Expression of the Necator americanus hookworm larval antigen Na-ASP-2 in Pichia pastoris and purification of the recombinant protein for use in human clinical trials

Vaccine. 2005 Sep 15;23(39):4754-64. doi: 10.1016/j.vaccine.2005.04.040.


The ASP-2 protein secreted by infective larvae of the human hookworm, Necator americanus, is under development as a recombinant vaccine. Recombinant Na-ASP-2 was expressed in Pichia pastoris, and the purified protein was characterized. At the 60 L scale, the 21.3 kDa recombinant protein was produced at a yield of 0.4 g/L. When formulated with Alhydrogel and injected into rats to determine immunological potency, three 50 microg doses of the formulated recombinant protein elicited geometric mean antibody titers up to 1:234,881. Rat anti-Na-ASP-2 antibody recognized larval-derived ASP-2 and also inhibited larval migration through skin in vitro. The processes developed and tested for the high yield production of recombinant Na-ASP-2 provide a foundation for clinical vaccine development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Clinical Trials as Topic
  • Helminth Proteins / immunology*
  • Helminth Proteins / isolation & purification
  • Humans
  • Larva / immunology
  • Necator americanus / immunology*
  • Pichia / genetics*
  • Rats
  • Rats, Sprague-Dawley
  • Recombinant Proteins / immunology
  • Recombinant Proteins / isolation & purification
  • Vaccination
  • Vaccines, Synthetic / immunology*


  • Helminth Proteins
  • Recombinant Proteins
  • Vaccines, Synthetic