The second PPI sub-network is from the components of the ESCRT (The endosomal sorting complexes required for transport) pathway, including CHMP3, CHMP4B, CHMP6, TSG101, VPS25, VPS28, VPS36, SNF8, VTA1, VPS4A, and PDCD6IP. The ESCRT pathway has been shown to play an important role in regulating the infection of enveloped viruses, such as human immunodeficiency virus (HIV)22. This evidence concerns the gene VPS4A and infection.