ESCRT pathway involvement in the release of human parainfluenza virus virions and matrix protein

Abstract

It has been shown that some enveloped viruses utilize cellular components to help facilitate viral budding and release. With these viruses, a viral protein interacts with the cellular ESCRT machinery, which is involved in the rearrangement of membranes and vesicle formation. Via this interaction, the virus directs the cellular machinery to form viral vesicles (particles) that bud from the infected cell. Little is known about the release of enveloped viruses belonging to the Paramyxovirinae subfamily and whether they utilize the ESCRT system. To better understand how human parainfluenza virus type 3 (HPIV3) mature virus particles are released from host cells an ESCRT inactivation system, developed with HIV-1, was used. Using siRNA targeting VPS4A/B, proteins essential for the recycling of ESCRT components, the levels of VPS4 protein in 293T and MK2-LLC cells were reduced by greater than 90%. These knocked down cells were then either transfected to express the HPIV3 Matrix protein or infected with HPIV3 whole virus. These results showed that even with the knockdown of VPS4, M-containing virus-like particles and virions were still able to be released from cells.