ABSTRACT
Like all alphaviruses, VEEV structurally is a 60-70 nm icosahedral virion with T = 4 symmetry [9,10]. The nucleocapsid core, which consists of 240 copies of the capsid protein combined with one molecule of genomic RNA, is encased in a lipid envelop acquired by budding from the host cell plasma membrane. This membrane contains heterodimers of two virally encoded membrane glycoproteins, E1 and E2, which are arranged as trimers on the virion surface. Alphavirus structural studies indicate that the E2 protein forms spikes
on the surface of the virion, while the E1 protein lies adjacent to the host cell-derived lipid envelope [9].
