Necator americanus Ancylostoma Secreted Protein-2 (Na-ASP-2)

Necator americanus Ancylostoma Secreted Protein-2 (Na-ASP-2) is a major 21-kDa protein secreted by the infective third-stage larvae (L3) of the human hookworm during host entry (UniProt Q9U960). It is a member of the CAP (Cysteine-rich secretory proteins, Antigen 5, and Pathogenesis-related 1) superfamily and is highly upregulated when larvae are stimulated to infect a host (Goud et al., 2005). Na-ASP-2 has been a lead candidate for a hookworm vaccine intended to reduce the global burden of iron-deficiency anemia caused by these parasites (Bethony et al., 2008). The protein is believed to play a role in larval migration or the modulation of the host immune environment to favor parasite survival. However, clinical trials in hookworm-endemic regions were halted because some participants developed immediate-type hypersensitivity reactions, linked to pre-existing anti-Na-ASP-2 IgE antibodies from prior natural infections (Diemert et al., 2012). Despite these safety challenges, Na-ASP-2 remains a critical target for studying helminth-host interactions and developing next-generation anti-parasitic strategies. The protein's structure, characterized by a central alpha-beta-alpha sandwich, is typical of the CAP family and suggests a role in extracellular signaling or binding (Asojo et al., 2005).

Other names

ASP-2Ancylostoma-secreted protein 2Na-ASP-2Pathogenesis-related protein 1 family member

Vaccine-induced production of host IgG antibodies that neutralize the protein's function, thereby inhibiting larval migration and reducing adult worm establishment in the gut.