No abstract

Despite progress in our knowledge of the internal organisation of influenza virus particles, little is known about the determinants of their morphology and, more particularly, of the actual abundance of structural proteins at the virion level. To address these issues, we used cryo-EM to focus on viral (and host) factors that might account for observed differences in virion morphology and characteristics such as size, shape and glycoprotein (GP) spike density. Twelve recombinant viruses were characterised in terms of their morphology, neuraminidase activity and virus growth. The genomic composition was shown to be important in determining the GP spike density. In particular, polymerase gene segments and especially PB1/PB2 were shown to have a prominent influence in addition to that for HA in determining GP spike density, a feature consistent with a functional link between these virus components important for virus fitness.

Herpes simplex viruses (HSV)-1 and -2 enter latency in peripheral ganglia during which time a number of latency associated transcripts (LATs) are produced. The most abundant (2 kb) LAT contains ORFs of significant size which could play a role in latency. We hypothesized that the leader sequence of the 2 kb LAT might regulate expression of the LAT ORFs in neurons and might thus enhance some aspect of the latency process. We show that constructs with the HSV-1 2 kb LAT leader sequence in front of a CAT gene are efficiently translated, with enhanced activity in cells of neuronal origin, but that from