For example, spermatozoa and Semen Derived Enhancer of Virus Infection (SEVI, small aggregates or fibrils) can bind HIV-1 and promote infection of target cells [21,22], whilst semenogelin-I inhibits direct infection of target cells and MUC6 and clusterin interfere with DC-SIGN mediated trans-infection [11,13,23]. This evidence concerns the gene CLU and infection.