Isolation, Amplification, and Sequencing of Human Mitochondrial DNA Obtained from Human Crab Louse, Pthirus Pubis (L.), Blood Meals

Abstract

The ability to identify individual human hosts based on analyses of blood recovered from the digestive tract of hematophagous arthropods has been a long-term pursuit in both medical and forensic entomology. Blood meal individualization techniques can bring important advancements to studies of vector-borne disease epidemiology. Forensically, these analyses may aid in assailant identification in violent crime cases where blood-feeding insects or their excreta are recovered from victims or at crime scenes. Successful isolation, amplification, and sequencing of human mitochondrial DNA obtained from adult human crab lice fed on human volunteers are reported. Adult lice were removed from recruited volunteers frequenting inner city health clinics. Live lice were killed by freezing and subsequently air dried at ambient temperature. A saliva sample was obtained from each volunteer and served as a DNA reference sample. Volunteers were afforded free, approved pediculosis treatment. Individual lice were subsequently processed using procedures developed for the extraction of mitochondrial DNA from human hair, teeth, and bone. The resulting DNA was amplified by the polymerase chain reaction and sequenced. Our results point to valuable avenues for future entomological research.

Use of Human Lice in Forensic Entomology

“…Although unable to polymerase chain reaction (PCR) amplify DNA from pooled samples of seven and 17 pubic lice, a DNA proÞle was obtained from louse excreta. Lord et al (1998) succeeded in amplifying mitochondrial DNA from pubic lice fed on human volunteers.…”

Role of Polymerase Chain Reaction in Forensic Entomology

“…Another area which has great potential use is identification of suspect from the gut content of a fed mosquito [44] or body louse [47] at the crime scene. In the case where the body has been moved, the carrion fly larvae or pupae may help identify the deceased indicating the relocation of the corpse.…”

Insects feeding on cadavers as an alternative source of human genetic material

“…owady hematofagiczne (krwiopijne): komary [29,[33][34][35][36][37], wszy [28,[38][39][40] oraz pluskwy domowe [41]. Badania przeprowadzone na komarach przez Curic i wsp.…”

“…haematophagous (bloodfeeding) insects: mosquitoes [29,[33][34][35][36][37], lice [28,[38][39][40] and bed bugs [41]. Studies conducted on mosquitoes by Cu ric et al have established that it is possible to de termine the human profile of 15 STR loci for up to 88 hours after biting [42].…”