-fold but these particles, altho ugh having a fairly normal protein composition, are greatly elongated and of extended irregular shape, We propose a model in which the inter actions of the cytoplasmic tails of HA and NA with an internal viral c omponent are so important for spherical virion shape that there is dua l redundancy in the interactions.