Quantification of chlamydiae in the endangered Houston toad (Anaxyrus houstonensis)

Abstract

Two primer set/probe combinations targeting variable regions on the 23S rRNA gene were designed to detect and quantify chlamydiae in DNA extracted from brain swabs of the endangered Houston toad (Anaxyrus houstonensis) using SYBRGreen- and Taqman-based quantitative polymerase chain reaction (qPCR). Prevalence and abundance values for samples were generally different between SYBRGreen- and Taqman-based detection methods, with higher specificity observed for Taqman-based detection. Of the 314 samples analyzed, initial screening with SYBRGreen-based qPCR retrieved 138 positive samples, of which 52 were confirmed by Taqman-based analyses as chlamydiae. All of these samples were subsequently identified as Chlamydia pneumoniae by specific qPCR and confirmed by comparative sequence analyses of 23S rRNA gene amplicons. These results demonstrate the usefulness of our developed qPCR methods to screen for and verify prevalence of chlamydiae in DNA of brain swabs, and ultimately specifically identify and quantify chlamydiae, specifically C. pneumoniae in these samples.

Keywords: Chlamydia; Taqman; amphibian; qPCR; toad.