VPS4A and acquired polycythemia vera: In addition, whilst previous studies had shown that TSG101 was also required for infection with BPV-1 PsVs30 here we show an important role for both TSG101 and VPS4 for infection with cutaneous HPV-5 PsVs and also mouse MmuPV-1 and rabbit SfPV-1 indicating that the ESCRT machinery most likely plays a role in infection with multiple PV types, and demonstrates an evolutionarily conserved step in the infectious entry of multiple PV types.