Bunyaviruses are emerging viral pathogens that cause encephalitis, hemorrhagic fevers, and meningitis. Rift Valley fever virus is a particularly devastating bunyavirus, infecting both humans and livestock with significant morbidity and mortality. By coordinating several host and viral processes Rift Valley fever virus is able to produce infectious virions. Polyamines are small, positively-charged host-derived molecules that play diverse roles in human cells and in infection. We previously demonstrated that polyamines are crucial for RNA viruses; however, the mechanisms by which polyamines function remain unknown. Here, we investigated polyamines\u27 role in the replication of the Rift Valley fever virus (vaccine strain MP-12). We found that polyamine depletion did not impact viral RNA or protein accumulation. Viral particles demonstrated no change in morphology, size, or density, however, targeting polyamines significantly reduced viral titers. In sum, polyamine depletion results in the accumulation of noninfectious particles which has important implications for targeting polyamines therapeutically, as well as enhancing vaccine strategies
