Immunoassay detection of fly artifacts produced by several species of necrophagous flies following feeding on human blood

David B Rivers; Gregory Cavanagh; Valerie Greisman; Andrew McGregor; Rebecca Brogan; Andrew Schoeffield

doi:10.1016/j.fsisyn.2018.11.001

Immunoassay detection of fly artifacts produced by several species of necrophagous flies following feeding on human blood

Forensic Sci Int. 2018 Dec 11:1:1-10. doi: 10.1016/j.fsisyn.2018.11.001. eCollection 2019.

Authors

David B Rivers^{1

2}, Gregory Cavanagh¹, Valerie Greisman^{1

2}, Andrew McGregor³, Rebecca Brogan¹, Andrew Schoeffield¹

Affiliations

¹ Department of Biology, Loyola University Maryland, 4501 North Charles Street, Baltimore, MD, 21210, USA.
² Forensic Studies Program, Loyola University Maryland, 4501 North Charles Street, Baltimore, MD, 21210, USA.
³ Department of Forensic Sciences, School of Graduate and Professional Studies, Stevenson University, Owings Mills, MD, 21117, USA.

Abstract

Foraging behavior of necrophagous flies commonly leads to distortion of human bloodstains and production of artifacts that confound reconstruction efforts at crime scenes. Currently there is no reliable method for detection of fly-derived stains or distinction of the artifacts from human bloodstains. To overcome these deficiencies, a confirmatory test was developed based on immunological detection of cathepsin D found in digestive fluids of Musca domestica and Protophormia terraenovae. Anti-serum (anti-md3 serum) was generated toward a 17-amino acid synthetic peptide based upon predicted antigenic amino acid sequences for the propeptide and mature enzyme of cathepsin D proteinase from larvae of M. domestica. The serum was used to test the hypothesis that digestive artifacts produced by an array of necrophagous flies associated with human decomposition could be detected with the immunoassay. Anti-md3 serum was able to bind artifacts from 27 species of flies representing 9 families. The antiserum reacted with both regurgitate and defecatory stains, but not transfer patterns. Stains from 4 fly species displayed no reactivity with anti-serum in dot blot assays. Anti-md3 serum did not bind to either human or bovine blood stains on filter paper. However, when both types of blood were spiked with synthetic md3 peptide the antiserum was able to bind. Dot blot assays displayed positive reactions with stains produced from larvae and teneral adults of Sarcophaga bullata, and with artifacts as old as 7-years after deposition. These observations indicate that the immunoassay permits distinction of artifacts from a wide range of species from human bloodstains, from multiple development stages, and from artifacts that remain at crime scenes for many months to years after deposition. Further work is needed to determine whether the detection of fly artifacts using the antiserum is suitable for non-laboratory conditions.

Keywords: Bloodstains; Defecatory stains; Forensic entomology; Immunodetection; Insect stains; Regurgitate.

MeSH terms

Animals
Blood Stains*
Diptera / physiology*
Entomology
Feeding Behavior
Forensic Sciences
Humans