Application of the Droplet Digital Polymerase Chain Reaction (ddPCR) Platform for Detection and Quantification of Vertebrate Host DNA in Engorged Mosquitoes.

Hematophagous arthropod bloodmeal identification has remained a challenge in the field of vector biology, but these studies are important to understand blood feeding patterns of arthropods, spatial, and temporal patterns in arbovirus transmission cycles, and risk of human and veterinary disease. We investigated the use of an existing vertebrate primer set for use on the droplet digital polymerase chain reaction (ddPCR) platform, to explore the use of this technology in the identification and quantification of vertebrate DNA in mosquito blood meals. Host DNA was detectable 48-h post-engorgement in some mosquitoes by ddPCR, compared with 24-h post-engorgement using traditional PCR. The capability of ddPCR for absolute quantification of template DNA offers unique potential applications of this new technology to field studies on the ecology of vector-borne diseases, but currently with limited scope.

Hb F Kingston (G gamma 55 (D6) Met leads to Arg)

A fetal haemoglobin variant was noted in a healthy Jamaican infant of mixed African/Chinese extration. A two-dimensional chromatogram of the soluble tryptic peptides (Tp) showed 2 'new' ones. One was composed of the last 4 residues of the usually insoluble Tpgamma41-59. To permit a tryptic split this required a change of residue gamma 55 Met to Lys or Arg. The other new Tp contained arginine and was in the position expected for a Ty gamma41-55 (55 Arg). As the material was limited it could not be analysed. When after more than 6 years no example of Hb F Kingston had become available it was decided to describe the variant on the basis of the present evidence. (AU)