To explore a low-cost novel probe for HIV detection, we designed and prepared a 50-amino acid-length short fusion peptide (FP-50) via Escherichia coli in vivo expression. It was employed as a novel probe to detect HIV-1 gp120 protein. The detectable level of gp120 protein using the FP-50 peptide was approximately 20-200 times lower than previously published methods that used a pair of monoclonal antibodies. Thus, this short peptide is a very promising component for detection of gp120 protein during early stages of HIV infection. Published by Elsevier Inc.